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chromium / external / github.com / rust-lang / rust / e85a0d70b86491752eb501f73b9d2025c5991e8e / . / src / libsyntax / parse / parser.rs
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// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use abi::{self, Abi};
use ast::BareFnTy;
use ast::{RegionTyParamBound, TraitTyParamBound, TraitBoundModifier};
use ast::Unsafety;
use ast::{Mod, Arg, Arm, Attribute, BindingMode, TraitItemKind};
use ast::Block;
use ast::{BlockCheckMode, CaptureBy};
use ast::{Constness, Crate};
use ast::Defaultness;
use ast::EnumDef;
use ast::{Expr, ExprKind, RangeLimits};
use ast::{Field, FnDecl};
use ast::{ForeignItem, ForeignItemKind, FunctionRetTy};
use ast::{Ident, ImplItem, Item, ItemKind};
use ast::{Lit, LitKind, UintTy};
use ast::Local;
use ast::MacStmtStyle;
use ast::Mac_;
use ast::{MutTy, Mutability};
use ast::{Pat, PatKind};
use ast::{PolyTraitRef, QSelf};
use ast::{Stmt, StmtKind};
use ast::{VariantData, StructField};
use ast::StrStyle;
use ast::SelfKind;
use ast::{TraitItem, TraitRef};
use ast::{Ty, TyKind, TypeBinding, TyParam, TyParamBounds};
use ast::{ViewPath, ViewPathGlob, ViewPathList, ViewPathSimple};
use ast::{Visibility, WhereClause};
use ast::{BinOpKind, UnOp};
use ast;
use codemap::{self, CodeMap, Spanned, spanned, respan};
use syntax_pos::{self, Span, BytePos, mk_sp};
use errors::{self, DiagnosticBuilder};
use ext::tt::macro_parser;
use parse;
use parse::classify;
use parse::common::SeqSep;
use parse::lexer::{Reader, TokenAndSpan};
use parse::obsolete::ObsoleteSyntax;
use parse::token::{self, MatchNt, SubstNt};
use parse::{new_sub_parser_from_file, ParseSess};
use util::parser::{AssocOp, Fixity};
use print::pprust;
use ptr::P;
use parse::PResult;
use tokenstream::{self, Delimited, SequenceRepetition, TokenTree};
use symbol::{Symbol, keywords};
use util::ThinVec;
use std::collections::HashSet;
use std::mem;
use std::path::{Path, PathBuf};
use std::rc::Rc;
use std::slice;
bitflags! {
flags Restrictions: u8 {
const RESTRICTION_STMT_EXPR = 1 << 0,
const RESTRICTION_NO_STRUCT_LITERAL = 1 << 1,
const NO_NONINLINE_MOD = 1 << 2,
}
}
type ItemInfo = (Ident, ItemKind, Option<Vec<Attribute> >);
/// How to parse a path. There are three different kinds of paths, all of which
/// are parsed somewhat differently.
#[derive(Copy, Clone, PartialEq)]
pub enum PathStyle {
/// A path with no type parameters, e.g. `foo::bar::Baz`, used in imports or visibilities.
Mod,
/// A path with a lifetime and type parameters, with no double colons
/// before the type parameters; e.g. `foo::bar<'a>::Baz<T>`, used in types.
/// Paths using this style can be passed into macros expecting `path` nonterminals.
Type,
/// A path with a lifetime and type parameters with double colons before
/// the type parameters; e.g. `foo::bar::<'a>::Baz::<T>`, used in expressions or patterns.
Expr,
}
/// How to parse a bound, whether to allow bound modifiers such as `?`.
#[derive(Copy, Clone, PartialEq)]
pub enum BoundParsingMode {
Bare,
Modified,
}
#[derive(Clone, Copy, PartialEq)]
pub enum SemiColonMode {
Break,
Ignore,
}
/// Possibly accept an `token::Interpolated` expression (a pre-parsed expression
/// dropped into the token stream, which happens while parsing the result of
/// macro expansion). Placement of these is not as complex as I feared it would
/// be. The important thing is to make sure that lookahead doesn't balk at
/// `token::Interpolated` tokens.
macro_rules! maybe_whole_expr {
($p:expr) => {
if let token::Interpolated(nt) = $p.token.clone() {
match *nt {
token::NtExpr(ref e) => {
$p.bump();
return Ok((*e).clone());
}
token::NtPath(ref path) => {
$p.bump();
let span = $p.span;
let kind = ExprKind::Path(None, (*path).clone());
return Ok($p.mk_expr(span.lo, span.hi, kind, ThinVec::new()));
}
token::NtBlock(ref block) => {
$p.bump();
let span = $p.span;
let kind = ExprKind::Block((*block).clone());
return Ok($p.mk_expr(span.lo, span.hi, kind, ThinVec::new()));
}
_ => {},
};
}
}
}
/// As maybe_whole_expr, but for things other than expressions
macro_rules! maybe_whole {
($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
if let token::Interpolated(nt) = $p.token.clone() {
if let token::$constructor($x) = (*nt).clone() {
$p.bump();
return Ok($e);
}
}
};
}
fn maybe_append(mut lhs: Vec<Attribute>, rhs: Option<Vec<Attribute>>)
-> Vec<Attribute> {
if let Some(ref attrs) = rhs {
lhs.extend(attrs.iter().cloned())
}
lhs
}
#[derive(PartialEq)]
enum PrevTokenKind {
DocComment,
Comma,
Interpolated,
Eof,
Other,
}
// Simple circular buffer used for keeping few next tokens.
#[derive(Default)]
struct LookaheadBuffer {
buffer: [TokenAndSpan; LOOKAHEAD_BUFFER_CAPACITY],
start: usize,
end: usize,
}
const LOOKAHEAD_BUFFER_CAPACITY: usize = 8;
impl LookaheadBuffer {
fn len(&self) -> usize {
(LOOKAHEAD_BUFFER_CAPACITY + self.end - self.start) % LOOKAHEAD_BUFFER_CAPACITY
}
}
/* ident is handled by common.rs */
pub struct Parser<'a> {
pub sess: &'a ParseSess,
/// the current token:
pub token: token::Token,
/// the span of the current token:
pub span: Span,
/// the span of the previous token:
pub prev_span: Span,
/// the previous token kind
prev_token_kind: PrevTokenKind,
lookahead_buffer: LookaheadBuffer,
pub tokens_consumed: usize,
pub restrictions: Restrictions,
pub quote_depth: usize, // not (yet) related to the quasiquoter
parsing_token_tree: bool,
pub reader: Box<Reader+'a>,
/// The set of seen errors about obsolete syntax. Used to suppress
/// extra detail when the same error is seen twice
pub obsolete_set: HashSet<ObsoleteSyntax>,
/// Used to determine the path to externally loaded source files
pub directory: PathBuf,
/// Stack of open delimiters and their spans. Used for error message.
pub open_braces: Vec<(token::DelimToken, Span)>,
/// Flag if this parser "owns" the directory that it is currently parsing
/// in. This will affect how nested files are looked up.
pub owns_directory: bool,
/// Name of the root module this parser originated from. If `None`, then the
/// name is not known. This does not change while the parser is descending
/// into modules, and sub-parsers have new values for this name.
pub root_module_name: Option<String>,
pub expected_tokens: Vec<TokenType>,
pub tts: Vec<(TokenTree, usize)>,
pub desugar_doc_comments: bool,
pub allow_interpolated_tts: bool,
}
#[derive(PartialEq, Eq, Clone)]
pub enum TokenType {
Token(token::Token),
Keyword(keywords::Keyword),
Operator,
}
impl TokenType {
fn to_string(&self) -> String {
match *self {
TokenType::Token(ref t) => format!("`{}`", Parser::token_to_string(t)),
TokenType::Operator => "an operator".to_string(),
TokenType::Keyword(kw) => format!("`{}`", kw.name()),
}
}
}
fn is_ident_or_underscore(t: &token::Token) -> bool {
t.is_ident() || *t == token::Underscore
}
/// Information about the path to a module.
pub struct ModulePath {
pub name: String,
pub path_exists: bool,
pub result: Result<ModulePathSuccess, ModulePathError>,
}
pub struct ModulePathSuccess {
pub path: ::std::path::PathBuf,
pub owns_directory: bool,
}
pub struct ModulePathError {
pub err_msg: String,
pub help_msg: String,
}
pub enum LhsExpr {
NotYetParsed,
AttributesParsed(ThinVec<Attribute>),
AlreadyParsed(P<Expr>),
}
impl From<Option<ThinVec<Attribute>>> for LhsExpr {
fn from(o: Option<ThinVec<Attribute>>) -> Self {
if let Some(attrs) = o {
LhsExpr::AttributesParsed(attrs)
} else {
LhsExpr::NotYetParsed
}
}
}
impl From<P<Expr>> for LhsExpr {
fn from(expr: P<Expr>) -> Self {
LhsExpr::AlreadyParsed(expr)
}
}
impl<'a> Parser<'a> {
pub fn new(sess: &'a ParseSess, rdr: Box<Reader+'a>) -> Self {
Parser::new_with_doc_flag(sess, rdr, false)
}
pub fn new_with_doc_flag(sess: &'a ParseSess, rdr: Box<Reader+'a>, desugar_doc_comments: bool)
-> Self {
let mut parser = Parser {
reader: rdr,
sess: sess,
token: token::Underscore,
span: syntax_pos::DUMMY_SP,
prev_span: syntax_pos::DUMMY_SP,
prev_token_kind: PrevTokenKind::Other,
lookahead_buffer: Default::default(),
tokens_consumed: 0,
restrictions: Restrictions::empty(),
quote_depth: 0,
parsing_token_tree: false,
obsolete_set: HashSet::new(),
directory: PathBuf::new(),
open_braces: Vec::new(),
owns_directory: true,
root_module_name: None,
expected_tokens: Vec::new(),
tts: Vec::new(),
desugar_doc_comments: desugar_doc_comments,
allow_interpolated_tts: true,
};
let tok = parser.next_tok();
parser.token = tok.tok;
parser.span = tok.sp;
if parser.span != syntax_pos::DUMMY_SP {
parser.directory = PathBuf::from(sess.codemap().span_to_filename(parser.span));
parser.directory.pop();
}
parser
}
fn next_tok(&mut self) -> TokenAndSpan {
'outer: loop {
let mut tok = if let Some((tts, i)) = self.tts.pop() {
let tt = tts.get_tt(i);
if i + 1 < tts.len() {
self.tts.push((tts, i + 1));
}
if let TokenTree::Token(sp, tok) = tt {
TokenAndSpan { tok: tok, sp: sp }
} else {
self.tts.push((tt, 0));
continue
}
} else {
self.reader.real_token()
};
loop {
let nt = match tok.tok {
token::Interpolated(ref nt) => nt.clone(),
token::DocComment(name) if self.desugar_doc_comments => {
self.tts.push((TokenTree::Token(tok.sp, token::DocComment(name)), 0));
continue 'outer
}
_ => return tok,
};
match *nt {
token::NtTT(TokenTree::Token(sp, ref t)) => {
tok = TokenAndSpan { tok: t.clone(), sp: sp };
}
token::NtTT(ref tt) => {
self.tts.push((tt.clone(), 0));
continue 'outer
}
_ => return tok,
}
}
}
}
/// Convert a token to a string using self's reader
pub fn token_to_string(token: &token::Token) -> String {
pprust::token_to_string(token)
}
/// Convert the current token to a string using self's reader
pub fn this_token_to_string(&self) -> String {
Parser::token_to_string(&self.token)
}
pub fn this_token_descr(&self) -> String {
let s = self.this_token_to_string();
if self.token.is_strict_keyword() {
format!("keyword `{}`", s)
} else if self.token.is_reserved_keyword() {
format!("reserved keyword `{}`", s)
} else {
format!("`{}`", s)
}
}
pub fn unexpected_last<T>(&self, t: &token::Token) -> PResult<'a, T> {
let token_str = Parser::token_to_string(t);
Err(self.span_fatal(self.prev_span, &format!("unexpected token: `{}`", token_str)))
}
pub fn unexpected<T>(&mut self) -> PResult<'a, T> {
match self.expect_one_of(&[], &[]) {
Err(e) => Err(e),
Ok(_) => unreachable!(),
}
}
/// Expect and consume the token t. Signal an error if
/// the next token is not t.
pub fn expect(&mut self, t: &token::Token) -> PResult<'a, ()> {
if self.expected_tokens.is_empty() {
if self.token == *t {
self.bump();
Ok(())
} else {
let token_str = Parser::token_to_string(t);
let this_token_str = self.this_token_to_string();
Err(self.fatal(&format!("expected `{}`, found `{}`",
token_str,
this_token_str)))
}
} else {
self.expect_one_of(unsafe { slice::from_raw_parts(t, 1) }, &[])
}
}
/// Expect next token to be edible or inedible token. If edible,
/// then consume it; if inedible, then return without consuming
/// anything. Signal a fatal error if next token is unexpected.
pub fn expect_one_of(&mut self,
edible: &[token::Token],
inedible: &[token::Token]) -> PResult<'a, ()>{
fn tokens_to_string(tokens: &[TokenType]) -> String {
let mut i = tokens.iter();
// This might be a sign we need a connect method on Iterator.
let b = i.next()
.map_or("".to_string(), |t| t.to_string());
i.enumerate().fold(b, |mut b, (i, ref a)| {
if tokens.len() > 2 && i == tokens.len() - 2 {
b.push_str(", or ");
} else if tokens.len() == 2 && i == tokens.len() - 2 {
b.push_str(" or ");
} else {
b.push_str(", ");
}
b.push_str(&a.to_string());
b
})
}
if edible.contains(&self.token) {
self.bump();
Ok(())
} else if inedible.contains(&self.token) {
// leave it in the input
Ok(())
} else {
let mut expected = edible.iter()
.map(|x| TokenType::Token(x.clone()))
.chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
.chain(self.expected_tokens.iter().cloned())
.collect::<Vec<_>>();
expected.sort_by(|a, b| a.to_string().cmp(&b.to_string()));
expected.dedup();
let expect = tokens_to_string(&expected[..]);
let actual = self.this_token_to_string();
Err(self.fatal(
&(if expected.len() > 1 {
(format!("expected one of {}, found `{}`",
expect,
actual))
} else if expected.is_empty() {
(format!("unexpected token: `{}`",
actual))
} else {
(format!("expected {}, found `{}`",
expect,
actual))
})[..]
))
}
}
/// returns the span of expr, if it was not interpolated or the span of the interpolated token
fn interpolated_or_expr_span(&self,
expr: PResult<'a, P<Expr>>)
-> PResult<'a, (Span, P<Expr>)> {
expr.map(|e| {
if self.prev_token_kind == PrevTokenKind::Interpolated {
(self.prev_span, e)
} else {
(e.span, e)
}
})
}
pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
self.check_strict_keywords();
self.check_reserved_keywords();
match self.token {
token::Ident(i) => {
self.bump();
Ok(i)
}
_ => {
Err(if self.prev_token_kind == PrevTokenKind::DocComment {
self.span_fatal_help(self.prev_span,
"found a documentation comment that doesn't document anything",
"doc comments must come before what they document, maybe a comment was \
intended with `//`?")
} else {
let mut err = self.fatal(&format!("expected identifier, found `{}`",
self.this_token_to_string()));
if self.token == token::Underscore {
err.note("`_` is a wildcard pattern, not an identifier");
}
err
})
}
}
}
/// Check if the next token is `tok`, and return `true` if so.
///
/// This method will automatically add `tok` to `expected_tokens` if `tok` is not
/// encountered.
pub fn check(&mut self, tok: &token::Token) -> bool {
let is_present = self.token == *tok;
if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
is_present
}
/// Consume token 'tok' if it exists. Returns true if the given
/// token was present, false otherwise.
pub fn eat(&mut self, tok: &token::Token) -> bool {
let is_present = self.check(tok);
if is_present { self.bump() }
is_present
}
pub fn check_keyword(&mut self, kw: keywords::Keyword) -> bool {
self.expected_tokens.push(TokenType::Keyword(kw));
self.token.is_keyword(kw)
}
/// If the next token is the given keyword, eat it and return
/// true. Otherwise, return false.
pub fn eat_keyword(&mut self, kw: keywords::Keyword) -> bool {
if self.check_keyword(kw) {
self.bump();
true
} else {
false
}
}
pub fn eat_keyword_noexpect(&mut self, kw: keywords::Keyword) -> bool {
if self.token.is_keyword(kw) {
self.bump();
true
} else {
false
}
}
pub fn check_contextual_keyword(&mut self, ident: Ident) -> bool {
self.expected_tokens.push(TokenType::Token(token::Ident(ident)));
if let token::Ident(ref cur_ident) = self.token {
cur_ident.name == ident.name
} else {
false
}
}
pub fn eat_contextual_keyword(&mut self, ident: Ident) -> bool {
if self.check_contextual_keyword(ident) {
self.bump();
true
} else {
false
}
}
/// If the given word is not a keyword, signal an error.
/// If the next token is not the given word, signal an error.
/// Otherwise, eat it.
pub fn expect_keyword(&mut self, kw: keywords::Keyword) -> PResult<'a, ()> {
if !self.eat_keyword(kw) {
self.unexpected()
} else {
Ok(())
}
}
/// Signal an error if the given string is a strict keyword
pub fn check_strict_keywords(&mut self) {
if self.token.is_strict_keyword() {
let token_str = self.this_token_to_string();
let span = self.span;
self.span_err(span,
&format!("expected identifier, found keyword `{}`",
token_str));
}
}
/// Signal an error if the current token is a reserved keyword
pub fn check_reserved_keywords(&mut self) {
if self.token.is_reserved_keyword() {
let token_str = self.this_token_to_string();
self.fatal(&format!("`{}` is a reserved keyword", token_str)).emit()
}
}
/// Expect and consume an `&`. If `&&` is seen, replace it with a single
/// `&` and continue. If an `&` is not seen, signal an error.
fn expect_and(&mut self) -> PResult<'a, ()> {
self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
match self.token {
token::BinOp(token::And) => {
self.bump();
Ok(())
}
token::AndAnd => {
let span = self.span;
let lo = span.lo + BytePos(1);
Ok(self.bump_with(token::BinOp(token::And), lo, span.hi))
}
_ => self.unexpected()
}
}
pub fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) {
match suffix {
None => {/* everything ok */}
Some(suf) => {
let text = suf.as_str();
if text.is_empty() {
self.span_bug(sp, "found empty literal suffix in Some")
}
self.span_err(sp, &format!("{} with a suffix is invalid", kind));
}
}
}
/// Attempt to consume a `<`. If `<<` is seen, replace it with a single
/// `<` and continue. If a `<` is not seen, return false.
///
/// This is meant to be used when parsing generics on a path to get the
/// starting token.
fn eat_lt(&mut self) -> bool {
self.expected_tokens.push(TokenType::Token(token::Lt));
match self.token {
token::Lt => {
self.bump();
true
}
token::BinOp(token::Shl) => {
let span = self.span;
let lo = span.lo + BytePos(1);
self.bump_with(token::Lt, lo, span.hi);
true
}
_ => false,
}
}
fn expect_lt(&mut self) -> PResult<'a, ()> {
if !self.eat_lt() {
self.unexpected()
} else {
Ok(())
}
}
/// Expect and consume a GT. if a >> is seen, replace it
/// with a single > and continue. If a GT is not seen,
/// signal an error.
pub fn expect_gt(&mut self) -> PResult<'a, ()> {
self.expected_tokens.push(TokenType::Token(token::Gt));
match self.token {
token::Gt => {
self.bump();
Ok(())
}
token::BinOp(token::Shr) => {
let span = self.span;
let lo = span.lo + BytePos(1);
Ok(self.bump_with(token::Gt, lo, span.hi))
}
token::BinOpEq(token::Shr) => {
let span = self.span;
let lo = span.lo + BytePos(1);
Ok(self.bump_with(token::Ge, lo, span.hi))
}
token::Ge => {
let span = self.span;
let lo = span.lo + BytePos(1);
Ok(self.bump_with(token::Eq, lo, span.hi))
}
_ => {
let gt_str = Parser::token_to_string(&token::Gt);
let this_token_str = self.this_token_to_string();
Err(self.fatal(&format!("expected `{}`, found `{}`",
gt_str,
this_token_str)))
}
}
}
pub fn parse_seq_to_before_gt_or_return<T, F>(&mut self,
sep: Option<token::Token>,
mut f: F)
-> PResult<'a, (P<[T]>, bool)>
where F: FnMut(&mut Parser<'a>) -> PResult<'a, Option<T>>,
{
let mut v = Vec::new();
// This loop works by alternating back and forth between parsing types
// and commas. For example, given a string `A, B,>`, the parser would
// first parse `A`, then a comma, then `B`, then a comma. After that it
// would encounter a `>` and stop. This lets the parser handle trailing
// commas in generic parameters, because it can stop either after
// parsing a type or after parsing a comma.
for i in 0.. {
if self.check(&token::Gt)
|| self.token == token::BinOp(token::Shr)
|| self.token == token::Ge
|| self.token == token::BinOpEq(token::Shr) {
break;
}
if i % 2 == 0 {
match f(self)? {
Some(result) => v.push(result),
None => return Ok((P::from_vec(v), true))
}
} else {
if let Some(t) = sep.as_ref() {
self.expect(t)?;
}
}
}
return Ok((P::from_vec(v), false));
}
/// Parse a sequence bracketed by '<' and '>', stopping
/// before the '>'.
pub fn parse_seq_to_before_gt<T, F>(&mut self,
sep: Option<token::Token>,
mut f: F)
-> PResult<'a, P<[T]>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let (result, returned) = self.parse_seq_to_before_gt_or_return(sep,
|p| Ok(Some(f(p)?)))?;
assert!(!returned);
return Ok(result);
}
pub fn parse_seq_to_gt<T, F>(&mut self,
sep: Option<token::Token>,
f: F)
-> PResult<'a, P<[T]>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let v = self.parse_seq_to_before_gt(sep, f)?;
self.expect_gt()?;
return Ok(v);
}
pub fn parse_seq_to_gt_or_return<T, F>(&mut self,
sep: Option<token::Token>,
f: F)
-> PResult<'a, (P<[T]>, bool)> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, Option<T>>,
{
let (v, returned) = self.parse_seq_to_before_gt_or_return(sep, f)?;
if !returned {
self.expect_gt()?;
}
return Ok((v, returned));
}
/// Eat and discard tokens until one of `kets` is encountered. Respects token trees,
/// passes through any errors encountered. Used for error recovery.
pub fn eat_to_tokens(&mut self, kets: &[&token::Token]) {
let handler = self.diagnostic();
self.parse_seq_to_before_tokens(kets,
SeqSep::none(),
|p| p.parse_token_tree(),
|mut e| handler.cancel(&mut e));
}
/// Parse a sequence, including the closing delimiter. The function
/// f must consume tokens until reaching the next separator or
/// closing bracket.
pub fn parse_seq_to_end<T, F>(&mut self,
ket: &token::Token,
sep: SeqSep,
f: F)
-> PResult<'a, Vec<T>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let val = self.parse_seq_to_before_end(ket, sep, f);
self.bump();
Ok(val)
}
/// Parse a sequence, not including the closing delimiter. The function
/// f must consume tokens until reaching the next separator or
/// closing bracket.
pub fn parse_seq_to_before_end<T, F>(&mut self,
ket: &token::Token,
sep: SeqSep,
f: F)
-> Vec<T>
where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>
{
self.parse_seq_to_before_tokens(&[ket], sep, f, |mut e| e.emit())
}
// `fe` is an error handler.
fn parse_seq_to_before_tokens<T, F, Fe>(&mut self,
kets: &[&token::Token],
sep: SeqSep,
mut f: F,
mut fe: Fe)
-> Vec<T>
where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
Fe: FnMut(DiagnosticBuilder)
{
let mut first: bool = true;
let mut v = vec![];
while !kets.contains(&&self.token) {
match sep.sep {
Some(ref t) => {
if first {
first = false;
} else {
if let Err(e) = self.expect(t) {
fe(e);
break;
}
}
}
_ => ()
}
if sep.trailing_sep_allowed && kets.iter().any(|k| self.check(k)) {
break;
}
match f(self) {
Ok(t) => v.push(t),
Err(e) => {
fe(e);
break;
}
}
}
v
}
/// Parse a sequence, including the closing delimiter. The function
/// f must consume tokens until reaching the next separator or
/// closing bracket.
pub fn parse_unspanned_seq<T, F>(&mut self,
bra: &token::Token,
ket: &token::Token,
sep: SeqSep,
f: F)
-> PResult<'a, Vec<T>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
self.expect(bra)?;
let result = self.parse_seq_to_before_end(ket, sep, f);
if self.token == *ket {
self.bump();
}
Ok(result)
}
// NB: Do not use this function unless you actually plan to place the
// spanned list in the AST.
pub fn parse_seq<T, F>(&mut self,
bra: &token::Token,
ket: &token::Token,
sep: SeqSep,
f: F)
-> PResult<'a, Spanned<Vec<T>>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let lo = self.span.lo;
self.expect(bra)?;
let result = self.parse_seq_to_before_end(ket, sep, f);
let hi = self.span.hi;
self.bump();
Ok(spanned(lo, hi, result))
}
/// Advance the parser by one token
pub fn bump(&mut self) {
if self.prev_token_kind == PrevTokenKind::Eof {
// Bumping after EOF is a bad sign, usually an infinite loop.
self.bug("attempted to bump the parser past EOF (may be stuck in a loop)");
}
self.prev_span = self.span;
// Record last token kind for possible error recovery.
self.prev_token_kind = match self.token {
token::DocComment(..) => PrevTokenKind::DocComment,
token::Comma => PrevTokenKind::Comma,
token::Interpolated(..) => PrevTokenKind::Interpolated,
token::Eof => PrevTokenKind::Eof,
_ => PrevTokenKind::Other,
};
let next = if self.lookahead_buffer.start == self.lookahead_buffer.end {
self.next_tok()
} else {
// Avoid token copies with `replace`.
let old_start = self.lookahead_buffer.start;
self.lookahead_buffer.start = (old_start + 1) % LOOKAHEAD_BUFFER_CAPACITY;
mem::replace(&mut self.lookahead_buffer.buffer[old_start], Default::default())
};
self.span = next.sp;
self.token = next.tok;
self.tokens_consumed += 1;
self.expected_tokens.clear();
// check after each token
self.check_unknown_macro_variable();
}
/// Advance the parser by one token and return the bumped token.
pub fn bump_and_get(&mut self) -> token::Token {
let old_token = mem::replace(&mut self.token, token::Underscore);
self.bump();
old_token
}
/// Advance the parser using provided token as a next one. Use this when
/// consuming a part of a token. For example a single `<` from `<<`.
pub fn bump_with(&mut self,
next: token::Token,
lo: BytePos,
hi: BytePos) {
self.prev_span = mk_sp(self.span.lo, lo);
// It would be incorrect to record the kind of the current token, but
// fortunately for tokens currently using `bump_with`, the
// prev_token_kind will be of no use anyway.
self.prev_token_kind = PrevTokenKind::Other;
self.span = mk_sp(lo, hi);
self.token = next;
self.expected_tokens.clear();
}
pub fn look_ahead<R, F>(&mut self, dist: usize, f: F) -> R where
F: FnOnce(&token::Token) -> R,
{
if dist == 0 {
f(&self.token)
} else if dist < LOOKAHEAD_BUFFER_CAPACITY {
while self.lookahead_buffer.len() < dist {
self.lookahead_buffer.buffer[self.lookahead_buffer.end] = self.next_tok();
self.lookahead_buffer.end =
(self.lookahead_buffer.end + 1) % LOOKAHEAD_BUFFER_CAPACITY;
}
let index = (self.lookahead_buffer.start + dist - 1) % LOOKAHEAD_BUFFER_CAPACITY;
f(&self.lookahead_buffer.buffer[index].tok)
} else {
self.bug("lookahead distance is too large");
}
}
pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
self.sess.span_diagnostic.struct_span_fatal(self.span, m)
}
pub fn span_fatal(&self, sp: Span, m: &str) -> DiagnosticBuilder<'a> {
self.sess.span_diagnostic.struct_span_fatal(sp, m)
}
pub fn span_fatal_help(&self, sp: Span, m: &str, help: &str) -> DiagnosticBuilder<'a> {
let mut err = self.sess.span_diagnostic.struct_span_fatal(sp, m);
err.help(help);
err
}
pub fn bug(&self, m: &str) -> ! {
self.sess.span_diagnostic.span_bug(self.span, m)
}
pub fn warn(&self, m: &str) {
self.sess.span_diagnostic.span_warn(self.span, m)
}
pub fn span_warn(&self, sp: Span, m: &str) {
self.sess.span_diagnostic.span_warn(sp, m)
}
pub fn span_err(&self, sp: Span, m: &str) {
self.sess.span_diagnostic.span_err(sp, m)
}
pub fn span_err_help(&self, sp: Span, m: &str, h: &str) {
let mut err = self.sess.span_diagnostic.mut_span_err(sp, m);
err.help(h);
err.emit();
}
pub fn span_bug(&self, sp: Span, m: &str) -> ! {
self.sess.span_diagnostic.span_bug(sp, m)
}
pub fn abort_if_errors(&self) {
self.sess.span_diagnostic.abort_if_errors();
}
fn cancel(&self, err: &mut DiagnosticBuilder) {
self.sess.span_diagnostic.cancel(err)
}
pub fn diagnostic(&self) -> &'a errors::Handler {
&self.sess.span_diagnostic
}
/// Is the current token one of the keywords that signals a bare function
/// type?
pub fn token_is_bare_fn_keyword(&mut self) -> bool {
self.check_keyword(keywords::Fn) ||
self.check_keyword(keywords::Unsafe) ||
self.check_keyword(keywords::Extern)
}
pub fn get_lifetime(&mut self) -> ast::Ident {
match self.token {
token::Lifetime(ref ident) => *ident,
_ => self.bug("not a lifetime"),
}
}
pub fn parse_for_in_type(&mut self) -> PResult<'a, TyKind> {
/*
Parses whatever can come after a `for` keyword in a type.
The `for` hasn't been consumed.
Deprecated:
- for <'lt> |S| -> T
Eventually:
- for <'lt> [unsafe] [extern "ABI"] fn (S) -> T
- for <'lt> path::foo(a, b)
*/
// parse <'lt>
let lo = self.span.lo;
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
// examine next token to decide to do
if self.token_is_bare_fn_keyword() {
self.parse_ty_bare_fn(lifetime_defs)
} else {
let hi = self.span.hi;
let trait_ref = self.parse_trait_ref()?;
let poly_trait_ref = ast::PolyTraitRef { bound_lifetimes: lifetime_defs,
trait_ref: trait_ref,
span: mk_sp(lo, hi)};
let other_bounds = if self.eat(&token::BinOp(token::Plus)) {
self.parse_ty_param_bounds(BoundParsingMode::Bare)?
} else {
P::new()
};
let all_bounds =
Some(TraitTyParamBound(poly_trait_ref, TraitBoundModifier::None)).into_iter()
.chain(other_bounds.into_vec())
.collect();
Ok(ast::TyKind::PolyTraitRef(all_bounds))
}
}
pub fn parse_impl_trait_type(&mut self) -> PResult<'a, TyKind> {
/*
Parses whatever can come after a `impl` keyword in a type.
The `impl` has already been consumed.
*/
let bounds = self.parse_ty_param_bounds(BoundParsingMode::Modified)?;
if !bounds.iter().any(|b| if let TraitTyParamBound(..) = *b { true } else { false }) {
self.span_err(self.prev_span, "at least one trait must be specified");
}
Ok(ast::TyKind::ImplTrait(bounds))
}
pub fn parse_ty_path(&mut self) -> PResult<'a, TyKind> {
Ok(TyKind::Path(None, self.parse_path(PathStyle::Type)?))
}
/// parse a TyKind::BareFn type:
pub fn parse_ty_bare_fn(&mut self, lifetime_defs: Vec<ast::LifetimeDef>)
-> PResult<'a, TyKind> {
/*
[unsafe] [extern "ABI"] fn (S) -> T
^~~~^ ^~~~^ ^~^ ^
| | | |
| | | Return type
| | Argument types
| |
| ABI
Function Style
*/
let unsafety = self.parse_unsafety()?;
let abi = if self.eat_keyword(keywords::Extern) {
self.parse_opt_abi()?.unwrap_or(Abi::C)
} else {
Abi::Rust
};
self.expect_keyword(keywords::Fn)?;
let (inputs, variadic) = self.parse_fn_args(false, true)?;
let ret_ty = self.parse_ret_ty()?;
let decl = P(FnDecl {
inputs: inputs,
output: ret_ty,
variadic: variadic
});
Ok(TyKind::BareFn(P(BareFnTy {
abi: abi,
unsafety: unsafety,
lifetimes: lifetime_defs,
decl: decl
})))
}
pub fn parse_unsafety(&mut self) -> PResult<'a, Unsafety> {
if self.eat_keyword(keywords::Unsafe) {
return Ok(Unsafety::Unsafe);
} else {
return Ok(Unsafety::Normal);
}
}
/// Parse the items in a trait declaration
pub fn parse_trait_item(&mut self) -> PResult<'a, TraitItem> {
maybe_whole!(self, NtTraitItem, |x| x);
let mut attrs = self.parse_outer_attributes()?;
let lo = self.span.lo;
let (name, node) = if self.eat_keyword(keywords::Type) {
let TyParam {ident, bounds, default, ..} = self.parse_ty_param(vec![])?;
self.expect(&token::Semi)?;
(ident, TraitItemKind::Type(bounds, default))
} else if self.is_const_item() {
self.expect_keyword(keywords::Const)?;
let ident = self.parse_ident()?;
self.expect(&token::Colon)?;
let ty = self.parse_ty_sum()?;
let default = if self.check(&token::Eq) {
self.bump();
let expr = self.parse_expr()?;
self.expect(&token::Semi)?;
Some(expr)
} else {
self.expect(&token::Semi)?;
None
};
(ident, TraitItemKind::Const(ty, default))
} else if self.token.is_path_start() {
// trait item macro.
// code copied from parse_macro_use_or_failure... abstraction!
let lo = self.span.lo;
let pth = self.parse_path(PathStyle::Mod)?;
self.expect(&token::Not)?;
// eat a matched-delimiter token tree:
let delim = self.expect_open_delim()?;
let tts = self.parse_seq_to_end(&token::CloseDelim(delim),
SeqSep::none(),
|pp| pp.parse_token_tree())?;
if delim != token::Brace {
self.expect(&token::Semi)?
}
let mac = spanned(lo, self.prev_span.hi, Mac_ { path: pth, tts: tts });
(keywords::Invalid.ident(), ast::TraitItemKind::Macro(mac))
} else {
let (constness, unsafety, abi) = match self.parse_fn_front_matter() {
Ok(cua) => cua,
Err(e) => {
loop {
match self.token {
token::Eof => break,
token::CloseDelim(token::Brace) |
token::Semi => {
self.bump();
break;
}
token::OpenDelim(token::Brace) => {
self.parse_token_tree()?;
break;
}
_ => self.bump(),
}
}
return Err(e);
}
};
let ident = self.parse_ident()?;
let mut generics = self.parse_generics()?;
let d = self.parse_fn_decl_with_self(|p: &mut Parser<'a>|{
// This is somewhat dubious; We don't want to allow
// argument names to be left off if there is a
// definition...
p.parse_arg_general(false)
})?;
generics.where_clause = self.parse_where_clause()?;
let sig = ast::MethodSig {
unsafety: unsafety,
constness: constness,
decl: d,
generics: generics,
abi: abi,
};
let body = match self.token {
token::Semi => {
self.bump();
debug!("parse_trait_methods(): parsing required method");
None
}
token::OpenDelim(token::Brace) => {
debug!("parse_trait_methods(): parsing provided method");
let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(inner_attrs.iter().cloned());
Some(body)
}
_ => {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `;` or `{{`, found `{}`", token_str)));
}
};
(ident, ast::TraitItemKind::Method(sig, body))
};
Ok(TraitItem {
id: ast::DUMMY_NODE_ID,
ident: name,
attrs: attrs,
node: node,
span: mk_sp(lo, self.prev_span.hi),
})
}
/// Parse the items in a trait declaration
pub fn parse_trait_items(&mut self) -> PResult<'a, Vec<TraitItem>> {
self.parse_unspanned_seq(
&token::OpenDelim(token::Brace),
&token::CloseDelim(token::Brace),
SeqSep::none(),
|p| -> PResult<'a, TraitItem> {
p.parse_trait_item()
})
}
/// Parse a possibly mutable type
pub fn parse_mt(&mut self) -> PResult<'a, MutTy> {
let mutbl = self.parse_mutability()?;
let t = self.parse_ty()?;
Ok(MutTy { ty: t, mutbl: mutbl })
}
/// Parse optional return type [ -> TY ] in function decl
pub fn parse_ret_ty(&mut self) -> PResult<'a, FunctionRetTy> {
if self.eat(&token::RArrow) {
Ok(FunctionRetTy::Ty(self.parse_ty()?))
} else {
let pos = self.span.lo;
Ok(FunctionRetTy::Default(mk_sp(pos, pos)))
}
}
/// Parse a type in a context where `T1+T2` is allowed.
pub fn parse_ty_sum(&mut self) -> PResult<'a, P<Ty>> {
let lo = self.span.lo;
let lhs = self.parse_ty()?;
if !self.eat(&token::BinOp(token::Plus)) {
return Ok(lhs);
}
let bounds = self.parse_ty_param_bounds(BoundParsingMode::Bare)?;
// In type grammar, `+` is treated like a binary operator,
// and hence both L and R side are required.
if bounds.is_empty() {
let prev_span = self.prev_span;
self.span_err(prev_span,
"at least one type parameter bound \
must be specified");
}
let sp = mk_sp(lo, self.prev_span.hi);
let sum = ast::TyKind::ObjectSum(lhs, bounds);
Ok(P(Ty {id: ast::DUMMY_NODE_ID, node: sum, span: sp}))
}
/// Parse a type.
pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
maybe_whole!(self, NtTy, |x| x);
let lo = self.span.lo;
let t = if self.check(&token::OpenDelim(token::Paren)) {
self.bump();
// (t) is a parenthesized ty
// (t,) is the type of a tuple with only one field,
// of type t
let mut ts = vec![];
let mut last_comma = false;
while self.token != token::CloseDelim(token::Paren) {
ts.push(self.parse_ty_sum()?);
if self.check(&token::Comma) {
last_comma = true;
self.bump();
} else {
last_comma = false;
break;
}
}
self.expect(&token::CloseDelim(token::Paren))?;
if ts.len() == 1 && !last_comma {
TyKind::Paren(ts.into_iter().nth(0).unwrap())
} else {
TyKind::Tup(ts)
}
} else if self.eat(&token::Not) {
TyKind::Never
} else if self.check(&token::BinOp(token::Star)) {
// STAR POINTER (bare pointer?)
self.bump();
TyKind::Ptr(self.parse_ptr()?)
} else if self.check(&token::OpenDelim(token::Bracket)) {
// VECTOR
self.expect(&token::OpenDelim(token::Bracket))?;
let t = self.parse_ty_sum()?;
// Parse the `; e` in `[ i32; e ]`
// where `e` is a const expression
let t = match self.maybe_parse_fixed_length_of_vec()? {
None => TyKind::Slice(t),
Some(suffix) => TyKind::Array(t, suffix)
};
self.expect(&token::CloseDelim(token::Bracket))?;
t
} else if self.check(&token::BinOp(token::And)) ||
self.token == token::AndAnd {
// BORROWED POINTER
self.expect_and()?;
self.parse_borrowed_pointee()?
} else if self.check_keyword(keywords::For) {
self.parse_for_in_type()?
} else if self.eat_keyword(keywords::Impl) {
self.parse_impl_trait_type()?
} else if self.token_is_bare_fn_keyword() {
// BARE FUNCTION
self.parse_ty_bare_fn(Vec::new())?
} else if self.eat_keyword_noexpect(keywords::Typeof) {
// TYPEOF
// In order to not be ambiguous, the type must be surrounded by parens.
self.expect(&token::OpenDelim(token::Paren))?;
let e = self.parse_expr()?;
self.expect(&token::CloseDelim(token::Paren))?;
TyKind::Typeof(e)
} else if self.eat_lt() {
let (qself, path) =
self.parse_qualified_path(PathStyle::Type)?;
TyKind::Path(Some(qself), path)
} else if self.token.is_path_start() {
let path = self.parse_path(PathStyle::Type)?;
if self.eat(&token::Not) {
// MACRO INVOCATION
let delim = self.expect_open_delim()?;
let tts = self.parse_seq_to_end(&token::CloseDelim(delim),
SeqSep::none(),
|p| p.parse_token_tree())?;
let hi = self.span.hi;
TyKind::Mac(spanned(lo, hi, Mac_ { path: path, tts: tts }))
} else {
// NAMED TYPE
TyKind::Path(None, path)
}
} else if self.eat(&token::Underscore) {
// TYPE TO BE INFERRED
TyKind::Infer
} else {
let msg = format!("expected type, found {}", self.this_token_descr());
return Err(self.fatal(&msg));
};
let sp = mk_sp(lo, self.prev_span.hi);
Ok(P(Ty {id: ast::DUMMY_NODE_ID, node: t, span: sp}))
}
pub fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
// look for `&'lt` or `&'foo ` and interpret `foo` as the region name:
let opt_lifetime = self.parse_opt_lifetime()?;
let mt = self.parse_mt()?;
return Ok(TyKind::Rptr(opt_lifetime, mt));
}
pub fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
let mutbl = if self.eat_keyword(keywords::Mut) {
Mutability::Mutable
} else if self.eat_keyword(keywords::Const) {
Mutability::Immutable
} else {
let span = self.prev_span;
self.span_err(span,
"expected mut or const in raw pointer type (use \
`*mut T` or `*const T` as appropriate)");
Mutability::Immutable
};
let t = self.parse_ty()?;
Ok(MutTy { ty: t, mutbl: mutbl })
}
pub fn is_named_argument(&mut self) -> bool {
let offset = match self.token {
token::BinOp(token::And) => 1,
token::AndAnd => 1,
_ if self.token.is_keyword(keywords::Mut) => 1,
_ => 0
};
debug!("parser is_named_argument offset:{}", offset);
if offset == 0 {
is_ident_or_underscore(&self.token)
&& self.look_ahead(1, |t| *t == token::Colon)
} else {
self.look_ahead(offset, |t| is_ident_or_underscore(t))
&& self.look_ahead(offset + 1, |t| *t == token::Colon)
}
}
/// This version of parse arg doesn't necessarily require
/// identifier names.
pub fn parse_arg_general(&mut self, require_name: bool) -> PResult<'a, Arg> {
maybe_whole!(self, NtArg, |x| x);
let pat = if require_name || self.is_named_argument() {
debug!("parse_arg_general parse_pat (require_name:{})",
require_name);
let pat = self.parse_pat()?;
self.expect(&token::Colon)?;
pat
} else {
debug!("parse_arg_general ident_to_pat");
let sp = self.prev_span;
let spanned = Spanned { span: sp, node: keywords::Invalid.ident() };
P(Pat {
id: ast::DUMMY_NODE_ID,
node: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable),
spanned, None),
span: sp
})
};
let t = self.parse_ty_sum()?;
Ok(Arg {
ty: t,
pat: pat,
id: ast::DUMMY_NODE_ID,
})
}
/// Parse a single function argument
pub fn parse_arg(&mut self) -> PResult<'a, Arg> {
self.parse_arg_general(true)
}
/// Parse an argument in a lambda header e.g. |arg, arg|
pub fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
let pat = self.parse_pat()?;
let t = if self.eat(&token::Colon) {
self.parse_ty_sum()?
} else {
P(Ty {
id: ast::DUMMY_NODE_ID,
node: TyKind::Infer,
span: mk_sp(self.span.lo, self.span.hi),
})
};
Ok(Arg {
ty: t,
pat: pat,
id: ast::DUMMY_NODE_ID
})
}
pub fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
if self.check(&token::Semi) {
self.bump();
Ok(Some(self.parse_expr()?))
} else {
Ok(None)
}
}
/// Matches token_lit = LIT_INTEGER | ...
pub fn parse_lit_token(&mut self) -> PResult<'a, LitKind> {
let out = match self.token {
token::Interpolated(ref nt) => match **nt {
token::NtExpr(ref v) => match v.node {
ExprKind::Lit(ref lit) => { lit.node.clone() }
_ => { return self.unexpected_last(&self.token); }
},
_ => { return self.unexpected_last(&self.token); }
},
token::Literal(lit, suf) => {
let (suffix_illegal, out) = match lit {
token::Byte(i) => (true, LitKind::Byte(parse::byte_lit(&i.as_str()).0)),
token::Char(i) => (true, LitKind::Char(parse::char_lit(&i.as_str()).0)),
// there are some valid suffixes for integer and
// float literals, so all the handling is done
// internally.
token::Integer(s) => {
let diag = &self.sess.span_diagnostic;
(false, parse::integer_lit(&s.as_str(), suf, diag, self.span))
}
token::Float(s) => {
let diag = &self.sess.span_diagnostic;
(false, parse::float_lit(&s.as_str(), suf, diag, self.span))
}
token::Str_(s) => {
let s = Symbol::intern(&parse::str_lit(&s.as_str()));
(true, LitKind::Str(s, ast::StrStyle::Cooked))
}
token::StrRaw(s, n) => {
let s = Symbol::intern(&parse::raw_str_lit(&s.as_str()));
(true, LitKind::Str(s, ast::StrStyle::Raw(n)))
}
token::ByteStr(i) => {
(true, LitKind::ByteStr(parse::byte_str_lit(&i.as_str())))
}
token::ByteStrRaw(i, _) => {
(true, LitKind::ByteStr(Rc::new(i.to_string().into_bytes())))
}
};
if suffix_illegal {
let sp = self.span;
self.expect_no_suffix(sp, &format!("{} literal", lit.short_name()), suf)
}
out
}
_ => { return self.unexpected_last(&self.token); }
};
self.bump();
Ok(out)
}
/// Matches lit = true | false | token_lit
pub fn parse_lit(&mut self) -> PResult<'a, Lit> {
let lo = self.span.lo;
let lit = if self.eat_keyword(keywords::True) {
LitKind::Bool(true)
} else if self.eat_keyword(keywords::False) {
LitKind::Bool(false)
} else {
let lit = self.parse_lit_token()?;
lit
};
Ok(codemap::Spanned { node: lit, span: mk_sp(lo, self.prev_span.hi) })
}
/// matches '-' lit | lit
pub fn parse_pat_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
let minus_lo = self.span.lo;
let minus_present = self.eat(&token::BinOp(token::Minus));
let lo = self.span.lo;
let literal = P(self.parse_lit()?);
let hi = self.prev_span.hi;
let expr = self.mk_expr(lo, hi, ExprKind::Lit(literal), ThinVec::new());
if minus_present {
let minus_hi = self.prev_span.hi;
let unary = self.mk_unary(UnOp::Neg, expr);
Ok(self.mk_expr(minus_lo, minus_hi, unary, ThinVec::new()))
} else {
Ok(expr)
}
}
pub fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> {
match self.token {
token::Ident(sid) if self.token.is_path_segment_keyword() => {
self.bump();
Ok(sid)
}
_ => self.parse_ident(),
}
}
/// Parses qualified path.
///
/// Assumes that the leading `<` has been parsed already.
///
/// Qualifed paths are a part of the universal function call
/// syntax (UFCS).
///
/// `qualified_path = <type [as trait_ref]>::path`
///
/// See `parse_path` for `mode` meaning.
///
/// # Examples:
///
/// `<T as U>::a`
/// `<T as U>::F::a::<S>`
pub fn parse_qualified_path(&mut self, mode: PathStyle)
-> PResult<'a, (QSelf, ast::Path)> {
let span = self.prev_span;
let self_type = self.parse_ty_sum()?;
let mut path = if self.eat_keyword(keywords::As) {
self.parse_path(PathStyle::Type)?
} else {
ast::Path {
span: span,
global: false,
segments: vec![]
}
};
let qself = QSelf {
ty: self_type,
position: path.segments.len()
};
self.expect(&token::Gt)?;
self.expect(&token::ModSep)?;
let segments = match mode {
PathStyle::Type => {
self.parse_path_segments_without_colons()?
}
PathStyle::Expr => {
self.parse_path_segments_with_colons()?
}
PathStyle::Mod => {
self.parse_path_segments_without_types()?
}
};
path.segments.extend(segments);
path.span.hi = self.prev_span.hi;
Ok((qself, path))
}
/// Parses a path and optional type parameter bounds, depending on the
/// mode. The `mode` parameter determines whether lifetimes, types, and/or
/// bounds are permitted and whether `::` must precede type parameter
/// groups.
pub fn parse_path(&mut self, mode: PathStyle) -> PResult<'a, ast::Path> {
maybe_whole!(self, NtPath, |x| x);
let lo = self.span.lo;
let is_global = self.eat(&token::ModSep);
// Parse any number of segments and bound sets. A segment is an
// identifier followed by an optional lifetime and a set of types.
// A bound set is a set of type parameter bounds.
let segments = match mode {
PathStyle::Type => {
self.parse_path_segments_without_colons()?
}
PathStyle::Expr => {
self.parse_path_segments_with_colons()?
}
PathStyle::Mod => {
self.parse_path_segments_without_types()?
}
};
// Assemble the span.
let span = mk_sp(lo, self.prev_span.hi);
// Assemble the result.
Ok(ast::Path {
span: span,
global: is_global,
segments: segments,
})
}
/// Examples:
/// - `a::b<T,U>::c<V,W>`
/// - `a::b<T,U>::c(V) -> W`
/// - `a::b<T,U>::c(V)`
pub fn parse_path_segments_without_colons(&mut self) -> PResult<'a, Vec<ast::PathSegment>> {
let mut segments = Vec::new();
loop {
// First, parse an identifier.
let identifier = self.parse_path_segment_ident()?;
if self.check(&token::ModSep) && self.look_ahead(1, |t| *t == token::Lt) {
self.bump();
let prev_span = self.prev_span;
let mut err = self.diagnostic().struct_span_err(prev_span,
"unexpected token: `::`");
err.help(
"use `<...>` instead of `::<...>` if you meant to specify type arguments");
err.emit();
}
// Parse types, optionally.
let parameters = if self.eat_lt() {
let (lifetimes, types, bindings) = self.parse_generic_values_after_lt()?;
ast::PathParameters::AngleBracketed(ast::AngleBracketedParameterData {
lifetimes: lifetimes,
types: P::from_vec(types),
bindings: P::from_vec(bindings),
})
} else if self.eat(&token::OpenDelim(token::Paren)) {
let lo = self.prev_span.lo;
let inputs = self.parse_seq_to_end(
&token::CloseDelim(token::Paren),
SeqSep::trailing_allowed(token::Comma),
|p| p.parse_ty_sum())?;
let output_ty = if self.eat(&token::RArrow) {
Some(self.parse_ty()?)
} else {
None
};
let hi = self.prev_span.hi;
ast::PathParameters::Parenthesized(ast::ParenthesizedParameterData {
span: mk_sp(lo, hi),
inputs: inputs,
output: output_ty,
})
} else {
ast::PathParameters::none()
};
// Assemble and push the result.
segments.push(ast::PathSegment { identifier: identifier,
parameters: parameters });
// Continue only if we see a `::`
if !self.eat(&token::ModSep) {
return Ok(segments);
}
}
}
/// Examples:
/// - `a::b::<T,U>::c`
pub fn parse_path_segments_with_colons(&mut self) -> PResult<'a, Vec<ast::PathSegment>> {
let mut segments = Vec::new();
loop {
// First, parse an identifier.
let identifier = self.parse_path_segment_ident()?;
// If we do not see a `::`, stop.
if !self.eat(&token::ModSep) {
segments.push(ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::none()
});
return Ok(segments);
}
// Check for a type segment.
if self.eat_lt() {
// Consumed `a::b::<`, go look for types
let (lifetimes, types, bindings) = self.parse_generic_values_after_lt()?;
let parameters = ast::AngleBracketedParameterData {
lifetimes: lifetimes,
types: P::from_vec(types),
bindings: P::from_vec(bindings),
};
segments.push(ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::AngleBracketed(parameters),
});
// Consumed `a::b::<T,U>`, check for `::` before proceeding
if !self.eat(&token::ModSep) {
return Ok(segments);
}
} else {
// Consumed `a::`, go look for `b`
segments.push(ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::none(),
});
}
}
}
/// Examples:
/// - `a::b::c`
pub fn parse_path_segments_without_types(&mut self)
-> PResult<'a, Vec<ast::PathSegment>> {
let mut segments = Vec::new();
loop {
// First, parse an identifier.
let identifier = self.parse_path_segment_ident()?;
// Assemble and push the result.
segments.push(ast::PathSegment {
identifier: identifier,
parameters: ast::PathParameters::none()
});
// If we do not see a `::` or see `::{`/`::*`, stop.
if !self.check(&token::ModSep) || self.is_import_coupler() {
return Ok(segments);
} else {
self.bump();
}
}
}
/// parses 0 or 1 lifetime
pub fn parse_opt_lifetime(&mut self) -> PResult<'a, Option<ast::Lifetime>> {
match self.token {
token::Lifetime(..) => {
Ok(Some(self.parse_lifetime()?))
}
_ => {
Ok(None)
}
}
}
/// Parses a single lifetime
/// Matches lifetime = LIFETIME
pub fn parse_lifetime(&mut self) -> PResult<'a, ast::Lifetime> {
match self.token {
token::Lifetime(i) => {
let span = self.span;
self.bump();
return Ok(ast::Lifetime {
id: ast::DUMMY_NODE_ID,
span: span,
name: i.name
});
}
_ => {
return Err(self.fatal("expected a lifetime name"));
}
}
}
/// Parses `lifetime_defs = [ lifetime_defs { ',' lifetime_defs } ]` where `lifetime_def =
/// lifetime [':' lifetimes]`
///
/// If `followed_by_ty_params` is None, then we are in a context
/// where only lifetime parameters are allowed, and thus we should
/// error if we encounter attributes after the bound lifetimes.
///
/// If `followed_by_ty_params` is Some(r), then there may be type
/// parameter bindings after the lifetimes, so we should pass
/// along the parsed attributes to be attached to the first such
/// type parmeter.
pub fn parse_lifetime_defs(&mut self,
followed_by_ty_params: Option<&mut Vec<ast::Attribute>>)
-> PResult<'a, Vec<ast::LifetimeDef>>
{
let mut res = Vec::new();
loop {
let attrs = self.parse_outer_attributes()?;
match self.token {
token::Lifetime(_) => {
let lifetime = self.parse_lifetime()?;
let bounds =
if self.eat(&token::Colon) {
self.parse_lifetimes(token::BinOp(token::Plus))?
} else {
Vec::new()
};
res.push(ast::LifetimeDef { attrs: attrs.into(),
lifetime: lifetime,
bounds: bounds });
}
_ => {
if let Some(recv) = followed_by_ty_params {
assert!(recv.is_empty());
*recv = attrs;
debug!("parse_lifetime_defs ret {:?}", res);
return Ok(res);
} else if !attrs.is_empty() {
let msg = "trailing attribute after lifetime parameters";
return Err(self.fatal(msg));
}
}
}
match self.token {
token::Comma => { self.bump();}
token::Gt => { return Ok(res); }
token::BinOp(token::Shr) => { return Ok(res); }
_ => {
let this_token_str = self.this_token_to_string();
let msg = format!("expected `,` or `>` after lifetime \
name, found `{}`",
this_token_str);
return Err(self.fatal(&msg[..]));
}
}
}
}
/// matches lifetimes = ( lifetime ) | ( lifetime , lifetimes ) actually, it matches the empty
/// one too, but putting that in there messes up the grammar....
///
/// Parses zero or more comma separated lifetimes. Expects each lifetime to be followed by
/// either a comma or `>`. Used when parsing type parameter lists, where we expect something
/// like `<'a, 'b, T>`.
pub fn parse_lifetimes(&mut self, sep: token::Token) -> PResult<'a, Vec<ast::Lifetime>> {
let mut res = Vec::new();
loop {
match self.token {
token::Lifetime(_) => {
res.push(self.parse_lifetime()?);
}
_ => {
return Ok(res);
}
}
if self.token != sep {
return Ok(res);
}
self.bump();
}
}
/// Parse mutability (`mut` or nothing).
pub fn parse_mutability(&mut self) -> PResult<'a, Mutability> {
if self.eat_keyword(keywords::Mut) {
Ok(Mutability::Mutable)
} else {
Ok(Mutability::Immutable)
}
}
pub fn parse_field_name(&mut self) -> PResult<'a, Ident> {
if let token::Literal(token::Integer(name), None) = self.token {
self.bump();
Ok(Ident::with_empty_ctxt(name))
} else {
self.parse_ident()
}
}
/// Parse ident (COLON expr)?
pub fn parse_field(&mut self) -> PResult<'a, Field> {
let lo = self.span.lo;
let hi;
// Check if a colon exists one ahead. This means we're parsing a fieldname.
let (fieldname, expr, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
let fieldname = self.parse_field_name()?;
self.bump();
hi = self.prev_span.hi;
(fieldname, self.parse_expr()?, false)
} else {
let fieldname = self.parse_ident()?;
hi = self.prev_span.hi;
// Mimic `x: x` for the `x` field shorthand.
let path = ast::Path::from_ident(mk_sp(lo, hi), fieldname);
(fieldname, self.mk_expr(lo, hi, ExprKind::Path(None, path), ThinVec::new()), true)
};
Ok(ast::Field {
ident: spanned(lo, hi, fieldname),
span: mk_sp(lo, expr.span.hi),
expr: expr,
is_shorthand: is_shorthand,
})
}
pub fn mk_expr(&mut self, lo: BytePos, hi: BytePos, node: ExprKind, attrs: ThinVec<Attribute>)
-> P<Expr> {
P(Expr {
id: ast::DUMMY_NODE_ID,
node: node,
span: mk_sp(lo, hi),
attrs: attrs.into(),
})
}
pub fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::ExprKind {
ExprKind::Unary(unop, expr)
}
pub fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
ExprKind::Binary(binop, lhs, rhs)
}
pub fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::ExprKind {
ExprKind::Call(f, args)
}
fn mk_method_call(&mut self,
ident: ast::SpannedIdent,
tps: Vec<P<Ty>>,
args: Vec<P<Expr>>)
-> ast::ExprKind {
ExprKind::MethodCall(ident, tps, args)
}
pub fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::ExprKind {
ExprKind::Index(expr, idx)
}
pub fn mk_range(&mut self,
start: Option<P<Expr>>,
end: Option<P<Expr>>,
limits: RangeLimits)
-> PResult<'a, ast::ExprKind> {
if end.is_none() && limits == RangeLimits::Closed {
Err(self.span_fatal_help(self.span,
"inclusive range with no end",
"inclusive ranges must be bounded at the end \
(`...b` or `a...b`)"))
} else {
Ok(ExprKind::Range(start, end, limits))
}
}
pub fn mk_field(&mut self, expr: P<Expr>, ident: ast::SpannedIdent) -> ast::ExprKind {
ExprKind::Field(expr, ident)
}
pub fn mk_tup_field(&mut self, expr: P<Expr>, idx: codemap::Spanned<usize>) -> ast::ExprKind {
ExprKind::TupField(expr, idx)
}
pub fn mk_assign_op(&mut self, binop: ast::BinOp,
lhs: P<Expr>, rhs: P<Expr>) -> ast::ExprKind {
ExprKind::AssignOp(binop, lhs, rhs)
}
pub fn mk_mac_expr(&mut self, lo: BytePos, hi: BytePos,
m: Mac_, attrs: ThinVec<Attribute>) -> P<Expr> {
P(Expr {
id: ast::DUMMY_NODE_ID,
node: ExprKind::Mac(codemap::Spanned {node: m, span: mk_sp(lo, hi)}),
span: mk_sp(lo, hi),
attrs: attrs,
})
}
pub fn mk_lit_u32(&mut self, i: u32, attrs: ThinVec<Attribute>) -> P<Expr> {
let span = &self.span;
let lv_lit = P(codemap::Spanned {
node: LitKind::Int(i as u64, ast::LitIntType::Unsigned(UintTy::U32)),
span: *span
});
P(Expr {
id: ast::DUMMY_NODE_ID,
node: ExprKind::Lit(lv_lit),
span: *span,
attrs: attrs,
})
}
fn expect_open_delim(&mut self) -> PResult<'a, token::DelimToken> {
self.expected_tokens.push(TokenType::Token(token::Gt));
match self.token {
token::OpenDelim(delim) => {
self.bump();
Ok(delim)
},
_ => Err(self.fatal("expected open delimiter")),
}
}
/// At the bottom (top?) of the precedence hierarchy,
/// parse things like parenthesized exprs,
/// macros, return, etc.
///
/// NB: This does not parse outer attributes,
/// and is private because it only works
/// correctly if called from parse_dot_or_call_expr().
fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
maybe_whole_expr!(self);
// Outer attributes are already parsed and will be
// added to the return value after the fact.
//
// Therefore, prevent sub-parser from parsing
// attributes by giving them a empty "already parsed" list.
let mut attrs = ThinVec::new();
let lo = self.span.lo;
let mut hi = self.span.hi;
let ex: ExprKind;
// Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
match self.token {
token::OpenDelim(token::Paren) => {
self.bump();
attrs.extend(self.parse_inner_attributes()?);
// (e) is parenthesized e
// (e,) is a tuple with only one field, e
let mut es = vec![];
let mut trailing_comma = false;
while self.token != token::CloseDelim(token::Paren) {
es.push(self.parse_expr()?);
self.expect_one_of(&[], &[token::Comma, token::CloseDelim(token::Paren)])?;
if self.check(&token::Comma) {
trailing_comma = true;
self.bump();
} else {
trailing_comma = false;
break;
}
}
self.bump();
hi = self.prev_span.hi;
return if es.len() == 1 && !trailing_comma {
Ok(self.mk_expr(lo, hi, ExprKind::Paren(es.into_iter().nth(0).unwrap()), attrs))
} else {
Ok(self.mk_expr(lo, hi, ExprKind::Tup(es), attrs))
}
},
token::OpenDelim(token::Brace) => {
return self.parse_block_expr(lo, BlockCheckMode::Default, attrs);
},
token::BinOp(token::Or) | token::OrOr => {
let lo = self.span.lo;
return self.parse_lambda_expr(lo, CaptureBy::Ref, attrs);
},
token::OpenDelim(token::Bracket) => {
self.bump();
attrs.extend(self.parse_inner_attributes()?);
if self.check(&token::CloseDelim(token::Bracket)) {
// Empty vector.
self.bump();
ex = ExprKind::Vec(Vec::new());
} else {
// Nonempty vector.
let first_expr = self.parse_expr()?;
if self.check(&token::Semi) {
// Repeating array syntax: [ 0; 512 ]
self.bump();
let count = self.parse_expr()?;
self.expect(&token::CloseDelim(token::Bracket))?;
ex = ExprKind::Repeat(first_expr, count);
} else if self.check(&token::Comma) {
// Vector with two or more elements.
self.bump();
let remaining_exprs = self.parse_seq_to_end(
&token::CloseDelim(token::Bracket),
SeqSep::trailing_allowed(token::Comma),
|p| Ok(p.parse_expr()?)
)?;
let mut exprs = vec![first_expr];
exprs.extend(remaining_exprs);
ex = ExprKind::Vec(exprs);
} else {
// Vector with one element.
self.expect(&token::CloseDelim(token::Bracket))?;
ex = ExprKind::Vec(vec![first_expr]);
}
}
hi = self.prev_span.hi;
}
_ => {
if self.eat_lt() {
let (qself, path) =
self.parse_qualified_path(PathStyle::Expr)?;
hi = path.span.hi;
return Ok(self.mk_expr(lo, hi, ExprKind::Path(Some(qself), path), attrs));
}
if self.eat_keyword(keywords::Move) {
let lo = self.prev_span.lo;
return self.parse_lambda_expr(lo, CaptureBy::Value, attrs);
}
if self.eat_keyword(keywords::If) {
return self.parse_if_expr(attrs);
}
if self.eat_keyword(keywords::For) {
let lo = self.prev_span.lo;
return self.parse_for_expr(None, lo, attrs);
}
if self.eat_keyword(keywords::While) {
let lo = self.prev_span.lo;
return self.parse_while_expr(None, lo, attrs);
}
if self.token.is_lifetime() {
let label = Spanned { node: self.get_lifetime(),
span: self.span };
let lo = self.span.lo;
self.bump();
self.expect(&token::Colon)?;
if self.eat_keyword(keywords::While) {
return self.parse_while_expr(Some(label), lo, attrs)
}
if self.eat_keyword(keywords::For) {
return self.parse_for_expr(Some(label), lo, attrs)
}
if self.eat_keyword(keywords::Loop) {
return self.parse_loop_expr(Some(label), lo, attrs)
}
return Err(self.fatal("expected `while`, `for`, or `loop` after a label"))
}
if self.eat_keyword(keywords::Loop) {
let lo = self.prev_span.lo;
return self.parse_loop_expr(None, lo, attrs);
}
if self.eat_keyword(keywords::Continue) {
let ex = if self.token.is_lifetime() {
let ex = ExprKind::Continue(Some(Spanned{
node: self.get_lifetime(),
span: self.span
}));
self.bump();
ex
} else {
ExprKind::Continue(None)
};
let hi = self.prev_span.hi;
return Ok(self.mk_expr(lo, hi, ex, attrs));
}
if self.eat_keyword(keywords::Match) {
return self.parse_match_expr(attrs);
}
if self.eat_keyword(keywords::Unsafe) {
return self.parse_block_expr(
lo,
BlockCheckMode::Unsafe(ast::UserProvided),
attrs);
}
if self.eat_keyword(keywords::Return) {
if self.token.can_begin_expr() {
let e = self.parse_expr()?;
hi = e.span.hi;
ex = ExprKind::Ret(Some(e));
} else {
ex = ExprKind::Ret(None);
}
} else if self.eat_keyword(keywords::Break) {
if self.token.is_lifetime() {
ex = ExprKind::Break(Some(Spanned {
node: self.get_lifetime(),
span: self.span
}));
self.bump();
} else {
ex = ExprKind::Break(None);
}
hi = self.prev_span.hi;
} else if self.token.is_keyword(keywords::Let) {
// Catch this syntax error here, instead of in `check_strict_keywords`, so
// that we can explicitly mention that let is not to be used as an expression
let mut db = self.fatal("expected expression, found statement (`let`)");
db.note("variable declaration using `let` is a statement");
return Err(db);
} else if self.token.is_path_start() {
let pth = self.parse_path(PathStyle::Expr)?;
// `!`, as an operator, is prefix, so we know this isn't that
if self.eat(&token::Not) {
// MACRO INVOCATION expression
let delim = self.expect_open_delim()?;
let tts = self.parse_seq_to_end(&token::CloseDelim(delim),
SeqSep::none(),
|p| p.parse_token_tree())?;
let hi = self.prev_span.hi;
return Ok(self.mk_mac_expr(lo, hi, Mac_ { path: pth, tts: tts }, attrs));
}
if self.check(&token::OpenDelim(token::Brace)) {
// This is a struct literal, unless we're prohibited
// from parsing struct literals here.
let prohibited = self.restrictions.contains(
Restrictions::RESTRICTION_NO_STRUCT_LITERAL
);
if !prohibited {
return self.parse_struct_expr(lo, pth, attrs);
}
}
hi = pth.span.hi;
ex = ExprKind::Path(None, pth);
} else {
match self.parse_lit() {
Ok(lit) => {
hi = lit.span.hi;
ex = ExprKind::Lit(P(lit));
}
Err(mut err) => {
self.cancel(&mut err);
let msg = format!("expected expression, found {}",
self.this_token_descr());
return Err(self.fatal(&msg));
}
}
}
}
}
return Ok(self.mk_expr(lo, hi, ex, attrs));
}
fn parse_struct_expr(&mut self, lo: BytePos, pth: ast::Path, mut attrs: ThinVec<Attribute>)
-> PResult<'a, P<Expr>> {
self.bump();
let mut fields = Vec::new();
let mut base = None;
attrs.extend(self.parse_inner_attributes()?);
while self.token != token::CloseDelim(token::Brace) {
if self.eat(&token::DotDot) {
match self.parse_expr() {
Ok(e) => {
base = Some(e);
}
Err(mut e) => {
e.emit();
self.recover_stmt();
}
}
break;
}
match self.parse_field() {
Ok(f) => fields.push(f),
Err(mut e) => {
e.emit();
self.recover_stmt();
break;
}
}
match self.expect_one_of(&[token::Comma],
&[token::CloseDelim(token::Brace)]) {
Ok(()) => {}
Err(mut e) => {
e.emit();
self.recover_stmt();
break;
}
}
}
let hi = self.span.hi;
self.expect(&token::CloseDelim(token::Brace))?;
return Ok(self.mk_expr(lo, hi, ExprKind::Struct(pth, fields, base), attrs));
}
fn parse_or_use_outer_attributes(&mut self,
already_parsed_attrs: Option<ThinVec<Attribute>>)
-> PResult<'a, ThinVec<Attribute>> {
if let Some(attrs) = already_parsed_attrs {
Ok(attrs)
} else {
self.parse_outer_attributes().map(|a| a.into())
}
}
/// Parse a block or unsafe block
pub fn parse_block_expr(&mut self, lo: BytePos, blk_mode: BlockCheckMode,
outer_attrs: ThinVec<Attribute>)
-> PResult<'a, P<Expr>> {
self.expect(&token::OpenDelim(token::Brace))?;
let mut attrs = outer_attrs;
attrs.extend(self.parse_inner_attributes()?);
let blk = self.parse_block_tail(lo, blk_mode)?;
return Ok(self.mk_expr(blk.span.lo, blk.span.hi, ExprKind::Block(blk), attrs));
}
/// parse a.b or a(13) or a[4] or just a
pub fn parse_dot_or_call_expr(&mut self,
already_parsed_attrs: Option<ThinVec<Attribute>>)
-> PResult<'a, P<Expr>> {
let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
let b = self.parse_bottom_expr();
let (span, b) = self.interpolated_or_expr_span(b)?;
self.parse_dot_or_call_expr_with(b, span.lo, attrs)
}
pub fn parse_dot_or_call_expr_with(&mut self,
e0: P<Expr>,
lo: BytePos,
mut attrs: ThinVec<Attribute>)
-> PResult<'a, P<Expr>> {
// Stitch the list of outer attributes onto the return value.
// A little bit ugly, but the best way given the current code
// structure
self.parse_dot_or_call_expr_with_(e0, lo)
.map(|expr|
expr.map(|mut expr| {
attrs.extend::<Vec<_>>(expr.attrs.into());
expr.attrs = attrs;
match expr.node {
ExprKind::If(..) | ExprKind::IfLet(..) => {
if !expr.attrs.is_empty() {
// Just point to the first attribute in there...
let span = expr.attrs[0].span;
self.span_err(span,
"attributes are not yet allowed on `if` \
expressions");
}
}
_ => {}
}
expr
})
)
}
// Assuming we have just parsed `.foo` (i.e., a dot and an ident), continue
// parsing into an expression.
fn parse_dot_suffix(&mut self,
ident: Ident,
ident_span: Span,
self_value: P<Expr>,
lo: BytePos)
-> PResult<'a, P<Expr>> {
let (_, tys, bindings) = if self.eat(&token::ModSep) {
self.expect_lt()?;
self.parse_generic_values_after_lt()?
} else {
(Vec::new(), Vec::new(), Vec::new())
};
if !bindings.is_empty() {
let prev_span = self.prev_span;
self.span_err(prev_span, "type bindings are only permitted on trait paths");
}
Ok(match self.token {
// expr.f() method call.
token::OpenDelim(token::Paren) => {
let mut es = self.parse_unspanned_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
SeqSep::trailing_allowed(token::Comma),
|p| Ok(p.parse_expr()?)
)?;
let hi = self.prev_span.hi;
es.insert(0, self_value);
let id = spanned(ident_span.lo, ident_span.hi, ident);
let nd = self.mk_method_call(id, tys, es);
self.mk_expr(lo, hi, nd, ThinVec::new())
}
// Field access.
_ => {
if !tys.is_empty() {
let prev_span = self.prev_span;
self.span_err(prev_span,
"field expressions may not \
have type parameters");
}
let id = spanned(ident_span.lo, ident_span.hi, ident);
let field = self.mk_field(self_value, id);
self.mk_expr(lo, ident_span.hi, field, ThinVec::new())
}
})
}
fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: BytePos) -> PResult<'a, P<Expr>> {
let mut e = e0;
let mut hi;
loop {
// expr?
while self.eat(&token::Question) {
let hi = self.prev_span.hi;
e = self.mk_expr(lo, hi, ExprKind::Try(e), ThinVec::new());
}
// expr.f
if self.eat(&token::Dot) {
match self.token {
token::Ident(i) => {
let dot_pos = self.prev_span.hi;
hi = self.span.hi;
self.bump();
e = self.parse_dot_suffix(i, mk_sp(dot_pos, hi), e, lo)?;
}
token::Literal(token::Integer(n), suf) => {
let sp = self.span;
// A tuple index may not have a suffix
self.expect_no_suffix(sp, "tuple index", suf);
let dot = self.prev_span.hi;
hi = self.span.hi;
self.bump();
let index = n.as_str().parse::<usize>().ok();
match index {
Some(n) => {
let id = spanned(dot, hi, n);
let field = self.mk_tup_field(e, id);
e = self.mk_expr(lo, hi, field, ThinVec::new());
}
None => {
let prev_span = self.prev_span;
self.span_err(prev_span, "invalid tuple or tuple struct index");
}
}
}
token::Literal(token::Float(n), _suf) => {
self.bump();
let prev_span = self.prev_span;
let fstr = n.as_str();
let mut err = self.diagnostic().struct_span_err(prev_span,
&format!("unexpected token: `{}`", n.as_str()));
if fstr.chars().all(|x| "0123456789.".contains(x)) {
let float = match fstr.parse::<f64>().ok() {
Some(f) => f,
None => continue,
};
err.help(&format!("try parenthesizing the first index; e.g., `(foo.{}){}`",
float.trunc() as usize,
format!(".{}", fstr.splitn(2, ".").last().unwrap())));
}
return Err(err);
}
_ => {
// FIXME Could factor this out into non_fatal_unexpected or something.
let actual = self.this_token_to_string();
self.span_err(self.span, &format!("unexpected token: `{}`", actual));
let dot_pos = self.prev_span.hi;
e = self.parse_dot_suffix(keywords::Invalid.ident(),
mk_sp(dot_pos, dot_pos),
e, lo)?;
}
}
continue;
}
if self.expr_is_complete(&e) { break; }
match self.token {
// expr(...)
token::OpenDelim(token::Paren) => {
let es = self.parse_unspanned_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
SeqSep::trailing_allowed(token::Comma),
|p| Ok(p.parse_expr()?)
)?;
hi = self.prev_span.hi;
let nd = self.mk_call(e, es);
e = self.mk_expr(lo, hi, nd, ThinVec::new());
}
// expr[...]
// Could be either an index expression or a slicing expression.
token::OpenDelim(token::Bracket) => {
self.bump();
let ix = self.parse_expr()?;
hi = self.span.hi;
self.expect(&token::CloseDelim(token::Bracket))?;
let index = self.mk_index(e, ix);
e = self.mk_expr(lo, hi, index, ThinVec::new())
}
_ => return Ok(e)
}
}
return Ok(e);
}
// Parse unquoted tokens after a `$` in a token tree
fn parse_unquoted(&mut self) -> PResult<'a, TokenTree> {
let mut sp = self.span;
let name = match self.token {
token::Dollar => {
self.bump();
if self.token == token::OpenDelim(token::Paren) {
let Spanned { node: seq, span: seq_span } = self.parse_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
SeqSep::none(),
|p| p.parse_token_tree()
)?;
let (sep, repeat) = self.parse_sep_and_kleene_op()?;
let name_num = macro_parser::count_names(&seq);
return Ok(TokenTree::Sequence(mk_sp(sp.lo, seq_span.hi),
Rc::new(SequenceRepetition {
tts: seq,
separator: sep,
op: repeat,
num_captures: name_num
})));
} else if self.token.is_keyword(keywords::Crate) {
let ident = match self.token {
token::Ident(id) => ast::Ident { name: Symbol::intern("$crate"), ..id },
_ => unreachable!(),
};
self.bump();
return Ok(TokenTree::Token(sp, token::Ident(ident)));
} else {
sp = mk_sp(sp.lo, self.span.hi);
self.parse_ident().unwrap_or_else(|mut e| {
e.emit();
keywords::Invalid.ident()
})
}
}
token::SubstNt(name) => {
self.bump();
name
}
_ => unreachable!()
};
// continue by trying to parse the `:ident` after `$name`
if self.token == token::Colon &&
self.look_ahead(1, |t| t.is_ident() && !t.is_any_keyword()) {
self.bump();
sp = mk_sp(sp.lo, self.span.hi);
let nt_kind = self.parse_ident()?;
Ok(TokenTree::Token(sp, MatchNt(name, nt_kind)))
} else {
Ok(TokenTree::Token(sp, SubstNt(name)))
}
}
pub fn check_unknown_macro_variable(&mut self) {
if self.quote_depth == 0 && !self.parsing_token_tree {
match self.token {
token::SubstNt(name) =>
self.fatal(&format!("unknown macro variable `{}`", name)).emit(),
_ => {}
}
}
}
/// Parse an optional separator followed by a Kleene-style
/// repetition token (+ or *).
pub fn parse_sep_and_kleene_op(&mut self)
-> PResult<'a, (Option<token::Token>, tokenstream::KleeneOp)> {
fn parse_kleene_op<'a>(parser: &mut Parser<'a>) ->
PResult<'a, Option<tokenstream::KleeneOp>> {
match parser.token {
token::BinOp(token::Star) => {
parser.bump();
Ok(Some(tokenstream::KleeneOp::ZeroOrMore))
},
token::BinOp(token::Plus) => {
parser.bump();
Ok(Some(tokenstream::KleeneOp::OneOrMore))
},
_ => Ok(None)
}
};
if let Some(kleene_op) = parse_kleene_op(self)? {
return Ok((None, kleene_op));
}
let separator = self.bump_and_get();
match parse_kleene_op(self)? {
Some(zerok) => Ok((Some(separator), zerok)),
None => return Err(self.fatal("expected `*` or `+`"))
}
}
/// parse a single token tree from the input.
pub fn parse_token_tree(&mut self) -> PResult<'a, TokenTree> {
// FIXME #6994: currently, this is too eager. It
// parses token trees but also identifies TokenType::Sequence's
// and token::SubstNt's; it's too early to know yet
// whether something will be a nonterminal or a seq
// yet.
match self.token {
token::Eof => {
let mut err: DiagnosticBuilder<'a> =
self.diagnostic().struct_span_err(self.span,
"this file contains an un-closed delimiter");
for &(_, sp) in &self.open_braces {
err.span_help(sp, "did you mean to close this delimiter?");
}
Err(err)
},
token::OpenDelim(delim) => {
if self.tts.last().map(|&(_, i)| i == 1).unwrap_or(false) {
let tt = self.tts.pop().unwrap().0;
self.bump();
return Ok(if self.allow_interpolated_tts {
// avoid needlessly reparsing token trees in recursive macro expansions
TokenTree::Token(tt.span(), token::Interpolated(Rc::new(token::NtTT(tt))))
} else {
tt
});
}
let parsing_token_tree = ::std::mem::replace(&mut self.parsing_token_tree, true);
// The span for beginning of the delimited section
let pre_span = self.span;
// Parse the open delimiter.
self.open_braces.push((delim, self.span));
let open_span = self.span;
self.bump();
// Parse the token trees within the delimiters.
// We stop at any delimiter so we can try to recover if the user
// uses an incorrect delimiter.
let tts = self.parse_seq_to_before_tokens(&[&token::CloseDelim(token::Brace),
&token::CloseDelim(token::Paren),
&token::CloseDelim(token::Bracket)],
SeqSep::none(),
|p| p.parse_token_tree(),
|mut e| e.emit());
let close_span = self.span;
// Expand to cover the entire delimited token tree
let span = Span { hi: close_span.hi, ..pre_span };
match self.token {
// Correct delimiter.
token::CloseDelim(d) if d == delim => {
self.open_braces.pop().unwrap();
// Parse the close delimiter.
self.bump();
}
// Incorrect delimiter.
token::CloseDelim(other) => {
let token_str = self.this_token_to_string();
let mut err = self.diagnostic().struct_span_err(self.span,
&format!("incorrect close delimiter: `{}`", token_str));
// This is a conservative error: only report the last unclosed delimiter.
// The previous unclosed delimiters could actually be closed! The parser
// just hasn't gotten to them yet.
if let Some(&(_, sp)) = self.open_braces.last() {
err.span_note(sp, "unclosed delimiter");
};
err.emit();
self.open_braces.pop().unwrap();
// If the incorrect delimiter matches an earlier opening
// delimiter, then don't consume it (it can be used to
// close the earlier one). Otherwise, consume it.
// E.g., we try to recover from:
// fn foo() {
// bar(baz(
// } // Incorrect delimiter but matches the earlier `{`
if !self.open_braces.iter().any(|&(b, _)| b == other) {
self.bump();
}
}
token::Eof => {
// Silently recover, the EOF token will be seen again
// and an error emitted then. Thus we don't pop from
// self.open_braces here.
},
_ => {}
}
self.parsing_token_tree = parsing_token_tree;
Ok(TokenTree::Delimited(span, Rc::new(Delimited {
delim: delim,
open_span: open_span,
tts: tts,
close_span: close_span,
})))
},
token::CloseDelim(_) => {
// An unexpected closing delimiter (i.e., there is no
// matching opening delimiter).
let token_str = self.this_token_to_string();
let err = self.diagnostic().struct_span_err(self.span,
&format!("unexpected close delimiter: `{}`", token_str));
Err(err)
},
/* we ought to allow different depths of unquotation */
token::Dollar | token::SubstNt(..) if self.quote_depth > 0 => {
self.parse_unquoted()
}
_ => {
Ok(TokenTree::Token(self.span, self.bump_and_get()))
}
}
}
// parse a stream of tokens into a list of TokenTree's,
// up to EOF.
pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
let mut tts = Vec::new();
while self.token != token::Eof {
tts.push(self.parse_token_tree()?);
}
Ok(tts)
}
/// Parse a prefix-unary-operator expr
pub fn parse_prefix_expr(&mut self,
already_parsed_attrs: Option<ThinVec<Attribute>>)
-> PResult<'a, P<Expr>> {
let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
let lo = self.span.lo;
let hi;
// Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
let ex = match self.token {
token::Not => {
self.bump();
let e = self.parse_prefix_expr(None);
let (span, e) = self.interpolated_or_expr_span(e)?;
hi = span.hi;
self.mk_unary(UnOp::Not, e)
}
token::BinOp(token::Minus) => {
self.bump();
let e = self.parse_prefix_expr(None);
let (span, e) = self.interpolated_or_expr_span(e)?;
hi = span.hi;
self.mk_unary(UnOp::Neg, e)
}
token::BinOp(token::Star) => {
self.bump();
let e = self.parse_prefix_expr(None);
let (span, e) = self.interpolated_or_expr_span(e)?;
hi = span.hi;
self.mk_unary(UnOp::Deref, e)
}
token::BinOp(token::And) | token::AndAnd => {
self.expect_and()?;
let m = self.parse_mutability()?;
let e = self.parse_prefix_expr(None);
let (span, e) = self.interpolated_or_expr_span(e)?;
hi = span.hi;
ExprKind::AddrOf(m, e)
}
token::Ident(..) if self.token.is_keyword(keywords::In) => {
self.bump();
let place = self.parse_expr_res(
Restrictions::RESTRICTION_NO_STRUCT_LITERAL,
None,
)?;
let blk = self.parse_block()?;
let span = blk.span;
hi = span.hi;
let blk_expr = self.mk_expr(span.lo, hi, ExprKind::Block(blk), ThinVec::new());
ExprKind::InPlace(place, blk_expr)
}
token::Ident(..) if self.token.is_keyword(keywords::Box) => {
self.bump();
let e = self.parse_prefix_expr(None);
let (span, e) = self.interpolated_or_expr_span(e)?;
hi = span.hi;
ExprKind::Box(e)
}
_ => return self.parse_dot_or_call_expr(Some(attrs))
};
return Ok(self.mk_expr(lo, hi, ex, attrs));
}
/// Parse an associative expression
///
/// This parses an expression accounting for associativity and precedence of the operators in
/// the expression.
pub fn parse_assoc_expr(&mut self,
already_parsed_attrs: Option<ThinVec<Attribute>>)
-> PResult<'a, P<Expr>> {
self.parse_assoc_expr_with(0, already_parsed_attrs.into())
}
/// Parse an associative expression with operators of at least `min_prec` precedence
pub fn parse_assoc_expr_with(&mut self,
min_prec: usize,
lhs: LhsExpr)
-> PResult<'a, P<Expr>> {
let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
expr
} else {
let attrs = match lhs {
LhsExpr::AttributesParsed(attrs) => Some(attrs),
_ => None,
};
if self.token == token::DotDot || self.token == token::DotDotDot {
return self.parse_prefix_range_expr(attrs);
} else {
self.parse_prefix_expr(attrs)?
}
};
if self.expr_is_complete(&lhs) {
// Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
return Ok(lhs);
}
self.expected_tokens.push(TokenType::Operator);
while let Some(op) = AssocOp::from_token(&self.token) {
let lhs_span = if self.prev_token_kind == PrevTokenKind::Interpolated {
self.prev_span
} else {
lhs.span
};
let cur_op_span = self.span;
let restrictions = if op.is_assign_like() {
self.restrictions & Restrictions::RESTRICTION_NO_STRUCT_LITERAL
} else {
self.restrictions
};
if op.precedence() < min_prec {
break;
}
self.bump();
if op.is_comparison() {
self.check_no_chained_comparison(&lhs, &op);
}
// Special cases:
if op == AssocOp::As {
let rhs = self.parse_ty()?;
let (lo, hi) = (lhs_span.lo, rhs.span.hi);
lhs = self.mk_expr(lo, hi, ExprKind::Cast(lhs, rhs), ThinVec::new());
continue
} else if op == AssocOp::Colon {
let rhs = self.parse_ty()?;
let (lo, hi) = (lhs_span.lo, rhs.span.hi);
lhs = self.mk_expr(lo, hi, ExprKind::Type(lhs, rhs), ThinVec::new());
continue
} else if op == AssocOp::DotDot || op == AssocOp::DotDotDot {
// If we didn’t have to handle `x..`/`x...`, it would be pretty easy to
// generalise it to the Fixity::None code.
//
// We have 2 alternatives here: `x..y`/`x...y` and `x..`/`x...` The other
// two variants are handled with `parse_prefix_range_expr` call above.
let rhs = if self.is_at_start_of_range_notation_rhs() {
Some(self.parse_assoc_expr_with(op.precedence() + 1,
LhsExpr::NotYetParsed)?)
} else {
None
};
let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
x.span
} else {
cur_op_span
});
let limits = if op == AssocOp::DotDot {
RangeLimits::HalfOpen
} else {
RangeLimits::Closed
};
let r = try!(self.mk_range(Some(lhs), rhs, limits));
lhs = self.mk_expr(lhs_span.lo, rhs_span.hi, r, ThinVec::new());
break
}
let rhs = match op.fixity() {
Fixity::Right => self.with_res(
restrictions - Restrictions::RESTRICTION_STMT_EXPR,
|this| {
this.parse_assoc_expr_with(op.precedence(),
LhsExpr::NotYetParsed)
}),
Fixity::Left => self.with_res(
restrictions - Restrictions::RESTRICTION_STMT_EXPR,
|this| {
this.parse_assoc_expr_with(op.precedence() + 1,
LhsExpr::NotYetParsed)
}),
// We currently have no non-associative operators that are not handled above by
// the special cases. The code is here only for future convenience.
Fixity::None => self.with_res(
restrictions - Restrictions::RESTRICTION_STMT_EXPR,
|this| {
this.parse_assoc_expr_with(op.precedence() + 1,
LhsExpr::NotYetParsed)
}),
}?;
let (lo, hi) = (lhs_span.lo, rhs.span.hi);
lhs = match op {
AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
AssocOp::Greater | AssocOp::GreaterEqual => {
let ast_op = op.to_ast_binop().unwrap();
let binary = self.mk_binary(codemap::respan(cur_op_span, ast_op), lhs, rhs);
self.mk_expr(lo, hi, binary, ThinVec::new())
}
AssocOp::Assign =>
self.mk_expr(lo, hi, ExprKind::Assign(lhs, rhs), ThinVec::new()),
AssocOp::Inplace =>
self.mk_expr(lo, hi, ExprKind::InPlace(lhs, rhs), ThinVec::new()),
AssocOp::AssignOp(k) => {
let aop = match k {
token::Plus => BinOpKind::Add,
token::Minus => BinOpKind::Sub,
token::Star => BinOpKind::Mul,
token::Slash => BinOpKind::Div,
token::Percent => BinOpKind::Rem,
token::Caret => BinOpKind::BitXor,
token::And => BinOpKind::BitAnd,
token::Or => BinOpKind::BitOr,
token::Shl => BinOpKind::Shl,
token::Shr => BinOpKind::Shr,
};
let aopexpr = self.mk_assign_op(codemap::respan(cur_op_span, aop), lhs, rhs);
self.mk_expr(lo, hi, aopexpr, ThinVec::new())
}
AssocOp::As | AssocOp::Colon | AssocOp::DotDot | AssocOp::DotDotDot => {
self.bug("As, Colon, DotDot or DotDotDot branch reached")
}
};
if op.fixity() == Fixity::None { break }
}
Ok(lhs)
}
/// Produce an error if comparison operators are chained (RFC #558).
/// We only need to check lhs, not rhs, because all comparison ops
/// have same precedence and are left-associative
fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: &AssocOp) {
debug_assert!(outer_op.is_comparison());
match lhs.node {
ExprKind::Binary(op, _, _) if op.node.is_comparison() => {
// respan to include both operators
let op_span = mk_sp(op.span.lo, self.span.hi);
let mut err = self.diagnostic().struct_span_err(op_span,
"chained comparison operators require parentheses");
if op.node == BinOpKind::Lt && *outer_op == AssocOp::Greater {
err.help(
"use `::<...>` instead of `<...>` if you meant to specify type arguments");
}
err.emit();
}
_ => {}
}
}
/// Parse prefix-forms of range notation: `..expr`, `..`, `...expr`
fn parse_prefix_range_expr(&mut self,
already_parsed_attrs: Option<ThinVec<Attribute>>)
-> PResult<'a, P<Expr>> {
debug_assert!(self.token == token::DotDot || self.token == token::DotDotDot);
let tok = self.token.clone();
let attrs = self.parse_or_use_outer_attributes(already_parsed_attrs)?;
let lo = self.span.lo;
let mut hi = self.span.hi;
self.bump();
let opt_end = if self.is_at_start_of_range_notation_rhs() {
// RHS must be parsed with more associativity than the dots.
let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
Some(self.parse_assoc_expr_with(next_prec,
LhsExpr::NotYetParsed)
.map(|x|{
hi = x.span.hi;
x
})?)
} else {
None
};
let limits = if tok == token::DotDot {
RangeLimits::HalfOpen
} else {
RangeLimits::Closed
};
let r = try!(self.mk_range(None,
opt_end,
limits));
Ok(self.mk_expr(lo, hi, r, attrs))
}
fn is_at_start_of_range_notation_rhs(&self) -> bool {
if self.token.can_begin_expr() {
// parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
if self.token == token::OpenDelim(token::Brace) {
return !self.restrictions.contains(Restrictions::RESTRICTION_NO_STRUCT_LITERAL);
}
true
} else {
false
}
}
/// Parse an 'if' or 'if let' expression ('if' token already eaten)
pub fn parse_if_expr(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
if self.check_keyword(keywords::Let) {
return self.parse_if_let_expr(attrs);
}
let lo = self.prev_span.lo;
let cond = self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None)?;
let thn = self.parse_block()?;
let mut els: Option<P<Expr>> = None;
let mut hi = thn.span.hi;
if self.eat_keyword(keywords::Else) {
let elexpr = self.parse_else_expr()?;
hi = elexpr.span.hi;
els = Some(elexpr);
}
Ok(self.mk_expr(lo, hi, ExprKind::If(cond, thn, els), attrs))
}
/// Parse an 'if let' expression ('if' token already eaten)
pub fn parse_if_let_expr(&mut self, attrs: ThinVec<Attribute>)
-> PResult<'a, P<Expr>> {
let lo = self.prev_span.lo;
self.expect_keyword(keywords::Let)?;
let pat = self.parse_pat()?;
self.expect(&token::Eq)?;
let expr = self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None)?;
let thn = self.parse_block()?;
let (hi, els) = if self.eat_keyword(keywords::Else) {
let expr = self.parse_else_expr()?;
(expr.span.hi, Some(expr))
} else {
(thn.span.hi, None)
};
Ok(self.mk_expr(lo, hi, ExprKind::IfLet(pat, expr, thn, els), attrs))
}
// `move |args| expr`
pub fn parse_lambda_expr(&mut self,
lo: BytePos,
capture_clause: CaptureBy,
attrs: ThinVec<Attribute>)
-> PResult<'a, P<Expr>>
{
let decl = self.parse_fn_block_decl()?;
let decl_hi = self.prev_span.hi;
let body = match decl.output {
FunctionRetTy::Default(_) => self.parse_expr()?,
_ => {
// If an explicit return type is given, require a
// block to appear (RFC 968).
let body_lo = self.span.lo;
self.parse_block_expr(body_lo, BlockCheckMode::Default, ThinVec::new())?
}
};
Ok(self.mk_expr(
lo,
body.span.hi,
ExprKind::Closure(capture_clause, decl, body, mk_sp(lo, decl_hi)),
attrs))
}
// `else` token already eaten
pub fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
if self.eat_keyword(keywords::If) {
return self.parse_if_expr(ThinVec::new());
} else {
let blk = self.parse_block()?;
return Ok(self.mk_expr(blk.span.lo, blk.span.hi, ExprKind::Block(blk), ThinVec::new()));
}
}
/// Parse a 'for' .. 'in' expression ('for' token already eaten)
pub fn parse_for_expr(&mut self, opt_ident: Option<ast::SpannedIdent>,
span_lo: BytePos,
mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
// Parse: `for <src_pat> in <src_expr> <src_loop_block>`
let pat = self.parse_pat()?;
self.expect_keyword(keywords::In)?;
let expr = self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None)?;
let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?;
attrs.extend(iattrs);
let hi = self.prev_span.hi;
Ok(self.mk_expr(span_lo, hi,
ExprKind::ForLoop(pat, expr, loop_block, opt_ident),
attrs))
}
/// Parse a 'while' or 'while let' expression ('while' token already eaten)
pub fn parse_while_expr(&mut self, opt_ident: Option<ast::SpannedIdent>,
span_lo: BytePos,
mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
if self.token.is_keyword(keywords::Let) {
return self.parse_while_let_expr(opt_ident, span_lo, attrs);
}
let cond = self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None)?;
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(iattrs);
let hi = body.span.hi;
return Ok(self.mk_expr(span_lo, hi, ExprKind::While(cond, body, opt_ident),
attrs));
}
/// Parse a 'while let' expression ('while' token already eaten)
pub fn parse_while_let_expr(&mut self, opt_ident: Option<ast::SpannedIdent>,
span_lo: BytePos,
mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
self.expect_keyword(keywords::Let)?;
let pat = self.parse_pat()?;
self.expect(&token::Eq)?;
let expr = self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None)?;
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(iattrs);
let hi = body.span.hi;
return Ok(self.mk_expr(span_lo, hi, ExprKind::WhileLet(pat, expr, body, opt_ident), attrs));
}
// parse `loop {...}`, `loop` token already eaten
pub fn parse_loop_expr(&mut self, opt_ident: Option<ast::SpannedIdent>,
span_lo: BytePos,
mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(iattrs);
let hi = body.span.hi;
Ok(self.mk_expr(span_lo, hi, ExprKind::Loop(body, opt_ident), attrs))
}
// `match` token already eaten
fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
let match_span = self.prev_span;
let lo = self.prev_span.lo;
let discriminant = self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL,
None)?;
if let Err(mut e) = self.expect(&token::OpenDelim(token::Brace)) {
if self.token == token::Token::Semi {
e.span_note(match_span, "did you mean to remove this `match` keyword?");
}
return Err(e)
}
attrs.extend(self.parse_inner_attributes()?);
let mut arms: Vec<Arm> = Vec::new();
while self.token != token::CloseDelim(token::Brace) {
match self.parse_arm() {
Ok(arm) => arms.push(arm),
Err(mut e) => {
// Recover by skipping to the end of the block.
e.emit();
self.recover_stmt();
let hi = self.span.hi;
if self.token == token::CloseDelim(token::Brace) {
self.bump();
}
return Ok(self.mk_expr(lo, hi, ExprKind::Match(discriminant, arms), attrs));
}
}
}
let hi = self.span.hi;
self.bump();
return Ok(self.mk_expr(lo, hi, ExprKind::Match(discriminant, arms), attrs));
}
pub fn parse_arm(&mut self) -> PResult<'a, Arm> {
maybe_whole!(self, NtArm, |x| x);
let attrs = self.parse_outer_attributes()?;
let pats = self.parse_pats()?;
let mut guard = None;
if self.eat_keyword(keywords::If) {
guard = Some(self.parse_expr()?);
}
self.expect(&token::FatArrow)?;
let expr = self.parse_expr_res(Restrictions::RESTRICTION_STMT_EXPR, None)?;
let require_comma =
!classify::expr_is_simple_block(&expr)
&& self.token != token::CloseDelim(token::Brace);
if require_comma {
self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Brace)])?;
} else {
self.eat(&token::Comma);
}
Ok(ast::Arm {
attrs: attrs,
pats: pats,
guard: guard,
body: expr,
})
}
/// Parse an expression
pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
self.parse_expr_res(Restrictions::empty(), None)
}
/// Evaluate the closure with restrictions in place.
///
/// After the closure is evaluated, restrictions are reset.
pub fn with_res<F, T>(&mut self, r: Restrictions, f: F) -> T
where F: FnOnce(&mut Self) -> T
{
let old = self.restrictions;
self.restrictions = r;
let r = f(self);
self.restrictions = old;
return r;
}
/// Parse an expression, subject to the given restrictions
pub fn parse_expr_res(&mut self, r: Restrictions,
already_parsed_attrs: Option<ThinVec<Attribute>>)
-> PResult<'a, P<Expr>> {
self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
}
/// Parse the RHS of a local variable declaration (e.g. '= 14;')
fn parse_initializer(&mut self) -> PResult<'a, Option<P<Expr>>> {
if self.check(&token::Eq) {
self.bump();
Ok(Some(self.parse_expr()?))
} else {
Ok(None)
}
}
/// Parse patterns, separated by '|' s
fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
let mut pats = Vec::new();
loop {
pats.push(self.parse_pat()?);
if self.check(&token::BinOp(token::Or)) { self.bump();}
else { return Ok(pats); }
};
}
fn parse_pat_tuple_elements(&mut self, unary_needs_comma: bool)
-> PResult<'a, (Vec<P<Pat>>, Option<usize>)> {
let mut fields = vec![];
let mut ddpos = None;
while !self.check(&token::CloseDelim(token::Paren)) {
if ddpos.is_none() && self.eat(&token::DotDot) {
ddpos = Some(fields.len());
if self.eat(&token::Comma) {
// `..` needs to be followed by `)` or `, pat`, `..,)` is disallowed.
fields.push(self.parse_pat()?);
}
} else if ddpos.is_some() && self.eat(&token::DotDot) {
// Emit a friendly error, ignore `..` and continue parsing
self.span_err(self.prev_span, "`..` can only be used once per \
tuple or tuple struct pattern");
} else {
fields.push(self.parse_pat()?);
}
if !self.check(&token::CloseDelim(token::Paren)) ||
(unary_needs_comma && fields.len() == 1 && ddpos.is_none()) {
self.expect(&token::Comma)?;
}
}
Ok((fields, ddpos))
}
fn parse_pat_vec_elements(
&mut self,
) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
let mut before = Vec::new();
let mut slice = None;
let mut after = Vec::new();
let mut first = true;
let mut before_slice = true;
while self.token != token::CloseDelim(token::Bracket) {
if first {
first = false;
} else {
self.expect(&token::Comma)?;
if self.token == token::CloseDelim(token::Bracket)
&& (before_slice || !after.is_empty()) {
break
}
}
if before_slice {
if self.check(&token::DotDot) {
self.bump();
if self.check(&token::Comma) ||
self.check(&token::CloseDelim(token::Bracket)) {
slice = Some(P(ast::Pat {
id: ast::DUMMY_NODE_ID,
node: PatKind::Wild,
span: self.span,
}));
before_slice = false;
}
continue
}
}
let subpat = self.parse_pat()?;
if before_slice && self.check(&token::DotDot) {
self.bump();
slice = Some(subpat);
before_slice = false;
} else if before_slice {
before.push(subpat);
} else {
after.push(subpat);
}
}
Ok((before, slice, after))
}
/// Parse the fields of a struct-like pattern
fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<codemap::Spanned<ast::FieldPat>>, bool)> {
let mut fields = Vec::new();
let mut etc = false;
let mut first = true;
while self.token != token::CloseDelim(token::Brace) {
if first {
first = false;
} else {
self.expect(&token::Comma)?;
// accept trailing commas
if self.check(&token::CloseDelim(token::Brace)) { break }
}
let lo = self.span.lo;
let hi;
if self.check(&token::DotDot) {
self.bump();
if self.token != token::CloseDelim(token::Brace) {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `{}`, found `{}`", "}",
token_str)))
}
etc = true;
break;
}
// Check if a colon exists one ahead. This means we're parsing a fieldname.
let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
// Parsing a pattern of the form "fieldname: pat"
let fieldname = self.parse_field_name()?;
self.bump();
let pat = self.parse_pat()?;
hi = pat.span.hi;
(pat, fieldname, false)
} else {
// Parsing a pattern of the form "(box) (ref) (mut) fieldname"
let is_box = self.eat_keyword(keywords::Box);
let boxed_span_lo = self.span.lo;
let is_ref = self.eat_keyword(keywords::Ref);
let is_mut = self.eat_keyword(keywords::Mut);
let fieldname = self.parse_ident()?;
hi = self.prev_span.hi;
let bind_type = match (is_ref, is_mut) {
(true, true) => BindingMode::ByRef(Mutability::Mutable),
(true, false) => BindingMode::ByRef(Mutability::Immutable),
(false, true) => BindingMode::ByValue(Mutability::Mutable),
(false, false) => BindingMode::ByValue(Mutability::Immutable),
};
let fieldpath = codemap::Spanned{span:self.prev_span, node:fieldname};
let fieldpat = P(ast::Pat{
id: ast::DUMMY_NODE_ID,
node: PatKind::Ident(bind_type, fieldpath, None),
span: mk_sp(boxed_span_lo, hi),
});
let subpat = if is_box {
P(ast::Pat{
id: ast::DUMMY_NODE_ID,
node: PatKind::Box(fieldpat),
span: mk_sp(lo, hi),
})
} else {
fieldpat
};
(subpat, fieldname, true)
};
fields.push(codemap::Spanned { span: mk_sp(lo, hi),
node: ast::FieldPat { ident: fieldname,
pat: subpat,
is_shorthand: is_shorthand }});
}
return Ok((fields, etc));
}
fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
if self.token.is_path_start() {
let lo = self.span.lo;
let (qself, path) = if self.eat_lt() {
// Parse a qualified path
let (qself, path) =
self.parse_qualified_path(PathStyle::Expr)?;
(Some(qself), path)
} else {
// Parse an unqualified path
(None, self.parse_path(PathStyle::Expr)?)
};
let hi = self.prev_span.hi;
Ok(self.mk_expr(lo, hi, ExprKind::Path(qself, path), ThinVec::new()))
} else {
self.parse_pat_literal_maybe_minus()
}
}
/// Parse a pattern.
pub fn parse_pat(&mut self) -> PResult<'a, P<Pat>> {
maybe_whole!(self, NtPat, |x| x);
let lo = self.span.lo;
let pat;
match self.token {
token::Underscore => {
// Parse _
self.bump();
pat = PatKind::Wild;
}
token::BinOp(token::And) | token::AndAnd => {
// Parse &pat / &mut pat
self.expect_and()?;
let mutbl = self.parse_mutability()?;
if let token::Lifetime(ident) = self.token {
return Err(self.fatal(&format!("unexpected lifetime `{}` in pattern", ident)));
}
let subpat = self.parse_pat()?;
pat = PatKind::Ref(subpat, mutbl);
}
token::OpenDelim(token::Paren) => {
// Parse (pat,pat,pat,...) as tuple pattern
self.bump();
let (fields, ddpos) = self.parse_pat_tuple_elements(true)?;
self.expect(&token::CloseDelim(token::Paren))?;
pat = PatKind::Tuple(fields, ddpos);
}
token::OpenDelim(token::Bracket) => {
// Parse [pat,pat,...] as slice pattern
self.bump();
let (before, slice, after) = self.parse_pat_vec_elements()?;
self.expect(&token::CloseDelim(token::Bracket))?;
pat = PatKind::Slice(before, slice, after);
}
// At this point, token != _, &, &&, (, [
_ => if self.eat_keyword(keywords::Mut) {
// Parse mut ident @ pat
pat = self.parse_pat_ident(BindingMode::ByValue(Mutability::Mutable))?;
} else if self.eat_keyword(keywords::Ref) {
// Parse ref ident @ pat / ref mut ident @ pat
let mutbl = self.parse_mutability()?;
pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
} else if self.eat_keyword(keywords::Box) {
// Parse box pat
let subpat = self.parse_pat()?;
pat = PatKind::Box(subpat);
} else if self.token.is_ident() && !self.token.is_any_keyword() &&
self.look_ahead(1, |t| match *t {
token::OpenDelim(token::Paren) | token::OpenDelim(token::Brace) |
token::DotDotDot | token::ModSep | token::Not => false,
_ => true,
}) {
// Parse ident @ pat
// This can give false positives and parse nullary enums,
// they are dealt with later in resolve
let binding_mode = BindingMode::ByValue(Mutability::Immutable);
pat = self.parse_pat_ident(binding_mode)?;
} else if self.token.is_path_start() {
// Parse pattern starting with a path
let (qself, path) = if self.eat_lt() {
// Parse a qualified path
let (qself, path) = self.parse_qualified_path(PathStyle::Expr)?;
(Some(qself), path)
} else {
// Parse an unqualified path
(None, self.parse_path(PathStyle::Expr)?)
};
match self.token {
token::Not if qself.is_none() => {
// Parse macro invocation
self.bump();
let delim = self.expect_open_delim()?;
let tts = self.parse_seq_to_end(&token::CloseDelim(delim),
SeqSep::none(),
|p| p.parse_token_tree())?;
let mac = spanned(lo, self.prev_span.hi, Mac_ { path: path, tts: tts });
pat = PatKind::Mac(mac);
}
token::DotDotDot => {
// Parse range
let hi = self.prev_span.hi;
let begin =
self.mk_expr(lo, hi, ExprKind::Path(qself, path), ThinVec::new());
self.bump();
let end = self.parse_pat_range_end()?;
pat = PatKind::Range(begin, end);
}
token::OpenDelim(token::Brace) => {
if qself.is_some() {
return Err(self.fatal("unexpected `{` after qualified path"));
}
// Parse struct pattern
self.bump();
let (fields, etc) = self.parse_pat_fields().unwrap_or_else(|mut e| {
e.emit();
self.recover_stmt();
(vec![], false)
});
self.bump();
pat = PatKind::Struct(path, fields, etc);
}
token::OpenDelim(token::Paren) => {
if qself.is_some() {
return Err(self.fatal("unexpected `(` after qualified path"));
}
// Parse tuple struct or enum pattern
self.bump();
let (fields, ddpos) = self.parse_pat_tuple_elements(false)?;
self.expect(&token::CloseDelim(token::Paren))?;
pat = PatKind::TupleStruct(path, fields, ddpos)
}
_ => pat = PatKind::Path(qself, path),
}
} else {
// Try to parse everything else as literal with optional minus
match self.parse_pat_literal_maybe_minus() {
Ok(begin) => {
if self.eat(&token::DotDotDot) {
let end = self.parse_pat_range_end()?;
pat = PatKind::Range(begin, end);
} else {
pat = PatKind::Lit(begin);
}
}
Err(mut err) => {
self.cancel(&mut err);
let msg = format!("expected pattern, found {}", self.this_token_descr());
return Err(self.fatal(&msg));
}
}
}
}
let hi = self.prev_span.hi;
Ok(P(ast::Pat {
id: ast::DUMMY_NODE_ID,
node: pat,
span: mk_sp(lo, hi),
}))
}
/// Parse ident or ident @ pat
/// used by the copy foo and ref foo patterns to give a good
/// error message when parsing mistakes like ref foo(a,b)
fn parse_pat_ident(&mut self,
binding_mode: ast::BindingMode)
-> PResult<'a, PatKind> {
let ident = self.parse_ident()?;
let prev_span = self.prev_span;
let name = codemap::Spanned{span: prev_span, node: ident};
let sub = if self.eat(&token::At) {
Some(self.parse_pat()?)
} else {
None
};
// just to be friendly, if they write something like
// ref Some(i)
// we end up here with ( as the current token. This shortly
// leads to a parse error. Note that if there is no explicit
// binding mode then we do not end up here, because the lookahead
// will direct us over to parse_enum_variant()
if self.token == token::OpenDelim(token::Paren) {
return Err(self.span_fatal(
self.prev_span,
"expected identifier, found enum pattern"))
}
Ok(PatKind::Ident(binding_mode, name, sub))
}
/// Parse a local variable declaration
fn parse_local(&mut self, attrs: ThinVec<Attribute>) -> PResult<'a, P<Local>> {
let lo = self.span.lo;
let pat = self.parse_pat()?;
let mut ty = None;
if self.eat(&token::Colon) {
ty = Some(self.parse_ty_sum()?);
}
let init = self.parse_initializer()?;
Ok(P(ast::Local {
ty: ty,
pat: pat,
init: init,
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, self.prev_span.hi),
attrs: attrs,
}))
}
/// Parse a structure field
fn parse_name_and_ty(&mut self,
lo: BytePos,
vis: Visibility,
attrs: Vec<Attribute>)
-> PResult<'a, StructField> {
let name = self.parse_ident()?;
self.expect(&token::Colon)?;
let ty = self.parse_ty_sum()?;
Ok(StructField {
span: mk_sp(lo, self.prev_span.hi),
ident: Some(name),
vis: vis,
id: ast::DUMMY_NODE_ID,
ty: ty,
attrs: attrs,
})
}
/// Emit an expected item after attributes error.
fn expected_item_err(&self, attrs: &[Attribute]) {
let message = match attrs.last() {
Some(&Attribute { is_sugared_doc: true, .. }) => "expected item after doc comment",
_ => "expected item after attributes",
};
self.span_err(self.prev_span, message);
}
/// Parse a statement. This stops just before trailing semicolons on everything but items.
/// e.g. a `StmtKind::Semi` parses to a `StmtKind::Expr`, leaving the trailing `;` unconsumed.
pub fn parse_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
Ok(self.parse_stmt_(true))
}
// Eat tokens until we can be relatively sure we reached the end of the
// statement. This is something of a best-effort heuristic.
//
// We terminate when we find an unmatched `}` (without consuming it).
fn recover_stmt(&mut self) {
self.recover_stmt_(SemiColonMode::Ignore)
}
// If `break_on_semi` is `Break`, then we will stop consuming tokens after
// finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
// approximate - it can mean we break too early due to macros, but that
// shoud only lead to sub-optimal recovery, not inaccurate parsing).
fn recover_stmt_(&mut self, break_on_semi: SemiColonMode) {
let mut brace_depth = 0;
let mut bracket_depth = 0;
debug!("recover_stmt_ enter loop");
loop {
debug!("recover_stmt_ loop {:?}", self.token);
match self.token {
token::OpenDelim(token::DelimToken::Brace) => {
brace_depth += 1;
self.bump();
}
token::OpenDelim(token::DelimToken::Bracket) => {
bracket_depth += 1;
self.bump();
}
token::CloseDelim(token::DelimToken::Brace) => {
if brace_depth == 0 {
debug!("recover_stmt_ return - close delim {:?}", self.token);
return;
}
brace_depth -= 1;
self.bump();
}
token::CloseDelim(token::DelimToken::Bracket) => {
bracket_depth -= 1;
if bracket_depth < 0 {
bracket_depth = 0;
}
self.bump();
}
token::Eof => {
debug!("recover_stmt_ return - Eof");
return;
}
token::Semi => {
self.bump();
if break_on_semi == SemiColonMode::Break &&
brace_depth == 0 &&
bracket_depth == 0 {
debug!("recover_stmt_ return - Semi");
return;
}
}
_ => {
self.bump()
}
}
}
}
fn parse_stmt_(&mut self, macro_legacy_warnings: bool) -> Option<Stmt> {
self.parse_stmt_without_recovery(macro_legacy_warnings).unwrap_or_else(|mut e| {
e.emit();
self.recover_stmt_(SemiColonMode::Break);
None
})
}
fn is_union_item(&mut self) -> bool {
self.token.is_keyword(keywords::Union) &&
self.look_ahead(1, |t| t.is_ident() && !t.is_any_keyword())
}
fn parse_stmt_without_recovery(&mut self,
macro_legacy_warnings: bool)
-> PResult<'a, Option<Stmt>> {
maybe_whole!(self, NtStmt, |x| Some(x));
let attrs = self.parse_outer_attributes()?;
let lo = self.span.lo;
Ok(Some(if self.eat_keyword(keywords::Let) {
Stmt {
id: ast::DUMMY_NODE_ID,
node: StmtKind::Local(self.parse_local(attrs.into())?),
span: mk_sp(lo, self.prev_span.hi),
}
// Starts like a simple path, but not a union item.
} else if self.token.is_path_start() &&
!self.token.is_qpath_start() &&
!self.is_union_item() {
let pth = self.parse_path(PathStyle::Expr)?;
if !self.eat(&token::Not) {
let expr = if self.check(&token::OpenDelim(token::Brace)) {
self.parse_struct_expr(lo, pth, ThinVec::new())?
} else {
let hi = self.prev_span.hi;
self.mk_expr(lo, hi, ExprKind::Path(None, pth), ThinVec::new())
};
let expr = self.with_res(Restrictions::RESTRICTION_STMT_EXPR, |this| {
let expr = this.parse_dot_or_call_expr_with(expr, lo, attrs.into())?;
this.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(expr))
})?;
return Ok(Some(Stmt {
id: ast::DUMMY_NODE_ID,
node: StmtKind::Expr(expr),
span: mk_sp(lo, self.prev_span.hi),
}));
}
// it's a macro invocation
let id = match self.token {
token::OpenDelim(_) => keywords::Invalid.ident(), // no special identifier
_ => self.parse_ident()?,
};
// check that we're pointing at delimiters (need to check
// again after the `if`, because of `parse_ident`
// consuming more tokens).
let delim = match self.token {
token::OpenDelim(delim) => delim,
_ => {
// we only expect an ident if we didn't parse one
// above.
let ident_str = if id.name == keywords::Invalid.name() {
"identifier, "
} else {
""
};
let tok_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected {}`(` or `{{`, found `{}`",
ident_str,
tok_str)))
},
};
let tts = self.parse_unspanned_seq(
&token::OpenDelim(delim),
&token::CloseDelim(delim),
SeqSep::none(),
|p| p.parse_token_tree()
)?;
let hi = self.prev_span.hi;
let style = if delim == token::Brace {
MacStmtStyle::Braces
} else {
MacStmtStyle::NoBraces
};
if id.name == keywords::Invalid.name() {
let mac = spanned(lo, hi, Mac_ { path: pth, tts: tts });
let node = if delim == token::Brace ||
self.token == token::Semi || self.token == token::Eof {
StmtKind::Mac(P((mac, style, attrs.into())))
}
// We used to incorrectly stop parsing macro-expanded statements here.
// If the next token will be an error anyway but could have parsed with the
// earlier behavior, stop parsing here and emit a warning to avoid breakage.
else if macro_legacy_warnings && self.token.can_begin_expr() && match self.token {
// These can continue an expression, so we can't stop parsing and warn.
token::OpenDelim(token::Paren) | token::OpenDelim(token::Bracket) |
token::BinOp(token::Minus) | token::BinOp(token::Star) |
token::BinOp(token::And) | token::BinOp(token::Or) |
token::AndAnd | token::OrOr |
token::DotDot | token::DotDotDot => false,
_ => true,
} {
self.warn_missing_semicolon();
StmtKind::Mac(P((mac, style, attrs.into())))
} else {
let e = self.mk_mac_expr(lo, hi, mac.node, ThinVec::new());
let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
StmtKind::Expr(e)
};
Stmt {
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, hi),
node: node,
}
} else {
// if it has a special ident, it's definitely an item
//
// Require a semicolon or braces.
if style != MacStmtStyle::Braces {
if !self.eat(&token::Semi) {
self.span_err(self.prev_span,
"macros that expand to items must \
either be surrounded with braces or \
followed by a semicolon");
}
}
Stmt {
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, hi),
node: StmtKind::Item({
self.mk_item(
lo, hi, id /*id is good here*/,
ItemKind::Mac(spanned(lo, hi, Mac_ { path: pth, tts: tts })),
Visibility::Inherited,
attrs)
}),
}
}
} else {
// FIXME: Bad copy of attrs
let restrictions = self.restrictions | Restrictions::NO_NONINLINE_MOD;
match self.with_res(restrictions,
|this| this.parse_item_(attrs.clone(), false, true))? {
Some(i) => Stmt {
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, i.span.hi),
node: StmtKind::Item(i),
},
None => {
let unused_attrs = |attrs: &[_], s: &mut Self| {
if attrs.len() > 0 {
if s.prev_token_kind == PrevTokenKind::DocComment {
s.span_err_help(s.prev_span,
"found a documentation comment that doesn't document anything",
"doc comments must come before what they document, maybe a \
comment was intended with `//`?");
} else {
s.span_err(s.span, "expected statement after outer attribute");
}
}
};
// Do not attempt to parse an expression if we're done here.
if self.token == token::Semi {
unused_attrs(&attrs, self);
self.bump();
return Ok(None);
}
if self.token == token::CloseDelim(token::Brace) {
unused_attrs(&attrs, self);
return Ok(None);
}
// Remainder are line-expr stmts.
let e = self.parse_expr_res(
Restrictions::RESTRICTION_STMT_EXPR, Some(attrs.into()))?;
Stmt {
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, e.span.hi),
node: StmtKind::Expr(e),
}
}
}
}))
}
/// Is this expression a successfully-parsed statement?
fn expr_is_complete(&mut self, e: &Expr) -> bool {
self.restrictions.contains(Restrictions::RESTRICTION_STMT_EXPR) &&
!classify::expr_requires_semi_to_be_stmt(e)
}
/// Parse a block. No inner attrs are allowed.
pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
maybe_whole!(self, NtBlock, |x| x);
let lo = self.span.lo;
if !self.eat(&token::OpenDelim(token::Brace)) {
let sp = self.span;
let tok = self.this_token_to_string();
let mut e = self.span_fatal(sp, &format!("expected `{{`, found `{}`", tok));
// Check to see if the user has written something like
//
// if (cond)
// bar;
//
// Which is valid in other languages, but not Rust.
match self.parse_stmt_without_recovery(false) {
Ok(Some(stmt)) => {
let mut stmt_span = stmt.span;
// expand the span to include the semicolon, if it exists
if self.eat(&token::Semi) {
stmt_span.hi = self.prev_span.hi;
}
e.span_help(stmt_span, "try placing this code inside a block");
}
Err(mut e) => {
self.recover_stmt_(SemiColonMode::Break);
self.cancel(&mut e);
}
_ => ()
}
return Err(e);
}
self.parse_block_tail(lo, BlockCheckMode::Default)
}
/// Parse a block. Inner attrs are allowed.
fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
maybe_whole!(self, NtBlock, |x| (Vec::new(), x));
let lo = self.span.lo;
self.expect(&token::OpenDelim(token::Brace))?;
Ok((self.parse_inner_attributes()?,
self.parse_block_tail(lo, BlockCheckMode::Default)?))
}
/// Parse the rest of a block expression or function body
/// Precondition: already parsed the '{'.
fn parse_block_tail(&mut self, lo: BytePos, s: BlockCheckMode) -> PResult<'a, P<Block>> {
let mut stmts = vec![];
while !self.eat(&token::CloseDelim(token::Brace)) {
if let Some(stmt) = self.parse_full_stmt(false)? {
stmts.push(stmt);
} else if self.token == token::Eof {
break;
} else {
// Found only `;` or `}`.
continue;
};
}
Ok(P(ast::Block {
stmts: stmts,
id: ast::DUMMY_NODE_ID,
rules: s,
span: mk_sp(lo, self.prev_span.hi),
}))
}
/// Parse a statement, including the trailing semicolon.
pub fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
let mut stmt = match self.parse_stmt_(macro_legacy_warnings) {
Some(stmt) => stmt,
None => return Ok(None),
};
match stmt.node {
StmtKind::Expr(ref expr) if self.token != token::Eof => {
// expression without semicolon
if classify::expr_requires_semi_to_be_stmt(expr) {
// Just check for errors and recover; do not eat semicolon yet.
if let Err(mut e) =
self.expect_one_of(&[], &[token::Semi, token::CloseDelim(token::Brace)])
{
e.emit();
self.recover_stmt();
}
}
}
StmtKind::Local(..) => {
// We used to incorrectly allow a macro-expanded let statement to lack a semicolon.
if macro_legacy_warnings && self.token != token::Semi {
self.warn_missing_semicolon();
} else {
self.expect_one_of(&[token::Semi], &[])?;
}
}
_ => {}
}
if self.eat(&token::Semi) {
stmt = stmt.add_trailing_semicolon();
}
stmt.span.hi = self.prev_span.hi;
Ok(Some(stmt))
}
fn warn_missing_semicolon(&self) {
self.diagnostic().struct_span_warn(self.span, {
&format!("expected `;`, found `{}`", self.this_token_to_string())
}).note({
"This was erroneously allowed and will become a hard error in a future release"
}).emit();
}
// Parses a sequence of bounds if a `:` is found,
// otherwise returns empty list.
fn parse_colon_then_ty_param_bounds(&mut self,
mode: BoundParsingMode)
-> PResult<'a, TyParamBounds>
{
if !self.eat(&token::Colon) {
Ok(P::new())
} else {
self.parse_ty_param_bounds(mode)
}
}
// matches bounds = ( boundseq )?
// where boundseq = ( polybound + boundseq ) | polybound
// and polybound = ( 'for' '<' 'region '>' )? bound
// and bound = 'region | trait_ref
fn parse_ty_param_bounds(&mut self,
mode: BoundParsingMode)
-> PResult<'a, TyParamBounds>
{
let mut result = vec![];
loop {
let question_span = self.span;
let ate_question = self.eat(&token::Question);
match self.token {
token::Lifetime(lifetime) => {
if ate_question {
self.span_err(question_span,
"`?` may only modify trait bounds, not lifetime bounds");
}
result.push(RegionTyParamBound(ast::Lifetime {
id: ast::DUMMY_NODE_ID,
span: self.span,
name: lifetime.name
}));
self.bump();
}
token::ModSep | token::Ident(..) => {
let poly_trait_ref = self.parse_poly_trait_ref()?;
let modifier = if ate_question {
if mode == BoundParsingMode::Modified {
TraitBoundModifier::Maybe
} else {
self.span_err(question_span,
"unexpected `?`");
TraitBoundModifier::None
}
} else {
TraitBoundModifier::None
};
result.push(TraitTyParamBound(poly_trait_ref, modifier))
}
_ => break,
}
if !self.eat(&token::BinOp(token::Plus)) {
break;
}
}
return Ok(P::from_vec(result));
}
/// Matches typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?
fn parse_ty_param(&mut self, preceding_attrs: Vec<ast::Attribute>) -> PResult<'a, TyParam> {
let span = self.span;
let ident = self.parse_ident()?;
let bounds = self.parse_colon_then_ty_param_bounds(BoundParsingMode::Modified)?;
let default = if self.check(&token::Eq) {
self.bump();
Some(self.parse_ty_sum()?)
} else {
None
};
Ok(TyParam {
attrs: preceding_attrs.into(),
ident: ident,
id: ast::DUMMY_NODE_ID,
bounds: bounds,
default: default,
span: span,
})
}
/// Parse a set of optional generic type parameter declarations. Where
/// clauses are not parsed here, and must be added later via
/// `parse_where_clause()`.
///
/// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
/// | ( < lifetimes , typaramseq ( , )? > )
/// where typaramseq = ( typaram ) | ( typaram , typaramseq )
pub fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
maybe_whole!(self, NtGenerics, |x| x);
let span_lo = self.span.lo;
if self.eat(&token::Lt) {
// Upon encountering attribute in generics list, we do not
// know if it is attached to lifetime or to type param.
//
// Solution: 1. eagerly parse attributes in tandem with
// lifetime defs, 2. store last set of parsed (and unused)
// attributes in `attrs`, and 3. pass in those attributes
// when parsing formal type param after lifetime defs.
let mut attrs = vec![];
let lifetime_defs = self.parse_lifetime_defs(Some(&mut attrs))?;
let mut seen_default = false;
let mut post_lifetime_attrs = Some(attrs);
let ty_params = self.parse_seq_to_gt(Some(token::Comma), |p| {
p.forbid_lifetime()?;
// Move out of `post_lifetime_attrs` if present. O/w
// not first type param: parse attributes anew.
let attrs = match post_lifetime_attrs.as_mut() {
None => p.parse_outer_attributes()?,
Some(attrs) => mem::replace(attrs, vec![]),
};
post_lifetime_attrs = None;
let ty_param = p.parse_ty_param(attrs)?;
if ty_param.default.is_some() {
seen_default = true;
} else if seen_default {
let prev_span = p.prev_span;
p.span_err(prev_span,
"type parameters with a default must be trailing");
}
Ok(ty_param)
})?;
if let Some(attrs) = post_lifetime_attrs {
if !attrs.is_empty() {
self.span_err(attrs[0].span,
"trailing attribute after lifetime parameters");
}
}
Ok(ast::Generics {
lifetimes: lifetime_defs,
ty_params: ty_params,
where_clause: WhereClause {
id: ast::DUMMY_NODE_ID,
predicates: Vec::new(),
},
span: mk_sp(span_lo, self.prev_span.hi),
})
} else {
Ok(ast::Generics::default())
}
}
fn parse_generic_values_after_lt(&mut self) -> PResult<'a, (Vec<ast::Lifetime>,
Vec<P<Ty>>,
Vec<TypeBinding>)> {
let span_lo = self.span.lo;
let lifetimes = self.parse_lifetimes(token::Comma)?;
let missing_comma = !lifetimes.is_empty() &&
!self.token.is_like_gt() &&
self.prev_token_kind != PrevTokenKind::Comma;
if missing_comma {
let msg = format!("expected `,` or `>` after lifetime \
name, found `{}`",
self.this_token_to_string());
let mut err = self.diagnostic().struct_span_err(self.span, &msg);
let span_hi = self.span.hi;
let span_hi = match self.parse_ty() {
Ok(..) => self.span.hi,
Err(ref mut err) => {
self.cancel(err);
span_hi
}
};
let msg = format!("did you mean a single argument type &'a Type, \
or did you mean the comma-separated arguments \
'a, Type?");
err.span_note(mk_sp(span_lo, span_hi), &msg);
return Err(err);
}
// First parse types.
let (types, returned) = self.parse_seq_to_gt_or_return(
Some(token::Comma),
|p| {
p.forbid_lifetime()?;
if p.look_ahead(1, |t| t == &token::Eq) {
Ok(None)
} else {
Ok(Some(p.parse_ty_sum()?))
}
}
)?;
// If we found the `>`, don't continue.
if !returned {
return Ok((lifetimes, types.into_vec(), Vec::new()));
}
// Then parse type bindings.
let bindings = self.parse_seq_to_gt(
Some(token::Comma),
|p| {
p.forbid_lifetime()?;
let lo = p.span.lo;
let ident = p.parse_ident()?;
p.expect(&token::Eq)?;
let ty = p.parse_ty()?;
let hi = ty.span.hi;
let span = mk_sp(lo, hi);
return Ok(TypeBinding{id: ast::DUMMY_NODE_ID,
ident: ident,
ty: ty,
span: span,
});
}
)?;
Ok((lifetimes, types.into_vec(), bindings.into_vec()))
}
fn forbid_lifetime(&mut self) -> PResult<'a, ()> {
if self.token.is_lifetime() {
let span = self.span;
return Err(self.diagnostic().struct_span_err(span, "lifetime parameters must be \
declared prior to type parameters"))
}
Ok(())
}
/// Parses an optional `where` clause and places it in `generics`.
///
/// ```ignore
/// where T : Trait<U, V> + 'b, 'a : 'b
/// ```
pub fn parse_where_clause(&mut self) -> PResult<'a, ast::WhereClause> {
maybe_whole!(self, NtWhereClause, |x| x);
let mut where_clause = WhereClause {
id: ast::DUMMY_NODE_ID,
predicates: Vec::new(),
};
if !self.eat_keyword(keywords::Where) {
return Ok(where_clause);
}
let mut parsed_something = false;
loop {
let lo = self.span.lo;
match self.token {
token::OpenDelim(token::Brace) => {
break
}
token::Lifetime(..) => {
let bounded_lifetime =
self.parse_lifetime()?;
self.expect(&token::Colon)?;
let bounds =
self.parse_lifetimes(token::BinOp(token::Plus))?;
let hi = self.prev_span.hi;
let span = mk_sp(lo, hi);
where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
ast::WhereRegionPredicate {
span: span,
lifetime: bounded_lifetime,
bounds: bounds
}
));
parsed_something = true;
}
_ => {
let bound_lifetimes = if self.eat_keyword(keywords::For) {
// Higher ranked constraint.
self.expect(&token::Lt)?;
let lifetime_defs = self.parse_lifetime_defs(None)?;
self.expect_gt()?;
lifetime_defs
} else {
vec![]
};
let bounded_ty = self.parse_ty()?;
if self.eat(&token::Colon) {
let bounds = self.parse_ty_param_bounds(BoundParsingMode::Bare)?;
let hi = self.prev_span.hi;
let span = mk_sp(lo, hi);
if bounds.is_empty() {
self.span_err(span,
"each predicate in a `where` clause must have \
at least one bound in it");
}
where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
ast::WhereBoundPredicate {
span: span,
bound_lifetimes: bound_lifetimes,
bounded_ty: bounded_ty,
bounds: bounds,
}));
parsed_something = true;
} else if self.eat(&token::Eq) {
// let ty = try!(self.parse_ty());
let hi = self.prev_span.hi;
let span = mk_sp(lo, hi);
// where_clause.predicates.push(
// ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
// id: ast::DUMMY_NODE_ID,
// span: span,
// path: panic!("NYI"), //bounded_ty,
// ty: ty,
// }));
// parsed_something = true;
// // FIXME(#18433)
self.span_err(span,
"equality constraints are not yet supported \
in where clauses (#20041)");
} else {
let prev_span = self.prev_span;
self.span_err(prev_span,
"unexpected token in `where` clause");
}
}
};
if !self.eat(&token::Comma) {
break
}
}
if !parsed_something {
let prev_span = self.prev_span;
self.span_err(prev_span,
"a `where` clause must have at least one predicate \
in it");
}
Ok(where_clause)
}
fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool)
-> PResult<'a, (Vec<Arg> , bool)> {
let sp = self.span;
let mut variadic = false;
let args: Vec<Option<Arg>> =
self.parse_unspanned_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
SeqSep::trailing_allowed(token::Comma),
|p| {
if p.token == token::DotDotDot {
p.bump();
if allow_variadic {
if p.token != token::CloseDelim(token::Paren) {
let span = p.span;
p.span_err(span,
"`...` must be last in argument list for variadic function");
}
} else {
let span = p.span;
p.span_err(span,
"only foreign functions are allowed to be variadic");
}
variadic = true;
Ok(None)
} else {
match p.parse_arg_general(named_args) {
Ok(arg) => Ok(Some(arg)),
Err(mut e) => {
e.emit();
p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
Ok(None)
}
}
}
}
)?;
let args: Vec<_> = args.into_iter().filter_map(|x| x).collect();
if variadic && args.is_empty() {
self.span_err(sp,
"variadic function must be declared with at least one named argument");
}
Ok((args, variadic))
}
/// Parse the argument list and result type of a function declaration
pub fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<'a, P<FnDecl>> {
let (args, variadic) = self.parse_fn_args(true, allow_variadic)?;
let ret_ty = self.parse_ret_ty()?;
Ok(P(FnDecl {
inputs: args,
output: ret_ty,
variadic: variadic
}))
}
/// Returns the parsed optional self argument and whether a self shortcut was used.
fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
let expect_ident = |this: &mut Self| match this.token {
// Preserve hygienic context.
token::Ident(ident) => { this.bump(); codemap::respan(this.prev_span, ident) }
_ => unreachable!()
};
let isolated_self = |this: &mut Self, n| {
this.look_ahead(n, |t| t.is_keyword(keywords::SelfValue)) &&
this.look_ahead(n + 1, |t| t != &token::ModSep)
};
// Parse optional self parameter of a method.
// Only a limited set of initial token sequences is considered self parameters, anything
// else is parsed as a normal function parameter list, so some lookahead is required.
let eself_lo = self.span.lo;
let (eself, eself_ident) = match self.token {
token::BinOp(token::And) => {
// &self
// &mut self
// &'lt self
// &'lt mut self
// &not_self
if isolated_self(self, 1) {
self.bump();
(SelfKind::Region(None, Mutability::Immutable), expect_ident(self))
} else if self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
isolated_self(self, 2) {
self.bump();
self.bump();
(SelfKind::Region(None, Mutability::Mutable), expect_ident(self))
} else if self.look_ahead(1, |t| t.is_lifetime()) &&
isolated_self(self, 2) {
self.bump();
let lt = self.parse_lifetime()?;
(SelfKind::Region(Some(lt), Mutability::Immutable), expect_ident(self))
} else if self.look_ahead(1, |t| t.is_lifetime()) &&
self.look_ahead(2, |t| t.is_keyword(keywords::Mut)) &&
isolated_self(self, 3) {
self.bump();
let lt = self.parse_lifetime()?;
self.bump();
(SelfKind::Region(Some(lt), Mutability::Mutable), expect_ident(self))
} else {
return Ok(None);
}
}
token::BinOp(token::Star) => {
// *self
// *const self
// *mut self
// *not_self
// Emit special error for `self` cases.
if isolated_self(self, 1) {
self.bump();
self.span_err(self.span, "cannot pass `self` by raw pointer");
(SelfKind::Value(Mutability::Immutable), expect_ident(self))
} else if self.look_ahead(1, |t| t.is_mutability()) &&
isolated_self(self, 2) {
self.bump();
self.bump();
self.span_err(self.span, "cannot pass `self` by raw pointer");
(SelfKind::Value(Mutability::Immutable), expect_ident(self))
} else {
return Ok(None);
}
}
token::Ident(..) => {
if isolated_self(self, 0) {
// self
// self: TYPE
let eself_ident = expect_ident(self);
if self.eat(&token::Colon) {
let ty = self.parse_ty_sum()?;
(SelfKind::Explicit(ty, Mutability::Immutable), eself_ident)
} else {
(SelfKind::Value(Mutability::Immutable), eself_ident)
}
} else if self.token.is_keyword(keywords::Mut) &&
isolated_self(self, 1) {
// mut self
// mut self: TYPE
self.bump();
let eself_ident = expect_ident(self);
if self.eat(&token::Colon) {
let ty = self.parse_ty_sum()?;
(SelfKind::Explicit(ty, Mutability::Mutable), eself_ident)
} else {
(SelfKind::Value(Mutability::Mutable), eself_ident)
}
} else {
return Ok(None);
}
}
_ => return Ok(None),
};
let eself = codemap::respan(mk_sp(eself_lo, self.prev_span.hi), eself);
Ok(Some(Arg::from_self(eself, eself_ident)))
}
/// Parse the parameter list and result type of a function that may have a `self` parameter.
fn parse_fn_decl_with_self<F>(&mut self, parse_arg_fn: F) -> PResult<'a, P<FnDecl>>
where F: FnMut(&mut Parser<'a>) -> PResult<'a, Arg>,
{
self.expect(&token::OpenDelim(token::Paren))?;
// Parse optional self argument
let self_arg = self.parse_self_arg()?;
// Parse the rest of the function parameter list.
let sep = SeqSep::trailing_allowed(token::Comma);
let fn_inputs = if let Some(self_arg) = self_arg {
if self.check(&token::CloseDelim(token::Paren)) {
vec![self_arg]
} else if self.eat(&token::Comma) {
let mut fn_inputs = vec![self_arg];
fn_inputs.append(&mut self.parse_seq_to_before_end(
&token::CloseDelim(token::Paren), sep, parse_arg_fn)
);
fn_inputs
} else {
return self.unexpected();
}
} else {
self.parse_seq_to_before_end(&token::CloseDelim(token::Paren), sep, parse_arg_fn)
};
// Parse closing paren and return type.
self.expect(&token::CloseDelim(token::Paren))?;
Ok(P(FnDecl {
inputs: fn_inputs,
output: self.parse_ret_ty()?,
variadic: false
}))
}
// parse the |arg, arg| header on a lambda
fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
let inputs_captures = {
if self.eat(&token::OrOr) {
Vec::new()
} else {
self.expect(&token::BinOp(token::Or))?;
let args = self.parse_seq_to_before_end(
&token::BinOp(token::Or),
SeqSep::trailing_allowed(token::Comma),
|p| p.parse_fn_block_arg()
);
self.bump();
args
}
};
let output = self.parse_ret_ty()?;
Ok(P(FnDecl {
inputs: inputs_captures,
output: output,
variadic: false
}))
}
/// Parse the name and optional generic types of a function header.
fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
let id = self.parse_ident()?;
let generics = self.parse_generics()?;
Ok((id, generics))
}
fn mk_item(&mut self, lo: BytePos, hi: BytePos, ident: Ident,
node: ItemKind, vis: Visibility,
attrs: Vec<Attribute>) -> P<Item> {
P(Item {
ident: ident,
attrs: attrs,
id: ast::DUMMY_NODE_ID,
node: node,
vis: vis,
span: mk_sp(lo, hi)
})
}
/// Parse an item-position function declaration.
fn parse_item_fn(&mut self,
unsafety: Unsafety,
constness: Spanned<Constness>,
abi: abi::Abi)
-> PResult<'a, ItemInfo> {
let (ident, mut generics) = self.parse_fn_header()?;
let decl = self.parse_fn_decl(false)?;
generics.where_clause = self.parse_where_clause()?;
let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
Ok((ident, ItemKind::Fn(decl, unsafety, constness, abi, generics, body), Some(inner_attrs)))
}
/// true if we are looking at `const ID`, false for things like `const fn` etc
pub fn is_const_item(&mut self) -> bool {
self.token.is_keyword(keywords::Const) &&
!self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) &&
!self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe))
}
/// parses all the "front matter" for a `fn` declaration, up to
/// and including the `fn` keyword:
///
/// - `const fn`
/// - `unsafe fn`
/// - `const unsafe fn`
/// - `extern fn`
/// - etc
pub fn parse_fn_front_matter(&mut self)
-> PResult<'a, (Spanned<ast::Constness>,
ast::Unsafety,
abi::Abi)> {
let is_const_fn = self.eat_keyword(keywords::Const);
let const_span = self.prev_span;
let unsafety = self.parse_unsafety()?;
let (constness, unsafety, abi) = if is_const_fn {
(respan(const_span, Constness::Const), unsafety, Abi::Rust)
} else {
let abi = if self.eat_keyword(keywords::Extern) {
self.parse_opt_abi()?.unwrap_or(Abi::C)
} else {
Abi::Rust
};
(respan(self.prev_span, Constness::NotConst), unsafety, abi)
};
self.expect_keyword(keywords::Fn)?;
Ok((constness, unsafety, abi))
}
/// Parse an impl item.
pub fn parse_impl_item(&mut self) -> PResult<'a, ImplItem> {
maybe_whole!(self, NtImplItem, |x| x);
let mut attrs = self.parse_outer_attributes()?;
let lo = self.span.lo;
let vis = self.parse_visibility(true)?;
let defaultness = self.parse_defaultness()?;
let (name, node) = if self.eat_keyword(keywords::Type) {
let name = self.parse_ident()?;
self.expect(&token::Eq)?;
let typ = self.parse_ty_sum()?;
self.expect(&token::Semi)?;
(name, ast::ImplItemKind::Type(typ))
} else if self.is_const_item() {
self.expect_keyword(keywords::Const)?;
let name = self.parse_ident()?;
self.expect(&token::Colon)?;
let typ = self.parse_ty_sum()?;
self.expect(&token::Eq)?;
let expr = self.parse_expr()?;
self.expect(&token::Semi)?;
(name, ast::ImplItemKind::Const(typ, expr))
} else {
let (name, inner_attrs, node) = self.parse_impl_method(&vis)?;
attrs.extend(inner_attrs);
(name, node)
};
Ok(ImplItem {
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, self.prev_span.hi),
ident: name,
vis: vis,
defaultness: defaultness,
attrs: attrs,
node: node
})
}
fn complain_if_pub_macro(&mut self, visa: &Visibility, span: Span) {
match *visa {
Visibility::Inherited => (),
_ => {
let is_macro_rules: bool = match self.token {
token::Ident(sid) => sid.name == Symbol::intern("macro_rules"),
_ => false,
};
if is_macro_rules {
self.diagnostic().struct_span_err(span, "can't qualify macro_rules \
invocation with `pub`")
.help("did you mean #[macro_export]?")
.emit();
} else {
self.diagnostic().struct_span_err(span, "can't qualify macro \
invocation with `pub`")
.help("try adjusting the macro to put `pub` \
inside the invocation")
.emit();
}
}
}
}
/// Parse a method or a macro invocation in a trait impl.
fn parse_impl_method(&mut self, vis: &Visibility)
-> PResult<'a, (Ident, Vec<ast::Attribute>, ast::ImplItemKind)> {
// code copied from parse_macro_use_or_failure... abstraction!
if self.token.is_path_start() {
// method macro.
let prev_span = self.prev_span;
self.complain_if_pub_macro(&vis, prev_span);
let lo = self.span.lo;
let pth = self.parse_path(PathStyle::Mod)?;
self.expect(&token::Not)?;
// eat a matched-delimiter token tree:
let delim = self.expect_open_delim()?;
let tts = self.parse_seq_to_end(&token::CloseDelim(delim),
SeqSep::none(),
|p| p.parse_token_tree())?;
if delim != token::Brace {
self.expect(&token::Semi)?
}
let mac = spanned(lo, self.prev_span.hi, Mac_ { path: pth, tts: tts });
Ok((keywords::Invalid.ident(), vec![], ast::ImplItemKind::Macro(mac)))
} else {
let (constness, unsafety, abi) = self.parse_fn_front_matter()?;
let ident = self.parse_ident()?;
let mut generics = self.parse_generics()?;
let decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?;
generics.where_clause = self.parse_where_clause()?;
let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
Ok((ident, inner_attrs, ast::ImplItemKind::Method(ast::MethodSig {
generics: generics,
abi: abi,
unsafety: unsafety,
constness: constness,
decl: decl
}, body)))
}
}
/// Parse trait Foo { ... }
fn parse_item_trait(&mut self, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
let ident = self.parse_ident()?;
let mut tps = self.parse_generics()?;
// Parse supertrait bounds.
let bounds = self.parse_colon_then_ty_param_bounds(BoundParsingMode::Bare)?;
tps.where_clause = self.parse_where_clause()?;
let meths = self.parse_trait_items()?;
Ok((ident, ItemKind::Trait(unsafety, tps, bounds, meths), None))
}
/// Parses items implementations variants
/// impl<T> Foo { ... }
/// impl<T> ToString for &'static T { ... }
/// impl Send for .. {}
fn parse_item_impl(&mut self, unsafety: ast::Unsafety) -> PResult<'a, ItemInfo> {
let impl_span = self.span;
// First, parse type parameters if necessary.
let mut generics = self.parse_generics()?;
// Special case: if the next identifier that follows is '(', don't
// allow this to be parsed as a trait.
let could_be_trait = self.token != token::OpenDelim(token::Paren);
let neg_span = self.span;
let polarity = if self.eat(&token::Not) {
ast::ImplPolarity::Negative
} else {
ast::ImplPolarity::Positive
};
// Parse the trait.
let mut ty = self.parse_ty_sum()?;
// Parse traits, if necessary.
let opt_trait = if could_be_trait && self.eat_keyword(keywords::For) {
// New-style trait. Reinterpret the type as a trait.
match ty.node {
TyKind::Path(None, ref path) => {
Some(TraitRef {
path: (*path).clone(),
ref_id: ty.id,
})
}
_ => {
self.span_err(ty.span, "not a trait");
None
}
}
} else {
match polarity {
ast::ImplPolarity::Negative => {
// This is a negated type implementation
// `impl !MyType {}`, which is not allowed.
self.span_err(neg_span, "inherent implementation can't be negated");
},
_ => {}
}
None
};
if opt_trait.is_some() && self.eat(&token::DotDot) {
if generics.is_parameterized() {
self.span_err(impl_span, "default trait implementations are not \
allowed to have generics");
}
self.expect(&token::OpenDelim(token::Brace))?;
self.expect(&token::CloseDelim(token::Brace))?;
Ok((keywords::Invalid.ident(),
ItemKind::DefaultImpl(unsafety, opt_trait.unwrap()), None))
} else {
if opt_trait.is_some() {
ty = self.parse_ty_sum()?;
}
generics.where_clause = self.parse_where_clause()?;
self.expect(&token::OpenDelim(token::Brace))?;
let attrs = self.parse_inner_attributes()?;
let mut impl_items = vec![];
while !self.eat(&token::CloseDelim(token::Brace)) {
impl_items.push(self.parse_impl_item()?);
}
Ok((keywords::Invalid.ident(),
ItemKind::Impl(unsafety, polarity, generics, opt_trait, ty, impl_items),
Some(attrs)))
}
}
/// Parse a::B<String,i32>
fn parse_trait_ref(&mut self) -> PResult<'a, TraitRef> {
Ok(ast::TraitRef {
path: self.parse_path(PathStyle::Type)?,
ref_id: ast::DUMMY_NODE_ID,
})
}
fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<ast::LifetimeDef>> {
if self.eat_keyword(keywords::For) {
self.expect(&token::Lt)?;
let lifetime_defs = self.parse_lifetime_defs(None)?;
self.expect_gt()?;
Ok(lifetime_defs)
} else {
Ok(Vec::new())
}
}
/// Parse for<'l> a::B<String,i32>
fn parse_poly_trait_ref(&mut self) -> PResult<'a, PolyTraitRef> {
let lo = self.span.lo;
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
Ok(ast::PolyTraitRef {
bound_lifetimes: lifetime_defs,
trait_ref: self.parse_trait_ref()?,
span: mk_sp(lo, self.prev_span.hi),
})
}
/// Parse struct Foo { ... }
fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
let class_name = self.parse_ident()?;
let mut generics = self.parse_generics()?;
// There is a special case worth noting here, as reported in issue #17904.
// If we are parsing a tuple struct it is the case that the where clause
// should follow the field list. Like so:
//
// struct Foo<T>(T) where T: Copy;
//
// If we are parsing a normal record-style struct it is the case
// that the where clause comes before the body, and after the generics.
// So if we look ahead and see a brace or a where-clause we begin
// parsing a record style struct.
//
// Otherwise if we look ahead and see a paren we parse a tuple-style
// struct.
let vdata = if self.token.is_keyword(keywords::Where) {
generics.where_clause = self.parse_where_clause()?;
if self.eat(&token::Semi) {
// If we see a: `struct Foo<T> where T: Copy;` style decl.
VariantData::Unit(ast::DUMMY_NODE_ID)
} else {
// If we see: `struct Foo<T> where T: Copy { ... }`
VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
}
// No `where` so: `struct Foo<T>;`
} else if self.eat(&token::Semi) {
VariantData::Unit(ast::DUMMY_NODE_ID)
// Record-style struct definition
} else if self.token == token::OpenDelim(token::Brace) {
VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
// Tuple-style struct definition with optional where-clause.
} else if self.token == token::OpenDelim(token::Paren) {
let body = VariantData::Tuple(self.parse_tuple_struct_body()?, ast::DUMMY_NODE_ID);
generics.where_clause = self.parse_where_clause()?;
self.expect(&token::Semi)?;
body
} else {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `where`, `{{`, `(`, or `;` after struct \
name, found `{}`", token_str)))
};
Ok((class_name, ItemKind::Struct(vdata, generics), None))
}
/// Parse union Foo { ... }
fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
let class_name = self.parse_ident()?;
let mut generics = self.parse_generics()?;
let vdata = if self.token.is_keyword(keywords::Where) {
generics.where_clause = self.parse_where_clause()?;
VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
} else if self.token == token::OpenDelim(token::Brace) {
VariantData::Struct(self.parse_record_struct_body()?, ast::DUMMY_NODE_ID)
} else {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `where` or `{{` after union \
name, found `{}`", token_str)))
};
Ok((class_name, ItemKind::Union(vdata, generics), None))
}
pub fn parse_record_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
let mut fields = Vec::new();
if self.eat(&token::OpenDelim(token::Brace)) {
while self.token != token::CloseDelim(token::Brace) {
fields.push(self.parse_struct_decl_field().map_err(|e| {
self.recover_stmt();
self.eat(&token::CloseDelim(token::Brace));
e
})?);
}
self.bump();
} else {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `where`, or `{{` after struct \
name, found `{}`",
token_str)));
}
Ok(fields)
}
pub fn parse_tuple_struct_body(&mut self) -> PResult<'a, Vec<StructField>> {
// This is the case where we find `struct Foo<T>(T) where T: Copy;`
// Unit like structs are handled in parse_item_struct function
let fields = self.parse_unspanned_seq(
&token::OpenDelim(token::Paren),
&token::CloseDelim(token::Paren),
SeqSep::trailing_allowed(token::Comma),
|p| {
let attrs = p.parse_outer_attributes()?;
let lo = p.span.lo;
let mut vis = p.parse_visibility(false)?;
let ty_is_interpolated =
p.token.is_interpolated() || p.look_ahead(1, |t| t.is_interpolated());
let mut ty = p.parse_ty_sum()?;
// Handle `pub(path) type`, in which `vis` will be `pub` and `ty` will be `(path)`.
if vis == Visibility::Public && !ty_is_interpolated &&
p.token != token::Comma && p.token != token::CloseDelim(token::Paren) {
ty = if let TyKind::Paren(ref path_ty) = ty.node {
if let TyKind::Path(None, ref path) = path_ty.node {
vis = Visibility::Restricted { path: P(path.clone()), id: path_ty.id };
Some(p.parse_ty_sum()?)
} else {
None
}
} else {
None
}.unwrap_or(ty);
}
Ok(StructField {
span: mk_sp(lo, p.span.hi),
vis: vis,
ident: None,
id: ast::DUMMY_NODE_ID,
ty: ty,
attrs: attrs,
})
})?;
Ok(fields)
}
/// Parse a structure field declaration
pub fn parse_single_struct_field(&mut self,
lo: BytePos,
vis: Visibility,
attrs: Vec<Attribute> )
-> PResult<'a, StructField> {
let a_var = self.parse_name_and_ty(lo, vis, attrs)?;
match self.token {
token::Comma => {
self.bump();
}
token::CloseDelim(token::Brace) => {}
token::DocComment(_) => return Err(self.span_fatal_help(self.span,
"found a documentation comment that doesn't document anything",
"doc comments must come before what they document, maybe a comment was \
intended with `//`?")),
_ => return Err(self.span_fatal_help(self.span,
&format!("expected `,`, or `}}`, found `{}`", self.this_token_to_string()),
"struct fields should be separated by commas")),
}
Ok(a_var)
}
/// Parse an element of a struct definition
fn parse_struct_decl_field(&mut self) -> PResult<'a, StructField> {
let attrs = self.parse_outer_attributes()?;
let lo = self.span.lo;
let vis = self.parse_visibility(true)?;
self.parse_single_struct_field(lo, vis, attrs)
}
// If `allow_path` is false, just parse the `pub` in `pub(path)` (but still parse `pub(crate)`)
fn parse_visibility(&mut self, allow_path: bool) -> PResult<'a, Visibility> {
let pub_crate = |this: &mut Self| {
let span = this.prev_span;
this.expect(&token::CloseDelim(token::Paren))?;
Ok(Visibility::Crate(span))
};
if !self.eat_keyword(keywords::Pub) {
Ok(Visibility::Inherited)
} else if !allow_path {
// Look ahead to avoid eating the `(` in `pub(path)` while still parsing `pub(crate)`
if self.token == token::OpenDelim(token::Paren) &&
self.look_ahead(1, |t| t.is_keyword(keywords::Crate)) {
self.bump(); self.bump();
pub_crate(self)
} else {
Ok(Visibility::Public)
}
} else if !self.eat(&token::OpenDelim(token::Paren)) {
Ok(Visibility::Public)
} else if self.eat_keyword(keywords::Crate) {
pub_crate(self)
} else {
let path = self.parse_path(PathStyle::Mod)?;
self.expect(&token::CloseDelim(token::Paren))?;
Ok(Visibility::Restricted { path: P(path), id: ast::DUMMY_NODE_ID })
}
}
/// Parse defaultness: DEFAULT or nothing
fn parse_defaultness(&mut self) -> PResult<'a, Defaultness> {
if self.eat_contextual_keyword(keywords::Default.ident()) {
Ok(Defaultness::Default)
} else {
Ok(Defaultness::Final)
}
}
/// Given a termination token, parse all of the items in a module
fn parse_mod_items(&mut self, term: &token::Token, inner_lo: BytePos) -> PResult<'a, Mod> {
let mut items = vec![];
while let Some(item) = self.parse_item()? {
items.push(item);
}
if !self.eat(term) {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected item, found `{}`", token_str)));
}
let hi = if self.span == syntax_pos::DUMMY_SP {
inner_lo
} else {
self.prev_span.hi
};
Ok(ast::Mod {
inner: mk_sp(inner_lo, hi),
items: items
})
}
fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
let id = self.parse_ident()?;
self.expect(&token::Colon)?;
let ty = self.parse_ty_sum()?;
self.expect(&token::Eq)?;
let e = self.parse_expr()?;
self.expect(&token::Semi)?;
let item = match m {
Some(m) => ItemKind::Static(ty, m, e),
None => ItemKind::Const(ty, e),
};
Ok((id, item, None))
}
/// Parse a `mod <foo> { ... }` or `mod <foo>;` item
fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
let (in_cfg, outer_attrs) = {
let mut strip_unconfigured = ::config::StripUnconfigured {
sess: self.sess,
should_test: false, // irrelevant
features: None, // don't perform gated feature checking
};
let outer_attrs = strip_unconfigured.process_cfg_attrs(outer_attrs.to_owned());
(strip_unconfigured.in_cfg(&outer_attrs), outer_attrs)
};
let id_span = self.span;
let id = self.parse_ident()?;
if self.check(&token::Semi) {
self.bump();
if in_cfg {
// This mod is in an external file. Let's go get it!
let (m, attrs) = self.eval_src_mod(id, &outer_attrs, id_span)?;
Ok((id, m, Some(attrs)))
} else {
let placeholder = ast::Mod { inner: syntax_pos::DUMMY_SP, items: Vec::new() };
Ok((id, ItemKind::Mod(placeholder), None))
}
} else {
let directory = self.directory.clone();
let restrictions = self.push_directory(id, &outer_attrs);
self.expect(&token::OpenDelim(token::Brace))?;
let mod_inner_lo = self.span.lo;
let attrs = self.parse_inner_attributes()?;
let m = self.with_res(restrictions, |this| {
this.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)
})?;
self.directory = directory;
Ok((id, ItemKind::Mod(m), Some(attrs)))
}
}
fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) -> Restrictions {
if let Some(path) = ::attr::first_attr_value_str_by_name(attrs, "path") {
self.directory.push(&*path.as_str());
self.restrictions - Restrictions::NO_NONINLINE_MOD
} else {
self.directory.push(&*id.name.as_str());
self.restrictions
}
}
pub fn submod_path_from_attr(attrs: &[ast::Attribute], dir_path: &Path) -> Option<PathBuf> {
::attr::first_attr_value_str_by_name(attrs, "path").map(|d| dir_path.join(&*d.as_str()))
}
/// Returns either a path to a module, or .
pub fn default_submod_path(id: ast::Ident, dir_path: &Path, codemap: &CodeMap) -> ModulePath
{
let mod_name = id.to_string();
let default_path_str = format!("{}.rs", mod_name);
let secondary_path_str = format!("{}/mod.rs", mod_name);
let default_path = dir_path.join(&default_path_str);
let secondary_path = dir_path.join(&secondary_path_str);
let default_exists = codemap.file_exists(&default_path);
let secondary_exists = codemap.file_exists(&secondary_path);
let result = match (default_exists, secondary_exists) {
(true, false) => Ok(ModulePathSuccess { path: default_path, owns_directory: false }),
(false, true) => Ok(ModulePathSuccess { path: secondary_path, owns_directory: true }),
(false, false) => Err(ModulePathError {
err_msg: format!("file not found for module `{}`", mod_name),
help_msg: format!("name the file either {} or {} inside the directory {:?}",
default_path_str,
secondary_path_str,
dir_path.display()),
}),
(true, true) => Err(ModulePathError {
err_msg: format!("file for module `{}` found at both {} and {}",
mod_name,
default_path_str,
secondary_path_str),
help_msg: "delete or rename one of them to remove the ambiguity".to_owned(),
}),
};
ModulePath {
name: mod_name,
path_exists: default_exists || secondary_exists,
result: result,
}
}
fn submod_path(&mut self,
id: ast::Ident,
outer_attrs: &[ast::Attribute],
id_sp: Span) -> PResult<'a, ModulePathSuccess> {
if let Some(p) = Parser::submod_path_from_attr(outer_attrs, &self.directory) {
return Ok(ModulePathSuccess { path: p, owns_directory: true });
}
let paths = Parser::default_submod_path(id, &self.directory, self.sess.codemap());
if self.restrictions.contains(Restrictions::NO_NONINLINE_MOD) {
let msg =
"Cannot declare a non-inline module inside a block unless it has a path attribute";
let mut err = self.diagnostic().struct_span_err(id_sp, msg);
if paths.path_exists {
let msg = format!("Maybe `use` the module `{}` instead of redeclaring it",
paths.name);
err.span_note(id_sp, &msg);
}
return Err(err);
} else if !self.owns_directory {
let mut err = self.diagnostic().struct_span_err(id_sp,
"cannot declare a new module at this location");
let this_module = match self.directory.file_name() {
Some(file_name) => file_name.to_str().unwrap().to_owned(),
None => self.root_module_name.as_ref().unwrap().clone(),
};
err.span_note(id_sp,
&format!("maybe move this module `{0}` to its own directory \
via `{0}/mod.rs`",
this_module));
if paths.path_exists {
err.span_note(id_sp,
&format!("... or maybe `use` the module `{}` instead \
of possibly redeclaring it",
paths.name));
}
return Err(err);
}
match paths.result {
Ok(succ) => Ok(succ),
Err(err) => Err(self.span_fatal_help(id_sp, &err.err_msg, &err.help_msg)),
}
}
/// Read a module from a source file.
fn eval_src_mod(&mut self,
id: ast::Ident,
outer_attrs: &[ast::Attribute],
id_sp: Span)
-> PResult<'a, (ast::ItemKind, Vec<ast::Attribute> )> {
let ModulePathSuccess { path, owns_directory } = self.submod_path(id,
outer_attrs,
id_sp)?;
self.eval_src_mod_from_path(path,
owns_directory,
id.to_string(),
id_sp)
}
fn eval_src_mod_from_path(&mut self,
path: PathBuf,
owns_directory: bool,
name: String,
id_sp: Span) -> PResult<'a, (ast::ItemKind, Vec<ast::Attribute> )> {
let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
let mut err = String::from("circular modules: ");
let len = included_mod_stack.len();
for p in &included_mod_stack[i.. len] {
err.push_str(&p.to_string_lossy());
err.push_str(" -> ");
}
err.push_str(&path.to_string_lossy());
return Err(self.span_fatal(id_sp, &err[..]));
}
included_mod_stack.push(path.clone());
drop(included_mod_stack);
let mut p0 = new_sub_parser_from_file(self.sess, &path, owns_directory, Some(name), id_sp);
let mod_inner_lo = p0.span.lo;
let mod_attrs = p0.parse_inner_attributes()?;
let m0 = p0.parse_mod_items(&token::Eof, mod_inner_lo)?;
self.sess.included_mod_stack.borrow_mut().pop();
Ok((ast::ItemKind::Mod(m0), mod_attrs))
}
/// Parse a function declaration from a foreign module
fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: BytePos,
attrs: Vec<Attribute>) -> PResult<'a, ForeignItem> {
self.expect_keyword(keywords::Fn)?;
let (ident, mut generics) = self.parse_fn_header()?;
let decl = self.parse_fn_decl(true)?;
generics.where_clause = self.parse_where_clause()?;
let hi = self.span.hi;
self.expect(&token::Semi)?;
Ok(ast::ForeignItem {
ident: ident,
attrs: attrs,
node: ForeignItemKind::Fn(decl, generics),
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, hi),
vis: vis
})
}
/// Parse a static item from a foreign module
fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: BytePos,
attrs: Vec<Attribute>) -> PResult<'a, ForeignItem> {
self.expect_keyword(keywords::Static)?;
let mutbl = self.eat_keyword(keywords::Mut);
let ident = self.parse_ident()?;
self.expect(&token::Colon)?;
let ty = self.parse_ty_sum()?;
let hi = self.span.hi;
self.expect(&token::Semi)?;
Ok(ForeignItem {
ident: ident,
attrs: attrs,
node: ForeignItemKind::Static(ty, mutbl),
id: ast::DUMMY_NODE_ID,
span: mk_sp(lo, hi),
vis: vis
})
}
/// Parse extern crate links
///
/// # Examples
///
/// extern crate foo;
/// extern crate bar as foo;
fn parse_item_extern_crate(&mut self,
lo: BytePos,
visibility: Visibility,
attrs: Vec<Attribute>)
-> PResult<'a, P<Item>> {
let crate_name = self.parse_ident()?;
let (maybe_path, ident) = if let Some(ident) = self.parse_rename()? {
(Some(crate_name.name), ident)
} else {
(None, crate_name)
};
self.expect(&token::Semi)?;
let prev_span = self.prev_span;
Ok(self.mk_item(lo,
prev_span.hi,
ident,
ItemKind::ExternCrate(maybe_path),
visibility,
attrs))
}
/// Parse `extern` for foreign ABIs
/// modules.
///
/// `extern` is expected to have been
/// consumed before calling this method
///
/// # Examples:
///
/// extern "C" {}
/// extern {}
fn parse_item_foreign_mod(&mut self,
lo: BytePos,
opt_abi: Option<abi::Abi>,
visibility: Visibility,
mut attrs: Vec<Attribute>)
-> PResult<'a, P<Item>> {
self.expect(&token::OpenDelim(token::Brace))?;
let abi = opt_abi.unwrap_or(Abi::C);
attrs.extend(self.parse_inner_attributes()?);
let mut foreign_items = vec![];
while let Some(item) = self.parse_foreign_item()? {
foreign_items.push(item);
}
self.expect(&token::CloseDelim(token::Brace))?;
let prev_span = self.prev_span;
let m = ast::ForeignMod {
abi: abi,
items: foreign_items
};
Ok(self.mk_item(lo,
prev_span.hi,
keywords::Invalid.ident(),
ItemKind::ForeignMod(m),
visibility,
attrs))
}
/// Parse type Foo = Bar;
fn parse_item_type(&mut self) -> PResult<'a, ItemInfo> {
let ident = self.parse_ident()?;
let mut tps = self.parse_generics()?;
tps.where_clause = self.parse_where_clause()?;
self.expect(&token::Eq)?;
let ty = self.parse_ty_sum()?;
self.expect(&token::Semi)?;
Ok((ident, ItemKind::Ty(ty, tps), None))
}
/// Parse the part of an "enum" decl following the '{'
fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
let mut variants = Vec::new();
let mut all_nullary = true;
let mut any_disr = None;
while self.token != token::CloseDelim(token::Brace) {
let variant_attrs = self.parse_outer_attributes()?;
let vlo = self.span.lo;
let struct_def;
let mut disr_expr = None;
let ident = self.parse_ident()?;
if self.check(&token::OpenDelim(token::Brace)) {
// Parse a struct variant.
all_nullary = false;
struct_def = VariantData::Struct(self.parse_record_struct_body()?,
ast::DUMMY_NODE_ID);
} else if self.check(&token::OpenDelim(token::Paren)) {
all_nullary = false;
struct_def = VariantData::Tuple(self.parse_tuple_struct_body()?,
ast::DUMMY_NODE_ID);
} else if self.eat(&token::Eq) {
disr_expr = Some(self.parse_expr()?);
any_disr = disr_expr.as_ref().map(|expr| expr.span);
struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
} else {
struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
}
let vr = ast::Variant_ {
name: ident,
attrs: variant_attrs,
data: struct_def,
disr_expr: disr_expr,
};
variants.push(spanned(vlo, self.prev_span.hi, vr));
if !self.eat(&token::Comma) { break; }
}
self.expect(&token::CloseDelim(token::Brace))?;
match any_disr {
Some(disr_span) if !all_nullary =>
self.span_err(disr_span,
"discriminator values can only be used with a c-like enum"),
_ => ()
}
Ok(ast::EnumDef { variants: variants })
}
/// Parse an "enum" declaration
fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
let id = self.parse_ident()?;
let mut generics = self.parse_generics()?;
generics.where_clause = self.parse_where_clause()?;
self.expect(&token::OpenDelim(token::Brace))?;
let enum_definition = self.parse_enum_def(&generics).map_err(|e| {
self.recover_stmt();
self.eat(&token::CloseDelim(token::Brace));
e
})?;
Ok((id, ItemKind::Enum(enum_definition, generics), None))
}
/// Parses a string as an ABI spec on an extern type or module. Consumes
/// the `extern` keyword, if one is found.
fn parse_opt_abi(&mut self) -> PResult<'a, Option<abi::Abi>> {
match self.token {
token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
let sp = self.span;
self.expect_no_suffix(sp, "ABI spec", suf);
self.bump();
match abi::lookup(&s.as_str()) {
Some(abi) => Ok(Some(abi)),
None => {
let prev_span = self.prev_span;
self.span_err(
prev_span,
&format!("invalid ABI: expected one of [{}], \
found `{}`",
abi::all_names().join(", "),
s));
Ok(None)
}
}
}
_ => Ok(None),
}
}
/// Parse one of the items allowed by the flags.
/// NB: this function no longer parses the items inside an
/// extern crate.
fn parse_item_(&mut self, attrs: Vec<Attribute>,
macros_allowed: bool, attributes_allowed: bool) -> PResult<'a, Option<P<Item>>> {
maybe_whole!(self, NtItem, |item| {
let mut item = item.unwrap();
let mut attrs = attrs;
mem::swap(&mut item.attrs, &mut attrs);
item.attrs.extend(attrs);
Some(P(item))
});
let lo = self.span.lo;
let visibility = self.parse_visibility(true)?;
if self.eat_keyword(keywords::Use) {
// USE ITEM
let item_ = ItemKind::Use(self.parse_view_path()?);
self.expect(&token::Semi)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
keywords::Invalid.ident(),
item_,
visibility,
attrs);
return Ok(Some(item));
}
if self.eat_keyword(keywords::Extern) {
if self.eat_keyword(keywords::Crate) {
return Ok(Some(self.parse_item_extern_crate(lo, visibility, attrs)?));
}
let opt_abi = self.parse_opt_abi()?;
if self.eat_keyword(keywords::Fn) {
// EXTERN FUNCTION ITEM
let fn_span = self.prev_span;
let abi = opt_abi.unwrap_or(Abi::C);
let (ident, item_, extra_attrs) =
self.parse_item_fn(Unsafety::Normal,
respan(fn_span, Constness::NotConst),
abi)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
} else if self.check(&token::OpenDelim(token::Brace)) {
return Ok(Some(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs)?));
}
self.unexpected()?;
}
if self.eat_keyword(keywords::Static) {
// STATIC ITEM
let m = if self.eat_keyword(keywords::Mut) {
Mutability::Mutable
} else {
Mutability::Immutable
};
let (ident, item_, extra_attrs) = self.parse_item_const(Some(m))?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Const) {
let const_span = self.prev_span;
if self.check_keyword(keywords::Fn)
|| (self.check_keyword(keywords::Unsafe)
&& self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) {
// CONST FUNCTION ITEM
let unsafety = if self.eat_keyword(keywords::Unsafe) {
Unsafety::Unsafe
} else {
Unsafety::Normal
};
self.bump();
let (ident, item_, extra_attrs) =
self.parse_item_fn(unsafety,
respan(const_span, Constness::Const),
Abi::Rust)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
// CONST ITEM
if self.eat_keyword(keywords::Mut) {
let prev_span = self.prev_span;
self.diagnostic().struct_span_err(prev_span, "const globals cannot be mutable")
.help("did you mean to declare a static?")
.emit();
}
let (ident, item_, extra_attrs) = self.parse_item_const(None)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.check_keyword(keywords::Unsafe) &&
self.look_ahead(1, |t| t.is_keyword(keywords::Trait))
{
// UNSAFE TRAIT ITEM
self.expect_keyword(keywords::Unsafe)?;
self.expect_keyword(keywords::Trait)?;
let (ident, item_, extra_attrs) =
self.parse_item_trait(ast::Unsafety::Unsafe)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.check_keyword(keywords::Unsafe) &&
self.look_ahead(1, |t| t.is_keyword(keywords::Impl))
{
// IMPL ITEM
self.expect_keyword(keywords::Unsafe)?;
self.expect_keyword(keywords::Impl)?;
let (ident, item_, extra_attrs) = self.parse_item_impl(ast::Unsafety::Unsafe)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.check_keyword(keywords::Fn) {
// FUNCTION ITEM
self.bump();
let fn_span = self.prev_span;
let (ident, item_, extra_attrs) =
self.parse_item_fn(Unsafety::Normal,
respan(fn_span, Constness::NotConst),
Abi::Rust)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.check_keyword(keywords::Unsafe)
&& self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
// UNSAFE FUNCTION ITEM
self.bump();
let abi = if self.eat_keyword(keywords::Extern) {
self.parse_opt_abi()?.unwrap_or(Abi::C)
} else {
Abi::Rust
};
self.expect_keyword(keywords::Fn)?;
let fn_span = self.prev_span;
let (ident, item_, extra_attrs) =
self.parse_item_fn(Unsafety::Unsafe,
respan(fn_span, Constness::NotConst),
abi)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Mod) {
// MODULE ITEM
let (ident, item_, extra_attrs) =
self.parse_item_mod(&attrs[..])?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Type) {
// TYPE ITEM
let (ident, item_, extra_attrs) = self.parse_item_type()?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Enum) {
// ENUM ITEM
let (ident, item_, extra_attrs) = self.parse_item_enum()?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Trait) {
// TRAIT ITEM
let (ident, item_, extra_attrs) =
self.parse_item_trait(ast::Unsafety::Normal)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Impl) {
// IMPL ITEM
let (ident, item_, extra_attrs) = self.parse_item_impl(ast::Unsafety::Normal)?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.eat_keyword(keywords::Struct) {
// STRUCT ITEM
let (ident, item_, extra_attrs) = self.parse_item_struct()?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
if self.is_union_item() {
// UNION ITEM
self.bump();
let (ident, item_, extra_attrs) = self.parse_item_union()?;
let prev_span = self.prev_span;
let item = self.mk_item(lo,
prev_span.hi,
ident,
item_,
visibility,
maybe_append(attrs, extra_attrs));
return Ok(Some(item));
}
self.parse_macro_use_or_failure(attrs,macros_allowed,attributes_allowed,lo,visibility)
}
/// Parse a foreign item.
fn parse_foreign_item(&mut self) -> PResult<'a, Option<ForeignItem>> {
let attrs = self.parse_outer_attributes()?;
let lo = self.span.lo;
let visibility = self.parse_visibility(true)?;
if self.check_keyword(keywords::Static) {
// FOREIGN STATIC ITEM
return Ok(Some(self.parse_item_foreign_static(visibility, lo, attrs)?));
}
if self.check_keyword(keywords::Fn) {
// FOREIGN FUNCTION ITEM
return Ok(Some(self.parse_item_foreign_fn(visibility, lo, attrs)?));
}
// FIXME #5668: this will occur for a macro invocation:
match self.parse_macro_use_or_failure(attrs, true, false, lo, visibility)? {
Some(item) => {
return Err(self.span_fatal(item.span, "macros cannot expand to foreign items"));
}
None => Ok(None)
}
}
/// This is the fall-through for parsing items.
fn parse_macro_use_or_failure(
&mut self,
attrs: Vec<Attribute> ,
macros_allowed: bool,
attributes_allowed: bool,
lo: BytePos,
visibility: Visibility
) -> PResult<'a, Option<P<Item>>> {
if macros_allowed && self.token.is_path_start() {
// MACRO INVOCATION ITEM
let prev_span = self.prev_span;
self.complain_if_pub_macro(&visibility, prev_span);
let mac_lo = self.span.lo;
// item macro.
let pth = self.parse_path(PathStyle::Mod)?;
self.expect(&token::Not)?;
// a 'special' identifier (like what `macro_rules!` uses)
// is optional. We should eventually unify invoc syntax
// and remove this.
let id = if self.token.is_ident() {
self.parse_ident()?
} else {
keywords::Invalid.ident() // no special identifier
};
// eat a matched-delimiter token tree:
let delim = self.expect_open_delim()?;
let tts = self.parse_seq_to_end(&token::CloseDelim(delim),
SeqSep::none(),
|p| p.parse_token_tree())?;
if delim != token::Brace {
if !self.eat(&token::Semi) {
let prev_span = self.prev_span;
self.span_err(prev_span,
"macros that expand to items must either \
be surrounded with braces or followed by \
a semicolon");
}
}
let hi = self.prev_span.hi;
let mac = spanned(mac_lo, hi, Mac_ { path: pth, tts: tts });
let item = self.mk_item(lo, hi, id, ItemKind::Mac(mac), visibility, attrs);
return Ok(Some(item));
}
// FAILURE TO PARSE ITEM
match visibility {
Visibility::Inherited => {}
_ => {
let prev_span = self.prev_span;
return Err(self.span_fatal(prev_span, "unmatched visibility `pub`"));
}
}
if !attributes_allowed && !attrs.is_empty() {
self.expected_item_err(&attrs);
}
Ok(None)
}
pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
let attrs = self.parse_outer_attributes()?;
self.parse_item_(attrs, true, false)
}
fn parse_path_list_items(&mut self) -> PResult<'a, Vec<ast::PathListItem>> {
self.parse_unspanned_seq(&token::OpenDelim(token::Brace),
&token::CloseDelim(token::Brace),
SeqSep::trailing_allowed(token::Comma), |this| {
let lo = this.span.lo;
let ident = if this.eat_keyword(keywords::SelfValue) {
keywords::SelfValue.ident()
} else {
this.parse_ident()?
};
let rename = this.parse_rename()?;
let node = ast::PathListItem_ {
name: ident,
rename: rename,
id: ast::DUMMY_NODE_ID
};
let hi = this.prev_span.hi;
Ok(spanned(lo, hi, node))
})
}
/// `::{` or `::*`
fn is_import_coupler(&mut self) -> bool {
self.check(&token::ModSep) &&
self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace) ||
*t == token::BinOp(token::Star))
}
/// Matches ViewPath:
/// MOD_SEP? non_global_path
/// MOD_SEP? non_global_path as IDENT
/// MOD_SEP? non_global_path MOD_SEP STAR
/// MOD_SEP? non_global_path MOD_SEP LBRACE item_seq RBRACE
/// MOD_SEP? LBRACE item_seq RBRACE
fn parse_view_path(&mut self) -> PResult<'a, P<ViewPath>> {
let lo = self.span.lo;
if self.check(&token::OpenDelim(token::Brace)) || self.check(&token::BinOp(token::Star)) ||
self.is_import_coupler() {
// `{foo, bar}`, `::{foo, bar}`, `*`, or `::*`.
let prefix = ast::Path {
global: self.eat(&token::ModSep),
segments: Vec::new(),
span: mk_sp(lo, self.span.hi),
};
let view_path_kind = if self.eat(&token::BinOp(token::Star)) {
ViewPathGlob(prefix)
} else {
ViewPathList(prefix, self.parse_path_list_items()?)
};
Ok(P(spanned(lo, self.span.hi, view_path_kind)))
} else {
let prefix = self.parse_path(PathStyle::Mod)?;
if self.is_import_coupler() {
// `foo::bar::{a, b}` or `foo::bar::*`
self.bump();
if self.check(&token::BinOp(token::Star)) {
self.bump();
Ok(P(spanned(lo, self.span.hi, ViewPathGlob(prefix))))
} else {
let items = self.parse_path_list_items()?;
Ok(P(spanned(lo, self.span.hi, ViewPathList(prefix, items))))
}
} else {
// `foo::bar` or `foo::bar as baz`
let rename = self.parse_rename()?.
unwrap_or(prefix.segments.last().unwrap().identifier);
Ok(P(spanned(lo, self.prev_span.hi, ViewPathSimple(rename, prefix))))
}
}
}
fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
if self.eat_keyword(keywords::As) {
self.parse_ident().map(Some)
} else {
Ok(None)
}
}
/// Parses a source module as a crate. This is the main
/// entry point for the parser.
pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
let lo = self.span.lo;
Ok(ast::Crate {
attrs: self.parse_inner_attributes()?,
module: self.parse_mod_items(&token::Eof, lo)?,
span: mk_sp(lo, self.span.lo),
exported_macros: Vec::new(),
})
}
pub fn parse_optional_str(&mut self) -> Option<(Symbol, ast::StrStyle, Option<ast::Name>)> {
let ret = match self.token {
token::Literal(token::Str_(s), suf) => (s, ast::StrStyle::Cooked, suf),
token::Literal(token::StrRaw(s, n), suf) => (s, ast::StrStyle::Raw(n), suf),
_ => return None
};
self.bump();
Some(ret)
}
pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
match self.parse_optional_str() {
Some((s, style, suf)) => {
let sp = self.prev_span;
self.expect_no_suffix(sp, "string literal", suf);
Ok((s, style))
}
_ => Err(self.fatal("expected string literal"))
}
}
}