src/libsyntax/ast_util.rs - external/github.com/rust-lang/rust - Git at Google

 // 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::Abi;
 use ast::*;
 use ast;
 use ast_util;
 use codemap;
 use codemap::Span;
 use owned_slice::OwnedSlice;
 use parse::token;
 use print::pprust;
 use ptr::P;
 use visit::Visitor;
 use visit;

 use std::cmp;
 use std::u32;

 pub fn path_name_i(idents: &[Ident]) -> String {
     // FIXME: Bad copies (#2543 -- same for everything else that says "bad")
     idents.iter().map(|i| {
         token::get_ident(*i).get().to_string()
     }).collect::<Vec<String>>().connect("::")
 }

 pub fn local_def(id: NodeId) -> DefId {
     ast::DefId { krate: LOCAL_CRATE, node: id }
 }

 pub fn is_local(did: ast::DefId) -> bool { did.krate == LOCAL_CRATE }

 pub fn stmt_id(s: &Stmt) -> NodeId {
     match s.node {
       StmtDecl(_, id) => id,
       StmtExpr(_, id) => id,
       StmtSemi(_, id) => id,
       StmtMac(..) => panic!("attempted to analyze unexpanded stmt")
     }
 }

 pub fn binop_to_string(op: BinOp) -> &'static str {
     match op {
         BiAdd => "+",
         BiSub => "-",
         BiMul => "*",
         BiDiv => "/",
         BiRem => "%",
         BiAnd => "&&",
         BiOr => "||",
         BiBitXor => "^",
         BiBitAnd => "&",
         BiBitOr => "|",
         BiShl => "<<",
         BiShr => ">>",
         BiEq => "==",
         BiLt => "<",
         BiLe => "<=",
         BiNe => "!=",
         BiGe => ">=",
         BiGt => ">"
     }
 }

 pub fn lazy_binop(b: BinOp) -> bool {
     match b {
       BiAnd => true,
       BiOr => true,
       _ => false
     }
 }

 pub fn is_shift_binop(b: BinOp) -> bool {
     match b {
       BiShl => true,
       BiShr => true,
       _ => false
     }
 }

 /// Returns `true` if the binary operator takes its arguments by value
 pub fn is_by_value_binop(b: BinOp) -> bool {
     match b {
         BiAdd | BiSub | BiMul | BiDiv | BiRem | BiBitXor | BiBitAnd | BiBitOr | BiShl | BiShr => {
             true
         }
         _ => false
     }
 }

 /// Returns `true` if the unary operator takes its argument by value
 pub fn is_by_value_unop(u: UnOp) -> bool {
     match u {
         UnNeg | UnNot => true,
         _ => false,
     }
 }

 pub fn unop_to_string(op: UnOp) -> &'static str {
     match op {
       UnUniq => "box() ",
       UnDeref => "*",
       UnNot => "!",
       UnNeg => "-",
     }
 }

 pub fn is_path(e: P<Expr>) -> bool {
     return match e.node { ExprPath(_) => true, _ => false };
 }

 /// Get a string representation of a signed int type, with its value.
 /// We want to avoid "45int" and "-3int" in favor of "45" and "-3"
 pub fn int_ty_to_string(t: IntTy, val: Option<i64>) -> String {
     let s = match t {
         TyIs if val.is_some() => "is",
         TyIs => "isize",
         TyI8 => "i8",
         TyI16 => "i16",
         TyI32 => "i32",
         TyI64 => "i64"
     };

     match val {
         // cast to a u64 so we can correctly print INT64_MIN. All integral types
         // are parsed as u64, so we wouldn't want to print an extra negative
         // sign.
         Some(n) => format!("{}{}", n as u64, s),
         None => s.to_string()
     }
 }

 pub fn int_ty_max(t: IntTy) -> u64 {
     match t {
         TyI8 => 0x80u64,
         TyI16 => 0x8000u64,
         TyIs | TyI32 => 0x80000000u64, // actually ni about TyIs
         TyI64 => 0x8000000000000000u64
     }
 }

 /// Get a string representation of an unsigned int type, with its value.
 /// We want to avoid "42uint" in favor of "42u"
 pub fn uint_ty_to_string(t: UintTy, val: Option<u64>) -> String {
     let s = match t {
         TyUs if val.is_some() => "us",
         TyUs => "usize",
         TyU8 => "u8",
         TyU16 => "u16",
         TyU32 => "u32",
         TyU64 => "u64"
     };

     match val {
         Some(n) => format!("{}{}", n, s),
         None => s.to_string()
     }
 }

 pub fn uint_ty_max(t: UintTy) -> u64 {
     match t {
         TyU8 => 0xffu64,
         TyU16 => 0xffffu64,
         TyUs | TyU32 => 0xffffffffu64, // actually ni about TyUs
         TyU64 => 0xffffffffffffffffu64
     }
 }

 pub fn float_ty_to_string(t: FloatTy) -> String {
     match t {
         TyF32 => "f32".to_string(),
         TyF64 => "f64".to_string(),
     }
 }

 // convert a span and an identifier to the corresponding
 // 1-segment path
 pub fn ident_to_path(s: Span, identifier: Ident) -> Path {
     ast::Path {
         span: s,
         global: false,
         segments: vec!(
             ast::PathSegment {
                 identifier: identifier,
                 parameters: ast::AngleBracketedParameters(ast::AngleBracketedParameterData {
                     lifetimes: Vec::new(),
                     types: OwnedSlice::empty(),
                     bindings: OwnedSlice::empty(),
                 })
             }
         ),
     }
 }

 // If path is a single segment ident path, return that ident. Otherwise, return
 // None.
 pub fn path_to_ident(path: &Path) -> Option<Ident> {
     if path.segments.len() != 1 {
         return None;
     }

     let segment = &path.segments[0];
     if !segment.parameters.is_empty() {
         return None;
     }

     Some(segment.identifier)
 }

 pub fn ident_to_pat(id: NodeId, s: Span, i: Ident) -> P<Pat> {
     P(Pat {
         id: id,
         node: PatIdent(BindByValue(MutImmutable), codemap::Spanned{span:s, node:i}, None),
         span: s
     })
 }

 pub fn name_to_dummy_lifetime(name: Name) -> Lifetime {
     Lifetime { id: DUMMY_NODE_ID,
                span: codemap::DUMMY_SP,
                name: name }
 }

 /// Generate a "pretty" name for an `impl` from its type and trait.
 /// This is designed so that symbols of `impl`'d methods give some
 /// hint of where they came from, (previously they would all just be
 /// listed as `__extensions__::method_name::hash`, with no indication
 /// of the type).
 pub fn impl_pretty_name(trait_ref: &Option<TraitRef>, ty: &Ty) -> Ident {
     let mut pretty = pprust::ty_to_string(ty);
     match *trait_ref {
         Some(ref trait_ref) => {
             pretty.push('.');
             pretty.push_str(&pprust::path_to_string(&trait_ref.path)[]);
         }
         None => {}
     }
     token::gensym_ident(&pretty[])
 }

 pub fn trait_method_to_ty_method(method: &Method) -> TypeMethod {
     match method.node {
         MethDecl(ident,
                  ref generics,
                  abi,
                  ref explicit_self,
                  unsafety,
                  ref decl,
                  _,
                  vis) => {
             TypeMethod {
                 ident: ident,
                 attrs: method.attrs.clone(),
                 unsafety: unsafety,
                 decl: (*decl).clone(),
                 generics: generics.clone(),
                 explicit_self: (*explicit_self).clone(),
                 id: method.id,
                 span: method.span,
                 vis: vis,
                 abi: abi,
             }
         },
         MethMac(_) => panic!("expected non-macro method declaration")
     }
 }

 /// extract a TypeMethod from a TraitItem. if the TraitItem is
 /// a default, pull out the useful fields to make a TypeMethod
 //
 // NB: to be used only after expansion is complete, and macros are gone.
 pub fn trait_item_to_ty_method(method: &TraitItem) -> TypeMethod {
     match *method {
         RequiredMethod(ref m) => (*m).clone(),
         ProvidedMethod(ref m) => trait_method_to_ty_method(&**m),
         TypeTraitItem(_) => {
             panic!("trait_method_to_ty_method(): expected method but found \
                    typedef")
         }
     }
 }

 pub fn split_trait_methods(trait_methods: &[TraitItem])
                            -> (Vec<TypeMethod>, Vec<P<Method>> ) {
     let mut reqd = Vec::new();
     let mut provd = Vec::new();
     for trt_method in trait_methods.iter() {
         match *trt_method {
             RequiredMethod(ref tm) => reqd.push((*tm).clone()),
             ProvidedMethod(ref m) => provd.push((*m).clone()),
             TypeTraitItem(_) => {}
         }
     };
     (reqd, provd)
 }

 pub fn struct_field_visibility(field: ast::StructField) -> Visibility {
     match field.node.kind {
         ast::NamedField(_, v) | ast::UnnamedField(v) => v
     }
 }

 /// Maps a binary operator to its precedence
 pub fn operator_prec(op: ast::BinOp) -> uint {
   match op {
       // 'as' sits here with 12
       BiMul | BiDiv | BiRem     => 11u,
       BiAdd | BiSub             => 10u,
       BiShl | BiShr             =>  9u,
       BiBitAnd                  =>  8u,
       BiBitXor                  =>  7u,
       BiBitOr                   =>  6u,
       BiLt | BiLe | BiGe | BiGt =>  4u,
       BiEq | BiNe               =>  3u,
       BiAnd                     =>  2u,
       BiOr                      =>  1u
   }
 }

 /// Precedence of the `as` operator, which is a binary operator
 /// not appearing in the prior table.
 #[allow(non_upper_case_globals)]
 pub static as_prec: uint = 12u;

 pub fn empty_generics() -> Generics {
     Generics {
         lifetimes: Vec::new(),
         ty_params: OwnedSlice::empty(),
         where_clause: WhereClause {
             id: DUMMY_NODE_ID,
             predicates: Vec::new(),
         }
     }
 }

 // ______________________________________________________________________
 // Enumerating the IDs which appear in an AST

 #[derive(RustcEncodable, RustcDecodable, Show, Copy)]
 pub struct IdRange {
     pub min: NodeId,
     pub max: NodeId,
 }

 impl IdRange {
     pub fn max() -> IdRange {
         IdRange {
             min: u32::MAX,
             max: u32::MIN,
         }
     }

     pub fn empty(&self) -> bool {
         self.min >= self.max
     }

     pub fn add(&mut self, id: NodeId) {
         self.min = cmp::min(self.min, id);
         self.max = cmp::max(self.max, id + 1);
     }
 }

 pub trait IdVisitingOperation {
     fn visit_id(&mut self, node_id: NodeId);
 }

 /// A visitor that applies its operation to all of the node IDs
 /// in a visitable thing.

 pub struct IdVisitor<'a, O:'a> {
     pub operation: &'a mut O,
     pub pass_through_items: bool,
     pub visited_outermost: bool,
 }

 impl<'a, O: IdVisitingOperation> IdVisitor<'a, O> {
     fn visit_generics_helper(&mut self, generics: &Generics) {
         for type_parameter in generics.ty_params.iter() {
             self.operation.visit_id(type_parameter.id)
         }
         for lifetime in generics.lifetimes.iter() {
             self.operation.visit_id(lifetime.lifetime.id)
         }
     }
 }

 impl<'a, 'v, O: IdVisitingOperation> Visitor<'v> for IdVisitor<'a, O> {
     fn visit_mod(&mut self,
                  module: &Mod,
                  _: Span,
                  node_id: NodeId) {
         self.operation.visit_id(node_id);
         visit::walk_mod(self, module)
     }

     fn visit_view_item(&mut self, view_item: &ViewItem) {
         if !self.pass_through_items {
             if self.visited_outermost {
                 return;
             } else {
                 self.visited_outermost = true;
             }
         }
         match view_item.node {
             ViewItemExternCrate(_, _, node_id) => {
                 self.operation.visit_id(node_id)
             }
             ViewItemUse(ref view_path) => {
                 match view_path.node {
                     ViewPathSimple(_, _, node_id) |
                     ViewPathGlob(_, node_id) => {
                         self.operation.visit_id(node_id)
                     }
                     ViewPathList(_, ref paths, node_id) => {
                         self.operation.visit_id(node_id);
                         for path in paths.iter() {
                             self.operation.visit_id(path.node.id())
                         }
                     }
                 }
             }
         }
         visit::walk_view_item(self, view_item);
         self.visited_outermost = false;
     }

     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
         self.operation.visit_id(foreign_item.id);
         visit::walk_foreign_item(self, foreign_item)
     }

     fn visit_item(&mut self, item: &Item) {
         if !self.pass_through_items {
             if self.visited_outermost {
                 return
             } else {
                 self.visited_outermost = true
             }
         }

         self.operation.visit_id(item.id);
         if let ItemEnum(ref enum_definition, _) = item.node {
             for variant in enum_definition.variants.iter() {
                 self.operation.visit_id(variant.node.id)
             }
         }

         visit::walk_item(self, item);

         self.visited_outermost = false
     }

     fn visit_local(&mut self, local: &Local) {
         self.operation.visit_id(local.id);
         visit::walk_local(self, local)
     }

     fn visit_block(&mut self, block: &Block) {
         self.operation.visit_id(block.id);
         visit::walk_block(self, block)
     }

     fn visit_stmt(&mut self, statement: &Stmt) {
         self.operation.visit_id(ast_util::stmt_id(statement));
         visit::walk_stmt(self, statement)
     }

     fn visit_pat(&mut self, pattern: &Pat) {
         self.operation.visit_id(pattern.id);
         visit::walk_pat(self, pattern)
     }

     fn visit_expr(&mut self, expression: &Expr) {
         self.operation.visit_id(expression.id);
         visit::walk_expr(self, expression)
     }

     fn visit_ty(&mut self, typ: &Ty) {
         self.operation.visit_id(typ.id);
         if let TyPath(_, id) = typ.node {
             self.operation.visit_id(id);
         }
         visit::walk_ty(self, typ)
     }

     fn visit_generics(&mut self, generics: &Generics) {
         self.visit_generics_helper(generics);
         visit::walk_generics(self, generics)
     }

     fn visit_fn(&mut self,
                 function_kind: visit::FnKind<'v>,
                 function_declaration: &'v FnDecl,
                 block: &'v Block,
                 span: Span,
                 node_id: NodeId) {
         if !self.pass_through_items {
             match function_kind {
                 visit::FkMethod(..) if self.visited_outermost => return,
                 visit::FkMethod(..) => self.visited_outermost = true,
                 _ => {}
             }
         }

         self.operation.visit_id(node_id);

         match function_kind {
             visit::FkItemFn(_, generics, _, _) |
             visit::FkMethod(_, generics, _) => {
                 self.visit_generics_helper(generics)
             }
             visit::FkFnBlock => {}
         }

         for argument in function_declaration.inputs.iter() {
             self.operation.visit_id(argument.id)
         }

         visit::walk_fn(self,
                        function_kind,
                        function_declaration,
                        block,
                        span);

         if !self.pass_through_items {
             if let visit::FkMethod(..) = function_kind {
                 self.visited_outermost = false;
             }
         }
     }

     fn visit_struct_field(&mut self, struct_field: &StructField) {
         self.operation.visit_id(struct_field.node.id);
         visit::walk_struct_field(self, struct_field)
     }

     fn visit_struct_def(&mut self,
                         struct_def: &StructDef,
                         _: ast::Ident,
                         _: &ast::Generics,
                         id: NodeId) {
         self.operation.visit_id(id);
         struct_def.ctor_id.map(|ctor_id| self.operation.visit_id(ctor_id));
         visit::walk_struct_def(self, struct_def);
     }

     fn visit_trait_item(&mut self, tm: &ast::TraitItem) {
         match *tm {
             ast::RequiredMethod(ref m) => self.operation.visit_id(m.id),
             ast::ProvidedMethod(ref m) => self.operation.visit_id(m.id),
             ast::TypeTraitItem(ref typ) => self.operation.visit_id(typ.ty_param.id),
         }
         visit::walk_trait_item(self, tm);
     }

     fn visit_lifetime_ref(&mut self, lifetime: &'v Lifetime) {
         self.operation.visit_id(lifetime.id);
     }

     fn visit_lifetime_def(&mut self, def: &'v LifetimeDef) {
         self.visit_lifetime_ref(&def.lifetime);
     }
 }

 pub fn visit_ids_for_inlined_item<O: IdVisitingOperation>(item: &InlinedItem,
                                                           operation: &mut O) {
     let mut id_visitor = IdVisitor {
         operation: operation,
         pass_through_items: true,
         visited_outermost: false,
     };

     visit::walk_inlined_item(&mut id_visitor, item);
 }

 struct IdRangeComputingVisitor {
     result: IdRange,
 }

 impl IdVisitingOperation for IdRangeComputingVisitor {
     fn visit_id(&mut self, id: NodeId) {
         self.result.add(id);
     }
 }

 pub fn compute_id_range_for_inlined_item(item: &InlinedItem) -> IdRange {
     let mut visitor = IdRangeComputingVisitor {
         result: IdRange::max()
     };
     visit_ids_for_inlined_item(item, &mut visitor);
     visitor.result
 }

 /// Computes the id range for a single fn body, ignoring nested items.
 pub fn compute_id_range_for_fn_body(fk: visit::FnKind,
                                     decl: &FnDecl,
                                     body: &Block,
                                     sp: Span,
                                     id: NodeId)
                                     -> IdRange
 {
     let mut visitor = IdRangeComputingVisitor {
         result: IdRange::max()
     };
     let mut id_visitor = IdVisitor {
         operation: &mut visitor,
         pass_through_items: false,
         visited_outermost: false,
     };
     id_visitor.visit_fn(fk, decl, body, sp, id);
     id_visitor.operation.result
 }

 pub fn walk_pat<F>(pat: &Pat, mut it: F) -> bool where F: FnMut(&Pat) -> bool {
     // FIXME(#19596) this is a workaround, but there should be a better way
     fn walk_pat_<G>(pat: &Pat, it: &mut G) -> bool where G: FnMut(&Pat) -> bool {
         if !(*it)(pat) {
             return false;
         }

         match pat.node {
             PatIdent(_, _, Some(ref p)) => walk_pat_(&**p, it),
             PatStruct(_, ref fields, _) => {
                 fields.iter().all(|field| walk_pat_(&*field.node.pat, it))
             }
             PatEnum(_, Some(ref s)) | PatTup(ref s) => {
                 s.iter().all(|p| walk_pat_(&**p, it))
             }
             PatBox(ref s) | PatRegion(ref s, _) => {
                 walk_pat_(&**s, it)
             }
             PatVec(ref before, ref slice, ref after) => {
                 before.iter().all(|p| walk_pat_(&**p, it)) &&
                 slice.iter().all(|p| walk_pat_(&**p, it)) &&
                 after.iter().all(|p| walk_pat_(&**p, it))
             }
             PatMac(_) => panic!("attempted to analyze unexpanded pattern"),
             PatWild(_) | PatLit(_) | PatRange(_, _) | PatIdent(_, _, _) |
             PatEnum(_, _) => {
                 true
             }
         }
     }

     walk_pat_(pat, &mut it)
 }

 pub trait EachViewItem {
     fn each_view_item<F>(&self, f: F) -> bool where F: FnMut(&ast::ViewItem) -> bool;
 }

 struct EachViewItemData<F> where F: FnMut(&ast::ViewItem) -> bool {
     callback: F,
 }

 impl<'v, F> Visitor<'v> for EachViewItemData<F> where F: FnMut(&ast::ViewItem) -> bool {
     fn visit_view_item(&mut self, view_item: &ast::ViewItem) {
         let _ = (self.callback)(view_item);
     }
 }

 impl EachViewItem for ast::Crate {
     fn each_view_item<F>(&self, f: F) -> bool where F: FnMut(&ast::ViewItem) -> bool {
         let mut visit = EachViewItemData {
             callback: f,
         };
         visit::walk_crate(&mut visit, self);
         true
     }
 }

 pub fn view_path_id(p: &ViewPath) -> NodeId {
     match p.node {
         ViewPathSimple(_, _, id) | ViewPathGlob(_, id)
         | ViewPathList(_, _, id) => id
     }
 }

 /// Returns true if the given struct def is tuple-like; i.e. that its fields
 /// are unnamed.
 pub fn struct_def_is_tuple_like(struct_def: &ast::StructDef) -> bool {
     struct_def.ctor_id.is_some()
 }

 /// Returns true if the given pattern consists solely of an identifier
 /// and false otherwise.
 pub fn pat_is_ident(pat: P<ast::Pat>) -> bool {
     match pat.node {
         ast::PatIdent(..) => true,
         _ => false,
     }
 }

 // are two paths equal when compared unhygienically?
 // since I'm using this to replace ==, it seems appropriate
 // to compare the span, global, etc. fields as well.
 pub fn path_name_eq(a : &ast::Path, b : &ast::Path) -> bool {
     (a.span == b.span)
     && (a.global == b.global)
     && (segments_name_eq(&a.segments[], &b.segments[]))
 }

 // are two arrays of segments equal when compared unhygienically?
 pub fn segments_name_eq(a : &[ast::PathSegment], b : &[ast::PathSegment]) -> bool {
     if a.len() != b.len() {
         false
     } else {
         for (idx,seg) in a.iter().enumerate() {
             if seg.identifier.name != b[idx].identifier.name
                 // FIXME #7743: ident -> name problems in lifetime comparison?
                 // can types contain idents?
                 || seg.parameters != b[idx].parameters
             {
                 return false;
             }
         }
         true
     }
 }

 /// Returns true if this literal is a string and false otherwise.
 pub fn lit_is_str(lit: &Lit) -> bool {
     match lit.node {
         LitStr(..) => true,
         _ => false,
     }
 }

 /// Macro invocations are guaranteed not to occur after expansion is complete.
 /// Extracting fields of a method requires a dynamic check to make sure that it's
 /// not a macro invocation. This check is guaranteed to succeed, assuming
 /// that the invocations are indeed gone.
 pub trait PostExpansionMethod {
     fn pe_ident(&self) -> ast::Ident;
     fn pe_generics<'a>(&'a self) -> &'a ast::Generics;
     fn pe_abi(&self) -> Abi;
     fn pe_explicit_self<'a>(&'a self) -> &'a ast::ExplicitSelf;
     fn pe_unsafety(&self) -> ast::Unsafety;
     fn pe_fn_decl<'a>(&'a self) -> &'a ast::FnDecl;
     fn pe_body<'a>(&'a self) -> &'a ast::Block;
     fn pe_vis(&self) -> ast::Visibility;
 }

 macro_rules! mf_method{
     ($meth_name:ident, $field_ty:ty, $field_pat:pat, $result:expr) => {
         fn $meth_name<'a>(&'a self) -> $field_ty {
             match self.node {
                 $field_pat => $result,
                 MethMac(_) => {
                     panic!("expected an AST without macro invocations");
                 }
             }
         }
     }
 }


 impl PostExpansionMethod for Method {
     mf_method! { pe_ident,ast::Ident,MethDecl(ident,_,_,_,_,_,_,_),ident }
     mf_method! {
         pe_generics,&'a ast::Generics,
         MethDecl(_,ref generics,_,_,_,_,_,_),generics
     }
     mf_method! { pe_abi,Abi,MethDecl(_,_,abi,_,_,_,_,_),abi }
     mf_method! {
         pe_explicit_self,&'a ast::ExplicitSelf,
         MethDecl(_,_,_,ref explicit_self,_,_,_,_),explicit_self
     }
     mf_method! { pe_unsafety,ast::Unsafety,MethDecl(_,_,_,_,unsafety,_,_,_),unsafety }
     mf_method! { pe_fn_decl,&'a ast::FnDecl,MethDecl(_,_,_,_,_,ref decl,_,_),&**decl }
     mf_method! { pe_body,&'a ast::Block,MethDecl(_,_,_,_,_,_,ref body,_),&**body }
     mf_method! { pe_vis,ast::Visibility,MethDecl(_,_,_,_,_,_,_,vis),vis }
 }

 #[cfg(test)]
 mod test {
     use ast::*;
     use super::*;

     fn ident_to_segment(id : &Ident) -> PathSegment {
         PathSegment {identifier: id.clone(),
                      parameters: PathParameters::none()}
     }

     #[test] fn idents_name_eq_test() {
         assert!(segments_name_eq(
             &[Ident{name:Name(3),ctxt:4}, Ident{name:Name(78),ctxt:82}]
                 .iter().map(ident_to_segment).collect::<Vec<PathSegment>>()[],
             &[Ident{name:Name(3),ctxt:104}, Ident{name:Name(78),ctxt:182}]
                 .iter().map(ident_to_segment).collect::<Vec<PathSegment>>()[]));
         assert!(!segments_name_eq(
             &[Ident{name:Name(3),ctxt:4}, Ident{name:Name(78),ctxt:82}]
                 .iter().map(ident_to_segment).collect::<Vec<PathSegment>>()[],
             &[Ident{name:Name(3),ctxt:104}, Ident{name:Name(77),ctxt:182}]
                 .iter().map(ident_to_segment).collect::<Vec<PathSegment>>()[]));
     }
 }
	// 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::Abi;
	use ast::*;
	use ast;
	use ast_util;
	use codemap;
	use codemap::Span;
	use owned_slice::OwnedSlice;
	use parse::token;
	use print::pprust;
	use ptr::P;
	use visit::Visitor;
	use visit;

	use std::cmp;
	use std::u32;

	pub fn path_name_i(idents: &[Ident]) -> String {
	// FIXME: Bad copies (#2543 -- same for everything else that says "bad")
	idents.iter().map(\|i\| {
	token::get_ident(*i).get().to_string()
	}).collect::<Vec<String>>().connect("::")
	}

	pub fn local_def(id: NodeId) -> DefId {
	ast::DefId { krate: LOCAL_CRATE, node: id }
	}

	pub fn is_local(did: ast::DefId) -> bool { did.krate == LOCAL_CRATE }

	pub fn stmt_id(s: &Stmt) -> NodeId {
	match s.node {
	StmtDecl(_, id) => id,
	StmtExpr(_, id) => id,
	StmtSemi(_, id) => id,
	StmtMac(..) => panic!("attempted to analyze unexpanded stmt")
	}
	}

	pub fn binop_to_string(op: BinOp) -> &'static str {
	match op {
	BiAdd => "+",
	BiSub => "-",
	BiMul => "*",
	BiDiv => "/",
	BiRem => "%",
	BiAnd => "&&",
	BiOr => "\|\|",
	BiBitXor => "^",
	BiBitAnd => "&",
	BiBitOr => "\|",
	BiShl => "<<",
	BiShr => ">>",
	BiEq => "==",
	BiLt => "<",
	BiLe => "<=",
	BiNe => "!=",
	BiGe => ">=",
	BiGt => ">"
	}
	}

	pub fn lazy_binop(b: BinOp) -> bool {
	match b {
	BiAnd => true,
	BiOr => true,
	_ => false
	}
	}

	pub fn is_shift_binop(b: BinOp) -> bool {
	match b {
	BiShl => true,
	BiShr => true,
	_ => false
	}
	}

	/// Returns `true` if the binary operator takes its arguments by value
	pub fn is_by_value_binop(b: BinOp) -> bool {
	match b {
	BiAdd \| BiSub \| BiMul \| BiDiv \| BiRem \| BiBitXor \| BiBitAnd \| BiBitOr \| BiShl \| BiShr => {
	true
	}
	_ => false
	}
	}

	/// Returns `true` if the unary operator takes its argument by value
	pub fn is_by_value_unop(u: UnOp) -> bool {
	match u {
	UnNeg \| UnNot => true,
	_ => false,
	}
	}

	pub fn unop_to_string(op: UnOp) -> &'static str {
	match op {
	UnUniq => "box() ",
	UnDeref => "*",
	UnNot => "!",
	UnNeg => "-",
	}
	}

	pub fn is_path(e: P<Expr>) -> bool {
	return match e.node { ExprPath(_) => true, _ => false };
	}

	/// Get a string representation of a signed int type, with its value.
	/// We want to avoid "45int" and "-3int" in favor of "45" and "-3"
	pub fn int_ty_to_string(t: IntTy, val: Option<i64>) -> String {
	let s = match t {
	TyIs if val.is_some() => "is",
	TyIs => "isize",
	TyI8 => "i8",
	TyI16 => "i16",
	TyI32 => "i32",
	TyI64 => "i64"
	};

	match val {
	// cast to a u64 so we can correctly print INT64_MIN. All integral types
	// are parsed as u64, so we wouldn't want to print an extra negative
	// sign.
	Some(n) => format!("{}{}", n as u64, s),
	None => s.to_string()
	}
	}

	pub fn int_ty_max(t: IntTy) -> u64 {
	match t {
	TyI8 => 0x80u64,
	TyI16 => 0x8000u64,
	TyIs \| TyI32 => 0x80000000u64, // actually ni about TyIs
	TyI64 => 0x8000000000000000u64
	}
	}

	/// Get a string representation of an unsigned int type, with its value.
	/// We want to avoid "42uint" in favor of "42u"
	pub fn uint_ty_to_string(t: UintTy, val: Option<u64>) -> String {
	let s = match t {
	TyUs if val.is_some() => "us",
	TyUs => "usize",
	TyU8 => "u8",
	TyU16 => "u16",
	TyU32 => "u32",
	TyU64 => "u64"
	};

	match val {
	Some(n) => format!("{}{}", n, s),
	None => s.to_string()
	}
	}

	pub fn uint_ty_max(t: UintTy) -> u64 {
	match t {
	TyU8 => 0xffu64,
	TyU16 => 0xffffu64,
	TyUs \| TyU32 => 0xffffffffu64, // actually ni about TyUs
	TyU64 => 0xffffffffffffffffu64
	}
	}

	pub fn float_ty_to_string(t: FloatTy) -> String {
	match t {
	TyF32 => "f32".to_string(),
	TyF64 => "f64".to_string(),
	}
	}

	// convert a span and an identifier to the corresponding
	// 1-segment path
	pub fn ident_to_path(s: Span, identifier: Ident) -> Path {
	ast::Path {
	span: s,
	global: false,
	segments: vec!(
	ast::PathSegment {
	identifier: identifier,
	parameters: ast::AngleBracketedParameters(ast::AngleBracketedParameterData {
	lifetimes: Vec::new(),
	types: OwnedSlice::empty(),
	bindings: OwnedSlice::empty(),
	})
	}
	),
	}
	}

	// If path is a single segment ident path, return that ident. Otherwise, return
	// None.
	pub fn path_to_ident(path: &Path) -> Option<Ident> {
	if path.segments.len() != 1 {
	return None;
	}

	let segment = &path.segments[0];
	if !segment.parameters.is_empty() {
	return None;
	}

	Some(segment.identifier)
	}

	pub fn ident_to_pat(id: NodeId, s: Span, i: Ident) -> P<Pat> {
	P(Pat {
	id: id,
	node: PatIdent(BindByValue(MutImmutable), codemap::Spanned{span:s, node:i}, None),
	span: s
	})
	}

	pub fn name_to_dummy_lifetime(name: Name) -> Lifetime {
	Lifetime { id: DUMMY_NODE_ID,
	span: codemap::DUMMY_SP,
	name: name }
	}

	/// Generate a "pretty" name for an `impl` from its type and trait.
	/// This is designed so that symbols of `impl`'d methods give some
	/// hint of where they came from, (previously they would all just be
	/// listed as `__extensions__::method_name::hash`, with no indication
	/// of the type).
	pub fn impl_pretty_name(trait_ref: &Option<TraitRef>, ty: &Ty) -> Ident {
	let mut pretty = pprust::ty_to_string(ty);
	match *trait_ref {
	Some(ref trait_ref) => {
	pretty.push('.');
	pretty.push_str(&pprust::path_to_string(&trait_ref.path)[]);
	}
	None => {}
	}
	token::gensym_ident(&pretty[])
	}

	pub fn trait_method_to_ty_method(method: &Method) -> TypeMethod {
	match method.node {
	MethDecl(ident,
	ref generics,
	abi,
	ref explicit_self,
	unsafety,
	ref decl,
	_,
	vis) => {
	TypeMethod {
	ident: ident,
	attrs: method.attrs.clone(),
	unsafety: unsafety,
	decl: (*decl).clone(),
	generics: generics.clone(),
	explicit_self: (*explicit_self).clone(),
	id: method.id,
	span: method.span,
	vis: vis,
	abi: abi,
	}
	},
	MethMac(_) => panic!("expected non-macro method declaration")
	}
	}

	/// extract a TypeMethod from a TraitItem. if the TraitItem is
	/// a default, pull out the useful fields to make a TypeMethod
	//
	// NB: to be used only after expansion is complete, and macros are gone.
	pub fn trait_item_to_ty_method(method: &TraitItem) -> TypeMethod {
	match *method {
	RequiredMethod(ref m) => (*m).clone(),
	ProvidedMethod(ref m) => trait_method_to_ty_method(&**m),
	TypeTraitItem(_) => {
	panic!("trait_method_to_ty_method(): expected method but found \
	typedef")
	}
	}
	}

	pub fn split_trait_methods(trait_methods: &[TraitItem])
	-> (Vec<TypeMethod>, Vec<P<Method>> ) {
	let mut reqd = Vec::new();
	let mut provd = Vec::new();
	for trt_method in trait_methods.iter() {
	match *trt_method {
	RequiredMethod(ref tm) => reqd.push((*tm).clone()),
	ProvidedMethod(ref m) => provd.push((*m).clone()),
	TypeTraitItem(_) => {}
	}
	};
	(reqd, provd)
	}

	pub fn struct_field_visibility(field: ast::StructField) -> Visibility {
	match field.node.kind {
	ast::NamedField(_, v) \| ast::UnnamedField(v) => v
	}
	}

	/// Maps a binary operator to its precedence
	pub fn operator_prec(op: ast::BinOp) -> uint {
	match op {
	// 'as' sits here with 12
	BiMul \| BiDiv \| BiRem => 11u,
	BiAdd \| BiSub => 10u,
	BiShl \| BiShr => 9u,
	BiBitAnd => 8u,
	BiBitXor => 7u,
	BiBitOr => 6u,
	BiLt \| BiLe \| BiGe \| BiGt => 4u,
	BiEq \| BiNe => 3u,
	BiAnd => 2u,
	BiOr => 1u
	}
	}

	/// Precedence of the `as` operator, which is a binary operator
	/// not appearing in the prior table.
	#[allow(non_upper_case_globals)]
	pub static as_prec: uint = 12u;

	pub fn empty_generics() -> Generics {
	Generics {
	lifetimes: Vec::new(),
	ty_params: OwnedSlice::empty(),
	where_clause: WhereClause {
	id: DUMMY_NODE_ID,
	predicates: Vec::new(),
	}
	}
	}

	// ______________________________________________________________________
	// Enumerating the IDs which appear in an AST

	#[derive(RustcEncodable, RustcDecodable, Show, Copy)]
	pub struct IdRange {
	pub min: NodeId,
	pub max: NodeId,
	}

	impl IdRange {
	pub fn max() -> IdRange {
	IdRange {
	min: u32::MAX,
	max: u32::MIN,
	}
	}

	pub fn empty(&self) -> bool {
	self.min >= self.max
	}

	pub fn add(&mut self, id: NodeId) {
	self.min = cmp::min(self.min, id);
	self.max = cmp::max(self.max, id + 1);
	}
	}

	pub trait IdVisitingOperation {
	fn visit_id(&mut self, node_id: NodeId);
	}

	/// A visitor that applies its operation to all of the node IDs
	/// in a visitable thing.

	pub struct IdVisitor<'a, O:'a> {
	pub operation: &'a mut O,
	pub pass_through_items: bool,
	pub visited_outermost: bool,
	}

	impl<'a, O: IdVisitingOperation> IdVisitor<'a, O> {
	fn visit_generics_helper(&mut self, generics: &Generics) {
	for type_parameter in generics.ty_params.iter() {
	self.operation.visit_id(type_parameter.id)
	}
	for lifetime in generics.lifetimes.iter() {
	self.operation.visit_id(lifetime.lifetime.id)
	}
	}
	}

	impl<'a, 'v, O: IdVisitingOperation> Visitor<'v> for IdVisitor<'a, O> {
	fn visit_mod(&mut self,
	module: &Mod,
	_: Span,
	node_id: NodeId) {
	self.operation.visit_id(node_id);
	visit::walk_mod(self, module)
	}

	fn visit_view_item(&mut self, view_item: &ViewItem) {
	if !self.pass_through_items {
	if self.visited_outermost {
	return;
	} else {
	self.visited_outermost = true;
	}
	}
	match view_item.node {
	ViewItemExternCrate(_, _, node_id) => {
	self.operation.visit_id(node_id)
	}
	ViewItemUse(ref view_path) => {
	match view_path.node {
	ViewPathSimple(_, _, node_id) \|
	ViewPathGlob(_, node_id) => {
	self.operation.visit_id(node_id)
	}
	ViewPathList(_, ref paths, node_id) => {
	self.operation.visit_id(node_id);
	for path in paths.iter() {
	self.operation.visit_id(path.node.id())
	}
	}
	}
	}
	}
	visit::walk_view_item(self, view_item);
	self.visited_outermost = false;
	}

	fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
	self.operation.visit_id(foreign_item.id);
	visit::walk_foreign_item(self, foreign_item)
	}

	fn visit_item(&mut self, item: &Item) {
	if !self.pass_through_items {
	if self.visited_outermost {
	return
	} else {
	self.visited_outermost = true
	}
	}

	self.operation.visit_id(item.id);
	if let ItemEnum(ref enum_definition, _) = item.node {
	for variant in enum_definition.variants.iter() {
	self.operation.visit_id(variant.node.id)
	}
	}

	visit::walk_item(self, item);

	self.visited_outermost = false
	}

	fn visit_local(&mut self, local: &Local) {
	self.operation.visit_id(local.id);
	visit::walk_local(self, local)
	}

	fn visit_block(&mut self, block: &Block) {
	self.operation.visit_id(block.id);
	visit::walk_block(self, block)
	}

	fn visit_stmt(&mut self, statement: &Stmt) {
	self.operation.visit_id(ast_util::stmt_id(statement));
	visit::walk_stmt(self, statement)
	}

	fn visit_pat(&mut self, pattern: &Pat) {
	self.operation.visit_id(pattern.id);
	visit::walk_pat(self, pattern)
	}

	fn visit_expr(&mut self, expression: &Expr) {
	self.operation.visit_id(expression.id);
	visit::walk_expr(self, expression)
	}

	fn visit_ty(&mut self, typ: &Ty) {
	self.operation.visit_id(typ.id);
	if let TyPath(_, id) = typ.node {
	self.operation.visit_id(id);
	}
	visit::walk_ty(self, typ)
	}

	fn visit_generics(&mut self, generics: &Generics) {
	self.visit_generics_helper(generics);
	visit::walk_generics(self, generics)
	}

	fn visit_fn(&mut self,
	function_kind: visit::FnKind<'v>,
	function_declaration: &'v FnDecl,
	block: &'v Block,
	span: Span,
	node_id: NodeId) {
	if !self.pass_through_items {
	match function_kind {
	visit::FkMethod(..) if self.visited_outermost => return,
	visit::FkMethod(..) => self.visited_outermost = true,
	_ => {}
	}
	}

	self.operation.visit_id(node_id);

	match function_kind {
	visit::FkItemFn(_, generics, _, _) \|
	visit::FkMethod(_, generics, _) => {
	self.visit_generics_helper(generics)
	}
	visit::FkFnBlock => {}
	}

	for argument in function_declaration.inputs.iter() {
	self.operation.visit_id(argument.id)
	}

	visit::walk_fn(self,
	function_kind,
	function_declaration,
	block,
	span);

	if !self.pass_through_items {
	if let visit::FkMethod(..) = function_kind {
	self.visited_outermost = false;
	}
	}
	}

	fn visit_struct_field(&mut self, struct_field: &StructField) {
	self.operation.visit_id(struct_field.node.id);
	visit::walk_struct_field(self, struct_field)
	}

	fn visit_struct_def(&mut self,
	struct_def: &StructDef,
	_: ast::Ident,
	_: &ast::Generics,
	id: NodeId) {
	self.operation.visit_id(id);
	struct_def.ctor_id.map(\|ctor_id\| self.operation.visit_id(ctor_id));
	visit::walk_struct_def(self, struct_def);
	}

	fn visit_trait_item(&mut self, tm: &ast::TraitItem) {
	match *tm {
	ast::RequiredMethod(ref m) => self.operation.visit_id(m.id),
	ast::ProvidedMethod(ref m) => self.operation.visit_id(m.id),
	ast::TypeTraitItem(ref typ) => self.operation.visit_id(typ.ty_param.id),
	}
	visit::walk_trait_item(self, tm);
	}

	fn visit_lifetime_ref(&mut self, lifetime: &'v Lifetime) {
	self.operation.visit_id(lifetime.id);
	}

	fn visit_lifetime_def(&mut self, def: &'v LifetimeDef) {
	self.visit_lifetime_ref(&def.lifetime);
	}
	}

	pub fn visit_ids_for_inlined_item<O: IdVisitingOperation>(item: &InlinedItem,
	operation: &mut O) {
	let mut id_visitor = IdVisitor {
	operation: operation,
	pass_through_items: true,
	visited_outermost: false,
	};

	visit::walk_inlined_item(&mut id_visitor, item);
	}

	struct IdRangeComputingVisitor {
	result: IdRange,
	}

	impl IdVisitingOperation for IdRangeComputingVisitor {
	fn visit_id(&mut self, id: NodeId) {
	self.result.add(id);
	}
	}

	pub fn compute_id_range_for_inlined_item(item: &InlinedItem) -> IdRange {
	let mut visitor = IdRangeComputingVisitor {
	result: IdRange::max()
	};
	visit_ids_for_inlined_item(item, &mut visitor);
	visitor.result
	}

	/// Computes the id range for a single fn body, ignoring nested items.
	pub fn compute_id_range_for_fn_body(fk: visit::FnKind,
	decl: &FnDecl,
	body: &Block,
	sp: Span,
	id: NodeId)
	-> IdRange
	{
	let mut visitor = IdRangeComputingVisitor {
	result: IdRange::max()
	};
	let mut id_visitor = IdVisitor {
	operation: &mut visitor,
	pass_through_items: false,
	visited_outermost: false,
	};
	id_visitor.visit_fn(fk, decl, body, sp, id);
	id_visitor.operation.result
	}

	pub fn walk_pat<F>(pat: &Pat, mut it: F) -> bool where F: FnMut(&Pat) -> bool {
	// FIXME(#19596) this is a workaround, but there should be a better way
	fn walk_pat_<G>(pat: &Pat, it: &mut G) -> bool where G: FnMut(&Pat) -> bool {
	if !(*it)(pat) {
	return false;
	}

	match pat.node {
	PatIdent(_, _, Some(ref p)) => walk_pat_(&**p, it),
	PatStruct(_, ref fields, _) => {
	fields.iter().all(\|field\| walk_pat_(&*field.node.pat, it))
	}
	PatEnum(_, Some(ref s)) \| PatTup(ref s) => {
	s.iter().all(\|p\| walk_pat_(&**p, it))
	}
	PatBox(ref s) \| PatRegion(ref s, _) => {
	walk_pat_(&**s, it)
	}
	PatVec(ref before, ref slice, ref after) => {
	before.iter().all(\|p\| walk_pat_(&**p, it)) &&
	slice.iter().all(\|p\| walk_pat_(&**p, it)) &&
	after.iter().all(\|p\| walk_pat_(&**p, it))
	}
	PatMac(_) => panic!("attempted to analyze unexpanded pattern"),
	PatWild(_) \| PatLit(_) \| PatRange(_, _) \| PatIdent(_, _, _) \|
	PatEnum(_, _) => {
	true
	}
	}
	}

	walk_pat_(pat, &mut it)
	}

	pub trait EachViewItem {
	fn each_view_item<F>(&self, f: F) -> bool where F: FnMut(&ast::ViewItem) -> bool;
	}

	struct EachViewItemData<F> where F: FnMut(&ast::ViewItem) -> bool {
	callback: F,
	}

	impl<'v, F> Visitor<'v> for EachViewItemData<F> where F: FnMut(&ast::ViewItem) -> bool {
	fn visit_view_item(&mut self, view_item: &ast::ViewItem) {
	let _ = (self.callback)(view_item);
	}
	}

	impl EachViewItem for ast::Crate {
	fn each_view_item<F>(&self, f: F) -> bool where F: FnMut(&ast::ViewItem) -> bool {
	let mut visit = EachViewItemData {
	callback: f,
	};
	visit::walk_crate(&mut visit, self);
	true
	}
	}

	pub fn view_path_id(p: &ViewPath) -> NodeId {
	match p.node {
	ViewPathSimple(_, _, id) \| ViewPathGlob(_, id)
	\| ViewPathList(_, _, id) => id
	}
	}

	/// Returns true if the given struct def is tuple-like; i.e. that its fields
	/// are unnamed.
	pub fn struct_def_is_tuple_like(struct_def: &ast::StructDef) -> bool {
	struct_def.ctor_id.is_some()
	}

	/// Returns true if the given pattern consists solely of an identifier
	/// and false otherwise.
	pub fn pat_is_ident(pat: P<ast::Pat>) -> bool {
	match pat.node {
	ast::PatIdent(..) => true,
	_ => false,
	}
	}

	// are two paths equal when compared unhygienically?
	// since I'm using this to replace ==, it seems appropriate
	// to compare the span, global, etc. fields as well.
	pub fn path_name_eq(a : &ast::Path, b : &ast::Path) -> bool {
	(a.span == b.span)
	&& (a.global == b.global)
	&& (segments_name_eq(&a.segments[], &b.segments[]))
	}

	// are two arrays of segments equal when compared unhygienically?
	pub fn segments_name_eq(a : &[ast::PathSegment], b : &[ast::PathSegment]) -> bool {
	if a.len() != b.len() {
	false
	} else {
	for (idx,seg) in a.iter().enumerate() {
	if seg.identifier.name != b[idx].identifier.name
	// FIXME #7743: ident -> name problems in lifetime comparison?
	// can types contain idents?
	\|\| seg.parameters != b[idx].parameters
	{
	return false;
	}
	}
	true
	}
	}

	/// Returns true if this literal is a string and false otherwise.
	pub fn lit_is_str(lit: &Lit) -> bool {
	match lit.node {
	LitStr(..) => true,
	_ => false,
	}
	}

	/// Macro invocations are guaranteed not to occur after expansion is complete.
	/// Extracting fields of a method requires a dynamic check to make sure that it's
	/// not a macro invocation. This check is guaranteed to succeed, assuming
	/// that the invocations are indeed gone.
	pub trait PostExpansionMethod {
	fn pe_ident(&self) -> ast::Ident;
	fn pe_generics<'a>(&'a self) -> &'a ast::Generics;
	fn pe_abi(&self) -> Abi;
	fn pe_explicit_self<'a>(&'a self) -> &'a ast::ExplicitSelf;
	fn pe_unsafety(&self) -> ast::Unsafety;
	fn pe_fn_decl<'a>(&'a self) -> &'a ast::FnDecl;
	fn pe_body<'a>(&'a self) -> &'a ast::Block;
	fn pe_vis(&self) -> ast::Visibility;
	}

	macro_rules! mf_method{
	($meth_name:ident, $field_ty:ty, $field_pat:pat, $result:expr) => {
	fn $meth_name<'a>(&'a self) -> $field_ty {
	match self.node {
	$field_pat => $result,
	MethMac(_) => {
	panic!("expected an AST without macro invocations");
	}
	}
	}
	}
	}


	impl PostExpansionMethod for Method {
	mf_method! { pe_ident,ast::Ident,MethDecl(ident,_,_,_,_,_,_,_),ident }
	mf_method! {
	pe_generics,&'a ast::Generics,
	MethDecl(_,ref generics,_,_,_,_,_,_),generics
	}
	mf_method! { pe_abi,Abi,MethDecl(_,_,abi,_,_,_,_,_),abi }
	mf_method! {
	pe_explicit_self,&'a ast::ExplicitSelf,
	MethDecl(_,_,_,ref explicit_self,_,_,_,_),explicit_self
	}
	mf_method! { pe_unsafety,ast::Unsafety,MethDecl(_,_,_,_,unsafety,_,_,_),unsafety }
	mf_method! { pe_fn_decl,&'a ast::FnDecl,MethDecl(_,_,_,_,_,ref decl,_,_),&**decl }
	mf_method! { pe_body,&'a ast::Block,MethDecl(_,_,_,_,_,_,ref body,_),&**body }
	mf_method! { pe_vis,ast::Visibility,MethDecl(_,_,_,_,_,_,_,vis),vis }
	}

	#[cfg(test)]
	mod test {
	use ast::*;
	use super::*;

	fn ident_to_segment(id : &Ident) -> PathSegment {
	PathSegment {identifier: id.clone(),
	parameters: PathParameters::none()}
	}

	#[test] fn idents_name_eq_test() {
	assert!(segments_name_eq(
	&[Ident{name:Name(3),ctxt:4}, Ident{name:Name(78),ctxt:82}]
	.iter().map(ident_to_segment).collect::<Vec<PathSegment>>()[],
	&[Ident{name:Name(3),ctxt:104}, Ident{name:Name(78),ctxt:182}]
	.iter().map(ident_to_segment).collect::<Vec<PathSegment>>()[]));
	assert!(!segments_name_eq(
	&[Ident{name:Name(3),ctxt:4}, Ident{name:Name(78),ctxt:82}]
	.iter().map(ident_to_segment).collect::<Vec<PathSegment>>()[],
	&[Ident{name:Name(3),ctxt:104}, Ident{name:Name(77),ctxt:182}]
	.iter().map(ident_to_segment).collect::<Vec<PathSegment>>()[]));
	}
	}