re-special-case Option in JSON encoding
diff --git a/src/libstd/json.rs b/src/libstd/json.rs
index dce4f42..07dbef6 100644
--- a/src/libstd/json.rs
+++ b/src/libstd/json.rs
@@ -126,16 +126,42 @@
}
fn emit_enum_variant(&self, name: &str, _id: uint, _cnt: uint, f: fn()) {
- // emitting enums as arrays where the first
- // element provides the enum variant name
- self.wr.write_char('[');
- self.wr.write_str(escape_str(name));
- f();
- self.wr.write_char(']');
+ // encoding of enums is special-cased for Option. Specifically:
+ // Some(34) => 34
+ // None => null
+
+ // other enums are encoded as vectors:
+ // Kangaroo(34,"William") => ["Kangaroo",[34,"William"]]
+
+ // the default expansion for enums is more verbose than I'd like;
+ // specifically, the inner pair of brackets seems superfluous,
+ // BUT the design of the enumeration framework and the requirements
+ // of the special-case for Option mean that a first argument must
+ // be encoded "naked"--with no commas--and that the option name
+ // can't be followed by just a comma, because there might not
+ // be any elements in the tuple.
+
+ // FIXME : this would be more precise and less frightening
+ // with fully-qualified option names. To get that information,
+ // we'd have to change the expansion of auto-encode to pass those along.
+
+ if (name == ~"Some") {
+ f();
+ } else if (name == ~"None") {
+ self.wr.write_str(~"null");
+ } else {
+ self.wr.write_char('[');
+ self.wr.write_str(escape_str(name));
+ self.wr.write_char(',');
+ self.wr.write_char('[');
+ f();
+ self.wr.write_char(']');
+ self.wr.write_char(']');
+ }
}
- fn emit_enum_variant_arg(&self, _idx: uint, f: fn()) {
- self.wr.write_char(',');
+ fn emit_enum_variant_arg(&self, idx: uint, f: fn()) {
+ if (idx != 0) {self.wr.write_char(',');}
f();
}
@@ -1286,7 +1312,36 @@
}
}
check_equal(str::from_bytes(bw.bytes.data),
- ~"[\"frog\",\"Henry\",349]");
+ ~"[\"frog\",[\"Henry\",349]]");
+ }
+
+ #[test]
+ fn test_write_some () {
+ let bw = @io::BytesWriter {bytes: dvec::DVec(), pos: 0};
+ let bww : @io::Writer = (bw as @io::Writer);
+ let encoder = (@Encoder(bww) as @serialize::Encoder);
+ do encoder.emit_enum(~"Option") {
+ do encoder.emit_enum_variant (~"Some",37,1242) {
+ do encoder.emit_enum_variant_arg (0) {
+ encoder.emit_owned_str(~"jodhpurs")
+ }
+ }
+ }
+ check_equal(str::from_bytes(bw.bytes.data),
+ ~"\"jodhpurs\"");
+ }
+
+ #[test]
+ fn test_write_none () {
+ let bw = @io::BytesWriter {bytes: dvec::DVec(), pos: 0};
+ let bww : @io::Writer = (bw as @io::Writer);
+ let encoder = (@Encoder(bww) as @serialize::Encoder);
+ do encoder.emit_enum(~"Option") {
+ do encoder.emit_enum_variant (~"None",37,1242) {
+ }
+ }
+ check_equal(str::from_bytes(bw.bytes.data),
+ ~"null");
}
#[test]
