fix typos in sample code, add enum to json encoder, add test case

src/libstd/json.rs

@@ -122,9 +122,15 @@ pub impl Encoder: serialize::Encoder {
     fn emit_managed(&self, f: fn()) { f() }
 
     fn emit_enum(&self, name: &str, f: fn()) {
-        if name != "option" { die!(~"only supports option enum") }
-        f()
+        // emitting enums as arrays where the first
+        // element provides the enum variant name
+        self.wr.write_char('[');
+        self.wr.write_str(name);
+        self.wr.write_char(',');
+        f();
+        self.wr.write_char(']');
     }
+    
     fn emit_enum_variant(&self, _name: &str, id: uint, _cnt: uint, f: fn()) {
         if id == 0 {
             self.emit_nil();

src/libsyntax/ext/auto_encode.rs

@@ -23,23 +23,23 @@ For example, a type like:
 
 would generate two implementations like:
 
-    impl<S: Encoder> node_id: Encodable<S> {
-        fn encode(s: &S) {
-            do s.emit_struct("Node", 1) {
-                s.emit_field("id", 0, || s.emit_uint(self))
-            }
+impl<S: std::serialize::Encoder> Node: Encodable<S> {
+    fn encode(&self, s: &S) {
+        do s.emit_struct("Node", 1) {
+            s.emit_field("id", 0, || s.emit_uint(self.id))
         }
     }
+}
 
-    impl<D: Decoder> node_id: Decodable {
-        static fn decode(d: &D) -> Node {
-            do d.read_struct("Node", 1) {
-                Node {
-                    id: d.read_field(~"x", 0, || decode(d))
-                }
+impl<D: Decoder> node_id: Decodable {
+    static fn decode(d: &D) -> Node {
+        do d.read_struct("Node", 1) {
+            Node {
+                id: d.read_field(~"x", 0, || decode(d))
             }
         }
     }
+}
 
 Other interesting scenarios are whe the item has type parameters or
 references other non-built-in types.  A type definition like:
@@ -1150,3 +1150,42 @@ fn mk_enum_deser_body(
         ]
     )
 }
+
+
+#[cfg(test)]
+mod test {
+    use std::serialize::Encodable;
+    use core::dvec::*;
+    use util::testing::*;
+    use core::io;
+    use core::str;
+    use std;
+    
+    
+    #[auto_decode]
+    #[auto_encode]
+    struct Node {id: uint}
+
+    fn to_json_str (val: Encodable<std::json::Encoder>) -> ~str{
+        let bw = @io::BytesWriter {bytes: DVec(), pos: 0};
+        val.encode(~std::json::Encoder(bw as io::Writer));
+        str::from_bytes(bw.bytes.data)
+    }
+    
+    #[test] fn encode_test () {
+        check_equal (to_json_str(Node{id:34} as Encodable::<std::json::Encoder>),~"{\"id\":34}");
+    }
+
+    #[auto_encode]
+    enum written {
+        Book(int),
+        Magazine(~str)
+    }
+
+    #[test] fn json_enum_encode_test () {
+        check_equal (to_json_str(Book(9) as Encodable::<std::json::Encoder>),
+                     ~"[\"Book\",9]");
+        check_equal (to_json_str(Magazine(~"Paris Match") as Encodable::<std::json::Encoder>),
+                     ~"[\"Magazine\",\"Paris Match\"]");
+    }
+}