Support calling to_s/to_json

Author: jhawthorn

ext/rapidjson/cext.cc

@@ -1,13 +1,16 @@
 #include "cext.hh"
 
-VALUE rb_mRapidjson;
-VALUE rb_eParseError;
-VALUE rb_eEncodeError;
-
 #include "rapidjson/writer.h"
 #include "rapidjson/prettywriter.h"
 #include "rapidjson/error/en.h"
 
+static VALUE rb_mRapidjson;
+static VALUE rb_eParseError;
+static VALUE rb_eEncodeError;
+
+static ID id_to_json;
+static ID id_to_s;
+
 #include "encoder.hh"
 #include "parser.hh"
 
@@ -57,6 +60,9 @@ VALUE valid_json_p(VALUE _self, VALUE string) {
 extern "C" void
 Init_rapidjson(void)
 {
+    id_to_s = rb_intern("to_s");
+    id_to_json = rb_intern("to_json");
+
     rb_mRapidjson = rb_define_module("RapidJSON");
     rb_define_module_function(rb_mRapidjson, "encode", encode, 1);
     rb_define_module_function(rb_mRapidjson, "pretty_encode", pretty_encode, 1);

ext/rapidjson/encoder.hh

@@ -84,6 +84,25 @@ class RubyObjectEncoder {
         encode_string(rb_sym2str(v));
     }
 
+    void encode_raw_json_str(VALUE s) {
+        const char *cstr = RSTRING_PTR(s);
+        size_t len = RSTRING_LEN(s);
+
+	writer.RawValue(cstr, len, kObjectType);
+    }
+
+    void encode_generic(VALUE obj) {
+        if (rb_respond_to(obj, id_to_json)) {
+            VALUE str = rb_funcall(obj, id_to_json, 0);
+            Check_Type(str, T_STRING);
+            encode_raw_json_str(str);
+        } else {
+            VALUE str = rb_funcall(obj, id_to_s, 0);
+            Check_Type(str, T_STRING);
+            encode_string(str);
+        }
+    }
+
     void encode_any(VALUE v) {
         switch(rb_type(v)) {
             case T_NIL:
@@ -110,7 +129,7 @@ class RubyObjectEncoder {
             case T_SYMBOL:
                 return encode_symbol(v);
             default:
-                raise_unknown(v);
+                encode_generic(v);
         }
     }
 

test/test_encoder.rb

@@ -73,10 +73,27 @@ def test_encode_symbol
   end
 
   def test_encode_object
-    ex = assert_raises RapidJSON::EncodeError do
-      encode(Object.new)
+    assert_match(/\A"#<Object:0x[0-9a-f]+>"\z/, encode(Object.new))
+  end
+
+  def test_to_json
+    klass = Class.new do
+      def to_json
+        '{ "amazing":"custom json" }'
+      end
     end
-    assert_match(/can't encode type/, ex.message)
+
+    assert_equal '{ "amazing":"custom json" }', encode(klass.new)
+  end
+
+  def test_to_s
+    klass = Class.new do
+      def to_s
+        "amazing object!"
+      end
+    end
+
+    assert_equal '"amazing object!"', encode(klass.new)
   end
 
   def test_encode_true