Allow JSON::Fragment to be used even in strict mode

java/src/json/ext/Generator.java

@@ -5,6 +5,8 @@
  */
 package json.ext;
 
+import json.ext.RuntimeInfo;
+
 import org.jcodings.Encoding;
 import org.jcodings.specific.ASCIIEncoding;
 import org.jcodings.specific.USASCIIEncoding;
@@ -115,6 +117,11 @@ private static <T extends IRubyObject> Handler<? super T> getHandlerFor(Ruby run
             case HASH   :
                 if (Helpers.metaclass(object) != runtime.getHash()) break;
                 return (Handler<T>) HASH_HANDLER;
+            case STRUCT :
+                RuntimeInfo info = RuntimeInfo.forRuntime(runtime);
+                RubyClass fragmentClass = info.jsonModule.get().getClass("Fragment");
+                if (Helpers.metaclass(object) != fragmentClass) break;
+                return (Handler<T>) FRAGMENT_HANDLER;
         }
         return GENERIC_HANDLER;
     }
@@ -481,6 +488,28 @@ static RubyString ensureValidEncoding(ThreadContext context, RubyString str) {
     static final Handler<IRubyObject> NIL_HANDLER =
             new KeywordHandler<>("null");
 
+    /**
+     * The default handler (<code>Object#to_json</code>): coerces the object
+     * to string using <code>#to_s</code>, and serializes that string.
+     */
+    static final Handler<IRubyObject> FRAGMENT_HANDLER =
+        new Handler<IRubyObject>() {
+            @Override
+            RubyString generateNew(ThreadContext context, Session session, IRubyObject object) {
+                GeneratorState state = session.getState(context);
+                IRubyObject result = object.callMethod(context, "to_json", state);
+                if (result instanceof RubyString) return (RubyString)result;
+                throw context.runtime.newTypeError("to_json must return a String");
+            }
+
+            @Override
+            void generate(ThreadContext context, Session session, IRubyObject object, OutputStream buffer) throws IOException {
+                RubyString result = generateNew(context, session, object);
+                ByteList bytes = result.getByteList();
+                buffer.write(bytes.unsafeBytes(), bytes.begin(), bytes.length());
+            }
+        };
+
     /**
      * The default handler (<code>Object#to_json</code>): coerces the object
      * to string using <code>#to_s</code>, and serializes that string.

lib/json/truffle_ruby/generator.rb

@@ -412,10 +412,10 @@ def to_json(state = nil, *)
             state = State.from_state(state) if state
             if state&.strict?
               value = self
-              if state.strict? && !(false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value)
+              if state.strict? && !(false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value || Fragment === value)
                 if state.as_json
                   value = state.as_json.call(value)
-                  unless false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value
+                  unless false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value || Fragment === value
                     raise GeneratorError.new("#{value.class} returned by #{state.as_json} not allowed in JSON", value)
                   end
                   value.to_json(state)
@@ -472,10 +472,10 @@ def json_transform(state)
               end
 
               result = +"#{result}#{key_json}#{state.space_before}:#{state.space}"
-              if state.strict? && !(false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value)
+              if state.strict? && !(false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value || Fragment === value)
                 if state.as_json
                   value = state.as_json.call(value)
-                  unless false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value
+                  unless false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value || Fragment === value
                     raise GeneratorError.new("#{value.class} returned by #{state.as_json} not allowed in JSON", value)
                   end
                   result << value.to_json(state)
@@ -533,10 +533,10 @@ def json_transform(state)
             each { |value|
               result << delim unless first
               result << state.indent * depth if indent
-              if state.strict? && !(false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value)
+              if state.strict? && !(false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value || Fragment === value)
                 if state.as_json
                   value = state.as_json.call(value)
-                  unless false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value
+                  unless false == value || true == value || nil == value || String === value || Array === value || Hash === value || Integer === value || Float === value || Fragment === value
                     raise GeneratorError.new("#{value.class} returned by #{state.as_json} not allowed in JSON", value)
                   end
                   result << value.to_json(state)

test/json/json_generator_test.rb

@@ -668,6 +668,7 @@ def test_nonutf8_encoding
   def test_fragment
     fragment = JSON::Fragment.new(" 42")
     assert_equal '{"number": 42}', JSON.generate({ number: fragment })
+    assert_equal '{"number": 42}', JSON.generate({ number: fragment }, strict: true)
   end
 
   def test_json_generate_as_json_convert_to_proc