support object map key type in codegen

Author: taowen

src/main/java/com/jsoniter/output/CodegenImplMap.java

@@ -19,7 +19,6 @@ public static CodegenResult genMap(String cacheKey, ClassInfo classInfo) {
             keyType = typeArgs[0];
             valueType = typeArgs[1];
         }
-        String mapCacheKey = JsoniterSpi.getMapKeyEncoderCacheKey(keyType);
         CodegenResult ctx = new CodegenResult();
         ctx.append("public static void encode_(java.lang.Object obj, com.jsoniter.output.JsonStream stream) throws java.io.IOException {");
         ctx.append("if (obj == null) { stream.writeNull(); return; }");
@@ -36,16 +35,7 @@ public static CodegenResult genMap(String cacheKey, ClassInfo classInfo) {
         } else {
             ctx.append("stream.writeObjectStart(); stream.writeIndention();");
         }
-        if (keyType == String.class) {
-            ctx.append("stream.writeVal((java.lang.String)entry.getKey());");
-        } else {
-            ctx.append(String.format("com.jsoniter.output.CodegenAccess.writeMapKey(\"%s\", entry.getKey(), stream);", mapCacheKey));
-        }
-        if (noIndention) {
-            ctx.append("stream.write(':');");
-        } else {
-            ctx.append("stream.write((byte)':', (byte)' ');");
-        }
+        genWriteMapKey(ctx, keyType, noIndention);
         if (isCollectionValueNullable) {
             ctx.append("if (entry.getValue() == null) { stream.writeNull(); } else {");
             CodegenImplNative.genWriteOp(ctx, "entry.getValue()", valueType, true);
@@ -60,11 +50,7 @@ public static CodegenResult genMap(String cacheKey, ClassInfo classInfo) {
         } else {
             ctx.append("stream.writeMore();");
         }
-        if (keyType == String.class) {
-            ctx.append("stream.writeVal((java.lang.String)entry.getKey());");
-        } else {
-            ctx.append(String.format("com.jsoniter.output.CodegenAccess.writeMapKey(\"%s\", entry.getKey(), stream);", mapCacheKey));
-        }
+        genWriteMapKey(ctx, keyType, noIndention);
         if (noIndention) {
             ctx.append("stream.write(':');");
         } else {
@@ -86,4 +72,24 @@ public static CodegenResult genMap(String cacheKey, ClassInfo classInfo) {
         ctx.append("}");
         return ctx;
     }
+
+    private static void genWriteMapKey(CodegenResult ctx, Type keyType, boolean noIndention) {
+        if (keyType == Object.class) {
+            ctx.append("stream.writeObjectField(entry.getKey());");
+            return;
+        }
+        if (keyType == String.class) {
+            ctx.append("stream.writeVal((java.lang.String)entry.getKey());");
+        } else if (CodegenImplNative.NATIVE_ENCODERS.containsKey(keyType)) {
+            ctx.append(String.format("stream.writeVal((%s)entry.getKey());", CodegenImplNative.getTypeName(keyType)));
+        } else {
+            String mapCacheKey = JsoniterSpi.getMapKeyEncoderCacheKey(keyType);
+            ctx.append(String.format("com.jsoniter.output.CodegenAccess.writeMapKey(\"%s\", entry.getKey(), stream);", mapCacheKey));
+        }
+        if (noIndention) {
+            ctx.append("stream.write(':');");
+        } else {
+            ctx.append("stream.write((byte)':', (byte)' ');");
+        }
+    }
 }

src/main/java/com/jsoniter/output/JsonStream.java

@@ -331,6 +331,11 @@ public final void writeObjectField(String field) throws IOException {
         }
     }
 
+    public final void writeObjectField(Object key) throws IOException {
+        Encoder encoder = MapKeyEncoders.registerOrGetExisting(key.getClass());
+        writeObjectField(key, encoder);
+    }
+
     public final void writeObjectField(Object key, Encoder keyEncoder) throws IOException {
         keyEncoder.encode(key, this);
         if (indention > 0) {

src/test/java/com/jsoniter/output/TestMap.java

@@ -122,9 +122,9 @@ public void test_indention_with_empty_map() {
     }
 
     public void test_int_as_map_key() {
-        HashMap<Integer, Integer> m = new HashMap<Integer, Integer>();
-        m.put(1, 2);
-        assertEquals("{\"1\":2}", JsonStream.serialize(new TypeLiteral<Map<Integer, Integer>>(){
+        HashMap<Integer, String> m = new HashMap<Integer, String>();
+        m.put(1, "2");
+        assertEquals("{\"1\":\"2\"}", JsonStream.serialize(new TypeLiteral<Map<Integer, String>>() {
         }, m));
     }