fix #181 support enum as map key

Author: taowen

src/main/java/com/jsoniter/MapKeyDecoders.java

@@ -22,11 +22,14 @@ private static Decoder createMapKeyDecoder(Type mapKeyType) {
         if (String.class == mapKeyType) {
             return new StringKeyDecoder();
         }
+        if (mapKeyType instanceof Class && ((Class) mapKeyType).isEnum()) {
+            return new EnumKeyDecoder((Class) mapKeyType);
+        }
         Decoder decoder = CodegenImplNative.NATIVE_DECODERS.get(mapKeyType);
         if (decoder != null) {
             return new NumberKeyDecoder(decoder);
         }
-        throw new JsonException("can not encode map key type: " + mapKeyType);
+        throw new JsonException("can not decode map key type: " + mapKeyType);
     }
 
     private static class StringKeyDecoder implements Decoder {
@@ -37,6 +40,20 @@ public Object decode(JsonIterator iter) throws IOException {
         }
     }
 
+    private static class EnumKeyDecoder implements Decoder {
+
+        private final Class enumClass;
+
+        private EnumKeyDecoder(Class enumClass) {
+            this.enumClass = enumClass;
+        }
+
+        @Override
+        public Object decode(JsonIterator iter) throws IOException {
+            return iter.read(enumClass);
+        }
+    }
+
     private static class NumberKeyDecoder implements Decoder {
 
         private final Decoder decoder;

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

@@ -29,6 +29,9 @@ private static Encoder createDefaultEncoder(Type mapKeyType) {
         if (mapKeyType instanceof WildcardType) {
             return new DynamicKeyEncoder();
         }
+        if (mapKeyType instanceof Class && ((Class) mapKeyType).isEnum()) {
+            return new StringKeyEncoder();
+        }
         Encoder.ReflectionEncoder encoder = CodegenImplNative.NATIVE_ENCODERS.get(mapKeyType);
         if (encoder != null) {
             return new NumberKeyEncoder(encoder);

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

@@ -41,6 +41,18 @@ public void test_integer_key() throws IOException {
         }}, map);
     }
 
+    public static enum EnumKey {
+        KeyA, KeyB
+    }
+
+    public void test_enum_key() {
+        Map<EnumKey, Object> map = JsonIterator.deserialize("{\"KeyA\":null}", new TypeLiteral<Map<EnumKey, Object>>() {
+        });
+        assertEquals(new HashMap<EnumKey, Object>() {{
+            put(EnumKey.KeyA, null);
+        }}, map);
+    }
+
     public static class TestObject1 {
         public int Field;
     }

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

@@ -1,5 +1,6 @@
 package com.jsoniter.output;
 
+import com.jsoniter.JsonIterator;
 import com.jsoniter.spi.Config;
 import com.jsoniter.spi.Encoder;
 import com.jsoniter.spi.JsoniterSpi;
@@ -65,6 +66,19 @@ public void test_integer_key() throws IOException {
         assertEquals("{\"100\":null}", baos.toString());
     }
 
+    public static enum EnumKey {
+        KeyA, KeyB
+    }
+
+    public void test_enum_key() throws IOException {
+        HashMap<EnumKey, Object> obj = new HashMap<EnumKey, Object>();
+        obj.put(EnumKey.KeyA, null);
+        stream.writeVal(new TypeLiteral<Map<EnumKey, Object>>() {
+        }, obj);
+        stream.close();
+        assertEquals("{\"KeyA\":null}", baos.toString());
+    }
+
     public static class TestObject1 {
         public int Field;
     }

src/test/java/com/jsoniter/suite/AllTestCases.java

@@ -8,6 +8,7 @@
 import com.jsoniter.TestObject;
 import com.jsoniter.TestString;
 import com.jsoniter.any.TestList;
+import com.jsoniter.any.TestLong;
 import com.jsoniter.output.*;
 import com.jsoniter.output.TestInteger;
 import org.junit.runner.RunWith;
@@ -54,6 +55,7 @@
         TestStreamBuffer.class,
         TestCollection.class,
         TestList.class,
-        TestAnnotationJsonObject.class})
+        TestAnnotationJsonObject.class,
+        TestLong.class})
 public abstract class AllTestCases {
 }