support enum

Author: huangxiyuan

bson_writer.h

@@ -29,6 +29,7 @@
 
 #include "util.h"
 #include "xtypes.h"
+#include "traits.h"
 
 struct _bson_t;
 
@@ -187,7 +188,7 @@ class BsonWriter {
     }
 
     template <typename T>
-    BsonWriter& convert(const char*key, const T& data, typename x_enable_if<(sizeof(T)>sizeof(int)), T>::type *p=0) {
+    BsonWriter& convert(const char*key, const T& data, x_for_class(T) *p=0) {
         if (_type!=top || key[0]!='\0') {
             BsonWriter child(key, _bson, doc);
             data.__struct_to_str(child, "");

config_writer.h

@@ -28,6 +28,7 @@
 
 #include "util.h"
 #include "xtypes.h"
+#include "traits.h"
 
 #define LIBCONFIG_BUFFER_SIZE 1024
 #define LIBCONFIG_TYPE_OBJECT 0
@@ -260,7 +261,7 @@ class ConfigWriter {
     }
 
     template <typename T>
-    void convert(const char*key, const T& data, typename x_enable_if<(sizeof(T)>sizeof(int)), T>::type *p=0) {
+    void convert(const char*key, const T& data, x_for_class(T) *p=0) {
         indent();
         x2struct_set_key(key);
         this->object_begin();

json_writer.h

@@ -27,6 +27,7 @@
 #include "thirdparty/rapidjson/stringbuffer.h"
 
 #include "xtypes.h"
+#include "traits.h"
 
 namespace x2struct {
 
@@ -245,7 +246,7 @@ class JsonWriter {
     }
 
     template <typename T>
-    void convert(const char*key, const T& data, typename x_enable_if<(sizeof(T)>sizeof(int)), T>::type *p=0) {
+    void convert(const char*key, const T& data, x_for_class(T) *p=0) {
         x2struct_set_key(key);
         this->object_begin();
         data.__struct_to_str(*this, key);

traits.h

@@ -0,0 +1,62 @@
+/*
+* Copyright (C) 2019 YY Inc. All rights reserved.
+*
+* Licensed under the Apache License, Version 2.0 (the "License"); 
+* you may not use this file except in compliance with the License. 
+* You may obtain a copy of the License at
+*
+*       http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, 
+* software distributed under the License is distributed on an "AS IS" BASIS, 
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
+* See the License for the specific language governing permissions and 
+* limitations under the License.
+*/
+
+
+#ifndef __X_TO_TRAITS_H
+#define __X_TO_TRAITS_H
+
+#if __GXX_EXPERIMENTAL_CXX0X__ || _MSC_VER>=1700
+#include <type_traits>
+#endif
+
+using namespace std;
+
+#if __GXX_EXPERIMENTAL_CXX0X__ || _MSC_VER>=1700
+//template <class T>
+//using x_for_class = typename std::enable_if<std::is_class<T>::value, int>::type;
+
+//template <class T>
+//using x_for_enum = typename std::enable_if<std::is_enum<T>::value, int>::type;
+
+// <c++11 not support using template. so we use macro all
+#define x_for_class(T) typename std::enable_if<std::is_class<T>::value, int>::type
+#define x_for_enum(T)  typename std::enable_if<std::is_enum<T>::value, int>::type
+#else
+template<bool B, class T = void>
+struct x_enable_if {};
+
+template <class T>
+struct x_enable_if<true, T> { typedef T type; };
+
+
+template <class T>
+struct x_tovoid {typedef void type;};
+
+template <class T, typename=void>
+struct x_is_class{static bool const value = false;};
+
+template <class T>
+struct x_is_class<T, typename x_tovoid<int T::*>::type >{static bool const value = true;};
+
+
+#define x_for_class(T) typename x_enable_if<x_is_class<T>::value, int>::type
+// too complicated to implement is_enum
+#define x_for_enum(T)  typename x_enable_if<!x_is_class<T>::value, int>::type
+
+#endif
+
+#endif
+

xml_writer.h

@@ -27,6 +27,7 @@
 
 #include "util.h"
 #include "xtypes.h"
+#include "traits.h"
 
 #define X2STRUCT_BUFFER_SIZE 1024
 #define X2STRUCT_TYPE_OBJECT 0
@@ -251,7 +252,7 @@ class XmlWriter {
     }
 
     template <typename T>
-    void convert(const char*key, const T& data, typename x_enable_if<(sizeof(T)>sizeof(int)), T>::type *p=0) {
+    void convert(const char*key, const T& data, x_for_class(T) *p=0) {
         XmlKey xkey(key, this, false);
         this->object_begin();
         data.__struct_to_str(*this, key);

xreader.h

@@ -32,6 +32,7 @@
 #endif
 
 #include "util.h"
+#include "traits.h"
 
 namespace x2struct {
 
@@ -123,9 +124,9 @@ class XReader {
         return true;
     }
 
-    // because struct has a set, it's size is bigger than sizeof(int). add this to avoid enum hit this function
+    // add x_for_class to avoid enum hit this function
     template <typename TYPE>
-    bool convert(const char*key, TYPE& val, typename x_enable_if<(sizeof(TYPE)>sizeof(int)), TYPE>::type *p=0) {
+    bool convert(const char*key, TYPE& val, x_for_class(TYPE) *p=0) {
         doc_type tmp;
         doc_type *obj = get_obj(key, &tmp);
         if (NULL == obj) {
@@ -149,7 +150,7 @@ class XReader {
 
     // for enum
     template <typename TYPE>
-    bool convert(const char*key, TYPE& val, typename x_enable_if<(sizeof(TYPE)==sizeof(int)), TYPE>::type *p=0) {
+    bool convert(const char*key, TYPE& val, x_for_enum(TYPE) *p=0) {
         return ((doc_type*)(this))->convert(key, *(int*)&val);
     }