Diff: rapidjson/internal/meta.h

Revision:

0:33d4e66780c0

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rapidjson/internal/meta.h	Fri Feb 24 11:23:12 2017 -0600
@@ -0,0 +1,181 @@
+// Tencent is pleased to support the open source community by making RapidJSON available.
+// 
+// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
+//
+// Licensed under the MIT License (the "License"); you may not use this file except
+// in compliance with the License. You may obtain a copy of the License at
+//
+// http://opensource.org/licenses/MIT
+//
+// 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 RAPIDJSON_INTERNAL_META_H_
+#define RAPIDJSON_INTERNAL_META_H_
+
+#include "../rapidjson.h"
+
+#ifdef __GNUC__
+RAPIDJSON_DIAG_PUSH
+RAPIDJSON_DIAG_OFF(effc++)
+#endif
+#if defined(_MSC_VER)
+RAPIDJSON_DIAG_PUSH
+RAPIDJSON_DIAG_OFF(6334)
+#endif
+
+#if RAPIDJSON_HAS_CXX11_TYPETRAITS
+#include <type_traits>
+#endif
+
+//@cond RAPIDJSON_INTERNAL
+RAPIDJSON_NAMESPACE_BEGIN
+namespace internal {
+
+// Helper to wrap/convert arbitrary types to void, useful for arbitrary type matching
+template <typename T> struct Void { typedef void Type; };
+
+///////////////////////////////////////////////////////////////////////////////
+// BoolType, TrueType, FalseType
+//
+template <bool Cond> struct BoolType {
+    static const bool Value = Cond;
+    typedef BoolType Type;
+};
+typedef BoolType<true> TrueType;
+typedef BoolType<false> FalseType;
+
+
+///////////////////////////////////////////////////////////////////////////////
+// SelectIf, BoolExpr, NotExpr, AndExpr, OrExpr
+//
+
+template <bool C> struct SelectIfImpl { template <typename T1, typename T2> struct Apply { typedef T1 Type; }; };
+template <> struct SelectIfImpl<false> { template <typename T1, typename T2> struct Apply { typedef T2 Type; }; };
+template <bool C, typename T1, typename T2> struct SelectIfCond : SelectIfImpl<C>::template Apply<T1,T2> {};
+template <typename C, typename T1, typename T2> struct SelectIf : SelectIfCond<C::Value, T1, T2> {};
+
+template <bool Cond1, bool Cond2> struct AndExprCond : FalseType {};
+template <> struct AndExprCond<true, true> : TrueType {};
+template <bool Cond1, bool Cond2> struct OrExprCond : TrueType {};
+template <> struct OrExprCond<false, false> : FalseType {};
+
+template <typename C> struct BoolExpr : SelectIf<C,TrueType,FalseType>::Type {};
+template <typename C> struct NotExpr  : SelectIf<C,FalseType,TrueType>::Type {};
+template <typename C1, typename C2> struct AndExpr : AndExprCond<C1::Value, C2::Value>::Type {};
+template <typename C1, typename C2> struct OrExpr  : OrExprCond<C1::Value, C2::Value>::Type {};
+
+
+///////////////////////////////////////////////////////////////////////////////
+// AddConst, MaybeAddConst, RemoveConst
+template <typename T> struct AddConst { typedef const T Type; };
+template <bool Constify, typename T> struct MaybeAddConst : SelectIfCond<Constify, const T, T> {};
+template <typename T> struct RemoveConst { typedef T Type; };
+template <typename T> struct RemoveConst<const T> { typedef T Type; };
+
+
+///////////////////////////////////////////////////////////////////////////////
+// IsSame, IsConst, IsMoreConst, IsPointer
+//
+template <typename T, typename U> struct IsSame : FalseType {};
+template <typename T> struct IsSame<T, T> : TrueType {};
+
+template <typename T> struct IsConst : FalseType {};
+template <typename T> struct IsConst<const T> : TrueType {};
+
+template <typename CT, typename T>
+struct IsMoreConst
+    : AndExpr<IsSame<typename RemoveConst<CT>::Type, typename RemoveConst<T>::Type>,
+              BoolType<IsConst<CT>::Value >= IsConst<T>::Value> >::Type {};
+
+template <typename T> struct IsPointer : FalseType {};
+template <typename T> struct IsPointer<T*> : TrueType {};
+
+///////////////////////////////////////////////////////////////////////////////
+// IsBaseOf
+//
+#if RAPIDJSON_HAS_CXX11_TYPETRAITS
+
+template <typename B, typename D> struct IsBaseOf
+    : BoolType< ::std::is_base_of<B,D>::value> {};
+
+#else // simplified version adopted from Boost
+
+template<typename B, typename D> struct IsBaseOfImpl {
+    RAPIDJSON_STATIC_ASSERT(sizeof(B) != 0);
+    RAPIDJSON_STATIC_ASSERT(sizeof(D) != 0);
+
+    typedef char (&Yes)[1];
+    typedef char (&No) [2];
+
+    template <typename T>
+    static Yes Check(const D*, T);
+    static No  Check(const B*, int);
+
+    struct Host {
+        operator const B*() const;
+        operator const D*();
+    };
+
+    enum { Value = (sizeof(Check(Host(), 0)) == sizeof(Yes)) };
+};
+
+template <typename B, typename D> struct IsBaseOf
+    : OrExpr<IsSame<B, D>, BoolExpr<IsBaseOfImpl<B, D> > >::Type {};
+
+#endif // RAPIDJSON_HAS_CXX11_TYPETRAITS
+
+
+//////////////////////////////////////////////////////////////////////////
+// EnableIf / DisableIf
+//
+template <bool Condition, typename T = void> struct EnableIfCond  { typedef T Type; };
+template <typename T> struct EnableIfCond<false, T> { /* empty */ };
+
+template <bool Condition, typename T = void> struct DisableIfCond { typedef T Type; };
+template <typename T> struct DisableIfCond<true, T> { /* empty */ };
+
+template <typename Condition, typename T = void>
+struct EnableIf : EnableIfCond<Condition::Value, T> {};
+
+template <typename Condition, typename T = void>
+struct DisableIf : DisableIfCond<Condition::Value, T> {};
+
+// SFINAE helpers
+struct SfinaeTag {};
+template <typename T> struct RemoveSfinaeTag;
+template <typename T> struct RemoveSfinaeTag<SfinaeTag&(*)(T)> { typedef T Type; };
+
+#define RAPIDJSON_REMOVEFPTR_(type) \
+    typename ::RAPIDJSON_NAMESPACE::internal::RemoveSfinaeTag \
+        < ::RAPIDJSON_NAMESPACE::internal::SfinaeTag&(*) type>::Type
+
+#define RAPIDJSON_ENABLEIF(cond) \
+    typename ::RAPIDJSON_NAMESPACE::internal::EnableIf \
+        <RAPIDJSON_REMOVEFPTR_(cond)>::Type * = NULL
+
+#define RAPIDJSON_DISABLEIF(cond) \
+    typename ::RAPIDJSON_NAMESPACE::internal::DisableIf \
+        <RAPIDJSON_REMOVEFPTR_(cond)>::Type * = NULL
+
+#define RAPIDJSON_ENABLEIF_RETURN(cond,returntype) \
+    typename ::RAPIDJSON_NAMESPACE::internal::EnableIf \
+        <RAPIDJSON_REMOVEFPTR_(cond), \
+         RAPIDJSON_REMOVEFPTR_(returntype)>::Type
+
+#define RAPIDJSON_DISABLEIF_RETURN(cond,returntype) \
+    typename ::RAPIDJSON_NAMESPACE::internal::DisableIf \
+        <RAPIDJSON_REMOVEFPTR_(cond), \
+         RAPIDJSON_REMOVEFPTR_(returntype)>::Type
+
+} // namespace internal
+RAPIDJSON_NAMESPACE_END
+//@endcond
+
+#if defined(__GNUC__) || defined(_MSC_VER)
+RAPIDJSON_DIAG_POP
+#endif
+
+#endif // RAPIDJSON_INTERNAL_META_H_