182 lines
6.4 KiB
C++
182 lines
6.4 KiB
C++
// Tencent is pleased to support the open source community by making RapidJSON available.
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//
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// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
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//
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// Licensed under the MIT License (the "License"); you may not use this file except
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// in compliance with the License. You may obtain a copy of the License at
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//
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// http://opensource.org/licenses/MIT
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//
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// Unless required by applicable law or agreed to in writing, software distributed
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// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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// CONDITIONS OF ANY KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations under the License.
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#ifndef RAPIDJSON_INTERNAL_META_H_
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#define RAPIDJSON_INTERNAL_META_H_
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#include "../rapidjson.h"
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#ifdef __GNUC__
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RAPIDJSON_DIAG_PUSH
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RAPIDJSON_DIAG_OFF(effc++)
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#endif
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#if defined(_MSC_VER)
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RAPIDJSON_DIAG_PUSH
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RAPIDJSON_DIAG_OFF(6334)
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#endif
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#if RAPIDJSON_HAS_CXX11_TYPETRAITS
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#include <type_traits>
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#endif
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//@cond RAPIDJSON_INTERNAL
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RAPIDJSON_NAMESPACE_BEGIN
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namespace internal {
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// Helper to wrap/convert arbitrary types to void, useful for arbitrary type matching
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template <typename T> struct Void { typedef void Type; };
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///////////////////////////////////////////////////////////////////////////////
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// BoolType, TrueType, FalseType
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//
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template <bool Cond> struct BoolType {
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static const bool Value = Cond;
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typedef BoolType Type;
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};
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typedef BoolType<true> TrueType;
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typedef BoolType<false> FalseType;
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///////////////////////////////////////////////////////////////////////////////
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// SelectIf, BoolExpr, NotExpr, AndExpr, OrExpr
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//
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template <bool C> struct SelectIfImpl { template <typename T1, typename T2> struct Apply { typedef T1 Type; }; };
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template <> struct SelectIfImpl<false> { template <typename T1, typename T2> struct Apply { typedef T2 Type; }; };
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template <bool C, typename T1, typename T2> struct SelectIfCond : SelectIfImpl<C>::template Apply<T1,T2> {};
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template <typename C, typename T1, typename T2> struct SelectIf : SelectIfCond<C::Value, T1, T2> {};
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template <bool Cond1, bool Cond2> struct AndExprCond : FalseType {};
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template <> struct AndExprCond<true, true> : TrueType {};
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template <bool Cond1, bool Cond2> struct OrExprCond : TrueType {};
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template <> struct OrExprCond<false, false> : FalseType {};
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template <typename C> struct BoolExpr : SelectIf<C,TrueType,FalseType>::Type {};
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template <typename C> struct NotExpr : SelectIf<C,FalseType,TrueType>::Type {};
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template <typename C1, typename C2> struct AndExpr : AndExprCond<C1::Value, C2::Value>::Type {};
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template <typename C1, typename C2> struct OrExpr : OrExprCond<C1::Value, C2::Value>::Type {};
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///////////////////////////////////////////////////////////////////////////////
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// AddConst, MaybeAddConst, RemoveConst
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template <typename T> struct AddConst { typedef const T Type; };
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template <bool Constify, typename T> struct MaybeAddConst : SelectIfCond<Constify, const T, T> {};
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template <typename T> struct RemoveConst { typedef T Type; };
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template <typename T> struct RemoveConst<const T> { typedef T Type; };
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///////////////////////////////////////////////////////////////////////////////
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// IsSame, IsConst, IsMoreConst, IsPointer
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//
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template <typename T, typename U> struct IsSame : FalseType {};
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template <typename T> struct IsSame<T, T> : TrueType {};
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template <typename T> struct IsConst : FalseType {};
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template <typename T> struct IsConst<const T> : TrueType {};
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template <typename CT, typename T>
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struct IsMoreConst
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: AndExpr<IsSame<typename RemoveConst<CT>::Type, typename RemoveConst<T>::Type>,
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BoolType<IsConst<CT>::Value >= IsConst<T>::Value> >::Type {};
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template <typename T> struct IsPointer : FalseType {};
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template <typename T> struct IsPointer<T*> : TrueType {};
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///////////////////////////////////////////////////////////////////////////////
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// IsBaseOf
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//
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#if RAPIDJSON_HAS_CXX11_TYPETRAITS
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template <typename B, typename D> struct IsBaseOf
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: BoolType< ::std::is_base_of<B,D>::value> {};
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#else // simplified version adopted from Boost
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template<typename B, typename D> struct IsBaseOfImpl {
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RAPIDJSON_STATIC_ASSERT(sizeof(B) != 0);
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RAPIDJSON_STATIC_ASSERT(sizeof(D) != 0);
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typedef char (&Yes)[1];
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typedef char (&No) [2];
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template <typename T>
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static Yes Check(const D*, T);
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static No Check(const B*, int);
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struct Host {
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operator const B*() const;
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operator const D*();
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};
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enum { Value = (sizeof(Check(Host(), 0)) == sizeof(Yes)) };
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};
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template <typename B, typename D> struct IsBaseOf
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: OrExpr<IsSame<B, D>, BoolExpr<IsBaseOfImpl<B, D> > >::Type {};
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#endif // RAPIDJSON_HAS_CXX11_TYPETRAITS
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//////////////////////////////////////////////////////////////////////////
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// EnableIf / DisableIf
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//
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template <bool Condition, typename T = void> struct EnableIfCond { typedef T Type; };
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template <typename T> struct EnableIfCond<false, T> { /* empty */ };
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template <bool Condition, typename T = void> struct DisableIfCond { typedef T Type; };
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template <typename T> struct DisableIfCond<true, T> { /* empty */ };
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template <typename Condition, typename T = void>
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struct EnableIf : EnableIfCond<Condition::Value, T> {};
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template <typename Condition, typename T = void>
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struct DisableIf : DisableIfCond<Condition::Value, T> {};
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// SFINAE helpers
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struct SfinaeTag {};
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template <typename T> struct RemoveSfinaeTag;
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template <typename T> struct RemoveSfinaeTag<SfinaeTag&(*)(T)> { typedef T Type; };
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#define RAPIDJSON_REMOVEFPTR_(type) \
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typename ::RAPIDJSON_NAMESPACE::internal::RemoveSfinaeTag \
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< ::RAPIDJSON_NAMESPACE::internal::SfinaeTag&(*) type>::Type
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#define RAPIDJSON_ENABLEIF(cond) \
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typename ::RAPIDJSON_NAMESPACE::internal::EnableIf \
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<RAPIDJSON_REMOVEFPTR_(cond)>::Type * = NULL
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#define RAPIDJSON_DISABLEIF(cond) \
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typename ::RAPIDJSON_NAMESPACE::internal::DisableIf \
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<RAPIDJSON_REMOVEFPTR_(cond)>::Type * = NULL
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#define RAPIDJSON_ENABLEIF_RETURN(cond,returntype) \
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typename ::RAPIDJSON_NAMESPACE::internal::EnableIf \
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<RAPIDJSON_REMOVEFPTR_(cond), \
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RAPIDJSON_REMOVEFPTR_(returntype)>::Type
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#define RAPIDJSON_DISABLEIF_RETURN(cond,returntype) \
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typename ::RAPIDJSON_NAMESPACE::internal::DisableIf \
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<RAPIDJSON_REMOVEFPTR_(cond), \
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RAPIDJSON_REMOVEFPTR_(returntype)>::Type
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} // namespace internal
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RAPIDJSON_NAMESPACE_END
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//@endcond
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#if defined(__GNUC__) || defined(_MSC_VER)
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RAPIDJSON_DIAG_POP
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#endif
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#endif // RAPIDJSON_INTERNAL_META_H_
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