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Diffstat (limited to 'include/rapidjson/internal/meta.h')
| -rw-r--r-- | include/rapidjson/internal/meta.h | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/include/rapidjson/internal/meta.h b/include/rapidjson/internal/meta.h new file mode 100644 index 00000000..5a9aaa42 --- /dev/null +++ b/include/rapidjson/internal/meta.h @@ -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_ |