stringbuffer.h

00001 // Tencent is pleased to support the open source community by making RapidJSON available.
00002 // 
00003 // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
00004 //
00005 // Licensed under the MIT License (the "License"); you may not use this file except
00006 // in compliance with the License. You may obtain a copy of the License at
00007 //
00008 // http://opensource.org/licenses/MIT
00009 //
00010 // Unless required by applicable law or agreed to in writing, software distributed 
00011 // under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
00012 // CONDITIONS OF ANY KIND, either express or implied. See the License for the 
00013 // specific language governing permissions and limitations under the License.
00014 
00015 #ifndef RAPIDJSON_STRINGBUFFER_H_
00016 #define RAPIDJSON_STRINGBUFFER_H_
00017 
00018 #include "stream.h"
00019 #include "internal/stack.h"
00020 
00021 #if RAPIDJSON_HAS_CXX11_RVALUE_REFS
00022 #include <utility> // std::move
00023 #endif
00024 
00025 #include "internal/stack.h"
00026 
00027 #if defined(__clang__)
00028 RAPIDJSON_DIAG_PUSH
00029 RAPIDJSON_DIAG_OFF(c++98-compat)
00030 #endif
00031 
00032 RAPIDJSON_NAMESPACE_BEGIN
00033 
00034 //! Represents an in-memory output stream.
00035 /*!
00036     \tparam Encoding Encoding of the stream.
00037     \tparam Allocator type for allocating memory buffer.
00038     \note implements Stream concept
00039 */
00040 template <typename Encoding, typename Allocator = CrtAllocator>
00041 class GenericStringBuffer {
00042 public:
00043     typedef typename Encoding::Ch Ch;
00044 
00045     GenericStringBuffer(Allocator* allocator = 0, size_t capacity = kDefaultCapacity) : stack_(allocator, capacity) {}
00046 
00047 #if RAPIDJSON_HAS_CXX11_RVALUE_REFS
00048     GenericStringBuffer(GenericStringBuffer&& rhs) : stack_(std::move(rhs.stack_)) {}
00049     GenericStringBuffer& operator=(GenericStringBuffer&& rhs) {
00050         if (&rhs != this)
00051             stack_ = std::move(rhs.stack_);
00052         return *this;
00053     }
00054 #endif
00055 
00056     void Put(Ch c) { *stack_.template Push<Ch>() = c; }
00057     void PutUnsafe(Ch c) { *stack_.template PushUnsafe<Ch>() = c; }
00058     void Flush() {}
00059 
00060     void Clear() { stack_.Clear(); }
00061     void ShrinkToFit() {
00062         // Push and pop a null terminator. This is safe.
00063         *stack_.template Push<Ch>() = '\0';
00064         stack_.ShrinkToFit();
00065         stack_.template Pop<Ch>(1);
00066     }
00067 
00068     void Reserve(size_t count) { stack_.template Reserve<Ch>(count); }
00069     Ch* Push(size_t count) { return stack_.template Push<Ch>(count); }
00070     Ch* PushUnsafe(size_t count) { return stack_.template PushUnsafe<Ch>(count); }
00071     void Pop(size_t count) { stack_.template Pop<Ch>(count); }
00072 
00073     const Ch* GetString() const {
00074         // Push and pop a null terminator. This is safe.
00075         *stack_.template Push<Ch>() = '\0';
00076         stack_.template Pop<Ch>(1);
00077 
00078         return stack_.template Bottom<Ch>();
00079     }
00080 
00081     //! Get the size of string in bytes in the string buffer.
00082     size_t GetSize() const { return stack_.GetSize(); }
00083 
00084     //! Get the length of string in Ch in the string buffer.
00085     size_t GetLength() const { return stack_.GetSize() / sizeof(Ch); }
00086 
00087     static const size_t kDefaultCapacity = 256;
00088     mutable internal::Stack<Allocator> stack_;
00089 
00090 private:
00091     // Prohibit copy constructor & assignment operator.
00092     GenericStringBuffer(const GenericStringBuffer&);
00093     GenericStringBuffer& operator=(const GenericStringBuffer&);
00094 };
00095 
00096 //! String buffer with UTF8 encoding
00097 typedef GenericStringBuffer<UTF8<> > StringBuffer;
00098 
00099 template<typename Encoding, typename Allocator>
00100 inline void PutReserve(GenericStringBuffer<Encoding, Allocator>& stream, size_t count) {
00101     stream.Reserve(count);
00102 }
00103 
00104 template<typename Encoding, typename Allocator>
00105 inline void PutUnsafe(GenericStringBuffer<Encoding, Allocator>& stream, typename Encoding::Ch c) {
00106     stream.PutUnsafe(c);
00107 }
00108 
00109 //! Implement specialized version of PutN() with memset() for better performance.
00110 template<>
00111 inline void PutN(GenericStringBuffer<UTF8<> >& stream, char c, size_t n) {
00112     std::memset(stream.stack_.Push<char>(n), c, n * sizeof(c));
00113 }
00114 
00115 RAPIDJSON_NAMESPACE_END
00116 
00117 #if defined(__clang__)
00118 RAPIDJSON_DIAG_POP
00119 #endif
00120 
00121 #endif // RAPIDJSON_STRINGBUFFER_H_