1// Tencent is pleased to support the open source community by making RapidJSON available.
 2// 
 3// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
 4//
 5// Licensed under the MIT License (the "License"); you may not use this file except
 6// in compliance with the License. You may obtain a copy of the License at
 7//
 8// http://opensource.org/licenses/MIT
 9//
10// Unless required by applicable law or agreed to in writing, software distributed 
11// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
12// CONDITIONS OF ANY KIND, either express or implied. See the License for the 
13// specific language governing permissions and limitations under the License.
14
15#ifndef RAPIDJSON_FILEREADSTREAM_H_
16#define RAPIDJSON_FILEREADSTREAM_H_
17
18#include "stream.h"
19#include <cstdio>
20
21#ifdef __clang__
22RAPIDJSON_DIAG_PUSH
23RAPIDJSON_DIAG_OFF(padded)
24RAPIDJSON_DIAG_OFF(unreachable-code)
25RAPIDJSON_DIAG_OFF(missing-noreturn)
26#endif
27
28RAPIDJSON_NAMESPACE_BEGIN
29
30//! File byte stream for input using fread().
31/*!
32    \note implements Stream concept
33*/
34class FileReadStream {
35public:
36    typedef char Ch;    //!< Character type (byte).
37
38    //! Constructor.
39    /*!
40        \param fp File pointer opened for read.
41        \param buffer user-supplied buffer.
42        \param bufferSize size of buffer in bytes. Must >=4 bytes.
43    */
44    FileReadStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferSize_(bufferSize), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false) { 
45        RAPIDJSON_ASSERT(fp_ != 0);
46        RAPIDJSON_ASSERT(bufferSize >= 4);
47        Read();
48    }
49
50    Ch Peek() const { return *current_; }
51    Ch Take() { Ch c = *current_; Read(); return c; }
52    size_t Tell() const { return count_ + static_cast<size_t>(current_ - buffer_); }
53
54    // Not implemented
55    void Put(Ch) { RAPIDJSON_ASSERT(false); }
56    void Flush() { RAPIDJSON_ASSERT(false); } 
57    Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
58    size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
59
60    // For encoding detection only.
61    const Ch* Peek4() const {
62        return (current_ + 4 <= bufferLast_) ? current_ : 0;
63    }
64
65private:
66    void Read() {
67        if (current_ < bufferLast_)
68            ++current_;
69        else if (!eof_) {
70            count_ += readCount_;
71            readCount_ = fread(buffer_, 1, bufferSize_, fp_);
72            bufferLast_ = buffer_ + readCount_ - 1;
73            current_ = buffer_;
74
75            if (readCount_ < bufferSize_) {
76                buffer_[readCount_] = '\0';
77                ++bufferLast_;
78                eof_ = true;
79            }
80        }
81    }
82
83    std::FILE* fp_;
84    Ch *buffer_;
85    size_t bufferSize_;
86    Ch *bufferLast_;
87    Ch *current_;
88    size_t readCount_;
89    size_t count_;  //!< Number of characters read
90    bool eof_;
91};
92
93RAPIDJSON_NAMESPACE_END
94
95#ifdef __clang__
96RAPIDJSON_DIAG_POP
97#endif
98
99#endif // RAPIDJSON_FILESTREAM_H_