openvcdiff@gmail.com | 732fff2 | 2010-08-04 18:00:00 +0000 | [diff] [blame^] | 1 | // Copyright 2009 Google Inc. |
| 2 | // Author: James deBoer |
| 3 | // |
| 4 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | // you may not use this file except in compliance with the License. |
| 6 | // You may obtain a copy of the License at |
| 7 | // |
| 8 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | // |
| 10 | // Unless required by applicable law or agreed to in writing, software |
| 11 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | // See the License for the specific language governing permissions and |
| 14 | // limitations under the License. |
| 15 | // |
| 16 | // A class for a code table writer which outputs JSON. |
| 17 | |
| 18 | #ifndef OPEN_VCDIFF_JSONWRITER_H_ |
| 19 | #define OPEN_VCDIFF_JSONWRITER_H_ |
| 20 | |
| 21 | #include <config.h> |
| 22 | #include <string> |
| 23 | #include "addrcache.h" |
| 24 | #include "checksum.h" |
| 25 | #include "codetable.h" |
| 26 | #include "codetablewriter_interface.h" |
| 27 | |
| 28 | namespace open_vcdiff { |
| 29 | |
| 30 | // class JSONCodeTableWriter: |
| 31 | // |
| 32 | // A code table writer which outputs a JSON representation of the diff. |
| 33 | // The output is a JSON array of commands. |
| 34 | // * Each ADD is represented by a single JSON string containing |
| 35 | // the data to add. |
| 36 | // * Each COPY is represented by two numbers. The first is an offset into |
| 37 | // the dictionary. The second is a length. |
| 38 | // * Each RUN is represented by a JSON string containing the data to add, |
| 39 | // similar to the ADD command. |
| 40 | // |
| 41 | class JSONCodeTableWriter : public CodeTableWriterInterface { |
| 42 | public: |
| 43 | JSONCodeTableWriter(); |
| 44 | ~JSONCodeTableWriter(); |
| 45 | |
| 46 | // Initializes the writer. |
| 47 | virtual bool Init(size_t dictionary_size); |
| 48 | |
| 49 | // Encode an ADD opcode with the "size" bytes starting at data |
| 50 | virtual void Add(const char* data, size_t size); |
| 51 | |
| 52 | // Encode a COPY opcode with args "offset" (into dictionary) and "size" bytes. |
| 53 | virtual void Copy(int32_t offset, size_t size); |
| 54 | |
| 55 | // Encode a RUN opcode for "size" copies of the value "byte". |
| 56 | virtual void Run(size_t size, unsigned char byte); |
| 57 | |
| 58 | // Writes the header to the output string. |
| 59 | virtual void WriteHeader(OutputStringInterface* out, |
| 60 | VCDiffFormatExtensionFlags format_extensions); |
| 61 | |
| 62 | virtual void AddChecksum(VCDChecksum) { } |
| 63 | |
| 64 | // Appends the encoded delta window to the output |
| 65 | // string. The output string is not null-terminated. |
| 66 | virtual void Output(OutputStringInterface* out); |
| 67 | |
| 68 | // Finishes the encoding. |
| 69 | virtual void FinishEncoding(OutputStringInterface *out); |
| 70 | |
| 71 | // Returns the number of target bytes processed, which is the sum of all the |
| 72 | // size arguments passed to Add(), Copy(), and Run(). |
| 73 | // TODO(ajenjo): Eliminate the need for this method. |
| 74 | virtual size_t target_length() const; |
| 75 | private: |
| 76 | typedef std::string string; |
| 77 | |
| 78 | // Escape the input data to conform with the JSON string spec |
| 79 | // and add it to the 'out' string. |
| 80 | void JSONEscape(const char* data, size_t size, string* out); |
| 81 | |
| 82 | // Stores the JSON data before it is sent to the OutputString. |
| 83 | string output_; |
| 84 | |
| 85 | // The sum of all the size arguments passed to Add(), Copy() and Run(). |
| 86 | size_t target_length_; |
| 87 | |
| 88 | // Set if some data has been output. |
| 89 | bool output_called_; |
| 90 | }; |
| 91 | |
| 92 | } // namespace open_vcdiff |
| 93 | #endif // OPEN_VCDIFF_JSONWRITER_H_ |