openvcdiff@gmail.com | 64fe232 | 2011-09-27 21:51:41 +0000 | [diff] [blame] | 1 | // Copyright 2008 Google Inc. |
| 2 | // Author: Lincoln Smith |
| 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. |
openvcdiff | d184578 | 2009-03-20 21:56:15 +0000 | [diff] [blame] | 15 | // |
| 16 | // Definition of an abstract class that describes the interface between the |
| 17 | // encoding engine (which finds the best string matches between the source and |
| 18 | // target data) and the code table writer. The code table writer is passed a |
| 19 | // series of Add, Copy, and Run instructions and produces an output file in the |
| 20 | // desired format. |
| 21 | |
openvcdiff@gmail.com | f1dd933 | 2009-10-09 22:40:32 +0000 | [diff] [blame] | 22 | #ifndef OPEN_VCDIFF_CODETABLEWRITER_INTERFACE_H_ |
| 23 | #define OPEN_VCDIFF_CODETABLEWRITER_INTERFACE_H_ |
openvcdiff | d184578 | 2009-03-20 21:56:15 +0000 | [diff] [blame] | 24 | |
| 25 | #include <stddef.h> // size_t |
openvcdiff@gmail.com | 732fff2 | 2010-08-04 18:00:00 +0000 | [diff] [blame] | 26 | #include "checksum.h" // VCDChecksum |
| 27 | #include "google/format_extension_flags.h" // VCDiffFormatExtensionFlags |
openvcdiff | d184578 | 2009-03-20 21:56:15 +0000 | [diff] [blame] | 28 | |
| 29 | namespace open_vcdiff { |
| 30 | |
| 31 | class OutputStringInterface; |
| 32 | |
| 33 | // The method calls after construction should follow this pattern: |
| 34 | // {{Add|Copy|Run}* Output}* |
| 35 | // |
| 36 | // Output() will produce an encoding using the given series of Add, Copy, |
| 37 | // and/or Run instructions. One implementation of the interface |
| 38 | // (VCDiffCodeTableWriter) produces a VCDIFF delta window, but other |
| 39 | // implementations may be used to produce other output formats, or as test |
| 40 | // mocks, or to gather encoding statistics. |
| 41 | // |
| 42 | class CodeTableWriterInterface { |
| 43 | public: |
| 44 | virtual ~CodeTableWriterInterface() { } |
| 45 | |
openvcdiff@gmail.com | 732fff2 | 2010-08-04 18:00:00 +0000 | [diff] [blame] | 46 | // Initializes the constructed object for use. It will return |
| 47 | // false if there was an error initializing the object, or true if it |
| 48 | // was successful. After the object has been initialized and used, |
| 49 | // Init() can be called again to restore the initial state of the object. |
| 50 | virtual bool Init(size_t dictionary_size) = 0; |
| 51 | |
| 52 | // Writes the header to the output string. |
| 53 | virtual void WriteHeader(OutputStringInterface* out, |
| 54 | VCDiffFormatExtensionFlags format_extensions) = 0; |
| 55 | |
openvcdiff | d184578 | 2009-03-20 21:56:15 +0000 | [diff] [blame] | 56 | // Encode an ADD opcode with the "size" bytes starting at data |
| 57 | virtual void Add(const char* data, size_t size) = 0; |
| 58 | |
| 59 | // Encode a COPY opcode with args "offset" (into dictionary) and "size" bytes. |
| 60 | virtual void Copy(int32_t offset, size_t size) = 0; |
| 61 | |
| 62 | // Encode a RUN opcode for "size" copies of the value "byte". |
| 63 | virtual void Run(size_t size, unsigned char byte) = 0; |
| 64 | |
openvcdiff@gmail.com | 732fff2 | 2010-08-04 18:00:00 +0000 | [diff] [blame] | 65 | // Adds a checksum to the output. |
| 66 | virtual void AddChecksum(VCDChecksum checksum) = 0; |
| 67 | |
| 68 | // Appends the encoded delta window to the output |
openvcdiff | d184578 | 2009-03-20 21:56:15 +0000 | [diff] [blame] | 69 | // string. The output string is not null-terminated and may contain embedded |
| 70 | // '\0' characters. |
| 71 | virtual void Output(OutputStringInterface* out) = 0; |
| 72 | |
openvcdiff@gmail.com | 732fff2 | 2010-08-04 18:00:00 +0000 | [diff] [blame] | 73 | // Finishes encoding. |
| 74 | virtual void FinishEncoding(OutputStringInterface* out) = 0; |
| 75 | |
openvcdiff | d184578 | 2009-03-20 21:56:15 +0000 | [diff] [blame] | 76 | // Returns the number of target bytes processed, which is the sum of all the |
| 77 | // size arguments passed to Add(), Copy(), and Run(). |
| 78 | virtual size_t target_length() const = 0; |
| 79 | }; |
| 80 | |
| 81 | } // namespace open_vcdiff |
| 82 | |
openvcdiff@gmail.com | f1dd933 | 2009-10-09 22:40:32 +0000 | [diff] [blame] | 83 | #endif // OPEN_VCDIFF_CODETABLEWRITER_INTERFACE_H_ |