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// Copyright 2009 Google Inc.
// Author: James deBoer
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
// A class for a code table writer which outputs JSON.
#include <config.h>
#include <string>
#include "addrcache.h"
#include "checksum.h"
#include "codetable.h"
#include "codetablewriter_interface.h"
namespace open_vcdiff {
// class JSONCodeTableWriter:
// A code table writer which outputs a JSON representation of the diff.
// The output is a JSON array of commands.
// * Each ADD is represented by a single JSON string containing
// the data to add.
// * Each COPY is represented by two numbers. The first is an offset into
// the dictionary. The second is a length.
// * Each RUN is represented by a JSON string containing the data to add,
// similar to the ADD command.
class JSONCodeTableWriter : public CodeTableWriterInterface {
// Initializes the writer.
virtual bool Init(size_t dictionary_size);
// Encode an ADD opcode with the "size" bytes starting at data
virtual void Add(const char* data, size_t size);
// Encode a COPY opcode with args "offset" (into dictionary) and "size" bytes.
virtual void Copy(int32_t offset, size_t size);
// Encode a RUN opcode for "size" copies of the value "byte".
virtual void Run(size_t size, unsigned char byte);
// Writes the header to the output string.
virtual void WriteHeader(OutputStringInterface* out,
VCDiffFormatExtensionFlags format_extensions);
virtual void AddChecksum(VCDChecksum) { }
// Appends the encoded delta window to the output
// string. The output string is not null-terminated.
virtual void Output(OutputStringInterface* out);
// Finishes the encoding.
virtual void FinishEncoding(OutputStringInterface *out);
// Returns the number of target bytes processed, which is the sum of all the
// size arguments passed to Add(), Copy(), and Run().
// TODO(ajenjo): Eliminate the need for this method.
virtual size_t target_length() const;
typedef std::string string;
// Escape the input data to conform with the JSON string spec
// and add it to the 'out' string.
void JSONEscape(const char* data, size_t size, string* out);
// Stores the JSON data before it is sent to the OutputString.
string output_;
// The sum of all the size arguments passed to Add(), Copy() and Run().
size_t target_length_;
// Set if some data has been output.
bool output_called_;
} // namespace open_vcdiff