enc/streams.h

/* Copyright 2009 Google Inc. All Rights Reserved.

   Distributed under MIT license.
   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/

/* Input and output classes for streaming brotli compression. */

#ifndef BROTLI_ENC_STREAMS_H_
#define BROTLI_ENC_STREAMS_H_

#include <stdio.h>
#include <string>

#include "../common/types.h"

namespace brotli {

/* Input interface for the compression routines. */
class BrotliIn {
 public:
  virtual ~BrotliIn(void) {}

  /* Return a pointer to the next block of input of at most n bytes.
     Return the actual length in *nread.
     At end of data, return NULL. Don't return NULL if there is more data
     to read, even if called with n == 0.
     Read will only be called if some of its bytes are needed. */
  virtual const void* Read(size_t n, size_t* nread) = 0;
};

/* Output interface for the compression routines. */
class BrotliOut {
 public:
  virtual ~BrotliOut(void) {}

  /* Write n bytes of data from buf.
     Return true if all written, false otherwise. */
  virtual bool Write(const void *buf, size_t n) = 0;
};

/* Adapter class to make BrotliIn objects from raw memory. */
class BrotliMemIn : public BrotliIn {
 public:
  BrotliMemIn(const void* buf, size_t len);

  void Reset(const void* buf, size_t len);

  /* returns the amount of data consumed */
  size_t position(void) const { return pos_; }

  const void* Read(size_t n, size_t* OUTPUT);

 private:
  const void* buf_;  /* start of input buffer */
  size_t len_;  /* length of input */
  size_t pos_;  /* current read position within input */
};

/* Adapter class to make BrotliOut objects from raw memory. */
class BrotliMemOut : public BrotliOut {
 public:
  BrotliMemOut(void* buf, size_t len);

  void Reset(void* buf, size_t len);

  /* returns the amount of data written */
  size_t position(void) const { return pos_; }

  bool Write(const void* buf, size_t n);

 private:
  void* buf_;  /* start of output buffer */
  size_t len_;  /* length of output */
  size_t pos_;  /* current write position within output */
};

/* Adapter class to make BrotliOut objects from a string. */
class BrotliStringOut : public BrotliOut {
 public:
  /* Create a writer that appends its data to buf.
     buf->size() will grow to at most max_size
     buf is expected to be empty when constructing BrotliStringOut. */
  BrotliStringOut(std::string* buf, size_t max_size);

  void Reset(std::string* buf, size_t max_len);

  bool Write(const void* buf, size_t n);

 private:
  std::string* buf_;  /* start of output buffer */
  size_t max_size_;  /* max length of output */
};

/* Adapter class to make BrotliIn object from a file. */
class BrotliFileIn : public BrotliIn {
 public:
  BrotliFileIn(FILE* f, size_t max_read_size);
  ~BrotliFileIn(void);

  const void* Read(size_t n, size_t* bytes_read);

 private:
  FILE* f_;
  char* buf_;
  size_t buf_size_;
};

/* Adapter class to make BrotliOut object from a file. */
class BrotliFileOut : public BrotliOut {
 public:
  explicit BrotliFileOut(FILE* f);

  bool Write(const void* buf, size_t n);
 private:
  FILE* f_;
};

}  /* namespace brotli */

#endif  /* BROTLI_ENC_STREAMS_H_ */