lineread.h

伯克利做的SFTP安全文件传输协议

// lineread.h
// module to buffer a stream input source to improve the cost
//   of partitioning that input source into lines during
//   online reading, such as from sockets or pipes
// it may be possible to generalize parts of this, but something
//   really useful like an arbirary EOL test isn't possible
//   without major restructuring, due to handling of pathological
//   cases like EOL straddling a buffer boundary
// copyright SafeTP Development Group, Inc., 2000  Terms of use are as specified in license.txt

#ifndef __LINEREAD_H
#define __LINEREAD_H

#include "typ.h"       // bool
#include "str.h"       // string

class StreamInputSource;

class StreamLineReader {
private:      // types
  enum {
    DEFAULT_BUFLEN = 1024,      // just some value
    ENDPOST_VALUE = 0xBB,       // mostly arbitrary
    CR = '\r', LF = '\n',       // separator components
  };

private:      // data
  // stream source
  StreamInputSource &source;
  bool eof;

  // character buffer for large-length reads
  char *buffer;
  int bufferLen;

  // active area of buffer; start is next character
  // to return to user, end is next byte of buffer
  // to fill from source
  char *start, *end;

  // invariants:
  //   buffer != NULL
  //   (byte)buffer[bufferLen] == ENDPOST_VALUE
  //   bufferLen > 0
  //   0 <= (start-buffer) <= bufferLen
  //   (start-buffer) <= (end-buffer) <= bufferLen

private:
  // xassert that the invariants are true
  void selfCheck() const;

  // read from source
  int fillBuffer();

public:
  StreamLineReader(StreamInputSource &src,
                   int buflen = DEFAULT_BUFLEN);
  ~StreamLineReader();

  // (blocking) read the next string from the input source
  // returns false (and leaves 's' unchanged) on EOF;
  // does NOT return the CRLF in the string; will throw an
  // exception iff source stream does
  bool getNextLine(string &s);

  // (nonblocking) does the buffer contain unprocessed data?
  bool hasUnprocessedData() const;
};

#endif // __LINEREAD_H