parsestream.h   [plain text]

/* This is part of libio/iostream, providing -*- C++ -*- input/output.
Copyright (C) 1993 Free Software Foundation

This file is part of the GNU IO Library.  This library is free
software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option)
any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this library; see the file COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

As a special exception, if you link this library with files
compiled with a GNU compiler to produce an executable, this does not cause
the resulting executable to be covered by the GNU General Public License.
This exception does not however invalidate any other reasons why
the executable file might be covered by the GNU General Public License.

Written by Per Bothner ( */

#ifdef __GNUG__
#pragma interface
#include "streambuf.h"

extern "C++" {
// A parsebuf is a streambuf optimized for scanning text files.
// It keeps track of line and column numbers.
// It is guaranteed to remember the entire current line,
// as well the '\n'-s on either side of it (if they exist).
// You can arbitrarily seek (or unget) within this extended line.
// Other backward seeks are not supported.
// Normal read semantics are supported (and hence istream operators like >>).

class parsebuf : public streambuf {
    _IO_fpos_t pos_at_line_start;
    long _line_length;
    unsigned long __line_number;
    char *buf_start;
    char *buf_end;

    parsebuf *chain;

    // Return column number (raw - don't handle tabs etc).
    // Retult can be -1, meaning: at '\n' before current line.
    virtual int tell_in_line();

    // seek to (raw) column I in current line.
    // Result is new (raw) column position - differs from I if unable to seek.
    // Seek to -1 tries to seek to before previous LF.
    virtual int seek_in_line(int i);

    // Note: there is no "current line" initially, until something is read.

    // Current line number, starting with 0.
    // If tell_in_line()==-1, then line number of next line.
    int line_number() { return __line_number; }

    // Length of current line, not counting either '\n'.
    int line_length() { return _line_length; }
    // Current line - not a copy, so file ops may trash it. 
    virtual char* current_line();
    virtual streampos seekoff(streamoff, _seek_dir, int mode=ios::in|ios::out);
    virtual streambuf* setbuf(char* p, int len);
    parsebuf() { chain= NULL;
	__line_number = 0; pos_at_line_start = 0; _line_length = -1; }
    virtual int pbackfail(int c);

// A string_parsebuf is a parsebuf whose source is a fixed string.

class string_parsebuf : public parsebuf {
    int do_delete;
    string_parsebuf(char *str, int len, int delete_at_close=0);
    virtual int underflow();
    virtual char* current_line();
    virtual int seek_in_line(int i);
    virtual int tell_in_line();
    char *left() const { return base(); }
    char *right() const { return ebuf(); }
//    streampos seekoff(streamoff, _seek_dir, int);

// A func_parsebuf calls a given function to get new input.
// Each call returns an entire NUL-terminated line (without the '\n').
// That line has been allocated with malloc(), not new.
// The interface is tailored to the GNU readline library.
// Example:
// char* DoReadLine(void* arg)
// {
//   char *line = readline((char*)arg); /* 'arg' is used as prompt. */
//   if line == NULL) { putc('\n', stderr); return NULL; }
//   if (line[0] != '\0') add_history(line);
//    return line;
// }
// char PromptBuffer[100] = "> ";
// func_parsebuf my_stream(DoReadLine, PromptBuffer);

typedef char *(*CharReader)(void *arg);
class istream;

class func_parsebuf : public parsebuf {
    void *arg;
    CharReader read_func;
    int backed_up_to_newline;
    func_parsebuf(CharReader func, void *argm = NULL);
    int underflow();
    virtual int tell_in_line();
    virtual int seek_in_line(int i);
    virtual char* current_line();

// A general_parsebuf is a parsebuf which gets its input from some
// other streambuf. It explicitly buffers up an entire line.

class general_parsebuf : public parsebuf {
    streambuf *sbuf;
    int delete_buf; // Delete sbuf when destroying this.
    general_parsebuf(streambuf *buf, int delete_arg_buf = 0);
    int underflow();
    virtual int tell_in_line();
    virtual int seek_in_line(int i);
    virtual char* current_line();

#if 0
class parsestream : public istream {
    streammarker marks[2];
    short _first; // of the two marks; either 0 or 1
    int _lineno;
    int first() { return _first; }
    int second() { return 1-_first; }
    int line_length() { marks[second].delta(marks[first]); }
    int line_length() { marks[second].delta(marks[first]); }
    int seek_in_line(int i);
    int tell_in_line();
    int line_number();
} // extern "C++"
#endif /*!defined(PARSESTREAM_H)*/