readline/examples/readlinebuf.h

   1 /*******************************************************************************
   2  * $Revision$
   3  * $Date$
   4  * $Author$
   5  *
   6  * Contents: A streambuf which uses the GNU readline library for line I/O
   7  * (c) 2001 by Dimitris Vyzovitis [vyzo@media.mit.edu]
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public
  20  * License along with this program; if not, write to the Free
  21  * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  22  * MA 02111-1307 USA
  23  *
  24  ******************************************************************************/
  25
  26 #ifndef _READLINEBUF_H_
  27 #define _READLINEBUF_H_
  28
  29 #include <iostream>
  30 #include <cstring>
  31 #include <cassert>
  32 #include <cstdlib>
  33 #include <cstdio>
  34
  35 #include <readline/readline.h>
  36 #include <readline/history.h>
  37
  38 #if (defined __GNUC__) && (__GNUC__ < 3)
  39 #include <streambuf.h>
  40 #else
  41 #include <streambuf>
  42 using std::streamsize;
  43 using std::streambuf;
  44 #endif
  45
  46 class readlinebuf : public streambuf {
  47 public:
  48 #if (defined __GNUC__) && (__GNUC__ < 3)
  49         typedef char char_type;
  50         typedef int int_type;
  51         typedef streampos pos_type;
  52         typedef streamoff off_type;
  53 #endif
  54         static const int_type eof = EOF; // this is -1
  55         static const int_type not_eof = 0;
  56
  57 private:
  58         const char* prompt_;
  59         bool history_;
  60         char* line_;
  61         int low_;
  62         int high_;
  63
  64 protected:
  65
  66         virtual int_type showmanyc() const { return high_ - low_; }
  67
  68         virtual streamsize xsgetn( char_type* buf, streamsize n ) {
  69                 int rd = n > (high_ - low_)? (high_ - low_) : n;
  70                 memcpy( buf, line_, rd );
  71                 low_ += rd;
  72
  73                 if ( rd < n ) {
  74                         low_ = high_ = 0;
  75                         free( line_ ); // free( NULL ) is a noop
  76                         line_ = readline( prompt_ );
  77                         if ( line_ ) {
  78                                 high_ = strlen( line_ );
  79                                 if ( history_ && high_ ) add_history( line_ );
  80                                 rd += xsgetn( buf + rd, n - rd );
  81                         }
  82                 }
  83
  84                 return rd;
  85         }
  86
  87         virtual int_type underflow() {
  88                 if ( high_ == low_ ) {
  89                         low_ = high_ = 0;
  90                         free( line_ ); // free( NULL ) is a noop
  91                         line_ = readline( prompt_ );
  92                         if ( line_ ) {
  93                                 high_ = strlen( line_ );
  94                                 if ( history_ && high_ ) add_history( line_ );
  95                         }
  96                 }
  97
  98                 if ( low_ < high_ ) return line_[low_];
  99                 else return eof;
 100         }
 101
 102         virtual int_type uflow() {
 103                 int_type c = underflow();
 104                 if ( c != eof ) ++low_;
 105                 return c;
 106         }
 107
 108         virtual int_type pbackfail( int_type c = eof ) {
 109                 if ( low_ > 0 ) --low_;
 110                 else if ( c != eof ) {
 111                         if ( high_ > 0 ) {
 112                                 char* nl = (char*)realloc( line_, high_ + 1 );
 113                                 if ( nl ) {
 114                                         line_ = (char*)memcpy( nl + 1, line_, high_ );
 115                                         high_ += 1;
 116                                         line_[0] = char( c );
 117                                 } else return eof;
 118                         } else {
 119                                 assert( !line_ );
 120                                 line_ = (char*)malloc( sizeof( char ) );
 121                                 *line_ = char( c );
 122                                 high_ = 1;
 123                         }
 124                 } else return eof;
 125
 126                 return not_eof;
 127         }
 128
 129 public:
 130         readlinebuf( const char* prompt = NULL, bool history = true )
 131                 : prompt_( prompt ), history_( history ),
 132                   line_( NULL ), low_( 0 ), high_( 0 ) {
 133                 setbuf( 0, 0 );
 134         }
 135
 136
 137 };
 138
 139 #endif