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/*******************************************************************************

 * $Revision: 1.2 $

 * $Date: 2001/09/11 06:19:36 $

 * $Author: vyzo $

 *

 * Contents: A streambuf which uses the GNU readline library for line I/O

 * (c) 2001 by Dimitris Vyzovitis [vyzo@media.mit.edu]

 *

 * This program 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 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public

 * License along with this program; if not, write to the Free

 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,

 * MA 02111-1307 USA

 *

 ******************************************************************************/

#ifndef _READLINEBUF_H_

#define _READLINEBUF_H_

#include <iostream>

#include <cstring>

#include <cassert>

#include <cstdlib>

#include <cstdio>

#include <readline/readline.h>

#include <readline/history.h>

#if (defined __GNUC__) && (__GNUC__ < 3)

#include <streambuf.h>

#else

#include <streambuf>

using std::streamsize;

using std::streambuf;

#endif

class readlinebuf : public streambuf {

public:

#if (defined __GNUC__) && (__GNUC__ < 3)

        typedef char char_type;

        typedef int int_type;

        typedef streampos pos_type;

        typedef streamoff off_type;

#endif

        static const int_type eof = EOF; // this is -1

        static const int_type not_eof = 0;

private:

        const char* prompt_;

        bool history_;

        char* line_;

        int low_;

        int high_;

protected:

        virtual int_type showmanyc() const { return high_ - low_; }

        virtual streamsize xsgetn( char_type* buf, streamsize n ) {

                int rd = n > (high_ - low_)? (high_ - low_) : n;

                memcpy( buf, line_, rd );

                low_ += rd;

                if ( rd < n ) {

                        low_ = high_ = 0;

                        free( line_ ); // free( NULL ) is a noop

                        line_ = readline( prompt_ );

                        if ( line_ ) {

                                high_ = strlen( line_ );

                                if ( history_ && high_ ) add_history( line_ );

                                rd += xsgetn( buf + rd, n - rd );

                        }

                }

                return rd;

        }

        virtual int_type underflow() {

                if ( high_ == low_ ) {

                        low_ = high_ = 0;

                        free( line_ ); // free( NULL ) is a noop

                        line_ = readline( prompt_ );

                        if ( line_ ) {

                                high_ = strlen( line_ );

                                if ( history_ && high_ ) add_history( line_ );

                        }

                }

                if ( low_ < high_ ) return line_[low_];

                else return eof;

        }

        virtual int_type uflow() {

                int_type c = underflow();

                if ( c != eof ) ++low_;

                return c;

        }

        virtual int_type pbackfail( int_type c = eof ) {

                if ( low_ > 0 )  --low_;

                else if ( c != eof ) {

                        if ( high_ > 0 ) {

                                char* nl = (char*)realloc( line_, high_ + 1 );

                                if ( nl ) {

                                        line_ = (char*)memcpy( nl + 1, line_, high_ );

                                        high_ += 1;

                                        line_[0] = char( c );

                                } else return eof;

                        } else {

                                assert( !line_ );

                                line_ = (char*)malloc( sizeof( char ) );

                                *line_ = char( c );

                                high_ = 1;

                        }

                } else return eof;

                return not_eof;

        }

public:

        readlinebuf( const char* prompt = NULL, bool history = true )

                : prompt_( prompt ), history_( history ),

                  line_( NULL ), low_( 0 ), high_( 0 ) {

                setbuf( 0, 0 );

        }

};

#endif