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input.c
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1998-03-03
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7KB
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320 lines
/*
* Copyright (c) 1984,1985,1989,1994,1995,1996 Mark Nudelman
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice in the documentation and/or other materials provided with
* the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* High level routines dealing with getting lines of input
* from the file being viewed.
*
* When we speak of "lines" here, we mean PRINTABLE lines;
* lines processed with respect to the screen width.
* We use the term "raw line" to refer to lines simply
* delimited by newlines; not processed with respect to screen width.
*/
#include "less.h"
extern int squeeze;
extern int chopline;
extern int sigs;
extern int ignore_eoi;
#if HILITE_SEARCH
extern int hilite_search;
extern int size_linebuf;
#endif
/*
* Get the next line.
* A "current" position is passed and a "new" position is returned.
* The current position is the position of the first character of
* a line. The new position is the position of the first character
* of the NEXT line. The line obtained is the line starting at curr_pos.
*/
public POSITION
forw_line(curr_pos)
POSITION curr_pos;
{
POSITION new_pos;
register int c;
int blankline;
int endline;
if (curr_pos == NULL_POSITION)
{
null_line();
return (NULL_POSITION);
}
#if HILITE_SEARCH
if (hilite_search == OPT_ONPLUS)
/*
* If we are ignoring EOI (command F), only prepare
* one line ahead, to avoid getting stuck waiting for
* slow data without displaying the data we already have.
* If we're not ignoring EOI, we *could* do the same, but
* for efficiency we prepare several lines ahead at once.
*/
prep_hilite(curr_pos, curr_pos + 3*size_linebuf,
ignore_eoi ? 1 : -1);
#endif
if (ch_seek(curr_pos))
{
null_line();
return (NULL_POSITION);
}
prewind();
plinenum(curr_pos);
(void) ch_seek(curr_pos);
c = ch_forw_get();
if (c == EOI)
{
null_line();
return (NULL_POSITION);
}
blankline = (c == '\n' || c == '\r');
for (;;)
{
if (ABORT_SIGS())
{
null_line();
return (NULL_POSITION);
}
if (c == '\n' || c == EOI)
{
/*
* End of the line.
*/
new_pos = ch_tell();
endline = 1;
break;
}
/*
* Append the char to the line and get the next char.
*/
if (pappend(c, ch_tell()-1))
{
/*
* The char won't fit in the line; the line
* is too long to print in the screen width.
* End the line here.
*/
if (chopline)
{
do
{
c = ch_forw_get();
} while (c != '\n' && c != EOI);
new_pos = ch_tell();
endline = 1;
} else
{
new_pos = ch_tell() - 1;
endline = 0;
}
break;
}
c = ch_forw_get();
}
pdone(endline);
if (squeeze && blankline)
{
/*
* This line is blank.
* Skip down to the last contiguous blank line
* and pretend it is the one which we are returning.
*/
while ((c = ch_forw_get()) == '\n' || c == '\r')
if (ABORT_SIGS())
{
null_line();
return (NULL_POSITION);
}
if (c != EOI)
(void) ch_back_get();
new_pos = ch_tell();
}
return (new_pos);
}
/*
* Get the previous line.
* A "current" position is passed and a "new" position is returned.
* The current position is the position of the first character of
* a line. The new position is the position of the first character
* of the PREVIOUS line. The line obtained is the one starting at new_pos.
*/
public POSITION
back_line(curr_pos)
POSITION curr_pos;
{
POSITION new_pos, begin_new_pos;
int c;
int endline;
if (curr_pos == NULL_POSITION || curr_pos <= ch_zero())
{
null_line();
return (NULL_POSITION);
}
#if HILITE_SEARCH
if (hilite_search == OPT_ONPLUS)
prep_hilite((curr_pos < 3*size_linebuf) ?
0 : curr_pos - 3*size_linebuf, curr_pos, -1);
#endif
if (ch_seek(curr_pos-1))
{
null_line();
return (NULL_POSITION);
}
if (squeeze)
{
/*
* Find out if the "current" line was blank.
*/
(void) ch_forw_get(); /* Skip the newline */
c = ch_forw_get(); /* First char of "current" line */
(void) ch_back_get(); /* Restore our position */
(void) ch_back_get();
if (c == '\n' || c == '\r')
{
/*
* The "current" line was blank.
* Skip over any preceding blank lines,
* since we skipped them in forw_line().
*/
while ((c = ch_back_get()) == '\n' || c == '\r')
if (ABORT_SIGS())
{
null_line();
return (NULL_POSITION);
}
if (c == EOI)
{
null_line();
return (NULL_POSITION);
}
(void) ch_forw_get();
}
}
/*
* Scan backwards until we hit the beginning of the line.
*/
for (;;)
{
if (ABORT_SIGS())
{
null_line();
return (NULL_POSITION);
}
c = ch_back_get();
if (c == '\n')
{
/*
* This is the newline ending the previous line.
* We have hit the beginning of the line.
*/
new_pos = ch_tell() + 1;
break;
}
if (c == EOI)
{
/*
* We have hit the beginning of the file.
* This must be the first line in the file.
* This must, of course, be the beginning of the line.
*/
new_pos = ch_tell();
break;
}
}
/*
* Now scan forwards from the beginning of this line.
* We keep discarding "printable lines" (based on screen width)
* until we reach the curr_pos.
*
* {{ This algorithm is pretty inefficient if the lines
* are much longer than the screen width,
* but I don't know of any better way. }}
*/
if (ch_seek(new_pos))
{
null_line();
return (NULL_POSITION);
}
endline = 0;
loop:
begin_new_pos = new_pos;
prewind();
plinenum(new_pos);
(void) ch_seek(new_pos);
do
{
c = ch_forw_get();
if (c == EOI || ABORT_SIGS())
{
null_line();
return (NULL_POSITION);
}
new_pos++;
if (c == '\n')
{
endline = 1;
break;
}
if (pappend(c, ch_tell()-1))
{
/*
* Got a full printable line, but we haven't
* reached our curr_pos yet. Discard the line
* and start a new one.
*/
if (chopline)
{
endline = 1;
break;
}
pdone(0);
(void) ch_back_get();
new_pos--;
goto loop;
}
} while (new_pos < curr_pos);
pdone(endline);
return (begin_new_pos);
}