269 lines
6.8 KiB
C
269 lines
6.8 KiB
C
/*
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* Copyright (c) 1988 Mark Nudleman
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* Copyright (c) 1988, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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static char sccsid[] = "@(#)input.c 8.1 (Berkeley) 6/6/93";
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#endif /* not lint */
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#ifndef lint
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static const char rcsid[] =
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"$Id$";
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#endif /* not lint */
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/*
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* High level routines dealing with getting lines of input
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* from the file being viewed.
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*
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* When we speak of "lines" here, we mean PRINTABLE lines;
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* lines processed with respect to the screen width.
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* We use the term "raw line" to refer to lines simply
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* delimited by newlines; not processed with respect to screen width.
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*/
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#include <sys/types.h>
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#include "less.h"
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int horiz_off = NO_HORIZ_OFF; /* # characters scrolled off left of screen */
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extern int squeeze;
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extern int sigs;
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extern char *line;
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off_t ch_tell();
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/*
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* Get the next printable line.
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*
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* A "current" position is passed and a "new" position is returned.
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* The current position is the position of the first character of
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* a line. The new position is the position of the first character
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* of the NEXT line. The line obtained is the line starting at curr_pos.
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* It is placed into the global line buffer ("line").
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*/
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off_t
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forw_line(curr_pos)
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off_t curr_pos;
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{
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off_t new_pos;
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register int c;
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if (curr_pos == NULL_POSITION || ch_seek(curr_pos))
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return (NULL_POSITION);
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c = ch_forw_get();
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if (c == EOI)
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return (NULL_POSITION);
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prewind();
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for (;;)
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{
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if (sigs)
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return (NULL_POSITION);
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if (c == '\n' || c == EOI)
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{
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/*
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* End of the line.
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*/
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new_pos = ch_tell();
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break;
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}
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/*
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* Append the char to the line and get the next char.
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* The pappend() will throw away any unimportant chars
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* (ie. not underlines or bolds) as per horiz_off.
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*
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* XXX line.c needs to be rewritten...
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*/
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if (pappend(c))
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{
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/*
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* The char won't fit in the line; the line
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* is too long to print in the screen width.
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* End the line here.
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*/
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if (horiz_off != NO_HORIZ_OFF) {
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/* Throw away left-over characters on line */
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c = ch_forw_get();
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while (c != '\n' && c != EOI)
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c = ch_forw_get();
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new_pos = ch_tell();
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} else {
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new_pos = ch_tell() - 1;
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}
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break;
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}
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c = ch_forw_get();
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}
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(void) pappend('\0');
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if (squeeze && *line == '\0')
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{
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/*
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* This line is blank.
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* Skip down to the last contiguous blank line
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* and pretend it is the one which we are returning.
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*/
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while ((c = ch_forw_get()) == '\n')
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if (sigs)
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return (NULL_POSITION);
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if (c != EOI)
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(void) ch_back_get();
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new_pos = ch_tell();
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}
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return (new_pos);
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}
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/*
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* Get the previous line.
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*
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* A "current" position is passed and a "new" position is returned.
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* The current position is the position of the first character of
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* a line. The new position is the position of the first character
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* of the PREVIOUS line. The line obtained is the one starting at new_pos.
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* It is placed into the global line buffer ("line").
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*/
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off_t
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back_line(curr_pos)
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off_t curr_pos;
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{
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off_t new_pos, begin_new_pos;
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int c;
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if (curr_pos == NULL_POSITION || curr_pos <= (off_t)0 ||
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ch_seek(curr_pos-1))
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return (NULL_POSITION);
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if (squeeze)
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{
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/*
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* Find out if the "current" line was blank.
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*/
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(void) ch_forw_get(); /* Skip the newline */
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c = ch_forw_get(); /* First char of "current" line */
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(void) ch_back_get(); /* Restore our position */
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(void) ch_back_get();
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if (c == '\n')
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{
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/*
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* The "current" line was blank.
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* Skip over any preceeding blank lines,
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* since we skipped them in forw_line().
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*/
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while ((c = ch_back_get()) == '\n')
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if (sigs)
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return (NULL_POSITION);
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if (c == EOI)
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return (NULL_POSITION);
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(void) ch_forw_get();
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}
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}
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/*
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* Scan backwards until we hit the beginning of the line.
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*/
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for (;;)
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{
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if (sigs)
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return (NULL_POSITION);
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c = ch_back_get();
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if (c == '\n')
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{
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/*
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* This is the newline ending the previous line.
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* We have hit the beginning of the line.
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*/
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new_pos = ch_tell() + 1;
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break;
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}
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if (c == EOI)
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{
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/*
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* We have hit the beginning of the file.
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* This must be the first line in the file.
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* This must, of course, be the beginning of the line.
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*/
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new_pos = ch_tell();
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break;
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}
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}
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/*
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* Now scan forwards from the beginning of this line.
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* We keep discarding "printable lines" (based on screen width)
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* until we reach the curr_pos.
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*
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* {{ This algorithm is pretty inefficient if the lines
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* are much longer than the screen width,
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* but I don't know of any better way. }}
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*/
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if (ch_seek(new_pos))
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return (NULL_POSITION);
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loop:
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begin_new_pos = new_pos;
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prewind();
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do
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{
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c = ch_forw_get();
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if (c == EOI || sigs)
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return (NULL_POSITION);
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new_pos++;
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if (c == '\n')
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break;
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if (pappend(c))
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{
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if (horiz_off == NO_HORIZ_OFF) {
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/*
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* Got a full printable line, but we haven't
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* reached our curr_pos yet. Discard the line
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* and start a new one.
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*/
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(void) pappend('\0');
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(void) ch_back_get();
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new_pos--;
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goto loop;
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} else
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break; /* Got everything we need */
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}
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} while (new_pos < curr_pos);
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(void) pappend('\0');
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return (begin_new_pos);
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}
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