344 lines
6.6 KiB
C
344 lines
6.6 KiB
C
/*
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* Copyright (C) 1984-2000 Mark Nudelman
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*
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* You may distribute under the terms of either the GNU General Public
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* License or the Less License, as specified in the README file.
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*
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* For more information about less, or for information on how to
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* contact the author, see the README file.
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*/
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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 "less.h"
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extern int squeeze;
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extern int chopline;
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extern int hshift;
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extern int quit_if_one_screen;
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extern int sigs;
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extern int ignore_eoi;
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extern POSITION start_attnpos;
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extern POSITION end_attnpos;
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#if HILITE_SEARCH
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extern int hilite_search;
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extern int size_linebuf;
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#endif
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/*
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* Get the next line.
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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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*/
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public POSITION
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forw_line(curr_pos)
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POSITION curr_pos;
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{
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POSITION new_pos;
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register int c;
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int blankline;
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int endline;
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if (curr_pos == NULL_POSITION)
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{
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null_line();
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return (NULL_POSITION);
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}
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#if HILITE_SEARCH
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if (hilite_search == OPT_ONPLUS)
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/*
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* If we are ignoring EOI (command F), only prepare
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* one line ahead, to avoid getting stuck waiting for
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* slow data without displaying the data we already have.
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* If we're not ignoring EOI, we *could* do the same, but
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* for efficiency we prepare several lines ahead at once.
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*/
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prep_hilite(curr_pos, curr_pos + 3*size_linebuf,
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ignore_eoi ? 1 : -1);
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#endif
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if (ch_seek(curr_pos))
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{
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null_line();
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return (NULL_POSITION);
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}
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prewind();
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plinenum(curr_pos);
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(void) ch_seek(curr_pos);
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c = ch_forw_get();
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if (c == EOI)
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{
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null_line();
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return (NULL_POSITION);
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}
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blankline = (c == '\n' || c == '\r');
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for (;;)
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{
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if (ABORT_SIGS())
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{
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null_line();
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return (NULL_POSITION);
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}
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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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endline = TRUE;
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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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*/
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if (pappend(c, ch_tell()-1))
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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 (chopline || hshift > 0)
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{
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do
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{
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c = ch_forw_get();
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} while (c != '\n' && c != EOI);
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new_pos = ch_tell();
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endline = TRUE;
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quit_if_one_screen = FALSE;
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} else
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{
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new_pos = ch_tell() - 1;
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endline = FALSE;
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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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pdone(endline);
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if (squeeze && blankline)
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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' || c == '\r')
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if (ABORT_SIGS())
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{
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null_line();
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return (NULL_POSITION);
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}
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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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* 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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*/
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public POSITION
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back_line(curr_pos)
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POSITION curr_pos;
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{
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POSITION new_pos, begin_new_pos;
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int c;
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int endline;
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if (curr_pos == NULL_POSITION || curr_pos <= ch_zero())
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{
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null_line();
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return (NULL_POSITION);
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}
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#if HILITE_SEARCH
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if (hilite_search == OPT_ONPLUS)
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prep_hilite((curr_pos < 3*size_linebuf) ?
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0 : curr_pos - 3*size_linebuf, curr_pos, -1);
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#endif
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if (ch_seek(curr_pos-1))
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{
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null_line();
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return (NULL_POSITION);
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}
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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' || c == '\r')
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{
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/*
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* The "current" line was blank.
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* Skip over any preceding 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' || c == '\r')
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if (ABORT_SIGS())
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{
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null_line();
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return (NULL_POSITION);
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}
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if (c == EOI)
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{
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null_line();
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return (NULL_POSITION);
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}
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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 (ABORT_SIGS())
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{
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null_line();
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return (NULL_POSITION);
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}
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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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{
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null_line();
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return (NULL_POSITION);
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}
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endline = FALSE;
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loop:
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begin_new_pos = new_pos;
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prewind();
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plinenum(new_pos);
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(void) ch_seek(new_pos);
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do
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{
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c = ch_forw_get();
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if (c == EOI || ABORT_SIGS())
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{
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null_line();
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return (NULL_POSITION);
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}
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new_pos++;
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if (c == '\n')
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{
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endline = TRUE;
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break;
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}
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if (pappend(c, ch_tell()-1))
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{
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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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if (chopline || hshift > 0)
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{
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endline = TRUE;
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quit_if_one_screen = FALSE;
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break;
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}
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pdone(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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}
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} while (new_pos < curr_pos);
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pdone(endline);
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return (begin_new_pos);
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}
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/*
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* Set attnpos.
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*/
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public void
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set_attnpos(pos)
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POSITION pos;
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{
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int c;
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if (pos != NULL_POSITION)
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{
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if (ch_seek(pos))
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return;
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for (;;)
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{
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c = ch_forw_get();
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if (c == EOI)
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return;
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if (c != '\n' && c != '\r')
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break;
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pos++;
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}
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}
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start_attnpos = pos;
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for (;;)
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{
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c = ch_forw_get();
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pos++;
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if (c == EOI || c == '\n' || c == '\r')
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break;
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}
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end_attnpos = pos;
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}
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