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Diffstat (limited to 'usr.bin/more/linenum.c')
-rw-r--r-- | usr.bin/more/linenum.c | 383 |
1 files changed, 0 insertions, 383 deletions
diff --git a/usr.bin/more/linenum.c b/usr.bin/more/linenum.c deleted file mode 100644 index 4bfefa8..0000000 --- a/usr.bin/more/linenum.c +++ /dev/null @@ -1,383 +0,0 @@ -/* - * Copyright (c) 1988 Mark Nudleman - * Copyright (c) 1988, 1993 - * The Regents of the University of California. 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, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * 3. All advertising materials mentioning features or use of this software - * must display the following acknowledgement: - * This product includes software developed by the University of - * California, Berkeley and its contributors. - * 4. Neither the name of the University nor the names of its contributors - * may be used to endorse or promote products derived from this software - * without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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. - */ - -#ifndef lint -static char sccsid[] = "@(#)linenum.c 8.1 (Berkeley) 6/6/93"; -#endif /* not lint */ - -/* - * Code to handle displaying line numbers. - * - * Finding the line number of a given file position is rather tricky. - * We don't want to just start at the beginning of the file and - * count newlines, because that is slow for large files (and also - * wouldn't work if we couldn't get to the start of the file; e.g. - * if input is a long pipe). - * - * So we use the function add_lnum to cache line numbers. - * We try to be very clever and keep only the more interesting - * line numbers when we run out of space in our table. A line - * number is more interesting than another when it is far from - * other line numbers. For example, we'd rather keep lines - * 100,200,300 than 100,101,300. 200 is more interesting than - * 101 because 101 can be derived very cheaply from 100, while - * 200 is more expensive to derive from 100. - * - * The function currline() returns the line number of a given - * position in the file. As a side effect, it calls add_lnum - * to cache the line number. Therefore currline is occasionally - * called to make sure we cache line numbers often enough. - */ - -#include <sys/types.h> -#include <stdio.h> -#include <less.h> - -/* - * Structure to keep track of a line number and the associated file position. - * A doubly-linked circular list of line numbers is kept ordered by line number. - */ -struct linenum -{ - struct linenum *next; /* Link to next in the list */ - struct linenum *prev; /* Line to previous in the list */ - off_t pos; /* File position */ - off_t gap; /* Gap between prev and next */ - int line; /* Line number */ -}; -/* - * "gap" needs some explanation: the gap of any particular line number - * is the distance between the previous one and the next one in the list. - * ("Distance" means difference in file position.) In other words, the - * gap of a line number is the gap which would be introduced if this - * line number were deleted. It is used to decide which one to replace - * when we have a new one to insert and the table is full. - */ - -#define NPOOL 50 /* Size of line number pool */ - -#define LONGTIME (2) /* In seconds */ - -int lnloop = 0; /* Are we in the line num loop? */ - -static struct linenum anchor; /* Anchor of the list */ -static struct linenum *freelist; /* Anchor of the unused entries */ -static struct linenum pool[NPOOL]; /* The pool itself */ -static struct linenum *spare; /* We always keep one spare entry */ - -extern int linenums; -extern int sigs; - -/* - * Initialize the line number structures. - */ -clr_linenum() -{ - register struct linenum *p; - - /* - * Put all the entries on the free list. - * Leave one for the "spare". - */ - for (p = pool; p < &pool[NPOOL-2]; p++) - p->next = p+1; - pool[NPOOL-2].next = NULL; - freelist = pool; - - spare = &pool[NPOOL-1]; - - /* - * Initialize the anchor. - */ - anchor.next = anchor.prev = &anchor; - anchor.gap = 0; - anchor.pos = (off_t)0; - anchor.line = 1; -} - -/* - * Calculate the gap for an entry. - */ -static -calcgap(p) - register struct linenum *p; -{ - /* - * Don't bother to compute a gap for the anchor. - * Also don't compute a gap for the last one in the list. - * The gap for that last one should be considered infinite, - * but we never look at it anyway. - */ - if (p == &anchor || p->next == &anchor) - return; - p->gap = p->next->pos - p->prev->pos; -} - -/* - * Add a new line number to the cache. - * The specified position (pos) should be the file position of the - * FIRST character in the specified line. - */ -add_lnum(line, pos) - int line; - off_t pos; -{ - register struct linenum *p; - register struct linenum *new; - register struct linenum *nextp; - register struct linenum *prevp; - register off_t mingap; - - /* - * Find the proper place in the list for the new one. - * The entries are sorted by position. - */ - for (p = anchor.next; p != &anchor && p->pos < pos; p = p->next) - if (p->line == line) - /* We already have this one. */ - return; - nextp = p; - prevp = p->prev; - - if (freelist != NULL) - { - /* - * We still have free (unused) entries. - * Use one of them. - */ - new = freelist; - freelist = freelist->next; - } else - { - /* - * No free entries. - * Use the "spare" entry. - */ - new = spare; - spare = NULL; - } - - /* - * Fill in the fields of the new entry, - * and insert it into the proper place in the list. - */ - new->next = nextp; - new->prev = prevp; - new->pos = pos; - new->line = line; - - nextp->prev = new; - prevp->next = new; - - /* - * Recalculate gaps for the new entry and the neighboring entries. - */ - calcgap(new); - calcgap(nextp); - calcgap(prevp); - - if (spare == NULL) - { - /* - * We have used the spare entry. - * Scan the list to find the one with the smallest - * gap, take it out and make it the spare. - * We should never remove the last one, so stop when - * we get to p->next == &anchor. This also avoids - * looking at the gap of the last one, which is - * not computed by calcgap. - */ - mingap = anchor.next->gap; - for (p = anchor.next; p->next != &anchor; p = p->next) - { - if (p->gap <= mingap) - { - spare = p; - mingap = p->gap; - } - } - spare->next->prev = spare->prev; - spare->prev->next = spare->next; - } -} - -/* - * If we get stuck in a long loop trying to figure out the - * line number, print a message to tell the user what we're doing. - */ -static -longloopmessage() -{ - ierror("Calculating line numbers"); - /* - * Set the lnloop flag here, so if the user interrupts while - * we are calculating line numbers, the signal handler will - * turn off line numbers (linenums=0). - */ - lnloop = 1; -} - -/* - * Find the line number associated with a given position. - * Return 0 if we can't figure it out. - */ -find_linenum(pos) - off_t pos; -{ - register struct linenum *p; - register int lno; - register int loopcount; - off_t cpos, back_raw_line(), forw_raw_line(); - time_t startime, time(); - - if (!linenums) - /* - * We're not using line numbers. - */ - return (0); - if (pos == NULL_POSITION) - /* - * Caller doesn't know what he's talking about. - */ - return (0); - if (pos == (off_t)0) - /* - * Beginning of file is always line number 1. - */ - return (1); - - /* - * Find the entry nearest to the position we want. - */ - for (p = anchor.next; p != &anchor && p->pos < pos; p = p->next) - continue; - if (p->pos == pos) - /* Found it exactly. */ - return (p->line); - - /* - * This is the (possibly) time-consuming part. - * We start at the line we just found and start - * reading the file forward or backward till we - * get to the place we want. - * - * First decide whether we should go forward from the - * previous one or backwards from the next one. - * The decision is based on which way involves - * traversing fewer bytes in the file. - */ - flush(); - (void)time(&startime); - if (p == &anchor || pos - p->prev->pos < p->pos - pos) - { - /* - * Go forward. - */ - p = p->prev; - if (ch_seek(p->pos)) - return (0); - loopcount = 0; - for (lno = p->line, cpos = p->pos; cpos < pos; lno++) - { - /* - * Allow a signal to abort this loop. - */ - cpos = forw_raw_line(cpos); - if (sigs || cpos == NULL_POSITION) - return (0); - if (loopcount >= 0 && ++loopcount > 100) { - loopcount = 0; - if (time((time_t *)NULL) - >= startime + LONGTIME) { - longloopmessage(); - loopcount = -1; - } - } - } - lnloop = 0; - /* - * If the given position is not at the start of a line, - * make sure we return the correct line number. - */ - if (cpos > pos) - lno--; - } else - { - /* - * Go backward. - */ - if (ch_seek(p->pos)) - return (0); - loopcount = 0; - for (lno = p->line, cpos = p->pos; cpos > pos; lno--) - { - /* - * Allow a signal to abort this loop. - */ - cpos = back_raw_line(cpos); - if (sigs || cpos == NULL_POSITION) - return (0); - if (loopcount >= 0 && ++loopcount > 100) { - loopcount = 0; - if (time((time_t *)NULL) - >= startime + LONGTIME) { - longloopmessage(); - loopcount = -1; - } - } - } - lnloop = 0; - } - - /* - * We might as well cache it. - */ - add_lnum(lno, cpos); - return (lno); -} - -/* - * Return the line number of the "current" line. - * The argument "where" tells which line is to be considered - * the "current" line (e.g. TOP, BOTTOM, MIDDLE, etc). - */ -currline(where) - int where; -{ - off_t pos, ch_length(), position(); - - if ((pos = position(where)) == NULL_POSITION) - pos = ch_length(); - return(find_linenum(pos)); -} |