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git/xdiff/xemit.c
Linus Torvalds a9ed376b15 xdiff: generate "anti-diffs" aka what is common to two files
This fairly trivial patch adds a new XDL_EMIT_xxx flag to tell libxdiff
that we don't want to generate the _diff_ between two files, we want to
see the lines that are _common_ to two files.

So when you set XDL_EMIT_COMMON, xdl_diff() will do everything exactly
like it used to do, but the output records it generates just contain the
lines that aren't part of the diff.

This is for doing things like generating the common base case for a file
that was added in both branches.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-06-28 22:24:32 -07:00

199 lines
4.8 KiB
C

/*
* LibXDiff by Davide Libenzi ( File Differential Library )
* Copyright (C) 2003 Davide Libenzi
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Davide Libenzi <davidel@xmailserver.org>
*
*/
#include "xinclude.h"
static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec);
static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb);
static xdchange_t *xdl_get_hunk(xdchange_t *xscr, xdemitconf_t const *xecfg);
static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec) {
*rec = xdf->recs[ri]->ptr;
return xdf->recs[ri]->size;
}
static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb) {
long size, psize = strlen(pre);
char const *rec;
size = xdl_get_rec(xdf, ri, &rec);
if (xdl_emit_diffrec(rec, size, pre, psize, ecb) < 0) {
return -1;
}
return 0;
}
/*
* Starting at the passed change atom, find the latest change atom to be included
* inside the differential hunk according to the specified configuration.
*/
static xdchange_t *xdl_get_hunk(xdchange_t *xscr, xdemitconf_t const *xecfg) {
xdchange_t *xch, *xchp;
for (xchp = xscr, xch = xscr->next; xch; xchp = xch, xch = xch->next)
if (xch->i1 - (xchp->i1 + xchp->chg1) > 2 * xecfg->ctxlen)
break;
return xchp;
}
static void xdl_find_func(xdfile_t *xf, long i, char *buf, long sz, long *ll) {
/*
* Be quite stupid about this for now. Find a line in the old file
* before the start of the hunk (and context) which starts with a
* plausible character.
*/
const char *rec;
long len;
*ll = 0;
while (i-- > 0) {
len = xdl_get_rec(xf, i, &rec);
if (len > 0 &&
(isalpha((unsigned char)*rec) || /* identifier? */
*rec == '_' || /* also identifier? */
*rec == '(' || /* lisp defun? */
*rec == '#')) { /* #define? */
if (len > sz)
len = sz;
if (len && rec[len - 1] == '\n')
len--;
memcpy(buf, rec, len);
*ll = len;
return;
}
}
}
int xdl_emit_common(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
xdemitconf_t const *xecfg) {
xdfile_t *xdf = &xe->xdf1;
const char *rchg = xdf->rchg;
long ix;
for (ix = 0; ix < xdf->nrec; ix++) {
if (rchg[ix])
continue;
if (xdl_emit_record(xdf, ix, "", ecb))
return -1;
}
return 0;
}
int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
xdemitconf_t const *xecfg) {
long s1, s2, e1, e2, lctx;
xdchange_t *xch, *xche;
char funcbuf[40];
long funclen = 0;
if (xecfg->flags & XDL_EMIT_COMMON)
return xdl_emit_common(xe, xscr, ecb, xecfg);
for (xch = xche = xscr; xch; xch = xche->next) {
xche = xdl_get_hunk(xch, xecfg);
s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
lctx = xecfg->ctxlen;
lctx = XDL_MIN(lctx, xe->xdf1.nrec - (xche->i1 + xche->chg1));
lctx = XDL_MIN(lctx, xe->xdf2.nrec - (xche->i2 + xche->chg2));
e1 = xche->i1 + xche->chg1 + lctx;
e2 = xche->i2 + xche->chg2 + lctx;
/*
* Emit current hunk header.
*/
if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
xdl_find_func(&xe->xdf1, s1, funcbuf,
sizeof(funcbuf), &funclen);
}
if (xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
funcbuf, funclen, ecb) < 0)
return -1;
/*
* Emit pre-context.
*/
for (; s1 < xch->i1; s1++)
if (xdl_emit_record(&xe->xdf1, s1, " ", ecb) < 0)
return -1;
for (s1 = xch->i1, s2 = xch->i2;; xch = xch->next) {
/*
* Merge previous with current change atom.
*/
for (; s1 < xch->i1 && s2 < xch->i2; s1++, s2++)
if (xdl_emit_record(&xe->xdf1, s1, " ", ecb) < 0)
return -1;
/*
* Removes lines from the first file.
*/
for (s1 = xch->i1; s1 < xch->i1 + xch->chg1; s1++)
if (xdl_emit_record(&xe->xdf1, s1, "-", ecb) < 0)
return -1;
/*
* Adds lines from the second file.
*/
for (s2 = xch->i2; s2 < xch->i2 + xch->chg2; s2++)
if (xdl_emit_record(&xe->xdf2, s2, "+", ecb) < 0)
return -1;
if (xch == xche)
break;
s1 = xch->i1 + xch->chg1;
s2 = xch->i2 + xch->chg2;
}
/*
* Emit post-context.
*/
for (s1 = xche->i1 + xche->chg1; s1 < e1; s1++)
if (xdl_emit_record(&xe->xdf1, s1, " ", ecb) < 0)
return -1;
}
return 0;
}