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![Junio C Hamano](/assets/img/avatar_default.png)
"git diff --indent-heuristic" had a bad corner case performance. * sb/indent-heuristic-optim: xdiff: reduce indent heuristic overhead
1044 lines
27 KiB
C
1044 lines
27 KiB
C
/*
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* LibXDiff by Davide Libenzi ( File Differential Library )
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* Copyright (C) 2003 Davide Libenzi
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see
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* <http://www.gnu.org/licenses/>.
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*
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* Davide Libenzi <davidel@xmailserver.org>
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*
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*/
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#include "xinclude.h"
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#define XDL_MAX_COST_MIN 256
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#define XDL_HEUR_MIN_COST 256
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#define XDL_LINE_MAX (long)((1UL << (CHAR_BIT * sizeof(long) - 1)) - 1)
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#define XDL_SNAKE_CNT 20
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#define XDL_K_HEUR 4
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typedef struct s_xdpsplit {
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long i1, i2;
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int min_lo, min_hi;
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} xdpsplit_t;
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/*
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* See "An O(ND) Difference Algorithm and its Variations", by Eugene Myers.
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* Basically considers a "box" (off1, off2, lim1, lim2) and scan from both
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* the forward diagonal starting from (off1, off2) and the backward diagonal
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* starting from (lim1, lim2). If the K values on the same diagonal crosses
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* returns the furthest point of reach. We might end up having to expensive
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* cases using this algorithm is full, so a little bit of heuristic is needed
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* to cut the search and to return a suboptimal point.
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*/
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static long xdl_split(unsigned long const *ha1, long off1, long lim1,
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unsigned long const *ha2, long off2, long lim2,
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long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl,
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xdalgoenv_t *xenv) {
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long dmin = off1 - lim2, dmax = lim1 - off2;
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long fmid = off1 - off2, bmid = lim1 - lim2;
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long odd = (fmid - bmid) & 1;
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long fmin = fmid, fmax = fmid;
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long bmin = bmid, bmax = bmid;
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long ec, d, i1, i2, prev1, best, dd, v, k;
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/*
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* Set initial diagonal values for both forward and backward path.
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*/
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kvdf[fmid] = off1;
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kvdb[bmid] = lim1;
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for (ec = 1;; ec++) {
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int got_snake = 0;
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/*
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* We need to extent the diagonal "domain" by one. If the next
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* values exits the box boundaries we need to change it in the
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* opposite direction because (max - min) must be a power of two.
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* Also we initialize the external K value to -1 so that we can
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* avoid extra conditions check inside the core loop.
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*/
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if (fmin > dmin)
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kvdf[--fmin - 1] = -1;
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else
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++fmin;
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if (fmax < dmax)
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kvdf[++fmax + 1] = -1;
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else
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--fmax;
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for (d = fmax; d >= fmin; d -= 2) {
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if (kvdf[d - 1] >= kvdf[d + 1])
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i1 = kvdf[d - 1] + 1;
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else
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i1 = kvdf[d + 1];
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prev1 = i1;
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i2 = i1 - d;
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for (; i1 < lim1 && i2 < lim2 && ha1[i1] == ha2[i2]; i1++, i2++);
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if (i1 - prev1 > xenv->snake_cnt)
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got_snake = 1;
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kvdf[d] = i1;
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if (odd && bmin <= d && d <= bmax && kvdb[d] <= i1) {
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spl->i1 = i1;
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spl->i2 = i2;
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spl->min_lo = spl->min_hi = 1;
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return ec;
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}
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}
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/*
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* We need to extent the diagonal "domain" by one. If the next
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* values exits the box boundaries we need to change it in the
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* opposite direction because (max - min) must be a power of two.
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* Also we initialize the external K value to -1 so that we can
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* avoid extra conditions check inside the core loop.
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*/
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if (bmin > dmin)
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kvdb[--bmin - 1] = XDL_LINE_MAX;
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else
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++bmin;
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if (bmax < dmax)
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kvdb[++bmax + 1] = XDL_LINE_MAX;
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else
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--bmax;
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for (d = bmax; d >= bmin; d -= 2) {
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if (kvdb[d - 1] < kvdb[d + 1])
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i1 = kvdb[d - 1];
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else
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i1 = kvdb[d + 1] - 1;
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prev1 = i1;
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i2 = i1 - d;
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for (; i1 > off1 && i2 > off2 && ha1[i1 - 1] == ha2[i2 - 1]; i1--, i2--);
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if (prev1 - i1 > xenv->snake_cnt)
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got_snake = 1;
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kvdb[d] = i1;
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if (!odd && fmin <= d && d <= fmax && i1 <= kvdf[d]) {
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spl->i1 = i1;
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spl->i2 = i2;
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spl->min_lo = spl->min_hi = 1;
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return ec;
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}
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}
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if (need_min)
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continue;
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/*
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* If the edit cost is above the heuristic trigger and if
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* we got a good snake, we sample current diagonals to see
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* if some of the, have reached an "interesting" path. Our
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* measure is a function of the distance from the diagonal
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* corner (i1 + i2) penalized with the distance from the
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* mid diagonal itself. If this value is above the current
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* edit cost times a magic factor (XDL_K_HEUR) we consider
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* it interesting.
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*/
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if (got_snake && ec > xenv->heur_min) {
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for (best = 0, d = fmax; d >= fmin; d -= 2) {
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dd = d > fmid ? d - fmid: fmid - d;
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i1 = kvdf[d];
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i2 = i1 - d;
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v = (i1 - off1) + (i2 - off2) - dd;
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if (v > XDL_K_HEUR * ec && v > best &&
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off1 + xenv->snake_cnt <= i1 && i1 < lim1 &&
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off2 + xenv->snake_cnt <= i2 && i2 < lim2) {
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for (k = 1; ha1[i1 - k] == ha2[i2 - k]; k++)
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if (k == xenv->snake_cnt) {
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best = v;
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spl->i1 = i1;
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spl->i2 = i2;
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break;
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}
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}
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}
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if (best > 0) {
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spl->min_lo = 1;
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spl->min_hi = 0;
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return ec;
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}
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for (best = 0, d = bmax; d >= bmin; d -= 2) {
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dd = d > bmid ? d - bmid: bmid - d;
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i1 = kvdb[d];
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i2 = i1 - d;
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v = (lim1 - i1) + (lim2 - i2) - dd;
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if (v > XDL_K_HEUR * ec && v > best &&
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off1 < i1 && i1 <= lim1 - xenv->snake_cnt &&
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off2 < i2 && i2 <= lim2 - xenv->snake_cnt) {
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for (k = 0; ha1[i1 + k] == ha2[i2 + k]; k++)
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if (k == xenv->snake_cnt - 1) {
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best = v;
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spl->i1 = i1;
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spl->i2 = i2;
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break;
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}
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}
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}
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if (best > 0) {
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spl->min_lo = 0;
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spl->min_hi = 1;
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return ec;
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}
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}
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/*
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* Enough is enough. We spent too much time here and now we collect
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* the furthest reaching path using the (i1 + i2) measure.
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*/
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if (ec >= xenv->mxcost) {
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long fbest, fbest1, bbest, bbest1;
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fbest = fbest1 = -1;
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for (d = fmax; d >= fmin; d -= 2) {
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i1 = XDL_MIN(kvdf[d], lim1);
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i2 = i1 - d;
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if (lim2 < i2)
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i1 = lim2 + d, i2 = lim2;
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if (fbest < i1 + i2) {
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fbest = i1 + i2;
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fbest1 = i1;
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}
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}
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bbest = bbest1 = XDL_LINE_MAX;
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for (d = bmax; d >= bmin; d -= 2) {
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i1 = XDL_MAX(off1, kvdb[d]);
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i2 = i1 - d;
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if (i2 < off2)
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i1 = off2 + d, i2 = off2;
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if (i1 + i2 < bbest) {
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bbest = i1 + i2;
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bbest1 = i1;
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}
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}
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if ((lim1 + lim2) - bbest < fbest - (off1 + off2)) {
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spl->i1 = fbest1;
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spl->i2 = fbest - fbest1;
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spl->min_lo = 1;
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spl->min_hi = 0;
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} else {
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spl->i1 = bbest1;
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spl->i2 = bbest - bbest1;
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spl->min_lo = 0;
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spl->min_hi = 1;
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}
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return ec;
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}
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}
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}
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/*
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* Rule: "Divide et Impera". Recursively split the box in sub-boxes by calling
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* the box splitting function. Note that the real job (marking changed lines)
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* is done in the two boundary reaching checks.
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*/
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int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1,
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diffdata_t *dd2, long off2, long lim2,
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long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv) {
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unsigned long const *ha1 = dd1->ha, *ha2 = dd2->ha;
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/*
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* Shrink the box by walking through each diagonal snake (SW and NE).
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*/
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for (; off1 < lim1 && off2 < lim2 && ha1[off1] == ha2[off2]; off1++, off2++);
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for (; off1 < lim1 && off2 < lim2 && ha1[lim1 - 1] == ha2[lim2 - 1]; lim1--, lim2--);
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/*
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* If one dimension is empty, then all records on the other one must
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* be obviously changed.
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*/
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if (off1 == lim1) {
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char *rchg2 = dd2->rchg;
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long *rindex2 = dd2->rindex;
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for (; off2 < lim2; off2++)
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rchg2[rindex2[off2]] = 1;
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} else if (off2 == lim2) {
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char *rchg1 = dd1->rchg;
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long *rindex1 = dd1->rindex;
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for (; off1 < lim1; off1++)
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rchg1[rindex1[off1]] = 1;
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} else {
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xdpsplit_t spl;
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spl.i1 = spl.i2 = 0;
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/*
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* Divide ...
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*/
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if (xdl_split(ha1, off1, lim1, ha2, off2, lim2, kvdf, kvdb,
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need_min, &spl, xenv) < 0) {
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return -1;
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}
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/*
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* ... et Impera.
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*/
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if (xdl_recs_cmp(dd1, off1, spl.i1, dd2, off2, spl.i2,
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kvdf, kvdb, spl.min_lo, xenv) < 0 ||
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xdl_recs_cmp(dd1, spl.i1, lim1, dd2, spl.i2, lim2,
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kvdf, kvdb, spl.min_hi, xenv) < 0) {
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return -1;
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}
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}
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return 0;
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}
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int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
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xdfenv_t *xe) {
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long ndiags;
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long *kvd, *kvdf, *kvdb;
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xdalgoenv_t xenv;
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diffdata_t dd1, dd2;
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if (XDF_DIFF_ALG(xpp->flags) == XDF_PATIENCE_DIFF)
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return xdl_do_patience_diff(mf1, mf2, xpp, xe);
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if (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF)
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return xdl_do_histogram_diff(mf1, mf2, xpp, xe);
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if (xdl_prepare_env(mf1, mf2, xpp, xe) < 0) {
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return -1;
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}
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/*
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* Allocate and setup K vectors to be used by the differential algorithm.
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* One is to store the forward path and one to store the backward path.
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*/
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ndiags = xe->xdf1.nreff + xe->xdf2.nreff + 3;
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if (!(kvd = (long *) xdl_malloc((2 * ndiags + 2) * sizeof(long)))) {
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xdl_free_env(xe);
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return -1;
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}
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kvdf = kvd;
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kvdb = kvdf + ndiags;
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kvdf += xe->xdf2.nreff + 1;
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kvdb += xe->xdf2.nreff + 1;
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xenv.mxcost = xdl_bogosqrt(ndiags);
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if (xenv.mxcost < XDL_MAX_COST_MIN)
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xenv.mxcost = XDL_MAX_COST_MIN;
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xenv.snake_cnt = XDL_SNAKE_CNT;
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xenv.heur_min = XDL_HEUR_MIN_COST;
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dd1.nrec = xe->xdf1.nreff;
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dd1.ha = xe->xdf1.ha;
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dd1.rchg = xe->xdf1.rchg;
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dd1.rindex = xe->xdf1.rindex;
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dd2.nrec = xe->xdf2.nreff;
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dd2.ha = xe->xdf2.ha;
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dd2.rchg = xe->xdf2.rchg;
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dd2.rindex = xe->xdf2.rindex;
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if (xdl_recs_cmp(&dd1, 0, dd1.nrec, &dd2, 0, dd2.nrec,
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kvdf, kvdb, (xpp->flags & XDF_NEED_MINIMAL) != 0, &xenv) < 0) {
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xdl_free(kvd);
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xdl_free_env(xe);
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return -1;
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}
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xdl_free(kvd);
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return 0;
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}
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static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2) {
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xdchange_t *xch;
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if (!(xch = (xdchange_t *) xdl_malloc(sizeof(xdchange_t))))
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return NULL;
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xch->next = xscr;
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xch->i1 = i1;
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xch->i2 = i2;
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xch->chg1 = chg1;
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xch->chg2 = chg2;
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xch->ignore = 0;
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return xch;
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}
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static int recs_match(xrecord_t *rec1, xrecord_t *rec2, long flags)
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{
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return (rec1->ha == rec2->ha &&
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xdl_recmatch(rec1->ptr, rec1->size,
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rec2->ptr, rec2->size,
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flags));
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}
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/*
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* If a line is indented more than this, get_indent() just returns this value.
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* This avoids having to do absurd amounts of work for data that are not
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* human-readable text, and also ensures that the output of get_indent fits within
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* an int.
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*/
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#define MAX_INDENT 200
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/*
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* Return the amount of indentation of the specified line, treating TAB as 8
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* columns. Return -1 if line is empty or contains only whitespace. Clamp the
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* output value at MAX_INDENT.
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*/
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static int get_indent(xrecord_t *rec)
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{
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long i;
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int ret = 0;
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for (i = 0; i < rec->size; i++) {
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char c = rec->ptr[i];
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if (!XDL_ISSPACE(c))
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return ret;
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else if (c == ' ')
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ret += 1;
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else if (c == '\t')
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ret += 8 - ret % 8;
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/* ignore other whitespace characters */
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if (ret >= MAX_INDENT)
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return MAX_INDENT;
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}
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/* The line contains only whitespace. */
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return -1;
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}
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/*
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* If more than this number of consecutive blank rows are found, just return this
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* value. This avoids requiring O(N^2) work for pathological cases, and also
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* ensures that the output of score_split fits in an int.
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*/
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#define MAX_BLANKS 20
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/* Characteristics measured about a hypothetical split position. */
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struct split_measurement {
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/*
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* Is the split at the end of the file (aside from any blank lines)?
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*/
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int end_of_file;
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/*
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* How much is the line immediately following the split indented (or -1 if
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* the line is blank):
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*/
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int indent;
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/*
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* How many consecutive lines above the split are blank?
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*/
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int pre_blank;
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/*
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* How much is the nearest non-blank line above the split indented (or -1
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* if there is no such line)?
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*/
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int pre_indent;
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/*
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* How many lines after the line following the split are blank?
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*/
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int post_blank;
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/*
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* How much is the nearest non-blank line after the line following the
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* split indented (or -1 if there is no such line)?
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*/
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int post_indent;
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};
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struct split_score {
|
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/* The effective indent of this split (smaller is preferred). */
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int effective_indent;
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/* Penalty for this split (smaller is preferred). */
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int penalty;
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};
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/*
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* Fill m with information about a hypothetical split of xdf above line split.
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*/
|
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static void measure_split(const xdfile_t *xdf, long split,
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struct split_measurement *m)
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{
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long i;
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if (split >= xdf->nrec) {
|
|
m->end_of_file = 1;
|
|
m->indent = -1;
|
|
} else {
|
|
m->end_of_file = 0;
|
|
m->indent = get_indent(xdf->recs[split]);
|
|
}
|
|
|
|
m->pre_blank = 0;
|
|
m->pre_indent = -1;
|
|
for (i = split - 1; i >= 0; i--) {
|
|
m->pre_indent = get_indent(xdf->recs[i]);
|
|
if (m->pre_indent != -1)
|
|
break;
|
|
m->pre_blank += 1;
|
|
if (m->pre_blank == MAX_BLANKS) {
|
|
m->pre_indent = 0;
|
|
break;
|
|
}
|
|
}
|
|
|
|
m->post_blank = 0;
|
|
m->post_indent = -1;
|
|
for (i = split + 1; i < xdf->nrec; i++) {
|
|
m->post_indent = get_indent(xdf->recs[i]);
|
|
if (m->post_indent != -1)
|
|
break;
|
|
m->post_blank += 1;
|
|
if (m->post_blank == MAX_BLANKS) {
|
|
m->post_indent = 0;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The empirically-determined weight factors used by score_split() below.
|
|
* Larger values means that the position is a less favorable place to split.
|
|
*
|
|
* Note that scores are only ever compared against each other, so multiplying
|
|
* all of these weight/penalty values by the same factor wouldn't change the
|
|
* heuristic's behavior. Still, we need to set that arbitrary scale *somehow*.
|
|
* In practice, these numbers are chosen to be large enough that they can be
|
|
* adjusted relative to each other with sufficient precision despite using
|
|
* integer math.
|
|
*/
|
|
|
|
/* Penalty if there are no non-blank lines before the split */
|
|
#define START_OF_FILE_PENALTY 1
|
|
|
|
/* Penalty if there are no non-blank lines after the split */
|
|
#define END_OF_FILE_PENALTY 21
|
|
|
|
/* Multiplier for the number of blank lines around the split */
|
|
#define TOTAL_BLANK_WEIGHT (-30)
|
|
|
|
/* Multiplier for the number of blank lines after the split */
|
|
#define POST_BLANK_WEIGHT 6
|
|
|
|
/*
|
|
* Penalties applied if the line is indented more than its predecessor
|
|
*/
|
|
#define RELATIVE_INDENT_PENALTY (-4)
|
|
#define RELATIVE_INDENT_WITH_BLANK_PENALTY 10
|
|
|
|
/*
|
|
* Penalties applied if the line is indented less than both its predecessor and
|
|
* its successor
|
|
*/
|
|
#define RELATIVE_OUTDENT_PENALTY 24
|
|
#define RELATIVE_OUTDENT_WITH_BLANK_PENALTY 17
|
|
|
|
/*
|
|
* Penalties applied if the line is indented less than its predecessor but not
|
|
* less than its successor
|
|
*/
|
|
#define RELATIVE_DEDENT_PENALTY 23
|
|
#define RELATIVE_DEDENT_WITH_BLANK_PENALTY 17
|
|
|
|
/*
|
|
* We only consider whether the sum of the effective indents for splits are
|
|
* less than (-1), equal to (0), or greater than (+1) each other. The resulting
|
|
* value is multiplied by the following weight and combined with the penalty to
|
|
* determine the better of two scores.
|
|
*/
|
|
#define INDENT_WEIGHT 60
|
|
|
|
/*
|
|
* How far do we slide a hunk at most?
|
|
*/
|
|
#define INDENT_HEURISTIC_MAX_SLIDING 100
|
|
|
|
/*
|
|
* Compute a badness score for the hypothetical split whose measurements are
|
|
* stored in m. The weight factors were determined empirically using the tools and
|
|
* corpus described in
|
|
*
|
|
* https://github.com/mhagger/diff-slider-tools
|
|
*
|
|
* Also see that project if you want to improve the weights based on, for example,
|
|
* a larger or more diverse corpus.
|
|
*/
|
|
static void score_add_split(const struct split_measurement *m, struct split_score *s)
|
|
{
|
|
/*
|
|
* A place to accumulate penalty factors (positive makes this index more
|
|
* favored):
|
|
*/
|
|
int post_blank, total_blank, indent, any_blanks;
|
|
|
|
if (m->pre_indent == -1 && m->pre_blank == 0)
|
|
s->penalty += START_OF_FILE_PENALTY;
|
|
|
|
if (m->end_of_file)
|
|
s->penalty += END_OF_FILE_PENALTY;
|
|
|
|
/*
|
|
* Set post_blank to the number of blank lines following the split,
|
|
* including the line immediately after the split:
|
|
*/
|
|
post_blank = (m->indent == -1) ? 1 + m->post_blank : 0;
|
|
total_blank = m->pre_blank + post_blank;
|
|
|
|
/* Penalties based on nearby blank lines: */
|
|
s->penalty += TOTAL_BLANK_WEIGHT * total_blank;
|
|
s->penalty += POST_BLANK_WEIGHT * post_blank;
|
|
|
|
if (m->indent != -1)
|
|
indent = m->indent;
|
|
else
|
|
indent = m->post_indent;
|
|
|
|
any_blanks = (total_blank != 0);
|
|
|
|
/* Note that the effective indent is -1 at the end of the file: */
|
|
s->effective_indent += indent;
|
|
|
|
if (indent == -1) {
|
|
/* No additional adjustments needed. */
|
|
} else if (m->pre_indent == -1) {
|
|
/* No additional adjustments needed. */
|
|
} else if (indent > m->pre_indent) {
|
|
/*
|
|
* The line is indented more than its predecessor.
|
|
*/
|
|
s->penalty += any_blanks ?
|
|
RELATIVE_INDENT_WITH_BLANK_PENALTY :
|
|
RELATIVE_INDENT_PENALTY;
|
|
} else if (indent == m->pre_indent) {
|
|
/*
|
|
* The line has the same indentation level as its predecessor.
|
|
* No additional adjustments needed.
|
|
*/
|
|
} else {
|
|
/*
|
|
* The line is indented less than its predecessor. It could be
|
|
* the block terminator of the previous block, but it could
|
|
* also be the start of a new block (e.g., an "else" block, or
|
|
* maybe the previous block didn't have a block terminator).
|
|
* Try to distinguish those cases based on what comes next:
|
|
*/
|
|
if (m->post_indent != -1 && m->post_indent > indent) {
|
|
/*
|
|
* The following line is indented more. So it is likely
|
|
* that this line is the start of a block.
|
|
*/
|
|
s->penalty += any_blanks ?
|
|
RELATIVE_OUTDENT_WITH_BLANK_PENALTY :
|
|
RELATIVE_OUTDENT_PENALTY;
|
|
} else {
|
|
/*
|
|
* That was probably the end of a block.
|
|
*/
|
|
s->penalty += any_blanks ?
|
|
RELATIVE_DEDENT_WITH_BLANK_PENALTY :
|
|
RELATIVE_DEDENT_PENALTY;
|
|
}
|
|
}
|
|
}
|
|
|
|
static int score_cmp(struct split_score *s1, struct split_score *s2)
|
|
{
|
|
/* -1 if s1.effective_indent < s2->effective_indent, etc. */
|
|
int cmp_indents = ((s1->effective_indent > s2->effective_indent) -
|
|
(s1->effective_indent < s2->effective_indent));
|
|
|
|
return INDENT_WEIGHT * cmp_indents + (s1->penalty - s2->penalty);
|
|
}
|
|
|
|
/*
|
|
* Represent a group of changed lines in an xdfile_t (i.e., a contiguous group
|
|
* of lines that was inserted or deleted from the corresponding version of the
|
|
* file). We consider there to be such a group at the beginning of the file, at
|
|
* the end of the file, and between any two unchanged lines, though most such
|
|
* groups will usually be empty.
|
|
*
|
|
* If the first line in a group is equal to the line following the group, then
|
|
* the group can be slid down. Similarly, if the last line in a group is equal
|
|
* to the line preceding the group, then the group can be slid up. See
|
|
* group_slide_down() and group_slide_up().
|
|
*
|
|
* Note that loops that are testing for changed lines in xdf->rchg do not need
|
|
* index bounding since the array is prepared with a zero at position -1 and N.
|
|
*/
|
|
struct xdlgroup {
|
|
/*
|
|
* The index of the first changed line in the group, or the index of
|
|
* the unchanged line above which the (empty) group is located.
|
|
*/
|
|
long start;
|
|
|
|
/*
|
|
* The index of the first unchanged line after the group. For an empty
|
|
* group, end is equal to start.
|
|
*/
|
|
long end;
|
|
};
|
|
|
|
/*
|
|
* Initialize g to point at the first group in xdf.
|
|
*/
|
|
static void group_init(xdfile_t *xdf, struct xdlgroup *g)
|
|
{
|
|
g->start = g->end = 0;
|
|
while (xdf->rchg[g->end])
|
|
g->end++;
|
|
}
|
|
|
|
/*
|
|
* Move g to describe the next (possibly empty) group in xdf and return 0. If g
|
|
* is already at the end of the file, do nothing and return -1.
|
|
*/
|
|
static inline int group_next(xdfile_t *xdf, struct xdlgroup *g)
|
|
{
|
|
if (g->end == xdf->nrec)
|
|
return -1;
|
|
|
|
g->start = g->end + 1;
|
|
for (g->end = g->start; xdf->rchg[g->end]; g->end++)
|
|
;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Move g to describe the previous (possibly empty) group in xdf and return 0.
|
|
* If g is already at the beginning of the file, do nothing and return -1.
|
|
*/
|
|
static inline int group_previous(xdfile_t *xdf, struct xdlgroup *g)
|
|
{
|
|
if (g->start == 0)
|
|
return -1;
|
|
|
|
g->end = g->start - 1;
|
|
for (g->start = g->end; xdf->rchg[g->start - 1]; g->start--)
|
|
;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* If g can be slid toward the end of the file, do so, and if it bumps into a
|
|
* following group, expand this group to include it. Return 0 on success or -1
|
|
* if g cannot be slid down.
|
|
*/
|
|
static int group_slide_down(xdfile_t *xdf, struct xdlgroup *g, long flags)
|
|
{
|
|
if (g->end < xdf->nrec &&
|
|
recs_match(xdf->recs[g->start], xdf->recs[g->end], flags)) {
|
|
xdf->rchg[g->start++] = 0;
|
|
xdf->rchg[g->end++] = 1;
|
|
|
|
while (xdf->rchg[g->end])
|
|
g->end++;
|
|
|
|
return 0;
|
|
} else {
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If g can be slid toward the beginning of the file, do so, and if it bumps
|
|
* into a previous group, expand this group to include it. Return 0 on success
|
|
* or -1 if g cannot be slid up.
|
|
*/
|
|
static int group_slide_up(xdfile_t *xdf, struct xdlgroup *g, long flags)
|
|
{
|
|
if (g->start > 0 &&
|
|
recs_match(xdf->recs[g->start - 1], xdf->recs[g->end - 1], flags)) {
|
|
xdf->rchg[--g->start] = 1;
|
|
xdf->rchg[--g->end] = 0;
|
|
|
|
while (xdf->rchg[g->start - 1])
|
|
g->start--;
|
|
|
|
return 0;
|
|
} else {
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
static void xdl_bug(const char *msg)
|
|
{
|
|
fprintf(stderr, "BUG: %s\n", msg);
|
|
exit(1);
|
|
}
|
|
|
|
/*
|
|
* Move back and forward change groups for a consistent and pretty diff output.
|
|
* This also helps in finding joinable change groups and reducing the diff
|
|
* size.
|
|
*/
|
|
int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
|
|
struct xdlgroup g, go;
|
|
long earliest_end, end_matching_other;
|
|
long groupsize;
|
|
|
|
group_init(xdf, &g);
|
|
group_init(xdfo, &go);
|
|
|
|
while (1) {
|
|
/* If the group is empty in the to-be-compacted file, skip it: */
|
|
if (g.end == g.start)
|
|
goto next;
|
|
|
|
/*
|
|
* Now shift the change up and then down as far as possible in
|
|
* each direction. If it bumps into any other changes, merge them.
|
|
*/
|
|
do {
|
|
groupsize = g.end - g.start;
|
|
|
|
/*
|
|
* Keep track of the last "end" index that causes this
|
|
* group to align with a group of changed lines in the
|
|
* other file. -1 indicates that we haven't found such
|
|
* a match yet:
|
|
*/
|
|
end_matching_other = -1;
|
|
|
|
/* Shift the group backward as much as possible: */
|
|
while (!group_slide_up(xdf, &g, flags))
|
|
if (group_previous(xdfo, &go))
|
|
xdl_bug("group sync broken sliding up");
|
|
|
|
/*
|
|
* This is this highest that this group can be shifted.
|
|
* Record its end index:
|
|
*/
|
|
earliest_end = g.end;
|
|
|
|
if (go.end > go.start)
|
|
end_matching_other = g.end;
|
|
|
|
/* Now shift the group forward as far as possible: */
|
|
while (1) {
|
|
if (group_slide_down(xdf, &g, flags))
|
|
break;
|
|
if (group_next(xdfo, &go))
|
|
xdl_bug("group sync broken sliding down");
|
|
|
|
if (go.end > go.start)
|
|
end_matching_other = g.end;
|
|
}
|
|
} while (groupsize != g.end - g.start);
|
|
|
|
/*
|
|
* If the group can be shifted, then we can possibly use this
|
|
* freedom to produce a more intuitive diff.
|
|
*
|
|
* The group is currently shifted as far down as possible, so the
|
|
* heuristics below only have to handle upwards shifts.
|
|
*/
|
|
|
|
if (g.end == earliest_end) {
|
|
/* no shifting was possible */
|
|
} else if (end_matching_other != -1) {
|
|
/*
|
|
* Move the possibly merged group of changes back to line
|
|
* up with the last group of changes from the other file
|
|
* that it can align with.
|
|
*/
|
|
while (go.end == go.start) {
|
|
if (group_slide_up(xdf, &g, flags))
|
|
xdl_bug("match disappeared");
|
|
if (group_previous(xdfo, &go))
|
|
xdl_bug("group sync broken sliding to match");
|
|
}
|
|
} else if (flags & XDF_INDENT_HEURISTIC) {
|
|
/*
|
|
* Indent heuristic: a group of pure add/delete lines
|
|
* implies two splits, one between the end of the "before"
|
|
* context and the start of the group, and another between
|
|
* the end of the group and the beginning of the "after"
|
|
* context. Some splits are aesthetically better and some
|
|
* are worse. We compute a badness "score" for each split,
|
|
* and add the scores for the two splits to define a
|
|
* "score" for each position that the group can be shifted
|
|
* to. Then we pick the shift with the lowest score.
|
|
*/
|
|
long shift, best_shift = -1;
|
|
struct split_score best_score;
|
|
|
|
shift = earliest_end;
|
|
if (g.end - groupsize - 1 > shift)
|
|
shift = g.end - groupsize - 1;
|
|
if (g.end - INDENT_HEURISTIC_MAX_SLIDING > shift)
|
|
shift = g.end - INDENT_HEURISTIC_MAX_SLIDING;
|
|
for (; shift <= g.end; shift++) {
|
|
struct split_measurement m;
|
|
struct split_score score = {0, 0};
|
|
|
|
measure_split(xdf, shift, &m);
|
|
score_add_split(&m, &score);
|
|
measure_split(xdf, shift - groupsize, &m);
|
|
score_add_split(&m, &score);
|
|
if (best_shift == -1 ||
|
|
score_cmp(&score, &best_score) <= 0) {
|
|
best_score.effective_indent = score.effective_indent;
|
|
best_score.penalty = score.penalty;
|
|
best_shift = shift;
|
|
}
|
|
}
|
|
|
|
while (g.end > best_shift) {
|
|
if (group_slide_up(xdf, &g, flags))
|
|
xdl_bug("best shift unreached");
|
|
if (group_previous(xdfo, &go))
|
|
xdl_bug("group sync broken sliding to blank line");
|
|
}
|
|
}
|
|
|
|
next:
|
|
/* Move past the just-processed group: */
|
|
if (group_next(xdf, &g))
|
|
break;
|
|
if (group_next(xdfo, &go))
|
|
xdl_bug("group sync broken moving to next group");
|
|
}
|
|
|
|
if (!group_next(xdfo, &go))
|
|
xdl_bug("group sync broken at end of file");
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int xdl_build_script(xdfenv_t *xe, xdchange_t **xscr) {
|
|
xdchange_t *cscr = NULL, *xch;
|
|
char *rchg1 = xe->xdf1.rchg, *rchg2 = xe->xdf2.rchg;
|
|
long i1, i2, l1, l2;
|
|
|
|
/*
|
|
* Trivial. Collects "groups" of changes and creates an edit script.
|
|
*/
|
|
for (i1 = xe->xdf1.nrec, i2 = xe->xdf2.nrec; i1 >= 0 || i2 >= 0; i1--, i2--)
|
|
if (rchg1[i1 - 1] || rchg2[i2 - 1]) {
|
|
for (l1 = i1; rchg1[i1 - 1]; i1--);
|
|
for (l2 = i2; rchg2[i2 - 1]; i2--);
|
|
|
|
if (!(xch = xdl_add_change(cscr, i1, i2, l1 - i1, l2 - i2))) {
|
|
xdl_free_script(cscr);
|
|
return -1;
|
|
}
|
|
cscr = xch;
|
|
}
|
|
|
|
*xscr = cscr;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
void xdl_free_script(xdchange_t *xscr) {
|
|
xdchange_t *xch;
|
|
|
|
while ((xch = xscr) != NULL) {
|
|
xscr = xscr->next;
|
|
xdl_free(xch);
|
|
}
|
|
}
|
|
|
|
static int xdl_call_hunk_func(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
|
|
xdemitconf_t const *xecfg)
|
|
{
|
|
xdchange_t *xch, *xche;
|
|
|
|
for (xch = xscr; xch; xch = xche->next) {
|
|
xche = xdl_get_hunk(&xch, xecfg);
|
|
if (!xch)
|
|
break;
|
|
if (xecfg->hunk_func(xch->i1, xche->i1 + xche->chg1 - xch->i1,
|
|
xch->i2, xche->i2 + xche->chg2 - xch->i2,
|
|
ecb->priv) < 0)
|
|
return -1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static void xdl_mark_ignorable(xdchange_t *xscr, xdfenv_t *xe, long flags)
|
|
{
|
|
xdchange_t *xch;
|
|
|
|
for (xch = xscr; xch; xch = xch->next) {
|
|
int ignore = 1;
|
|
xrecord_t **rec;
|
|
long i;
|
|
|
|
rec = &xe->xdf1.recs[xch->i1];
|
|
for (i = 0; i < xch->chg1 && ignore; i++)
|
|
ignore = xdl_blankline(rec[i]->ptr, rec[i]->size, flags);
|
|
|
|
rec = &xe->xdf2.recs[xch->i2];
|
|
for (i = 0; i < xch->chg2 && ignore; i++)
|
|
ignore = xdl_blankline(rec[i]->ptr, rec[i]->size, flags);
|
|
|
|
xch->ignore = ignore;
|
|
}
|
|
}
|
|
|
|
int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
|
|
xdemitconf_t const *xecfg, xdemitcb_t *ecb) {
|
|
xdchange_t *xscr;
|
|
xdfenv_t xe;
|
|
emit_func_t ef = xecfg->hunk_func ? xdl_call_hunk_func : xdl_emit_diff;
|
|
|
|
if (xdl_do_diff(mf1, mf2, xpp, &xe) < 0) {
|
|
|
|
return -1;
|
|
}
|
|
if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
|
|
xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
|
|
xdl_build_script(&xe, &xscr) < 0) {
|
|
|
|
xdl_free_env(&xe);
|
|
return -1;
|
|
}
|
|
if (xscr) {
|
|
if (xpp->flags & XDF_IGNORE_BLANK_LINES)
|
|
xdl_mark_ignorable(xscr, &xe, xpp->flags);
|
|
|
|
if (ef(&xe, xscr, ecb, xecfg) < 0) {
|
|
|
|
xdl_free_script(xscr);
|
|
xdl_free_env(&xe);
|
|
return -1;
|
|
}
|
|
xdl_free_script(xscr);
|
|
}
|
|
xdl_free_env(&xe);
|
|
|
|
return 0;
|
|
}
|