forked from AuroraMiddleware/gtk
a6079b9b7b
This includes a copy of the diff(1) algorithm used by git diff by Davide Libenzi. It's used for the common case ofcontainer nodes having only very few changes for the few nodes of child widgets that changed (like a button lighting up when hilighted or a spinning spinner).
440 lines
13 KiB
C
440 lines
13 KiB
C
/*
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* Copyright © 2003 Davide Libenzi
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* 2018 Benjamin Otte
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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 <http://www.gnu.org/licenses/>.
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*
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* Authors: Davide Libenzi <davidel@xmailserver.org>
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* Benjamin Otte <otte@gnome.org>
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*/
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#include "config.h"
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#include "gskdiffprivate.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 G_MAXSSIZE
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#define XDL_SNAKE_CNT 20
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#define XDL_K_HEUR 4
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#define MAXCOST 20
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typedef struct _SplitResult {
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long i1, i2;
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int min_lo, min_hi;
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} SplitResult;
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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 void
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split (gconstpointer *elem1,
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gssize off1,
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gssize lim1,
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gconstpointer *elem2,
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gssize off2,
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gssize lim2,
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gssize *kvdf,
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gssize *kvdb,
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gboolean need_min,
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GCompareDataFunc compare_func,
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gpointer data,
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SplitResult *spl)
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{
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gssize dmin = off1 - lim2, dmax = lim1 - off2;
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gssize fmid = off1 - off2, bmid = lim1 - lim2;
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gboolean odd = (fmid - bmid) & 1;
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gssize fmin = fmid, fmax = fmid;
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gssize bmin = bmid, bmax = bmid;
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gssize 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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{
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gboolean got_snake = FALSE;
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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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{
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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; i1++, i2++)
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{
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if (compare_func (elem1[i1], elem2[i2], data) != 0)
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break;
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}
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if (i1 - prev1 > XDL_SNAKE_CNT)
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got_snake = TRUE;
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kvdf[d] = i1;
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if (odd && bmin <= d && d <= bmax && kvdb[d] <= i1)
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{
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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;
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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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{
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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; i1--, i2--)
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{
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if (compare_func (elem1[i1 - 1], elem2[i2 - 1], data) != 0)
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break;
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}
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if (prev1 - i1 > XDL_SNAKE_CNT)
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got_snake = TRUE;
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kvdb[d] = i1;
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if (!odd && fmin <= d && d <= fmax && i1 <= kvdf[d])
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{
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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;
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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 > XDL_HEUR_MIN_COST)
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{
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for (best = 0, d = fmax; d >= fmin; d -= 2)
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{
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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 + XDL_SNAKE_CNT <= i1 && i1 < lim1 &&
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off2 + XDL_SNAKE_CNT <= i2 && i2 < lim2)
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{
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for (k = 1; ; k++)
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{
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if (compare_func (elem1[i1 - k], elem2[i2 - k], data) != 0)
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break;
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if (k == XDL_SNAKE_CNT)
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{
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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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}
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if (best > 0)
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{
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spl->min_lo = 1;
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spl->min_hi = 0;
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return;
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}
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for (best = 0, d = bmax; d >= bmin; d -= 2)
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{
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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 - XDL_SNAKE_CNT &&
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off2 < i2 && i2 <= lim2 - XDL_SNAKE_CNT)
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{
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for (k = 0; ; k++)
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{
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if (compare_func (elem1[i1 + k], elem2[i2 + k], data) != 0)
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break;
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if (k == XDL_SNAKE_CNT - 1)
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{
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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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}
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if (best > 0)
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{
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spl->min_lo = 0;
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spl->min_hi = 1;
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return;
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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 >= MAXCOST)
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{
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gssize 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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{
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i1 = 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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{
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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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{
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i1 = 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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{
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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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{
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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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}
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else
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{
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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;
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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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static void
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compare (gconstpointer *elem1,
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gssize off1,
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gssize lim1,
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gconstpointer *elem2,
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gssize off2,
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gssize lim2,
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gssize *kvdf,
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gssize *kvdb,
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gboolean need_min,
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GCompareDataFunc compare_func,
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GskKeepFunc keep_func,
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GskDeleteFunc delete_func,
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GskInsertFunc insert_func,
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gpointer data)
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{
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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; off1++, off2++)
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{
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if (compare_func (elem1[off1], elem2[off2], data) != 0)
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break;
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keep_func (elem1[off1], elem2[off2], data);
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}
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for (; off1 < lim1 && off2 < lim2; lim1--, lim2--)
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{
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if (compare_func (elem1[lim1 - 1], elem2[lim2 - 1], data) != 0)
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break;
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keep_func (elem1[lim1 - 1], elem2[lim2 - 1], data);
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}
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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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{
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for (; off2 < lim2; off2++)
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{
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insert_func (elem2[off2], off2, data);
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}
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}
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else if (off2 == lim2)
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{
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for (; off1 < lim1; off1++)
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{
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delete_func (elem1[off1], off1, data);
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}
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}
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else
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{
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SplitResult spl = { 0, };
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/*
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* Divide ...
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*/
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split (elem1, off1, lim1,
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elem2, off2, lim2,
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kvdf, kvdb, need_min,
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compare_func, data,
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&spl);
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/*
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* ... et Impera.
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*/
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compare (elem1, off1, spl.i1,
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elem2, off2, spl.i2,
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kvdf, kvdb, spl.min_lo,
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compare_func, keep_func, delete_func, insert_func, data);
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compare (elem1, spl.i1, lim1,
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elem2, spl.i2, lim2,
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kvdf, kvdb, spl.min_hi,
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compare_func, keep_func, delete_func, insert_func, data);
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}
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}
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#if 0
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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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#endif
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void
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gsk_diff (gconstpointer *elem1,
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gsize n1,
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gconstpointer *elem2,
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gsize n2,
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GCompareDataFunc compare_func,
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GskKeepFunc keep_func,
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GskDeleteFunc delete_func,
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GskInsertFunc insert_func,
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gpointer data)
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{
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gsize ndiags;
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gssize *kvd, *kvdf, *kvdb;
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ndiags = n1 + n2 + 3;
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kvd = g_new (gssize, 2 * ndiags + 2);
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kvdf = kvd;
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kvdb = kvd + ndiags;
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kvdf += n2 + 1;
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kvdb += n2 + 1;
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compare (elem1, 0, n1,
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elem2, 0, n2,
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kvdf, kvdb, FALSE,
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compare_func, keep_func, delete_func, insert_func, data);
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g_free (kvd);
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}
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