| /* |
| * 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" |
| |
| |
| |
| #define XDL_MAX_COST_MIN 256 |
| #define XDL_HEUR_MIN_COST 256 |
| #define XDL_LINE_MAX (long)((1UL << (CHAR_BIT * sizeof(long) - 1)) - 1) |
| #define XDL_SNAKE_CNT 20 |
| #define XDL_K_HEUR 4 |
| |
| |
| |
| typedef struct s_xdpsplit { |
| long i1, i2; |
| int min_lo, min_hi; |
| } xdpsplit_t; |
| |
| |
| |
| |
| static long xdl_split(unsigned long const *ha1, long off1, long lim1, |
| unsigned long const *ha2, long off2, long lim2, |
| long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl, |
| xdalgoenv_t *xenv); |
| static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2); |
| |
| |
| |
| |
| |
| /* |
| * See "An O(ND) Difference Algorithm and its Variations", by Eugene Myers. |
| * Basically considers a "box" (off1, off2, lim1, lim2) and scan from both |
| * the forward diagonal starting from (off1, off2) and the backward diagonal |
| * starting from (lim1, lim2). If the K values on the same diagonal crosses |
| * returns the furthest point of reach. We might end up having to expensive |
| * cases using this algorithm is full, so a little bit of heuristic is needed |
| * to cut the search and to return a suboptimal point. |
| */ |
| static long xdl_split(unsigned long const *ha1, long off1, long lim1, |
| unsigned long const *ha2, long off2, long lim2, |
| long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl, |
| xdalgoenv_t *xenv) { |
| long dmin = off1 - lim2, dmax = lim1 - off2; |
| long fmid = off1 - off2, bmid = lim1 - lim2; |
| long odd = (fmid - bmid) & 1; |
| long fmin = fmid, fmax = fmid; |
| long bmin = bmid, bmax = bmid; |
| long ec, d, i1, i2, prev1, best, dd, v, k; |
| |
| /* |
| * Set initial diagonal values for both forward and backward path. |
| */ |
| kvdf[fmid] = off1; |
| kvdb[bmid] = lim1; |
| |
| for (ec = 1;; ec++) { |
| int got_snake = 0; |
| |
| /* |
| * We need to extent the diagonal "domain" by one. If the next |
| * values exits the box boundaries we need to change it in the |
| * opposite direction because (max - min) must be a power of two. |
| * Also we initialize the external K value to -1 so that we can |
| * avoid extra conditions check inside the core loop. |
| */ |
| if (fmin > dmin) |
| kvdf[--fmin - 1] = -1; |
| else |
| ++fmin; |
| if (fmax < dmax) |
| kvdf[++fmax + 1] = -1; |
| else |
| --fmax; |
| |
| for (d = fmax; d >= fmin; d -= 2) { |
| if (kvdf[d - 1] >= kvdf[d + 1]) |
| i1 = kvdf[d - 1] + 1; |
| else |
| i1 = kvdf[d + 1]; |
| prev1 = i1; |
| i2 = i1 - d; |
| for (; i1 < lim1 && i2 < lim2 && ha1[i1] == ha2[i2]; i1++, i2++); |
| if (i1 - prev1 > xenv->snake_cnt) |
| got_snake = 1; |
| kvdf[d] = i1; |
| if (odd && bmin <= d && d <= bmax && kvdb[d] <= i1) { |
| spl->i1 = i1; |
| spl->i2 = i2; |
| spl->min_lo = spl->min_hi = 1; |
| return ec; |
| } |
| } |
| |
| /* |
| * We need to extent the diagonal "domain" by one. If the next |
| * values exits the box boundaries we need to change it in the |
| * opposite direction because (max - min) must be a power of two. |
| * Also we initialize the external K value to -1 so that we can |
| * avoid extra conditions check inside the core loop. |
| */ |
| if (bmin > dmin) |
| kvdb[--bmin - 1] = XDL_LINE_MAX; |
| else |
| ++bmin; |
| if (bmax < dmax) |
| kvdb[++bmax + 1] = XDL_LINE_MAX; |
| else |
| --bmax; |
| |
| for (d = bmax; d >= bmin; d -= 2) { |
| if (kvdb[d - 1] < kvdb[d + 1]) |
| i1 = kvdb[d - 1]; |
| else |
| i1 = kvdb[d + 1] - 1; |
| prev1 = i1; |
| i2 = i1 - d; |
| for (; i1 > off1 && i2 > off2 && ha1[i1 - 1] == ha2[i2 - 1]; i1--, i2--); |
| if (prev1 - i1 > xenv->snake_cnt) |
| got_snake = 1; |
| kvdb[d] = i1; |
| if (!odd && fmin <= d && d <= fmax && i1 <= kvdf[d]) { |
| spl->i1 = i1; |
| spl->i2 = i2; |
| spl->min_lo = spl->min_hi = 1; |
| return ec; |
| } |
| } |
| |
| if (need_min) |
| continue; |
| |
| /* |
| * If the edit cost is above the heuristic trigger and if |
| * we got a good snake, we sample current diagonals to see |
| * if some of the, have reached an "interesting" path. Our |
| * measure is a function of the distance from the diagonal |
| * corner (i1 + i2) penalized with the distance from the |
| * mid diagonal itself. If this value is above the current |
| * edit cost times a magic factor (XDL_K_HEUR) we consider |
| * it interesting. |
| */ |
| if (got_snake && ec > xenv->heur_min) { |
| for (best = 0, d = fmax; d >= fmin; d -= 2) { |
| dd = d > fmid ? d - fmid: fmid - d; |
| i1 = kvdf[d]; |
| i2 = i1 - d; |
| v = (i1 - off1) + (i2 - off2) - dd; |
| |
| if (v > XDL_K_HEUR * ec && v > best && |
| off1 + xenv->snake_cnt <= i1 && i1 < lim1 && |
| off2 + xenv->snake_cnt <= i2 && i2 < lim2) { |
| for (k = 1; ha1[i1 - k] == ha2[i2 - k]; k++) |
| if (k == xenv->snake_cnt) { |
| best = v; |
| spl->i1 = i1; |
| spl->i2 = i2; |
| break; |
| } |
| } |
| } |
| if (best > 0) { |
| spl->min_lo = 1; |
| spl->min_hi = 0; |
| return ec; |
| } |
| |
| for (best = 0, d = bmax; d >= bmin; d -= 2) { |
| dd = d > bmid ? d - bmid: bmid - d; |
| i1 = kvdb[d]; |
| i2 = i1 - d; |
| v = (lim1 - i1) + (lim2 - i2) - dd; |
| |
| if (v > XDL_K_HEUR * ec && v > best && |
| off1 < i1 && i1 <= lim1 - xenv->snake_cnt && |
| off2 < i2 && i2 <= lim2 - xenv->snake_cnt) { |
| for (k = 0; ha1[i1 + k] == ha2[i2 + k]; k++) |
| if (k == xenv->snake_cnt - 1) { |
| best = v; |
| spl->i1 = i1; |
| spl->i2 = i2; |
| break; |
| } |
| } |
| } |
| if (best > 0) { |
| spl->min_lo = 0; |
| spl->min_hi = 1; |
| return ec; |
| } |
| } |
| |
| /* |
| * Enough is enough. We spent too much time here and now we collect |
| * the furthest reaching path using the (i1 + i2) measure. |
| */ |
| if (ec >= xenv->mxcost) { |
| long fbest, fbest1, bbest, bbest1; |
| |
| fbest = fbest1 = -1; |
| for (d = fmax; d >= fmin; d -= 2) { |
| i1 = XDL_MIN(kvdf[d], lim1); |
| i2 = i1 - d; |
| if (lim2 < i2) |
| i1 = lim2 + d, i2 = lim2; |
| if (fbest < i1 + i2) { |
| fbest = i1 + i2; |
| fbest1 = i1; |
| } |
| } |
| |
| bbest = bbest1 = XDL_LINE_MAX; |
| for (d = bmax; d >= bmin; d -= 2) { |
| i1 = XDL_MAX(off1, kvdb[d]); |
| i2 = i1 - d; |
| if (i2 < off2) |
| i1 = off2 + d, i2 = off2; |
| if (i1 + i2 < bbest) { |
| bbest = i1 + i2; |
| bbest1 = i1; |
| } |
| } |
| |
| if ((lim1 + lim2) - bbest < fbest - (off1 + off2)) { |
| spl->i1 = fbest1; |
| spl->i2 = fbest - fbest1; |
| spl->min_lo = 1; |
| spl->min_hi = 0; |
| } else { |
| spl->i1 = bbest1; |
| spl->i2 = bbest - bbest1; |
| spl->min_lo = 0; |
| spl->min_hi = 1; |
| } |
| return ec; |
| } |
| } |
| } |
| |
| |
| /* |
| * Rule: "Divide et Impera". Recursively split the box in sub-boxes by calling |
| * the box splitting function. Note that the real job (marking changed lines) |
| * is done in the two boundary reaching checks. |
| */ |
| int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1, |
| diffdata_t *dd2, long off2, long lim2, |
| long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv) { |
| unsigned long const *ha1 = dd1->ha, *ha2 = dd2->ha; |
| |
| /* |
| * Shrink the box by walking through each diagonal snake (SW and NE). |
| */ |
| for (; off1 < lim1 && off2 < lim2 && ha1[off1] == ha2[off2]; off1++, off2++); |
| for (; off1 < lim1 && off2 < lim2 && ha1[lim1 - 1] == ha2[lim2 - 1]; lim1--, lim2--); |
| |
| /* |
| * If one dimension is empty, then all records on the other one must |
| * be obviously changed. |
| */ |
| if (off1 == lim1) { |
| char *rchg2 = dd2->rchg; |
| long *rindex2 = dd2->rindex; |
| |
| for (; off2 < lim2; off2++) |
| rchg2[rindex2[off2]] = 1; |
| } else if (off2 == lim2) { |
| char *rchg1 = dd1->rchg; |
| long *rindex1 = dd1->rindex; |
| |
| for (; off1 < lim1; off1++) |
| rchg1[rindex1[off1]] = 1; |
| } else { |
| xdpsplit_t spl; |
| spl.i1 = spl.i2 = 0; |
| |
| /* |
| * Divide ... |
| */ |
| if (xdl_split(ha1, off1, lim1, ha2, off2, lim2, kvdf, kvdb, |
| need_min, &spl, xenv) < 0) { |
| |
| return -1; |
| } |
| |
| /* |
| * ... et Impera. |
| */ |
| if (xdl_recs_cmp(dd1, off1, spl.i1, dd2, off2, spl.i2, |
| kvdf, kvdb, spl.min_lo, xenv) < 0 || |
| xdl_recs_cmp(dd1, spl.i1, lim1, dd2, spl.i2, lim2, |
| kvdf, kvdb, spl.min_hi, xenv) < 0) { |
| |
| return -1; |
| } |
| } |
| |
| return 0; |
| } |
| |
| |
| int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, |
| xdfenv_t *xe) { |
| long ndiags; |
| long *kvd, *kvdf, *kvdb; |
| xdalgoenv_t xenv; |
| diffdata_t dd1, dd2; |
| |
| if (xpp->flags & XDF_PATIENCE_DIFF) |
| return xdl_do_patience_diff(mf1, mf2, xpp, xe); |
| |
| if (xpp->flags & XDF_HISTOGRAM_DIFF) |
| return xdl_do_histogram_diff(mf1, mf2, xpp, xe); |
| |
| if (xdl_prepare_env(mf1, mf2, xpp, xe) < 0) { |
| |
| return -1; |
| } |
| |
| /* |
| * Allocate and setup K vectors to be used by the differential algorithm. |
| * One is to store the forward path and one to store the backward path. |
| */ |
| ndiags = xe->xdf1.nreff + xe->xdf2.nreff + 3; |
| if (!(kvd = (long *) xdl_malloc((2 * ndiags + 2) * sizeof(long)))) { |
| |
| xdl_free_env(xe); |
| return -1; |
| } |
| kvdf = kvd; |
| kvdb = kvdf + ndiags; |
| kvdf += xe->xdf2.nreff + 1; |
| kvdb += xe->xdf2.nreff + 1; |
| |
| xenv.mxcost = xdl_bogosqrt(ndiags); |
| if (xenv.mxcost < XDL_MAX_COST_MIN) |
| xenv.mxcost = XDL_MAX_COST_MIN; |
| xenv.snake_cnt = XDL_SNAKE_CNT; |
| xenv.heur_min = XDL_HEUR_MIN_COST; |
| |
| dd1.nrec = xe->xdf1.nreff; |
| dd1.ha = xe->xdf1.ha; |
| dd1.rchg = xe->xdf1.rchg; |
| dd1.rindex = xe->xdf1.rindex; |
| dd2.nrec = xe->xdf2.nreff; |
| dd2.ha = xe->xdf2.ha; |
| dd2.rchg = xe->xdf2.rchg; |
| dd2.rindex = xe->xdf2.rindex; |
| |
| if (xdl_recs_cmp(&dd1, 0, dd1.nrec, &dd2, 0, dd2.nrec, |
| kvdf, kvdb, (xpp->flags & XDF_NEED_MINIMAL) != 0, &xenv) < 0) { |
| |
| xdl_free(kvd); |
| xdl_free_env(xe); |
| return -1; |
| } |
| |
| xdl_free(kvd); |
| |
| return 0; |
| } |
| |
| |
| static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, long chg2) { |
| xdchange_t *xch; |
| |
| if (!(xch = (xdchange_t *) xdl_malloc(sizeof(xdchange_t)))) |
| return NULL; |
| |
| xch->next = xscr; |
| xch->i1 = i1; |
| xch->i2 = i2; |
| xch->chg1 = chg1; |
| xch->chg2 = chg2; |
| |
| return xch; |
| } |
| |
| |
| int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { |
| long ix, ixo, ixs, ixref, grpsiz, nrec = xdf->nrec; |
| char *rchg = xdf->rchg, *rchgo = xdfo->rchg; |
| xrecord_t **recs = xdf->recs; |
| |
| /* |
| * This is the same of what GNU diff does. Move back and forward |
| * change groups for a consistent and pretty diff output. This also |
| * helps in finding joinable change groups and reduce the diff size. |
| */ |
| for (ix = ixo = 0;;) { |
| /* |
| * Find the first changed line in the to-be-compacted file. |
| * We need to keep track of both indexes, so if we find a |
| * changed lines group on the other file, while scanning the |
| * to-be-compacted file, we need to skip it properly. Note |
| * that loops that are testing for changed lines on rchg* do |
| * not need index bounding since the array is prepared with |
| * a zero at position -1 and N. |
| */ |
| for (; ix < nrec && !rchg[ix]; ix++) |
| while (rchgo[ixo++]); |
| if (ix == nrec) |
| break; |
| |
| /* |
| * Record the start of a changed-group in the to-be-compacted file |
| * and find the end of it, on both to-be-compacted and other file |
| * indexes (ix and ixo). |
| */ |
| ixs = ix; |
| for (ix++; rchg[ix]; ix++); |
| for (; rchgo[ixo]; ixo++); |
| |
| do { |
| grpsiz = ix - ixs; |
| |
| /* |
| * If the line before the current change group, is equal to |
| * the last line of the current change group, shift backward |
| * the group. |
| */ |
| while (ixs > 0 && recs[ixs - 1]->ha == recs[ix - 1]->ha && |
| xdl_recmatch(recs[ixs - 1]->ptr, recs[ixs - 1]->size, recs[ix - 1]->ptr, recs[ix - 1]->size, flags)) { |
| rchg[--ixs] = 1; |
| rchg[--ix] = 0; |
| |
| /* |
| * This change might have joined two change groups, |
| * so we try to take this scenario in account by moving |
| * the start index accordingly (and so the other-file |
| * end-of-group index). |
| */ |
| for (; rchg[ixs - 1]; ixs--); |
| while (rchgo[--ixo]); |
| } |
| |
| /* |
| * Record the end-of-group position in case we are matched |
| * with a group of changes in the other file (that is, the |
| * change record before the end-of-group index in the other |
| * file is set). |
| */ |
| ixref = rchgo[ixo - 1] ? ix: nrec; |
| |
| /* |
| * If the first line of the current change group, is equal to |
| * the line next of the current change group, shift forward |
| * the group. |
| */ |
| while (ix < nrec && recs[ixs]->ha == recs[ix]->ha && |
| xdl_recmatch(recs[ixs]->ptr, recs[ixs]->size, recs[ix]->ptr, recs[ix]->size, flags)) { |
| rchg[ixs++] = 0; |
| rchg[ix++] = 1; |
| |
| /* |
| * This change might have joined two change groups, |
| * so we try to take this scenario in account by moving |
| * the start index accordingly (and so the other-file |
| * end-of-group index). Keep tracking the reference |
| * index in case we are shifting together with a |
| * corresponding group of changes in the other file. |
| */ |
| for (; rchg[ix]; ix++); |
| while (rchgo[++ixo]) |
| ixref = ix; |
| } |
| } while (grpsiz != ix - ixs); |
| |
| /* |
| * Try to move back the possibly merged group of changes, to match |
| * the recorded postion in the other file. |
| */ |
| while (ixref < ix) { |
| rchg[--ixs] = 1; |
| rchg[--ix] = 0; |
| while (rchgo[--ixo]); |
| } |
| } |
| |
| 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); |
| } |
| } |
| |
| |
| 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->emit_func ? |
| (emit_func_t)xecfg->emit_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 (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; |
| } |