diff options
Diffstat (limited to 'src/xdiff/xdiffi.c')
-rw-r--r-- | src/xdiff/xdiffi.c | 572 |
1 files changed, 572 insertions, 0 deletions
diff --git a/src/xdiff/xdiffi.c b/src/xdiff/xdiffi.c new file mode 100644 index 000000000..75a392275 --- /dev/null +++ b/src/xdiff/xdiffi.c @@ -0,0 +1,572 @@ +/* + * 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; +} |