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Diffstat (limited to 'src/xdiff/xdiffi.c')
| -rw-r--r-- | src/xdiff/xdiffi.c | 1062 |
1 files changed, 0 insertions, 1062 deletions
diff --git a/src/xdiff/xdiffi.c b/src/xdiff/xdiffi.c deleted file mode 100644 index 916295b44..000000000 --- a/src/xdiff/xdiffi.c +++ /dev/null @@ -1,1062 +0,0 @@ -/* - * 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, see - * <http://www.gnu.org/licenses/>. - * - * Davide Libenzi <davidel@xmailserver.org> - * - */ - -#include "xinclude.h" -#include "integer.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 - -/** Declare a function as always inlined. */ -#if defined(_MSC_VER) -# define XDL_INLINE(type) static __inline type -#elif defined(__GNUC__) -# define XDL_INLINE(type) static __inline__ type -#else -# define XDL_INLINE(type) static type -#endif - -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) { - size_t ndiags, allocsize; - long *kvd, *kvdf, *kvdb; - xdalgoenv_t xenv; - diffdata_t dd1, dd2; - - if (XDF_DIFF_ALG(xpp->flags) == XDF_PATIENCE_DIFF) - return xdl_do_patience_diff(mf1, mf2, xpp, xe); - - if (XDF_DIFF_ALG(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. - */ - GIT_ERROR_CHECK_ALLOC_ADD3(&ndiags, xe->xdf1.nreff, xe->xdf2.nreff, 3); - GIT_ERROR_CHECK_ALLOC_MULTIPLY(&allocsize, ndiags, 2); - GIT_ERROR_CHECK_ALLOC_ADD(&allocsize, allocsize, 2); - GIT_ERROR_CHECK_ALLOC_MULTIPLY(&allocsize, allocsize, sizeof(long)); - - if (!(kvd = (long *) xdl_malloc(allocsize))) { - 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; - xch->ignore = 0; - - return xch; -} - - -static int recs_match(xrecord_t *rec1, xrecord_t *rec2, long flags) -{ - return (rec1->ha == rec2->ha && - xdl_recmatch(rec1->ptr, rec1->size, - rec2->ptr, rec2->size, - flags)); -} - -/* - * If a line is indented more than this, get_indent() just returns this value. - * This avoids having to do absurd amounts of work for data that are not - * human-readable text, and also ensures that the output of get_indent fits within - * an int. - */ -#define MAX_INDENT 200 - -/* - * Return the amount of indentation of the specified line, treating TAB as 8 - * columns. Return -1 if line is empty or contains only whitespace. Clamp the - * output value at MAX_INDENT. - */ -static int get_indent(xrecord_t *rec) -{ - long i; - int ret = 0; - - for (i = 0; i < rec->size; i++) { - char c = rec->ptr[i]; - - if (!XDL_ISSPACE(c)) - return ret; - else if (c == ' ') - ret += 1; - else if (c == '\t') - ret += 8 - ret % 8; - /* ignore other whitespace characters */ - - if (ret >= MAX_INDENT) - return MAX_INDENT; - } - - /* The line contains only whitespace. */ - return -1; -} - -/* - * If more than this number of consecutive blank rows are found, just return this - * value. This avoids requiring O(N^2) work for pathological cases, and also - * ensures that the output of score_split fits in an int. - */ -#define MAX_BLANKS 20 - -/* Characteristics measured about a hypothetical split position. */ -struct split_measurement { - /* - * Is the split at the end of the file (aside from any blank lines)? - */ - int end_of_file; - - /* - * How much is the line immediately following the split indented (or -1 if - * the line is blank): - */ - int indent; - - /* - * How many consecutive lines above the split are blank? - */ - int pre_blank; - - /* - * How much is the nearest non-blank line above the split indented (or -1 - * if there is no such line)? - */ - int pre_indent; - - /* - * How many lines after the line following the split are blank? - */ - int post_blank; - - /* - * How much is the nearest non-blank line after the line following the - * split indented (or -1 if there is no such line)? - */ - int post_indent; -}; - -struct split_score { - /* The effective indent of this split (smaller is preferred). */ - int effective_indent; - - /* Penalty for this split (smaller is preferred). */ - int penalty; -}; - -/* - * Fill m with information about a hypothetical split of xdf above line split. - */ -static void measure_split(const xdfile_t *xdf, long split, - struct split_measurement *m) -{ - long i; - - 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 - -/* - * 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. - */ -XDL_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. - */ -XDL_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; - - for (shift = earliest_end; 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; - - (void)xe; - - 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; -} |