| /* |
| * 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" |
| |
| #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; |
| |
| /* |
| * 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 encounter expensive edge cases |
| * using this algorithm, 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 extend 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 in the 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 extend 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 in the 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 them 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" (divide & conquer). 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 (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. |
| */ |
| 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; |
| xch->ignore = 0; |
| |
| return xch; |
| } |
| |
| |
| static int recs_match(xrecord_t *rec1, xrecord_t *rec2) |
| { |
| return (rec1->ha == rec2->ha); |
| } |
| |
| /* |
| * 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 |
| |
| /* |
| * 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) |
| { |
| if (g->end < xdf->nrec && |
| recs_match(xdf->recs[g->start], xdf->recs[g->end])) { |
| 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) |
| { |
| if (g->start > 0 && |
| recs_match(xdf->recs[g->start - 1], xdf->recs[g->end - 1])) { |
| xdf->rchg[--g->start] = 1; |
| xdf->rchg[--g->end] = 0; |
| |
| while (xdf->rchg[g->start - 1]) |
| g->start--; |
| |
| return 0; |
| } else { |
| return -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)) |
| if (group_previous(xdfo, &go)) |
| 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)) |
| break; |
| if (group_next(xdfo, &go)) |
| 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)) |
| BUG("match disappeared"); |
| if (group_previous(xdfo, &go)) |
| 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)) |
| BUG("best shift unreached"); |
| if (group_previous(xdfo, &go)) |
| 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)) |
| BUG("group sync broken moving to next group"); |
| } |
| |
| if (!group_next(xdfo, &go)) |
| 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_lines(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; |
| } |
| } |
| |
| static int record_matches_regex(xrecord_t *rec, xpparam_t const *xpp) { |
| regmatch_t regmatch; |
| int i; |
| |
| for (i = 0; i < xpp->ignore_regex_nr; i++) |
| if (!regexec_buf(xpp->ignore_regex[i], rec->ptr, rec->size, 1, |
| ®match, 0)) |
| return 1; |
| |
| return 0; |
| } |
| |
| static void xdl_mark_ignorable_regex(xdchange_t *xscr, const xdfenv_t *xe, |
| xpparam_t const *xpp) |
| { |
| xdchange_t *xch; |
| |
| for (xch = xscr; xch; xch = xch->next) { |
| xrecord_t **rec; |
| int ignore = 1; |
| long i; |
| |
| /* |
| * Do not override --ignore-blank-lines. |
| */ |
| if (xch->ignore) |
| continue; |
| |
| rec = &xe->xdf1.recs[xch->i1]; |
| for (i = 0; i < xch->chg1 && ignore; i++) |
| ignore = record_matches_regex(rec[i], xpp); |
| |
| rec = &xe->xdf2.recs[xch->i2]; |
| for (i = 0; i < xch->chg2 && ignore; i++) |
| ignore = record_matches_regex(rec[i], xpp); |
| |
| 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_lines(xscr, &xe, xpp->flags); |
| |
| if (xpp->ignore_regex) |
| xdl_mark_ignorable_regex(xscr, &xe, xpp); |
| |
| 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; |
| } |