diff options
Diffstat (limited to 'third_party/git/xdiff/xpatience.c')
-rw-r--r-- | third_party/git/xdiff/xpatience.c | 388 |
1 files changed, 0 insertions, 388 deletions
diff --git a/third_party/git/xdiff/xpatience.c b/third_party/git/xdiff/xpatience.c deleted file mode 100644 index 3c5601b602a2..000000000000 --- a/third_party/git/xdiff/xpatience.c +++ /dev/null @@ -1,388 +0,0 @@ -/* - * LibXDiff by Davide Libenzi ( File Differential Library ) - * Copyright (C) 2003-2016 Davide Libenzi, Johannes E. Schindelin - * - * 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" - -/* - * The basic idea of patience diff is to find lines that are unique in - * both files. These are intuitively the ones that we want to see as - * common lines. - * - * The maximal ordered sequence of such line pairs (where ordered means - * that the order in the sequence agrees with the order of the lines in - * both files) naturally defines an initial set of common lines. - * - * Now, the algorithm tries to extend the set of common lines by growing - * the line ranges where the files have identical lines. - * - * Between those common lines, the patience diff algorithm is applied - * recursively, until no unique line pairs can be found; these line ranges - * are handled by the well-known Myers algorithm. - */ - -#define NON_UNIQUE ULONG_MAX - -/* - * This is a hash mapping from line hash to line numbers in the first and - * second file. - */ -struct hashmap { - int nr, alloc; - struct entry { - unsigned long hash; - /* - * 0 = unused entry, 1 = first line, 2 = second, etc. - * line2 is NON_UNIQUE if the line is not unique - * in either the first or the second file. - */ - unsigned long line1, line2; - /* - * "next" & "previous" are used for the longest common - * sequence; - * initially, "next" reflects only the order in file1. - */ - struct entry *next, *previous; - - /* - * If 1, this entry can serve as an anchor. See - * Documentation/diff-options.txt for more information. - */ - unsigned anchor : 1; - } *entries, *first, *last; - /* were common records found? */ - unsigned long has_matches; - mmfile_t *file1, *file2; - xdfenv_t *env; - xpparam_t const *xpp; -}; - -static int is_anchor(xpparam_t const *xpp, const char *line) -{ - int i; - for (i = 0; i < xpp->anchors_nr; i++) { - if (!strncmp(line, xpp->anchors[i], strlen(xpp->anchors[i]))) - return 1; - } - return 0; -} - -/* The argument "pass" is 1 for the first file, 2 for the second. */ -static void insert_record(xpparam_t const *xpp, int line, struct hashmap *map, - int pass) -{ - xrecord_t **records = pass == 1 ? - map->env->xdf1.recs : map->env->xdf2.recs; - xrecord_t *record = records[line - 1], *other; - /* - * After xdl_prepare_env() (or more precisely, due to - * xdl_classify_record()), the "ha" member of the records (AKA lines) - * is _not_ the hash anymore, but a linearized version of it. In - * other words, the "ha" member is guaranteed to start with 0 and - * the second record's ha can only be 0 or 1, etc. - * - * So we multiply ha by 2 in the hope that the hashing was - * "unique enough". - */ - int index = (int)((record->ha << 1) % map->alloc); - - while (map->entries[index].line1) { - other = map->env->xdf1.recs[map->entries[index].line1 - 1]; - if (map->entries[index].hash != record->ha || - !xdl_recmatch(record->ptr, record->size, - other->ptr, other->size, - map->xpp->flags)) { - if (++index >= map->alloc) - index = 0; - continue; - } - if (pass == 2) - map->has_matches = 1; - if (pass == 1 || map->entries[index].line2) - map->entries[index].line2 = NON_UNIQUE; - else - map->entries[index].line2 = line; - return; - } - if (pass == 2) - return; - map->entries[index].line1 = line; - map->entries[index].hash = record->ha; - map->entries[index].anchor = is_anchor(xpp, map->env->xdf1.recs[line - 1]->ptr); - if (!map->first) - map->first = map->entries + index; - if (map->last) { - map->last->next = map->entries + index; - map->entries[index].previous = map->last; - } - map->last = map->entries + index; - map->nr++; -} - -/* - * This function has to be called for each recursion into the inter-hunk - * parts, as previously non-unique lines can become unique when being - * restricted to a smaller part of the files. - * - * It is assumed that env has been prepared using xdl_prepare(). - */ -static int fill_hashmap(mmfile_t *file1, mmfile_t *file2, - xpparam_t const *xpp, xdfenv_t *env, - struct hashmap *result, - int line1, int count1, int line2, int count2) -{ - result->file1 = file1; - result->file2 = file2; - result->xpp = xpp; - result->env = env; - - /* We know exactly how large we want the hash map */ - result->alloc = count1 * 2; - result->entries = (struct entry *) - xdl_malloc(result->alloc * sizeof(struct entry)); - if (!result->entries) - return -1; - memset(result->entries, 0, result->alloc * sizeof(struct entry)); - - /* First, fill with entries from the first file */ - while (count1--) - insert_record(xpp, line1++, result, 1); - - /* Then search for matches in the second file */ - while (count2--) - insert_record(xpp, line2++, result, 2); - - return 0; -} - -/* - * Find the longest sequence with a smaller last element (meaning a smaller - * line2, as we construct the sequence with entries ordered by line1). - */ -static int binary_search(struct entry **sequence, int longest, - struct entry *entry) -{ - int left = -1, right = longest; - - while (left + 1 < right) { - int middle = left + (right - left) / 2; - /* by construction, no two entries can be equal */ - if (sequence[middle]->line2 > entry->line2) - right = middle; - else - left = middle; - } - /* return the index in "sequence", _not_ the sequence length */ - return left; -} - -/* - * The idea is to start with the list of common unique lines sorted by - * the order in file1. For each of these pairs, the longest (partial) - * sequence whose last element's line2 is smaller is determined. - * - * For efficiency, the sequences are kept in a list containing exactly one - * item per sequence length: the sequence with the smallest last - * element (in terms of line2). - */ -static struct entry *find_longest_common_sequence(struct hashmap *map) -{ - struct entry **sequence = xdl_malloc(map->nr * sizeof(struct entry *)); - int longest = 0, i; - struct entry *entry; - - /* - * If not -1, this entry in sequence must never be overridden. - * Therefore, overriding entries before this has no effect, so - * do not do that either. - */ - int anchor_i = -1; - - for (entry = map->first; entry; entry = entry->next) { - if (!entry->line2 || entry->line2 == NON_UNIQUE) - continue; - i = binary_search(sequence, longest, entry); - entry->previous = i < 0 ? NULL : sequence[i]; - ++i; - if (i <= anchor_i) - continue; - sequence[i] = entry; - if (entry->anchor) { - anchor_i = i; - longest = anchor_i + 1; - } else if (i == longest) { - longest++; - } - } - - /* No common unique lines were found */ - if (!longest) { - xdl_free(sequence); - return NULL; - } - - /* Iterate starting at the last element, adjusting the "next" members */ - entry = sequence[longest - 1]; - entry->next = NULL; - while (entry->previous) { - entry->previous->next = entry; - entry = entry->previous; - } - xdl_free(sequence); - return entry; -} - -static int match(struct hashmap *map, int line1, int line2) -{ - xrecord_t *record1 = map->env->xdf1.recs[line1 - 1]; - xrecord_t *record2 = map->env->xdf2.recs[line2 - 1]; - return xdl_recmatch(record1->ptr, record1->size, - record2->ptr, record2->size, map->xpp->flags); -} - -static int patience_diff(mmfile_t *file1, mmfile_t *file2, - xpparam_t const *xpp, xdfenv_t *env, - int line1, int count1, int line2, int count2); - -static int walk_common_sequence(struct hashmap *map, struct entry *first, - int line1, int count1, int line2, int count2) -{ - int end1 = line1 + count1, end2 = line2 + count2; - int next1, next2; - - for (;;) { - /* Try to grow the line ranges of common lines */ - if (first) { - next1 = first->line1; - next2 = first->line2; - while (next1 > line1 && next2 > line2 && - match(map, next1 - 1, next2 - 1)) { - next1--; - next2--; - } - } else { - next1 = end1; - next2 = end2; - } - while (line1 < next1 && line2 < next2 && - match(map, line1, line2)) { - line1++; - line2++; - } - - /* Recurse */ - if (next1 > line1 || next2 > line2) { - struct hashmap submap; - - memset(&submap, 0, sizeof(submap)); - if (patience_diff(map->file1, map->file2, - map->xpp, map->env, - line1, next1 - line1, - line2, next2 - line2)) - return -1; - } - - if (!first) - return 0; - - while (first->next && - first->next->line1 == first->line1 + 1 && - first->next->line2 == first->line2 + 1) - first = first->next; - - line1 = first->line1 + 1; - line2 = first->line2 + 1; - - first = first->next; - } -} - -static int fall_back_to_classic_diff(struct hashmap *map, - int line1, int count1, int line2, int count2) -{ - xpparam_t xpp; - xpp.flags = map->xpp->flags & ~XDF_DIFF_ALGORITHM_MASK; - - return xdl_fall_back_diff(map->env, &xpp, - line1, count1, line2, count2); -} - -/* - * Recursively find the longest common sequence of unique lines, - * and if none was found, ask xdl_do_diff() to do the job. - * - * This function assumes that env was prepared with xdl_prepare_env(). - */ -static int patience_diff(mmfile_t *file1, mmfile_t *file2, - xpparam_t const *xpp, xdfenv_t *env, - int line1, int count1, int line2, int count2) -{ - struct hashmap map; - struct entry *first; - int result = 0; - - /* trivial case: one side is empty */ - if (!count1) { - while(count2--) - env->xdf2.rchg[line2++ - 1] = 1; - return 0; - } else if (!count2) { - while(count1--) - env->xdf1.rchg[line1++ - 1] = 1; - return 0; - } - - memset(&map, 0, sizeof(map)); - if (fill_hashmap(file1, file2, xpp, env, &map, - line1, count1, line2, count2)) - return -1; - - /* are there any matching lines at all? */ - if (!map.has_matches) { - while(count1--) - env->xdf1.rchg[line1++ - 1] = 1; - while(count2--) - env->xdf2.rchg[line2++ - 1] = 1; - xdl_free(map.entries); - return 0; - } - - first = find_longest_common_sequence(&map); - if (first) - result = walk_common_sequence(&map, first, - line1, count1, line2, count2); - else - result = fall_back_to_classic_diff(&map, - line1, count1, line2, count2); - - xdl_free(map.entries); - return result; -} - -int xdl_do_patience_diff(mmfile_t *file1, mmfile_t *file2, - xpparam_t const *xpp, xdfenv_t *env) -{ - if (xdl_prepare_env(file1, file2, xpp, env) < 0) - return -1; - - /* environment is cleaned up in xdl_diff() */ - return patience_diff(file1, file2, xpp, env, - 1, env->xdf1.nrec, 1, env->xdf2.nrec); -} |