diff options
Diffstat (limited to 'src/libgit2/xdiff/xmerge.c')
| -rw-r--r-- | src/libgit2/xdiff/xmerge.c | 750 |
1 files changed, 750 insertions, 0 deletions
diff --git a/src/libgit2/xdiff/xmerge.c b/src/libgit2/xdiff/xmerge.c new file mode 100644 index 000000000..278cbe124 --- /dev/null +++ b/src/libgit2/xdiff/xmerge.c @@ -0,0 +1,750 @@ +/* + * LibXDiff by Davide Libenzi ( File Differential Library ) + * Copyright (C) 2003-2006 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" + +typedef struct s_xdmerge { + struct s_xdmerge *next; + /* + * 0 = conflict, + * 1 = no conflict, take first, + * 2 = no conflict, take second. + * 3 = no conflict, take both. + */ + int mode; + /* + * These point at the respective postimages. E.g. <i1,chg1> is + * how side #1 wants to change the common ancestor; if there is no + * overlap, lines before i1 in the postimage of side #1 appear + * in the merge result as a region touched by neither side. + */ + long i1, i2; + long chg1, chg2; + /* + * These point at the preimage; of course there is just one + * preimage, that is from the shared common ancestor. + */ + long i0; + long chg0; +} xdmerge_t; + +static int xdl_append_merge(xdmerge_t **merge, int mode, + long i0, long chg0, + long i1, long chg1, + long i2, long chg2) +{ + xdmerge_t *m = *merge; + if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) { + if (mode != m->mode) + m->mode = 0; + m->chg0 = i0 + chg0 - m->i0; + m->chg1 = i1 + chg1 - m->i1; + m->chg2 = i2 + chg2 - m->i2; + } else { + m = xdl_malloc(sizeof(xdmerge_t)); + if (!m) + return -1; + m->next = NULL; + m->mode = mode; + m->i0 = i0; + m->chg0 = chg0; + m->i1 = i1; + m->chg1 = chg1; + m->i2 = i2; + m->chg2 = chg2; + if (*merge) + (*merge)->next = m; + *merge = m; + } + return 0; +} + +static int xdl_cleanup_merge(xdmerge_t *c) +{ + int count = 0; + xdmerge_t *next_c; + + /* were there conflicts? */ + for (; c; c = next_c) { + if (c->mode == 0) + count++; + next_c = c->next; + free(c); + } + return count; +} + +static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2, + int line_count, long flags) +{ + int i; + xrecord_t **rec1 = xe1->xdf2.recs + i1; + xrecord_t **rec2 = xe2->xdf2.recs + i2; + + for (i = 0; i < line_count; i++) { + int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size, + rec2[i]->ptr, rec2[i]->size, flags); + if (!result) + return -1; + } + return 0; +} + +static int xdl_recs_copy_0(size_t *out, int use_orig, xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest) +{ + xrecord_t **recs; + size_t size = 0; + + *out = 0; + + recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i; + + if (count < 1) + return 0; + + for (i = 0; i < count; ) { + if (dest) + memcpy(dest + size, recs[i]->ptr, recs[i]->size); + + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, recs[i++]->size); + } + + if (add_nl) { + i = recs[count - 1]->size; + if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') { + if (needs_cr) { + if (dest) + dest[size] = '\r'; + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, 1); + } + + if (dest) + dest[size] = '\n'; + + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, 1); + } + } + + *out = size; + return 0; +} + +static int xdl_recs_copy(size_t *out, xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest) +{ + return xdl_recs_copy_0(out, 0, xe, i, count, needs_cr, add_nl, dest); +} + +static int xdl_orig_copy(size_t *out, xdfenv_t *xe, int i, int count, int needs_cr, int add_nl, char *dest) +{ + return xdl_recs_copy_0(out, 1, xe, i, count, needs_cr, add_nl, dest); +} + +/* + * Returns 1 if the i'th line ends in CR/LF (if it is the last line and + * has no eol, the preceding line, if any), 0 if it ends in LF-only, and + * -1 if the line ending cannot be determined. + */ +static int is_eol_crlf(xdfile_t *file, int i) +{ + long size; + + if (i < file->nrec - 1) + /* All lines before the last *must* end in LF */ + return (size = file->recs[i]->size) > 1 && + file->recs[i]->ptr[size - 2] == '\r'; + if (!file->nrec) + /* Cannot determine eol style from empty file */ + return -1; + if ((size = file->recs[i]->size) && + file->recs[i]->ptr[size - 1] == '\n') + /* Last line; ends in LF; Is it CR/LF? */ + return size > 1 && + file->recs[i]->ptr[size - 2] == '\r'; + if (!i) + /* The only line has no eol */ + return -1; + /* Determine eol from second-to-last line */ + return (size = file->recs[i - 1]->size) > 1 && + file->recs[i - 1]->ptr[size - 2] == '\r'; +} + +static int is_cr_needed(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m) +{ + int needs_cr; + + /* Match post-images' preceding, or first, lines' end-of-line style */ + needs_cr = is_eol_crlf(&xe1->xdf2, m->i1 ? m->i1 - 1 : 0); + if (needs_cr) + needs_cr = is_eol_crlf(&xe2->xdf2, m->i2 ? m->i2 - 1 : 0); + /* Look at pre-image's first line, unless we already settled on LF */ + if (needs_cr) + needs_cr = is_eol_crlf(&xe1->xdf1, 0); + /* If still undecided, use LF-only */ + return needs_cr < 0 ? 0 : needs_cr; +} + +static int fill_conflict_hunk(size_t *out, xdfenv_t *xe1, const char *name1, + xdfenv_t *xe2, const char *name2, + const char *name3, + size_t size, int i, int style, + xdmerge_t *m, char *dest, int marker_size) +{ + int marker1_size = (name1 ? (int)strlen(name1) + 1 : 0); + int marker2_size = (name2 ? (int)strlen(name2) + 1 : 0); + int marker3_size = (name3 ? (int)strlen(name3) + 1 : 0); + int needs_cr = is_cr_needed(xe1, xe2, m); + size_t copied; + + *out = 0; + + if (marker_size <= 0) + marker_size = DEFAULT_CONFLICT_MARKER_SIZE; + + /* Before conflicting part */ + if (xdl_recs_copy(&copied, xe1, i, m->i1 - i, 0, 0, + dest ? dest + size : NULL) < 0) + return -1; + + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied); + + if (!dest) { + GIT_ERROR_CHECK_ALLOC_ADD5(&size, size, marker_size, 1, needs_cr, marker1_size); + } else { + memset(dest + size, '<', marker_size); + size += marker_size; + if (marker1_size) { + dest[size] = ' '; + memcpy(dest + size + 1, name1, marker1_size - 1); + size += marker1_size; + } + if (needs_cr) + dest[size++] = '\r'; + dest[size++] = '\n'; + } + + /* Postimage from side #1 */ + if (xdl_recs_copy(&copied, xe1, m->i1, m->chg1, needs_cr, 1, + dest ? dest + size : NULL) < 0) + return -1; + + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied); + + if (style == XDL_MERGE_DIFF3) { + /* Shared preimage */ + if (!dest) { + GIT_ERROR_CHECK_ALLOC_ADD5(&size, size, marker_size, 1, needs_cr, marker3_size); + } else { + memset(dest + size, '|', marker_size); + size += marker_size; + if (marker3_size) { + dest[size] = ' '; + memcpy(dest + size + 1, name3, marker3_size - 1); + size += marker3_size; + } + if (needs_cr) + dest[size++] = '\r'; + dest[size++] = '\n'; + } + + if (xdl_orig_copy(&copied, xe1, m->i0, m->chg0, needs_cr, 1, + dest ? dest + size : NULL) < 0) + return -1; + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied); + } + + if (!dest) { + GIT_ERROR_CHECK_ALLOC_ADD4(&size, size, marker_size, 1, needs_cr); + } else { + memset(dest + size, '=', marker_size); + size += marker_size; + if (needs_cr) + dest[size++] = '\r'; + dest[size++] = '\n'; + } + + /* Postimage from side #2 */ + + if (xdl_recs_copy(&copied, xe2, m->i2, m->chg2, needs_cr, 1, + dest ? dest + size : NULL) < 0) + return -1; + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied); + + if (!dest) { + GIT_ERROR_CHECK_ALLOC_ADD5(&size, size, marker_size, 1, needs_cr, marker2_size); + } else { + memset(dest + size, '>', marker_size); + size += marker_size; + if (marker2_size) { + dest[size] = ' '; + memcpy(dest + size + 1, name2, marker2_size - 1); + size += marker2_size; + } + if (needs_cr) + dest[size++] = '\r'; + dest[size++] = '\n'; + } + + *out = size; + return 0; +} + +static int xdl_fill_merge_buffer(size_t *out, + xdfenv_t *xe1, const char *name1, + xdfenv_t *xe2, const char *name2, + const char *ancestor_name, + int favor, + xdmerge_t *m, char *dest, int style, + int marker_size) +{ + size_t size, copied; + int i; + + *out = 0; + + for (size = i = 0; m; m = m->next) { + if (favor && !m->mode) + m->mode = favor; + + if (m->mode == 0) { + if (fill_conflict_hunk(&size, xe1, name1, xe2, name2, + ancestor_name, + size, i, style, m, dest, + marker_size) < 0) + return -1; + } + else if (m->mode & 3) { + /* Before conflicting part */ + if (xdl_recs_copy(&copied, xe1, i, m->i1 - i, 0, 0, + dest ? dest + size : NULL) < 0) + return -1; + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied); + + /* Postimage from side #1 */ + if (m->mode & 1) { + int needs_cr = is_cr_needed(xe1, xe2, m); + + if (xdl_recs_copy(&copied, xe1, m->i1, m->chg1, needs_cr, (m->mode & 2), + dest ? dest + size : NULL) < 0) + return -1; + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied); + } + + /* Postimage from side #2 */ + if (m->mode & 2) { + if (xdl_recs_copy(&copied, xe2, m->i2, m->chg2, 0, 0, + dest ? dest + size : NULL) < 0) + return -1; + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied); + } + } else + continue; + i = m->i1 + m->chg1; + } + + if (xdl_recs_copy(&copied, xe1, i, xe1->xdf2.nrec - i, 0, 0, + dest ? dest + size : NULL) < 0) + return -1; + GIT_ERROR_CHECK_ALLOC_ADD(&size, size, copied); + + *out = size; + return 0; +} + +/* + * Sometimes, changes are not quite identical, but differ in only a few + * lines. Try hard to show only these few lines as conflicting. + */ +static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m, + xpparam_t const *xpp) +{ + for (; m; m = m->next) { + mmfile_t t1, t2; + xdfenv_t xe; + xdchange_t *xscr, *x; + int i1 = m->i1, i2 = m->i2; + + /* let's handle just the conflicts */ + if (m->mode) + continue; + + /* no sense refining a conflict when one side is empty */ + if (m->chg1 == 0 || m->chg2 == 0) + continue; + + /* + * This probably does not work outside git, since + * we have a very simple mmfile structure. + */ + t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr; + t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr + + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr; + t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr; + t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr + + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr; + if (xdl_do_diff(&t1, &t2, 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 this happens, the changes are identical. */ + xdl_free_env(&xe); + m->mode = 4; + continue; + } + x = xscr; + m->i1 = xscr->i1 + i1; + m->chg1 = xscr->chg1; + m->i2 = xscr->i2 + i2; + m->chg2 = xscr->chg2; + while (xscr->next) { + xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t)); + if (!m2) { + xdl_free_env(&xe); + xdl_free_script(x); + return -1; + } + xscr = xscr->next; + m2->next = m->next; + m->next = m2; + m = m2; + m->mode = 0; + m->i1 = xscr->i1 + i1; + m->chg1 = xscr->chg1; + m->i2 = xscr->i2 + i2; + m->chg2 = xscr->chg2; + } + xdl_free_env(&xe); + xdl_free_script(x); + } + return 0; +} + +static int line_contains_alnum(const char *ptr, long size) +{ + while (size--) + if (isalnum((unsigned char)*(ptr++))) + return 1; + return 0; +} + +static int lines_contain_alnum(xdfenv_t *xe, int i, int chg) +{ + for (; chg; chg--, i++) + if (line_contains_alnum(xe->xdf2.recs[i]->ptr, + xe->xdf2.recs[i]->size)) + return 1; + return 0; +} + +/* + * This function merges m and m->next, marking everything between those hunks + * as conflicting, too. + */ +static void xdl_merge_two_conflicts(xdmerge_t *m) +{ + xdmerge_t *next_m = m->next; + m->chg1 = next_m->i1 + next_m->chg1 - m->i1; + m->chg2 = next_m->i2 + next_m->chg2 - m->i2; + m->next = next_m->next; + free(next_m); +} + +/* + * If there are less than 3 non-conflicting lines between conflicts, + * it appears simpler -- because it takes up less (or as many) lines -- + * if the lines are moved into the conflicts. + */ +static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m, + int simplify_if_no_alnum) +{ + int result = 0; + + if (!m) + return result; + for (;;) { + xdmerge_t *next_m = m->next; + int begin, end; + + if (!next_m) + return result; + + begin = m->i1 + m->chg1; + end = next_m->i1; + + if (m->mode != 0 || next_m->mode != 0 || + (end - begin > 3 && + (!simplify_if_no_alnum || + lines_contain_alnum(xe1, begin, end - begin)))) { + m = next_m; + } else { + result++; + xdl_merge_two_conflicts(m); + } + } +} + +/* + * level == 0: mark all overlapping changes as conflict + * level == 1: mark overlapping changes as conflict only if not identical + * level == 2: analyze non-identical changes for minimal conflict set + * level == 3: analyze non-identical changes for minimal conflict set, but + * treat hunks not containing any letter or number as conflicting + * + * returns < 0 on error, == 0 for no conflicts, else number of conflicts + */ +static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, + xdfenv_t *xe2, xdchange_t *xscr2, + xmparam_t const *xmp, mmbuffer_t *result) +{ + xdmerge_t *changes, *c; + xpparam_t const *xpp = &xmp->xpp; + const char *const ancestor_name = xmp->ancestor; + const char *const name1 = xmp->file1; + const char *const name2 = xmp->file2; + int i0, i1, i2, chg0, chg1, chg2; + int level = xmp->level; + int style = xmp->style; + int favor = xmp->favor; + + if (style == XDL_MERGE_DIFF3) { + /* + * "diff3 -m" output does not make sense for anything + * more aggressive than XDL_MERGE_EAGER. + */ + if (XDL_MERGE_EAGER < level) + level = XDL_MERGE_EAGER; + } + + c = changes = NULL; + + while (xscr1 && xscr2) { + if (!changes) + changes = c; + if (xscr1->i1 + xscr1->chg1 < xscr2->i1) { + i0 = xscr1->i1; + i1 = xscr1->i2; + i2 = xscr2->i2 - xscr2->i1 + xscr1->i1; + chg0 = xscr1->chg1; + chg1 = xscr1->chg2; + chg2 = xscr1->chg1; + if (xdl_append_merge(&c, 1, + i0, chg0, i1, chg1, i2, chg2)) { + xdl_cleanup_merge(changes); + return -1; + } + xscr1 = xscr1->next; + continue; + } + if (xscr2->i1 + xscr2->chg1 < xscr1->i1) { + i0 = xscr2->i1; + i1 = xscr1->i2 - xscr1->i1 + xscr2->i1; + i2 = xscr2->i2; + chg0 = xscr2->chg1; + chg1 = xscr2->chg1; + chg2 = xscr2->chg2; + if (xdl_append_merge(&c, 2, + i0, chg0, i1, chg1, i2, chg2)) { + xdl_cleanup_merge(changes); + return -1; + } + xscr2 = xscr2->next; + continue; + } + if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 || + xscr1->chg1 != xscr2->chg1 || + xscr1->chg2 != xscr2->chg2 || + xdl_merge_cmp_lines(xe1, xscr1->i2, + xe2, xscr2->i2, + xscr1->chg2, xpp->flags)) { + /* conflict */ + int off = xscr1->i1 - xscr2->i1; + int ffo = off + xscr1->chg1 - xscr2->chg1; + + i0 = xscr1->i1; + i1 = xscr1->i2; + i2 = xscr2->i2; + if (off > 0) { + i0 -= off; + i1 -= off; + } + else + i2 += off; + chg0 = xscr1->i1 + xscr1->chg1 - i0; + chg1 = xscr1->i2 + xscr1->chg2 - i1; + chg2 = xscr2->i2 + xscr2->chg2 - i2; + if (ffo < 0) { + chg0 -= ffo; + chg1 -= ffo; + } else + chg2 += ffo; + if (xdl_append_merge(&c, 0, + i0, chg0, i1, chg1, i2, chg2)) { + xdl_cleanup_merge(changes); + return -1; + } + } + + i1 = xscr1->i1 + xscr1->chg1; + i2 = xscr2->i1 + xscr2->chg1; + + if (i1 >= i2) + xscr2 = xscr2->next; + if (i2 >= i1) + xscr1 = xscr1->next; + } + while (xscr1) { + if (!changes) + changes = c; + i0 = xscr1->i1; + i1 = xscr1->i2; + i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec; + chg0 = xscr1->chg1; + chg1 = xscr1->chg2; + chg2 = xscr1->chg1; + if (xdl_append_merge(&c, 1, + i0, chg0, i1, chg1, i2, chg2)) { + xdl_cleanup_merge(changes); + return -1; + } + xscr1 = xscr1->next; + } + while (xscr2) { + if (!changes) + changes = c; + i0 = xscr2->i1; + i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec; + i2 = xscr2->i2; + chg0 = xscr2->chg1; + chg1 = xscr2->chg1; + chg2 = xscr2->chg2; + if (xdl_append_merge(&c, 2, + i0, chg0, i1, chg1, i2, chg2)) { + xdl_cleanup_merge(changes); + return -1; + } + xscr2 = xscr2->next; + } + if (!changes) + changes = c; + /* refine conflicts */ + if (XDL_MERGE_ZEALOUS <= level && + (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 || + xdl_simplify_non_conflicts(xe1, changes, + XDL_MERGE_ZEALOUS < level) < 0)) { + xdl_cleanup_merge(changes); + return -1; + } + /* output */ + if (result) { + int marker_size = xmp->marker_size; + size_t size; + + if (xdl_fill_merge_buffer(&size, xe1, name1, xe2, name2, + ancestor_name, + favor, changes, NULL, style, + marker_size) < 0) + return -1; + + result->ptr = xdl_malloc(size); + if (!result->ptr) { + xdl_cleanup_merge(changes); + return -1; + } + result->size = size; + if (xdl_fill_merge_buffer(&size, xe1, name1, xe2, name2, + ancestor_name, favor, changes, + result->ptr, style, marker_size) < 0) + return -1; + } + return xdl_cleanup_merge(changes); +} + +int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2, + xmparam_t const *xmp, mmbuffer_t *result) +{ + xdchange_t *xscr1, *xscr2; + xdfenv_t xe1, xe2; + int status; + xpparam_t const *xpp = &xmp->xpp; + + result->ptr = NULL; + result->size = 0; + + if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0) { + return -1; + } + if (xdl_do_diff(orig, mf2, xpp, &xe2) < 0) { + xdl_free_env(&xe1); + return -1; + } + if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 || + xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 || + xdl_build_script(&xe1, &xscr1) < 0) { + xdl_free_env(&xe1); + return -1; + } + if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 || + xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 || + xdl_build_script(&xe2, &xscr2) < 0) { + xdl_free_script(xscr1); + xdl_free_env(&xe1); + xdl_free_env(&xe2); + return -1; + } + status = 0; + if (!xscr1) { + result->ptr = xdl_malloc(mf2->size); + if (!result->ptr) { + xdl_free_script(xscr2); + xdl_free_env(&xe1); + xdl_free_env(&xe2); + return -1; + } + memcpy(result->ptr, mf2->ptr, mf2->size); + result->size = mf2->size; + } else if (!xscr2) { + result->ptr = xdl_malloc(mf1->size); + if (!result->ptr) { + xdl_free_script(xscr1); + xdl_free_env(&xe1); + xdl_free_env(&xe2); + return -1; + } + memcpy(result->ptr, mf1->ptr, mf1->size); + result->size = mf1->size; + } else { + status = xdl_do_merge(&xe1, xscr1, + &xe2, xscr2, + xmp, result); + } + xdl_free_script(xscr1); + xdl_free_script(xscr2); + + xdl_free_env(&xe1); + xdl_free_env(&xe2); + + return status; +} |