git/xdiff/xdiff.h
Phillip Wood 4496526f80 xdiff: implement a zealous diff3, or "zdiff3"
"zdiff3" is identical to ordinary diff3 except that it allows compaction
of common lines on the two sides of history at the beginning or end of
the conflict hunk.  For example, the following diff3 conflict:

    1
    2
    3
    4
    <<<<<<
    A
    B
    C
    D
    E
    ||||||
    5
    6
    ======
    A
    X
    C
    Y
    E
    >>>>>>
    7
    8
    9

has common lines 'A', 'C', and 'E' on the two sides.  With zdiff3, one
would instead get the following conflict:

    1
    2
    3
    4
    A
    <<<<<<
    B
    C
    D
    ||||||
    5
    6
    ======
    X
    C
    Y
    >>>>>>
    E
    7
    8
    9

Note that the common lines, 'A', and 'E' were moved outside the
conflict.  Unlike with the two-way conflicts from the 'merge'
conflictStyle, the zdiff3 conflict is NOT split into multiple conflict
regions to allow the common 'C' lines to be shown outside a conflict,
because zdiff3 shows the base version too and the base version cannot be
reasonably split.

Note also that the removing of lines common to the two sides might make
the remaining text inside the conflict region match the base text inside
the conflict region (for example, if the diff3 conflict had '5 6 E' on
the right side of the conflict, then the common line 'E' would be moved
outside and both the base and right side's remaining conflict text would
be the lines '5' and '6').  This has the potential to surprise users and
make them think there should not have been a conflict, but there
definitely was a conflict and it should remain.

Based-on-patch-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Co-authored-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Phillip Wood <phillip.wood123@gmail.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-01 14:45:58 -08:00

153 lines
3.9 KiB
C

/*
* 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>
*
*/
#if !defined(XDIFF_H)
#define XDIFF_H
#ifdef __cplusplus
extern "C" {
#endif /* #ifdef __cplusplus */
/* xpparm_t.flags */
#define XDF_NEED_MINIMAL (1 << 0)
#define XDF_IGNORE_WHITESPACE (1 << 1)
#define XDF_IGNORE_WHITESPACE_CHANGE (1 << 2)
#define XDF_IGNORE_WHITESPACE_AT_EOL (1 << 3)
#define XDF_IGNORE_CR_AT_EOL (1 << 4)
#define XDF_WHITESPACE_FLAGS (XDF_IGNORE_WHITESPACE | \
XDF_IGNORE_WHITESPACE_CHANGE | \
XDF_IGNORE_WHITESPACE_AT_EOL | \
XDF_IGNORE_CR_AT_EOL)
#define XDF_IGNORE_BLANK_LINES (1 << 7)
#define XDF_PATIENCE_DIFF (1 << 14)
#define XDF_HISTOGRAM_DIFF (1 << 15)
#define XDF_DIFF_ALGORITHM_MASK (XDF_PATIENCE_DIFF | XDF_HISTOGRAM_DIFF)
#define XDF_DIFF_ALG(x) ((x) & XDF_DIFF_ALGORITHM_MASK)
#define XDF_INDENT_HEURISTIC (1 << 23)
/* xdemitconf_t.flags */
#define XDL_EMIT_FUNCNAMES (1 << 0)
#define XDL_EMIT_NO_HUNK_HDR (1 << 1)
#define XDL_EMIT_FUNCCONTEXT (1 << 2)
/* merge simplification levels */
#define XDL_MERGE_MINIMAL 0
#define XDL_MERGE_EAGER 1
#define XDL_MERGE_ZEALOUS 2
#define XDL_MERGE_ZEALOUS_ALNUM 3
/* merge favor modes */
#define XDL_MERGE_FAVOR_OURS 1
#define XDL_MERGE_FAVOR_THEIRS 2
#define XDL_MERGE_FAVOR_UNION 3
/* merge output styles */
#define XDL_MERGE_DIFF3 1
#define XDL_MERGE_ZEALOUS_DIFF3 2
typedef struct s_mmfile {
char *ptr;
long size;
} mmfile_t;
typedef struct s_mmbuffer {
char *ptr;
long size;
} mmbuffer_t;
typedef struct s_xpparam {
unsigned long flags;
/* -I<regex> */
regex_t **ignore_regex;
size_t ignore_regex_nr;
/* See Documentation/diff-options.txt. */
char **anchors;
size_t anchors_nr;
} xpparam_t;
typedef struct s_xdemitcb {
void *priv;
int (*out_hunk)(void *,
long old_begin, long old_nr,
long new_begin, long new_nr,
const char *func, long funclen);
int (*out_line)(void *, mmbuffer_t *, int);
} xdemitcb_t;
typedef long (*find_func_t)(const char *line, long line_len, char *buffer, long buffer_size, void *priv);
typedef int (*xdl_emit_hunk_consume_func_t)(long start_a, long count_a,
long start_b, long count_b,
void *cb_data);
typedef struct s_xdemitconf {
long ctxlen;
long interhunkctxlen;
unsigned long flags;
find_func_t find_func;
void *find_func_priv;
xdl_emit_hunk_consume_func_t hunk_func;
} xdemitconf_t;
typedef struct s_bdiffparam {
long bsize;
} bdiffparam_t;
#define xdl_malloc(x) xmalloc(x)
#define xdl_free(ptr) free(ptr)
#define xdl_realloc(ptr,x) xrealloc(ptr,x)
void *xdl_mmfile_first(mmfile_t *mmf, long *size);
long xdl_mmfile_size(mmfile_t *mmf);
int xdl_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
xdemitconf_t const *xecfg, xdemitcb_t *ecb);
typedef struct s_xmparam {
xpparam_t xpp;
int marker_size;
int level;
int favor;
int style;
const char *ancestor; /* label for orig */
const char *file1; /* label for mf1 */
const char *file2; /* label for mf2 */
} xmparam_t;
#define DEFAULT_CONFLICT_MARKER_SIZE 7
int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
xmparam_t const *xmp, mmbuffer_t *result);
#ifdef __cplusplus
}
#endif /* #ifdef __cplusplus */
#endif /* #if !defined(XDIFF_H) */