[PATCH v2 3/3] diff: Introduce --diff-algorithm command line option
Since command line options have higher priority than config file variables and taking previous commit into account, we need a way how to specify myers algorithm on command line. However, inventing `--myers` is not the right answer. We need far more general option, and that is `--diff-algorithm`.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
Documentation/diff-options.txt | 23 +++++++++++++++++++++++
contrib/completion/git-completion.bash | 11 +++++++++++
diff.c | 12 +++++++++++-
diff.h | 2 ++
merge-recursive.c | 9 +++++++++
5 files changed, 56 insertions(+), 1 deletion(-)
Show changes to 5 files +56 −1
Documentation/diff-options.txt, contrib/completion/git-completion.bash, diff.c, diff.h, merge-recursive.c
diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 39f2c50..01b97b3 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -55,6 +55,29 @@ endif::git-format-patch[]
--histogram::
Generate a diff using the "histogram diff" algorithm.
+--diff-algorithm={patience|minimal|histogram|myers}::
+ Choose a diff algorithm. The variants are as follows:
++
+--
+`myers`;;
+ The basic greedy diff algorithm.
+`minimal`;;
+ Spend extra time to make sure the smallest possible diff is
+ produced.
+`patience`;;
+ Use "patience diff" algorithm when generating patches.
+`histogram`;;
+ This algorithm extends the patience algorithm to "support
+ low-occurrence common elements".
+--
++
+For instance, if you configured diff.algorithm variable to a
+non-default value and want to use the default one, then you
+have to use `--diff-algorithm=myers` option.
+
+You should prefer this option over the `--minimal`, `--patience` and
+`--histogram` which are kept just for backwards compatibility.
+
--stat[=<width>[,<name-width>[,<count>]]]::
Generate a diffstat. By default, as much space as necessary
will be used for the filename part, and the rest for the graph
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 33e25dc..d592cf9 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -1021,6 +1021,8 @@ _git_describe ()
__gitcomp_nl "$(__git_refs)"
}
+__git_diff_algorithms="myers minimal patience histogram"
+
__git_diff_common_options="--stat --numstat --shortstat --summary
--patch-with-stat --name-only --name-status --color
--no-color --color-words --no-renames --check
@@ -1035,6 +1037,7 @@ __git_diff_common_options="--stat --numstat --shortstat --summary
--raw
--dirstat --dirstat= --dirstat-by-file
--dirstat-by-file= --cumulative
+ --diff-algorithm=
"
_git_diff ()
@@ -1042,6 +1045,10 @@ _git_diff ()
__git_has_doubledash && return
case "$cur" in
+ --diff-algorithm=*)
+ __gitcomp "$__git_diff_algorithms" "" "${cur##--diff-algorithm=}"
+ return
+ ;;
--*)
__gitcomp "--cached --staged --pickaxe-all --pickaxe-regex
--base --ours --theirs --no-index
@@ -2114,6 +2121,10 @@ _git_show ()
" "" "${cur#*=}"
return
;;
+ --diff-algorithm=*)
+ __gitcomp "$__git_diff_algorithms" "" "${cur##--diff-algorithm=}"
+ return
+ ;;
--*)
__gitcomp "--pretty= --format= --abbrev-commit --oneline
$__git_diff_common_options
diff --git a/diff.c b/diff.c
index e9a7e4d..3e021d5 100644
--- a/diff.c
+++ b/diff.c
@@ -144,7 +144,7 @@ static int git_config_rename(const char *var, const char *value)
return git_config_bool(var,value) ? DIFF_DETECT_RENAME : 0;
}
-static long parse_algorithm_value(const char *value)
+long parse_algorithm_value(const char *value)
{
if (!value || !strcasecmp(value, "myers"))
return 0;
@@ -3633,6 +3633,16 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
else if (!strcmp(arg, "--histogram"))
options->xdl_opts = DIFF_WITH_ALG(options, HISTOGRAM_DIFF);
+ else if (!prefixcmp(arg, "--diff-algorithm=")) {
+ long value = parse_algorithm_value(arg+17);
+ if (value < 0)
+ return error("option diff-algorithm accepts \"myers\", "
+ "\"minimal\", \"patience\" and \"histogram\"");
+ /* clear out previous settings */
+ DIFF_XDL_CLR(options, NEED_MINIMAL);
+ options->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
+ options->xdl_opts |= value;
+ }
/* flags options */
else if (!strcmp(arg, "--binary")) {
diff --git a/diff.h b/diff.h
index a47bae4..54c2590 100644
--- a/diff.h
+++ b/diff.h
@@ -333,6 +333,8 @@ extern struct userdiff_driver *get_textconv(struct diff_filespec *one);
extern int parse_rename_score(const char **cp_p);
+extern long parse_algorithm_value(const char *value);
+
extern int print_stat_summary(FILE *fp, int files,
int insertions, int deletions);
extern void setup_diff_pager(struct diff_options *);
diff --git a/merge-recursive.c b/merge-recursive.c
index 33ba5dc..ea9dbd3 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -2068,6 +2068,15 @@ int parse_merge_opt(struct merge_options *o, const char *s)
o->xdl_opts = DIFF_WITH_ALG(o, PATIENCE_DIFF);
else if (!strcmp(s, "histogram"))
o->xdl_opts = DIFF_WITH_ALG(o, HISTOGRAM_DIFF);
+ else if (!strcmp(s, "diff-algorithm=")) {
+ long value = parse_algorithm_value(s+15);
+ if (value < 0)
+ return -1;
+ /* clear out previous settings */
+ DIFF_XDL_CLR(o, NEED_MINIMAL);
+ o->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
+ o->xdl_opts |= value;
+ }
else if (!strcmp(s, "ignore-space-change"))
o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
else if (!strcmp(s, "ignore-all-space"))
--
1.8.0.2
Michal Privoznik
