Merge branch 'mp/diff-algo-config'

Add diff.algorithm configuration so that the user does not type
"diff --histogram".

* mp/diff-algo-config:
  diff: Introduce --diff-algorithm command line option
  config: Introduce diff.algorithm variable
  git-completion.bash: Autocomplete --minimal and --histogram for git-diff

1 files changed, 34 insertions, 0 deletions

diff --git a/diff.c b/diff.c
index f441f6c7f8..156fec4470 100644
--- a/diff.c
+++ b/diff.c
@@ -36,6 +36,7 @@ static int diff_no_prefix;
 static int diff_stat_graph_width;
 static int diff_dirstat_permille_default = 30;
 static struct diff_options default_diff_options;
+static long diff_algorithm;
 
 static char diff_colors[][COLOR_MAXLEN] = {
 	GIT_COLOR_RESET,
@@ -143,6 +144,21 @@ static int git_config_rename(const char *var, const char *value)
 	return git_config_bool(var,value) ? DIFF_DETECT_RENAME : 0;
 }
 
+long parse_algorithm_value(const char *value)
+{
+	if (!value)
+		return -1;
+	else if (!strcasecmp(value, "myers") || !strcasecmp(value, "default"))
+		return 0;
+	else if (!strcasecmp(value, "minimal"))
+		return XDF_NEED_MINIMAL;
+	else if (!strcasecmp(value, "patience"))
+		return XDF_PATIENCE_DIFF;
+	else if (!strcasecmp(value, "histogram"))
+		return XDF_HISTOGRAM_DIFF;
+	return -1;
+}
+
 /*
  * These are to give UI layer defaults.
  * The core-level commands such as git-diff-files should
@@ -196,6 +212,13 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	if (!strcmp(var, "diff.algorithm")) {
+		diff_algorithm = parse_algorithm_value(value);
+		if (diff_algorithm < 0)
+			return -1;
+		return 0;
+	}
+
 	if (git_color_config(var, value, cb) < 0)
 		return -1;
 
@@ -3163,6 +3186,7 @@ void diff_setup(struct diff_options *options)
 	options->add_remove = diff_addremove;
 	options->use_color = diff_use_color_default;
 	options->detect_rename = diff_detect_rename_default;
+	options->xdl_opts |= diff_algorithm;
 
 	if (diff_no_prefix) {
 		options->a_prefix = options->b_prefix = "";
@@ -3560,6 +3584,16 @@ 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")) {