Merge branch 'mh/diff-indent-heuristic'

Output from "git diff" can be made easier to read by selecting
which lines are common and which lines are added/deleted
intelligently when the lines before and after the changed section
are the same.  A command line option is added to help with the
experiment to find a good heuristics.

* mh/diff-indent-heuristic:
  blame: honor the diff heuristic options and config
  parse-options: add parse_opt_unknown_cb()
  diff: improve positioning of add/delete blocks in diffs
  xdl_change_compact(): introduce the concept of a change group
  recs_match(): take two xrecord_t pointers as arguments
  is_blank_line(): take a single xrecord_t as argument
  xdl_change_compact(): only use heuristic if group can't be matched
  xdl_change_compact(): fix compaction heuristic to adjust ixo

1 files changed, 29 insertions, 7 deletions

diff --git a/diff.c b/diff.c
index c6da383c56..dc5ab8b4fb 100644
--- a/diff.c
+++ b/diff.c
@@ -27,6 +27,7 @@
 #endif
 
 static int diff_detect_rename_default;
+static int diff_indent_heuristic; /* experimental */
 static int diff_compaction_heuristic; /* experimental */
 static int diff_rename_limit_default = 400;
 static int diff_suppress_blank_empty;
@@ -177,6 +178,21 @@ void init_diff_ui_defaults(void)
 	diff_detect_rename_default = 1;
 }
 
+int git_diff_heuristic_config(const char *var, const char *value, void *cb)
+{
+	if (!strcmp(var, "diff.indentheuristic")) {
+		diff_indent_heuristic = git_config_bool(var, value);
+		if (diff_indent_heuristic)
+			diff_compaction_heuristic = 0;
+	}
+	if (!strcmp(var, "diff.compactionheuristic")) {
+		diff_compaction_heuristic = git_config_bool(var, value);
+		if (diff_compaction_heuristic)
+			diff_indent_heuristic = 0;
+	}
+	return 0;
+}
+
 int git_diff_ui_config(const char *var, const char *value, void *cb)
 {
 	if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
@@ -193,10 +209,6 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 		diff_detect_rename_default = git_config_rename(var, value);
 		return 0;
 	}
-	if (!strcmp(var, "diff.compactionheuristic")) {
-		diff_compaction_heuristic = git_config_bool(var, value);
-		return 0;
-	}
 	if (!strcmp(var, "diff.autorefreshindex")) {
 		diff_auto_refresh_index = git_config_bool(var, value);
 		return 0;
@@ -237,6 +249,8 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	if (git_diff_heuristic_config(var, value, cb) < 0)
+		return -1;
 	if (git_color_config(var, value, cb) < 0)
 		return -1;
 
@@ -3296,7 +3310,9 @@ void diff_setup(struct diff_options *options)
 	options->use_color = diff_use_color_default;
 	options->detect_rename = diff_detect_rename_default;
 	options->xdl_opts |= diff_algorithm;
-	if (diff_compaction_heuristic)
+	if (diff_indent_heuristic)
+		DIFF_XDL_SET(options, INDENT_HEURISTIC);
+	else if (diff_compaction_heuristic)
 		DIFF_XDL_SET(options, COMPACTION_HEURISTIC);
 
 	options->orderfile = diff_order_file_cfg;
@@ -3818,9 +3834,15 @@ int diff_opt_parse(struct diff_options *options,
 		DIFF_XDL_SET(options, IGNORE_WHITESPACE_AT_EOL);
 	else if (!strcmp(arg, "--ignore-blank-lines"))
 		DIFF_XDL_SET(options, IGNORE_BLANK_LINES);
-	else if (!strcmp(arg, "--compaction-heuristic"))
+	else if (!strcmp(arg, "--indent-heuristic")) {
+		DIFF_XDL_SET(options, INDENT_HEURISTIC);
+		DIFF_XDL_CLR(options, COMPACTION_HEURISTIC);
+	} else if (!strcmp(arg, "--no-indent-heuristic"))
+		DIFF_XDL_CLR(options, INDENT_HEURISTIC);
+	else if (!strcmp(arg, "--compaction-heuristic")) {
 		DIFF_XDL_SET(options, COMPACTION_HEURISTIC);
-	else if (!strcmp(arg, "--no-compaction-heuristic"))
+		DIFF_XDL_CLR(options, INDENT_HEURISTIC);
+	} else if (!strcmp(arg, "--no-compaction-heuristic"))
 		DIFF_XDL_CLR(options, COMPACTION_HEURISTIC);
 	else if (!strcmp(arg, "--patience"))
 		options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);