log: add log.excludeDecoration config option

In 'git log', the --decorate-refs-exclude option appends a pattern
to a string_list. This list is used to prevent showing some refs
in the decoration output, or even by --simplify-by-decoration.

Users may want to use their refs space to store utility refs that
should not appear in the decoration output. For example, Scalar [1]
runs a background fetch but places the "new" refs inside the
refs/scalar/hidden/<remote>/* refspace instead of refs/<remote>/*
to avoid updating remote refs when the user is not looking. However,
these "hidden" refs appear during regular 'git log' queries.

A similar idea to use "hidden" refs is under consideration for core
Git [2].

Add the 'log.excludeDecoration' config option so users can exclude
some refs from decorations by default instead of needing to use
--decorate-refs-exclude manually. The config value is multi-valued
much like the command-line option. The documentation is careful to
point out that the config value can be overridden by the
--decorate-refs option, even though --decorate-refs-exclude would
always "win" over --decorate-refs.

Since the 'log.excludeDecoration' takes lower precedence to
--decorate-refs, and --decorate-refs-exclude takes higher
precedence, the struct decoration_filter needed another field.
This led also to new logic in load_ref_decorations() and
ref_filter_match().

There are several tests in t4202-log.sh that test the
--decorate-refs-(include|exclude) options, so these are extended.
Since the expected output is already stored as a file, most tests
could simply replace a "--decorate-refs-exclude" option with an
in-line config setting. Other tests involve the precedence of
the config option compared to command-line options and needed more
modification.

[1] https://github.com/microsoft/scalar
[2] https://lore.kernel.org/git/77b1da5d3063a2404cd750adfe3bb8be9b6c497d.1585946894.git.gitgitgadget@gmail.com/

Helped-by: Junio C Hamano <gister@pobox.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 15 insertions, 7 deletions

diff --git a/log-tree.c b/log-tree.c
index fa6af69da3..1cfd345861 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -103,6 +103,8 @@ static int ref_filter_match(const char *refname,
 	struct string_list_item *item;
 	const struct string_list *exclude_patterns = filter->exclude_ref_pattern;
 	const struct string_list *include_patterns = filter->include_ref_pattern;
+	const struct string_list *exclude_patterns_config =
+				filter->exclude_ref_config_pattern;
 
 	if (exclude_patterns && exclude_patterns->nr) {
 		for_each_string_list_item(item, exclude_patterns) {
@@ -112,17 +114,20 @@ static int ref_filter_match(const char *refname,
 	}
 
 	if (include_patterns && include_patterns->nr) {
-		int found = 0;
 		for_each_string_list_item(item, include_patterns) {
-			if (match_ref_pattern(refname, item)) {
-				found = 1;
-				break;
-			}
+			if (match_ref_pattern(refname, item))
+				return 1;
 		}
+		return 0;
+	}
 
-		if (!found)
-			return 0;
+	if (exclude_patterns_config && exclude_patterns_config->nr) {
+		for_each_string_list_item(item, exclude_patterns_config) {
+			if (match_ref_pattern(refname, item))
+				return 0;
+		}
 	}
+
 	return 1;
 }
 
@@ -198,6 +203,9 @@ void load_ref_decorations(struct decoration_filter *filter, int flags)
 			for_each_string_list_item(item, filter->include_ref_pattern) {
 				normalize_glob_ref(item, NULL, item->string);
 			}
+			for_each_string_list_item(item, filter->exclude_ref_config_pattern) {
+				normalize_glob_ref(item, NULL, item->string);
+			}
 		}
 		decoration_loaded = 1;
 		decoration_flags = flags;