log: add option to choose which refs to decorate

When `log --decorate` is used, git will decorate commits with all
available refs. While in most cases this may give the desired effect,
under some conditions it can lead to excessively verbose output.

Introduce two command line options, `--decorate-refs=<pattern>` and
`--decorate-refs-exclude=<pattern>` to allow the user to select which
refs are used in decoration.

When "--decorate-refs=<pattern>" is given, only the refs that match the
pattern are used in decoration. The refs that match the pattern when
"--decorate-refs-exclude=<pattern>" is given, are never used in
decoration.

These options follow the same convention for mixing negative and
positive patterns across the system, assuming that the inclusive default
is to match all refs available.

 (1) if there is no positive pattern given, pretend as if an
     inclusive default positive pattern was given;

 (2) for each candidate, reject it if it matches no positive
     pattern, or if it matches any one of the negative patterns.

The rules for what is considered a match are slightly different from the
rules used elsewhere.

Commands like `log --glob` assume a trailing '/*' when glob chars are
not present in the pattern. This makes it difficult to specify a single
ref.  On the other hand, commands like `describe --match --all` allow
specifying exact refs, but do not have the convenience of allowing
"shorthand refs" like 'refs/heads' or 'heads' to refer to
'refs/heads/*'.

The commands introduced in this patch consider a match if:

  (a) the pattern contains globs chars,
	and regular pattern matching returns a match.

  (b) the pattern does not contain glob chars,
         and ref '<pattern>' exists, or if ref exists under '<pattern>/'

This allows both behaviours (allowing single refs and shorthand refs)
yet remaining compatible with existent commands.

Helped-by: Kevin Daudt <me@ikke.info>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Rafael Ascensão <rafa.almas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 65 insertions, 0 deletions

diff --git a/refs.c b/refs.c
index 339d4318ee..20ba82b434 100644
--- a/refs.c
+++ b/refs.c
@@ -242,6 +242,50 @@ int ref_exists(const char *refname)
 	return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, NULL, NULL);
 }
 
+static int match_ref_pattern(const char *refname,
+			     const struct string_list_item *item)
+{
+	int matched = 0;
+	if (item->util == NULL) {
+		if (!wildmatch(item->string, refname, 0))
+			matched = 1;
+	} else {
+		const char *rest;
+		if (skip_prefix(refname, item->string, &rest) &&
+		    (!*rest || *rest == '/'))
+			matched = 1;
+	}
+	return matched;
+}
+
+int ref_filter_match(const char *refname,
+		     const struct string_list *include_patterns,
+		     const struct string_list *exclude_patterns)
+{
+	struct string_list_item *item;
+
+	if (exclude_patterns && exclude_patterns->nr) {
+		for_each_string_list_item(item, exclude_patterns) {
+			if (match_ref_pattern(refname, item))
+				return 0;
+		}
+	}
+
+	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 (!found)
+			return 0;
+	}
+	return 1;
+}
+
 static int filter_refs(const char *refname, const struct object_id *oid,
 			   int flags, void *data)
 {
@@ -369,6 +413,27 @@ int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 	return ret;
 }
 
+void normalize_glob_ref(struct string_list_item *item, const char *prefix,
+			const char *pattern)
+{
+	struct strbuf normalized_pattern = STRBUF_INIT;
+
+	if (*pattern == '/')
+		BUG("pattern must not start with '/'");
+
+	if (prefix) {
+		strbuf_addstr(&normalized_pattern, prefix);
+	}
+	else if (!starts_with(pattern, "refs/"))
+		strbuf_addstr(&normalized_pattern, "refs/");
+	strbuf_addstr(&normalized_pattern, pattern);
+	strbuf_strip_suffix(&normalized_pattern, "/");
+
+	item->string = strbuf_detach(&normalized_pattern, NULL);
+	item->util = has_glob_specials(pattern) ? NULL : item->string;
+	strbuf_release(&normalized_pattern);
+}
+
 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 	const char *prefix, void *cb_data)
 {