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, 7 insertions, 0 deletions

diff --git a/Documentation/git-log.txt b/Documentation/git-log.txt
index 32246fdb00..5437f8b0f0 100644
--- a/Documentation/git-log.txt
+++ b/Documentation/git-log.txt
@@ -38,6 +38,13 @@ OPTIONS
 	are shown as if 'short' were given, otherwise no ref names are
 	shown. The default option is 'short'.
 
+--decorate-refs=<pattern>::
+--decorate-refs-exclude=<pattern>::
+	If no `--decorate-refs` is given, pretend as if all refs were
+	included.  For each candidate, do not use it for decoration if it
+	matches any patterns given to `--decorate-refs-exclude` or if it
+	doesn't match any of the patterns given to `--decorate-refs`.
+
 --source::
 	Print out the ref name given on the command line by which each
 	commit was reached.