[PATCH] for-each-ref: introduce color format

[Ramkumar Ramachandra <artagnon@gmail.com>]

You can now do something like

$ git for-each-ref --format='%C(red)%(refname:short)%C(reset)
%C(blue)%(upstream:diff)%C(reset)' --count 5 --sort='-committerdate'
refs/heads

To get output that's much more customizable 'git branch' output.  Future
patches will attempt unify the semantics of 'git branch' and 'git
for-each-ref'.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 So my evil plan is to keep extending this format until it's on par
 with pretty-formats.  Then, we can move towards unifying 'git branch'
 and 'git for-each-ref'.  This will involve deprecating badly
 thought-out options like '-v', and replacing it with the more
 powerful '--format'.

 I just have one major doubt: in the above output, how do I align all
 the upstream branches to the same column?  How can I achieve it with
 pretty-formats?  Something like %*d?  But * is already taken to mean
 deref in for-each-ref's --format.

 By the way, the main motivation for all this comes from the fact that
 git for-each-ref is very nicely written :) Look at how it breaks
 everything up into atoms and lazily gets the information it needs to
 display.

 builtin/for-each-ref.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 7f059c3..1563b25 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -9,6 +9,7 @@
 #include "quote.h"
 #include "parse-options.h"
 #include "remote.h"
+#include "color.h"
 
 /* Quoting styles */
 #define QUOTE_NONE 0
@@ -155,10 +156,13 @@ static const char *find_next(const char *cp)
 	while (*cp) {
 		if (*cp == '%') {
 			/*
+			 * %C( is the start of a color;
 			 * %( is the start of an atom;
 			 * %% is a quoted per-cent.
 			 */
-			if (cp[1] == '(')
+			if (cp[1] == 'C' && cp[2] == '(')
+				return cp;
+			else if (cp[1] == '(')
 				return cp;
 			else if (cp[1] == '%')
 				cp++; /* skip over two % */
@@ -180,8 +184,12 @@ static int verify_format(const char *format)
 		const char *ep = strchr(sp, ')');
 		if (!ep)
 			return error("malformed format string %s", sp);
-		/* sp points at "%(" and ep points at the closing ")" */
-		parse_atom(sp + 2, ep);
+		/*
+		 * Ignore color specifications: %C(
+		 * sp points at "%(" and ep points at the closing ")"
+		 */
+		if (prefixcmp(sp, "%C("))
+			parse_atom(sp + 2, ep);
 		cp = ep + 1;
 	}
 	return 0;
@@ -928,12 +936,22 @@ static void emit(const char *cp, const char *ep)
 static void show_ref(struct refinfo *info, const char *format, int quote_style)
 {
 	const char *cp, *sp, *ep;
+	char color[COLOR_MAXLEN];
 
 	for (cp = format; *cp && (sp = find_next(cp)); cp = ep + 1) {
 		ep = strchr(sp, ')');
 		if (cp < sp)
 			emit(cp, sp);
-		print_value(info, parse_atom(sp + 2, ep), quote_style);
+
+		/* Do we have a color specification? */
+		if (!prefixcmp(sp, "%C("))
+			color_parse_mem(sp + 3,
+					ep - sp - 3,
+					"--format ", color);
+		else {
+			printf("%s", color);
+			print_value(info, parse_atom(sp + 2, ep), quote_style);
+		}
 	}
 	if (*cp) {
 		sp = cp + strlen(cp);
-- 
1.8.3.rc2.13.g629b60a.dirty