[PATCH/RFC 4/4] grep: provide option to match line number

[Bert Wesarg <bert.wesarg@googlemail.com>]

Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
---
 Documentation/git-grep.txt |    6 +++++-
 builtin/grep.c             |   10 ++++++++++
 2 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
index d7523b3..05deb58 100644
--- a/Documentation/git-grep.txt
+++ b/Documentation/git-grep.txt
@@ -21,7 +21,7 @@ SYNOPSIS
 	   [--color[=<when>] | --no-color]
 	   [-A <post-context>] [-B <pre-context>] [-C <context>]
 	   [-f <file>] [-e] <pattern>
-	   [--and|--or|--not|(|)|-e <pattern>...]
+	   [--and|--or|--not|(|)|-e <pattern>|-@ <line>...]
 	   [--cached | --no-index | <tree>...]
 	   [--] [<pathspec>...]
 
@@ -168,6 +168,10 @@ OPTIONS
 	scripts passing user input to grep.  Multiple patterns are
 	combined by 'or'.
 
+-@::
+	The next parameter is a line number. This special pattern matches
+	this line of the input file.
+
 --and::
 --or::
 --not::
diff --git a/builtin/grep.c b/builtin/grep.c
index 10a1f65..8b11c87 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -733,6 +733,14 @@ static int pattern_callback(const struct option *opt, const char *arg,
 	return 0;
 }
 
+static int lno_pattern_callback(const struct option *opt, const char *arg,
+				int unset)
+{
+	struct grep_opt *grep_opt = opt->value;
+	append_grep_pattern(grep_opt, arg, "-@ option", 0, GREP_LNO);
+	return 0;
+}
+
 static int help_callback(const struct option *opt, const char *arg, int unset)
 {
 	return -1;
@@ -816,6 +824,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			"read patterns from file", file_callback),
 		{ OPTION_CALLBACK, 'e', NULL, &opt, "pattern",
 			"match <pattern>", PARSE_OPT_NONEG, pattern_callback },
+		{ OPTION_CALLBACK, '@', NULL, &opt, "lno",
+			"match <line>", PARSE_OPT_NONEG, lno_pattern_callback },
 		{ OPTION_CALLBACK, 0, "and", &opt, NULL,
 		  "combine patterns specified with -e",
 		  PARSE_OPT_NOARG | PARSE_OPT_NONEG, and_callback },
-- 
1.7.5.349.gfeb1a