[PATCH 5/6] builtin/grep.c: show column numbers via --column-number

[Taylor Blau <me@ttaylorr.com>]

This commit teaches 'git-grep(1)' a new option, '--column-number'. This
option builds upon previous commits to show the column number of the
first match on a non-context line.

For example:

  $ git grep -mn example | head -n3
  .clang-format:51:14:# myFunction(foo, bar, baz);
  .clang-format:64:7:# int foo();
  .clang-format:75:8:# void foo()

Now that configuration variables such as grep.columnNumber and
color.grep.columnNumber have a visible effect, we document them in this
patch as well.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 Documentation/config.txt   |  5 +++++
 Documentation/git-grep.txt |  9 ++++++++-
 builtin/grep.c             |  1 +
 t/t7810-grep.sh            | 22 ++++++++++++++++++++++
 4 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 2659153cb3..02fd4b662b 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1159,6 +1159,8 @@ color.grep.<slot>::
 	function name lines (when using `-p`)
 `linenumber`;;
 	line number prefix (when using `-n`)
+`columnnumber`;;
+	column number prefix (when using `-m`)
 `match`;;
 	matching text (same as setting `matchContext` and `matchSelected`)
 `matchContext`;;
@@ -1708,6 +1710,9 @@ gitweb.snapshot::
 grep.lineNumber::
 	If set to true, enable `-n` option by default.
 
+grep.columnNumber::
+	If set to true, enable `-m` option by default.
+
 grep.patternType::
 	Set the default matching behavior. Using a value of 'basic', 'extended',
 	'fixed', or 'perl' will enable the `--basic-regexp`, `--extended-regexp`,
diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
index 18b494731f..dd90f74ded 100644
--- a/Documentation/git-grep.txt
+++ b/Documentation/git-grep.txt
@@ -13,7 +13,7 @@ SYNOPSIS
 	   [-v | --invert-match] [-h|-H] [--full-name]
 	   [-E | --extended-regexp] [-G | --basic-regexp]
 	   [-P | --perl-regexp]
-	   [-F | --fixed-strings] [-n | --line-number]
+	   [-F | --fixed-strings] [-n | --line-number] [-m | --column-number]
 	   [-l | --files-with-matches] [-L | --files-without-match]
 	   [(-O | --open-files-in-pager) [<pager>]]
 	   [-z | --null]
@@ -44,6 +44,9 @@ CONFIGURATION
 grep.lineNumber::
 	If set to true, enable `-n` option by default.
 
+grep.columnNumber::
+	If set to true, enable `-m` option by default.
+
 grep.patternType::
 	Set the default matching behavior. Using a value of 'basic', 'extended',
 	'fixed', or 'perl' will enable the `--basic-regexp`, `--extended-regexp`,
@@ -169,6 +172,10 @@ providing this option will cause it to die.
 --line-number::
 	Prefix the line number to matching lines.
 
+-m::
+--column-number::
+	Prefix the 1-indexed column number of the first match on non-context lines.
+
 -l::
 --files-with-matches::
 --name-only::
diff --git a/builtin/grep.c b/builtin/grep.c
index 5f32d2ce84..faa65abab5 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -829,6 +829,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			    GREP_PATTERN_TYPE_PCRE),
 		OPT_GROUP(""),
 		OPT_BOOL('n', "line-number", &opt.linenum, N_("show line numbers")),
+		OPT_BOOL('m', "column-number", &opt.columnnum, N_("show column numbers")),
 		OPT_NEGBIT('h', NULL, &opt.pathname, N_("don't show filenames"), 1),
 		OPT_BIT('H', NULL, &opt.pathname, N_("show filenames"), 1),
 		OPT_NEGBIT(0, "full-name", &opt.relative,
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index 1797f632a3..0cf654824d 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -99,6 +99,28 @@ do
 		test_cmp expected actual
 	'
 
+	test_expect_success "grep -w $L" '
+		{
+			echo ${HC}file:5:foo mmap bar
+			echo ${HC}file:14:foo_mmap bar mmap
+			echo ${HC}file:5:foo mmap bar_mmap
+			echo ${HC}file:14:foo_mmap bar mmap baz
+		} >expected &&
+		git -c grep.linenumber=false grep -m -w -e mmap $H >actual &&
+		test_cmp expected actual
+	'
+
+	test_expect_success "grep -w $L" '
+		{
+			echo ${HC}file:1:5:foo mmap bar
+			echo ${HC}file:3:14:foo_mmap bar mmap
+			echo ${HC}file:4:5:foo mmap bar_mmap
+			echo ${HC}file:5:14:foo_mmap bar mmap baz
+		} >expected &&
+		git -c grep.linenumber=false grep -n -m -w -e mmap $H >actual &&
+		test_cmp expected actual
+	'
+
 	test_expect_success "grep -w $L" '
 		{
 			echo ${HC}file:1:foo mmap bar
-- 
2.17.0