Merge branch 'rs/grep-p'

* rs/grep-p:
  grep: simplify -p output
  grep -p: support user defined regular expressions
  grep: add option -p/--show-function
  grep: handle pre context lines on demand
  grep: print context hunk marks between files
  grep: move context hunk mark handling into show_line()
  userdiff: add xdiff_clear_find_func()

8 files changed, 228 insertions, 44 deletions

diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
index fccb82deb..b753c9d76 100644
--- a/Documentation/git-grep.txt
+++ b/Documentation/git-grep.txt
@@ -122,6 +122,14 @@ OPTIONS
 -<num>::
 	A shortcut for specifying -C<num>.
 
+-p::
+--show-function::
+	Show the preceding line that contains the function name of
+	the match, unless the matching line is a function name itself.
+	The name is determined in the same way as 'git diff' works out
+	patch hunk headers (see 'Defining a custom hunk-header' in
+	linkgit:gitattributes[5]).
+
 -f <file>::
 	Read patterns from <file>, one per line.
 
diff --git a/builtin-grep.c b/builtin-grep.c
index e5583686a..f47765910 100644
--- a/builtin-grep.c
+++ b/builtin-grep.c
@@ -11,6 +11,7 @@
 #include "tree-walk.h"
 #include "builtin.h"
 #include "parse-options.h"
+#include "userdiff.h"
 #include "grep.h"
 
 #ifndef NO_EXTERNAL_GREP
@@ -30,6 +31,12 @@ static int grep_config(const char *var, const char *value, void *cb)
 {
 	struct grep_opt *opt = cb;
 
+	switch (userdiff_config(var, value)) {
+	case 0: break;
+	case -1: return -1;
+	default: return 0;
+	}
+
 	if (!strcmp(var, "color.grep")) {
 		opt->color = git_config_colorbool(var, value, -1);
 		return 0;
@@ -278,6 +285,17 @@ static int flush_grep(struct grep_opt *opt,
 		argc -= 2;
 	}
 
+	if (opt->pre_context || opt->post_context) {
+		/*
+		 * grep handles hunk marks between files, but we need to
+		 * do that ourselves between multiple calls.
+		 */
+		if (opt->show_hunk_mark)
+			write_or_die(1, "--\n", 3);
+		else
+			opt->show_hunk_mark = 1;
+	}
+
 	status = exec_grep(argc, argv);
 
 	if (kept_0) {
@@ -710,6 +728,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			"show <n> context lines after matches"),
 		OPT_NUMBER_CALLBACK(&opt, "shortcut for -C NUM",
 			context_callback),
+		OPT_BOOLEAN('p', "show-function", &opt.funcname,
+			"show a line with the function name before matches"),
 		OPT_GROUP(""),
 		OPT_CALLBACK('f', NULL, &opt, "file",
 			"read patterns from file", file_callback),
@@ -778,7 +798,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		argc--;
 	}
 
-	if (opt.color && !opt.color_external)
+	if ((opt.color && !opt.color_external) || opt.funcname)
 		external_grep_allowed = 0;
 	if (!opt.pattern_list)
 		die("no pattern given.");
diff --git a/diff.c b/diff.c
index 0a020ffab..cd35e0c2d 100644
--- a/diff.c
+++ b/diff.c
@@ -1603,6 +1603,7 @@ static void builtin_diff(const char *name_a,
 			free(mf1.ptr);
 		if (textconv_two)
 			free(mf2.ptr);
+		xdiff_clear_find_func(&xecfg);
 	}
 
  free_ab_and_return:
diff --git a/grep.c b/grep.c
index 92a47c71e..5d162dae6 100644
--- a/grep.c
+++ b/grep.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "grep.h"
+#include "userdiff.h"
 #include "xdiff-interface.h"
 
 void append_header_grep_pattern(struct grep_opt *opt, enum grep_header_field field, const char *pat)
@@ -490,6 +491,17 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 {
 	int rest = eol - bol;
 
+	if (opt->pre_context || opt->post_context) {
+		if (opt->last_shown == 0) {
+			if (opt->show_hunk_mark)
+				fputs("--\n", stdout);
+			else
+				opt->show_hunk_mark = 1;
+		} else if (lno > opt->last_shown + 1)
+			fputs("--\n", stdout);
+	}
+	opt->last_shown = lno;
+
 	if (opt->null_following_name)
 		sign = '\0';
 	if (opt->pathname)
@@ -520,22 +532,95 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 	printf("%.*s\n", rest, bol);
 }
 
+static int match_funcname(struct grep_opt *opt, char *bol, char *eol)
+{
+	xdemitconf_t *xecfg = opt->priv;
+	if (xecfg && xecfg->find_func) {
+		char buf[1];
+		return xecfg->find_func(bol, eol - bol, buf, 1,
+					xecfg->find_func_priv) >= 0;
+	}
+
+	if (bol == eol)
+		return 0;
+	if (isalpha(*bol) || *bol == '_' || *bol == '$')
+		return 1;
+	return 0;
+}
+
+static void show_funcname_line(struct grep_opt *opt, const char *name,
+			       char *buf, char *bol, unsigned lno)
+{
+	while (bol > buf) {
+		char *eol = --bol;
+
+		while (bol > buf && bol[-1] != '\n')
+			bol--;
+		lno--;
+
+		if (lno <= opt->last_shown)
+			break;
+
+		if (match_funcname(opt, bol, eol)) {
+			show_line(opt, bol, eol, name, lno, '=');
+			break;
+		}
+	}
+}
+
+static void show_pre_context(struct grep_opt *opt, const char *name, char *buf,
+			     char *bol, unsigned lno)
+{
+	unsigned cur = lno, from = 1, funcname_lno = 0;
+	int funcname_needed = opt->funcname;
+
+	if (opt->pre_context < lno)
+		from = lno - opt->pre_context;
+	if (from <= opt->last_shown)
+		from = opt->last_shown + 1;
+
+	/* Rewind. */
+	while (bol > buf && cur > from) {
+		char *eol = --bol;
+
+		while (bol > buf && bol[-1] != '\n')
+			bol--;
+		cur--;
+		if (funcname_needed && match_funcname(opt, bol, eol)) {
+			funcname_lno = cur;
+			funcname_needed = 0;
+		}
+	}
+
+	/* We need to look even further back to find a function signature. */
+	if (opt->funcname && funcname_needed)
+		show_funcname_line(opt, name, buf, bol, cur);
+
+	/* Back forward. */
+	while (cur < lno) {
+		char *eol = bol, sign = (cur == funcname_lno) ? '=' : '-';
+
+		while (*eol != '\n')
+			eol++;
+		show_line(opt, bol, eol, name, cur, sign);
+		bol = eol + 1;
+		cur++;
+	}
+}
+
 static int grep_buffer_1(struct grep_opt *opt, const char *name,
 			 char *buf, unsigned long size, int collect_hits)
 {
 	char *bol = buf;
 	unsigned long left = size;
 	unsigned lno = 1;
-	struct pre_context_line {
-		char *bol;
-		char *eol;
-	} *prev = NULL, *pcl;
 	unsigned last_hit = 0;
-	unsigned last_shown = 0;
 	int binary_match_only = 0;
-	const char *hunk_mark = "";
 	unsigned count = 0;
 	enum grep_context ctx = GREP_CONTEXT_HEAD;
+	xdemitconf_t xecfg;
+
+	opt->last_shown = 0;
 
 	if (buffer_is_binary(buf, size)) {
 		switch (opt->binary) {
@@ -550,10 +635,16 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 		}
 	}
 
-	if (opt->pre_context)
-		prev = xcalloc(opt->pre_context, sizeof(*prev));
-	if (opt->pre_context || opt->post_context)
-		hunk_mark = "--\n";
+	memset(&xecfg, 0, sizeof(xecfg));
+	if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
+	    !opt->name_only && !binary_match_only && !collect_hits) {
+		struct userdiff_driver *drv = userdiff_find_by_path(name);
+		if (drv && drv->funcname.pattern) {
+			const struct userdiff_funcname *pe = &drv->funcname;
+			xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
+			opt->priv = &xecfg;
+		}
+	}
 
 	while (left) {
 		char *eol, ch;
@@ -601,45 +692,20 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 			 * the context which is nonsense, but the user
 			 * deserves to get that ;-).
 			 */
-			if (opt->pre_context) {
-				unsigned from;
-				if (opt->pre_context < lno)
-					from = lno - opt->pre_context;
-				else
-					from = 1;
-				if (from <= last_shown)
-					from = last_shown + 1;
-				if (last_shown && from != last_shown + 1)
-					fputs(hunk_mark, stdout);
-				while (from < lno) {
-					pcl = &prev[lno-from-1];
-					show_line(opt, pcl->bol, pcl->eol,
-						  name, from, '-');
-					from++;
-				}
-				last_shown = lno-1;
-			}
-			if (last_shown && lno != last_shown + 1)
-				fputs(hunk_mark, stdout);
+			if (opt->pre_context)
+				show_pre_context(opt, name, buf, bol, lno);
+			else if (opt->funcname)
+				show_funcname_line(opt, name, buf, bol, lno);
 			if (!opt->count)
 				show_line(opt, bol, eol, name, lno, ':');
-			last_shown = last_hit = lno;
+			last_hit = lno;
 		}
 		else if (last_hit &&
 			 lno <= last_hit + opt->post_context) {
 			/* If the last hit is within the post context,
 			 * we need to show this line.
 			 */
-			if (last_shown && lno != last_shown + 1)
-				fputs(hunk_mark, stdout);
 			show_line(opt, bol, eol, name, lno, '-');
-			last_shown = lno;
-		}
-		if (opt->pre_context) {
-			memmove(prev+1, prev,
-				(opt->pre_context-1) * sizeof(*prev));
-			prev->bol = bol;
-			prev->eol = eol;
 		}
 
 	next_line:
@@ -650,7 +716,6 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 		lno++;
 	}
 
-	free(prev);
 	if (collect_hits)
 		return 0;
 
@@ -662,6 +727,9 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 		return 1;
 	}
 
+	xdiff_clear_find_func(&xecfg);
+	opt->priv = NULL;
+
 	/* NEEDSWORK:
 	 * The real "grep -c foo *.c" gives many "bar.c:0" lines,
 	 * which feels mostly useless but sometimes useful.  Maybe
diff --git a/grep.h b/grep.h
index 464e272ed..f00db0e40 100644
--- a/grep.h
+++ b/grep.h
@@ -79,11 +79,15 @@ struct grep_opt {
 	int pathname;
 	int null_following_name;
 	int color;
+	int funcname;
 	char color_match[COLOR_MAXLEN];
 	const char *color_external;
 	int regflags;
 	unsigned pre_context;
 	unsigned post_context;
+	unsigned last_shown;
+	int show_hunk_mark;
+	void *priv;
 };
 
 extern void append_grep_pattern(struct grep_opt *opt, const char *pat, const char *origin, int no, enum grep_pat_token t);
diff --git a/t/t7002-grep.sh b/t/t7002-grep.sh
index 7868af8f1..b13aa7e89 100755
--- a/t/t7002-grep.sh
+++ b/t/t7002-grep.sh
@@ -8,6 +8,15 @@ test_description='git grep various.
 
 . ./test-lib.sh
 
+cat >hello.c <<EOF
+#include <stdio.h>
+int main(int argc, const char **argv)
+{
+	printf("Hello world.\n");
+	return 0;
+}
+EOF
+
 test_expect_success setup '
 	{
 		echo foo mmap bar
@@ -22,7 +31,7 @@ test_expect_success setup '
 	echo zzz > z &&
 	mkdir t &&
 	echo test >t/t &&
-	git add file w x y z t/t &&
+	git add file w x y z t/t hello.c &&
 	test_tick &&
 	git commit -m initial
 '
@@ -155,6 +164,28 @@ test_expect_success 'grep -e A --and --not -e B' '
 	test_cmp expected actual
 '
 
+cat >expected <<EOF
+y:y yy
+--
+z:zzz
+EOF
+
+# Create 1024 file names that sort between "y" and "z" to make sure
+# the two files are handled by different calls to an external grep.
+# This depends on MAXARGS in builtin-grep.c being 1024 or less.
+c32="0 1 2 3 4 5 6 7 8 9 a b c d e f g h i j k l m n o p q r s t u v"
+test_expect_success 'grep -C1, hunk mark between files' '
+	for a in $c32; do for b in $c32; do : >y-$a$b; done; done &&
+	git add y-?? &&
+	git grep -C1 "^[yz]" >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'grep -C1 --no-ext-grep, hunk mark between files' '
+	git grep -C1 --no-ext-grep "^[yz]" >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'log grep setup' '
 	echo a >>file &&
 	test_tick &&
@@ -207,9 +238,45 @@ test_expect_success 'log grep (6)' '
 test_expect_success 'grep with CE_VALID file' '
 	git update-index --assume-unchanged t/t &&
 	rm t/t &&
-	test "$(git grep --no-ext-grep t)" = "t/t:test" &&
+	test "$(git grep --no-ext-grep test)" = "t/t:test" &&
 	git update-index --no-assume-unchanged t/t &&
 	git checkout t/t
 '
 
+cat >expected <<EOF
+hello.c=#include <stdio.h>
+hello.c:	return 0;
+EOF
+
+test_expect_success 'grep -p with userdiff' '
+	git config diff.custom.funcname "^#" &&
+	echo "hello.c diff=custom" >.gitattributes &&
+	git grep -p return >actual &&
+	test_cmp expected actual
+'
+
+cat >expected <<EOF
+hello.c=int main(int argc, const char **argv)
+hello.c:	return 0;
+EOF
+
+test_expect_success 'grep -p' '
+	rm -f .gitattributes &&
+	git grep -p return >actual &&
+	test_cmp expected actual
+'
+
+cat >expected <<EOF
+hello.c-#include <stdio.h>
+hello.c=int main(int argc, const char **argv)
+hello.c-{
+hello.c-	printf("Hello world.\n");
+hello.c:	return 0;
+EOF
+
+test_expect_success 'grep -p -B5' '
+	git grep -p -B5 return >actual &&
+	test_cmp expected actual
+'
+
 test_done
diff --git a/xdiff-interface.c b/xdiff-interface.c
index b9b0db8d8..01f14fb50 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -309,6 +309,21 @@ void xdiff_set_find_func(xdemitconf_t *xecfg, const char *value, int cflags)
 	}
 }
 
+void xdiff_clear_find_func(xdemitconf_t *xecfg)
+{
+	if (xecfg->find_func) {
+		int i;
+		struct ff_regs *regs = xecfg->find_func_priv;
+
+		for (i = 0; i < regs->nr; i++)
+			regfree(&regs->array[i].re);
+		free(regs->array);
+		free(regs);
+		xecfg->find_func = NULL;
+		xecfg->find_func_priv = NULL;
+	}
+}
+
 int git_xmerge_style = -1;
 
 int git_xmerge_config(const char *var, const char *value, void *cb)
diff --git a/xdiff-interface.h b/xdiff-interface.h
index 7352b9a9c..55572c39a 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -21,6 +21,7 @@ int read_mmfile(mmfile_t *ptr, const char *filename);
 int buffer_is_binary(const char *ptr, unsigned long size);
 
 extern void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
+extern void xdiff_clear_find_func(xdemitconf_t *xecfg);
 extern int git_xmerge_config(const char *var, const char *value, void *cb);
 extern int git_xmerge_style;