git-pickaxe: -L /regexp/,/regexp/

With this change, you can specify the beginning and the ending
line of the range you wish to inspect with pattern matching.

For example, these are equivalent with the git.git sources:

    git pickaxe -L 7,21                       v1.4.0 -- commit.c
    git pickaxe -L '/^struct sort_node/,/^}/' v1.4.0 -- commit.c
    git pickaxe -L '7,/^}/'                   v1.4.0 -- commit.c
    git pickaxe -L '/^struct sort_node/,21'   v1.4.0 -- commit.c

Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-pickaxe.c

@@ -17,6 +17,7 @@
 
 #include <time.h>
 #include <sys/time.h>
+#include <regex.h>
 
 static char pickaxe_usage[] =
 "git-pickaxe [-c] [-l] [-t] [-f] [-n] [-p] [-L n,m] [-S <revs-file>] [-M] [-C] [-C] [commit] [--] file\n"
@@ -1533,6 +1534,78 @@ static const char *add_prefix(const char *prefix, const char *path)
 	return prefix_path(prefix, strlen(prefix), path);
 }
 
+static const char *parse_loc(const char *spec,
+			     struct scoreboard *sb, long lno,
+			     long begin, long *ret)
+{
+	char *term;
+	const char *line;
+	long num;
+	int reg_error;
+	regex_t regexp;
+	regmatch_t match[1];
+
+	num = strtol(spec, &term, 10);
+	if (term != spec) {
+		*ret = num;
+		return term;
+	}
+	if (spec[0] != '/')
+		return spec;
+
+	/* it could be a regexp of form /.../ */
+	for (term = (char*) spec + 1; *term && *term != '/'; term++) {
+		if (*term == '\\')
+			term++;
+	}
+	if (*term != '/')
+		return spec;
+
+	/* try [spec+1 .. term-1] as regexp */
+	*term = 0;
+	begin--; /* input is in human terms */
+	line = nth_line(sb, begin);
+
+	if (!(reg_error = regcomp(&regexp, spec + 1, REG_NEWLINE)) &&
+	    !(reg_error = regexec(&regexp, line, 1, match, 0))) {
+		const char *cp = line + match[0].rm_so;
+		const char *nline;
+
+		while (begin++ < lno) {
+			nline = nth_line(sb, begin);
+			if (line <= cp && cp < nline)
+				break;
+			line = nline;
+		}
+		*ret = begin;
+		regfree(&regexp);
+		*term++ = '/';
+		return term;
+	}
+	else {
+		char errbuf[1024];
+		regerror(reg_error, &regexp, errbuf, 1024);
+		die("-L parameter '%s': %s", spec + 1, errbuf);
+	}
+}
+
+static void prepare_blame_range(struct scoreboard *sb,
+				const char *bottomtop,
+				long lno,
+				long *bottom, long *top)
+{
+	const char *term;
+
+	term = parse_loc(bottomtop, sb, lno, 1, bottom);
+	if (*term == ',') {
+		term = parse_loc(term + 1, sb, lno, *bottom + 1, top);
+		if (*term)
+			usage(pickaxe_usage);
+	}
+	if (*term)
+		usage(pickaxe_usage);
+}
+
 int cmd_pickaxe(int argc, const char **argv, const char *prefix)
 {
 	struct rev_info revs;
@@ -1546,11 +1619,11 @@ int cmd_pickaxe(int argc, const char **argv, const char *prefix)
 	const char *revs_file = NULL;
 	const char *final_commit_name = NULL;
 	char type[10];
+	const char *bottomtop = NULL;
 
 	save_commit_buffer = 0;
 
 	opt = 0;
-	bottom = top = 0;
 	seen_dashdash = 0;
 	for (unk = i = 1; i < argc; i++) {
 		const char *arg = argv[i];
@@ -1575,7 +1648,6 @@ int cmd_pickaxe(int argc, const char **argv, const char *prefix)
 			blame_copy_score = parse_score(arg+2);
 		}
 		else if (!strncmp("-L", arg, 2)) {
-			char *term;
 			if (!arg[2]) {
 				if (++i >= argc)
 					usage(pickaxe_usage);
@@ -1583,18 +1655,9 @@ int cmd_pickaxe(int argc, const char **argv, const char *prefix)
 			}
 			else
 				arg += 2;
-			if (bottom || top)
+			if (bottomtop)
 				die("More than one '-L n,m' option given");
-			bottom = strtol(arg, &term, 10);
+			bottomtop = arg;
-			if (*term == ',') {
-				top = strtol(term + 1, &term, 10);
-				if (*term)
-					usage(pickaxe_usage);
-			}
-			if (bottom && top && top < bottom) {
-				unsigned long tmp;
-				tmp = top; top = bottom; bottom = tmp;
-			}
 		}
 		else if (!strcmp("--score-debug", arg))
 			output_option |= OUTPUT_SHOW_SCORE;
@@ -1755,6 +1818,13 @@ int cmd_pickaxe(int argc, const char **argv, const char *prefix)
 	num_read_blob++;
 	lno = prepare_lines(&sb);
 
+	bottom = top = 0;
+	if (bottomtop)
+		prepare_blame_range(&sb, bottomtop, lno, &bottom, &top);
+	if (bottom && top && top < bottom) {
+		long tmp;
+		tmp = top; top = bottom; bottom = tmp;
+	}
 	if (bottom < 1)
 		bottom = 1;
 	if (top < 1)