grep: move pattern-type bits support to top-level grep.[ch]

Switching between -E/-G/-P/-F correctly needs a lot more than just
flipping opt->regflags bit these days, and we have a nice helper
function buried in builtin/grep.c for the sole use of "git grep".

Extract it so that "log --grep" family can also use it.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin/grep.c

@@ -261,38 +261,6 @@ static int wait_all(void)
 }
 #endif
 
-static void grep_pattern_type_options(const int pattern_type, struct grep_opt *opt)
-{
-	switch (pattern_type) {
-	case GREP_PATTERN_TYPE_UNSPECIFIED:
-		/* fall through */
-
-	case GREP_PATTERN_TYPE_BRE:
-		opt->fixed = 0;
-		opt->pcre = 0;
-		opt->regflags &= ~REG_EXTENDED;
-		break;
-
-	case GREP_PATTERN_TYPE_ERE:
-		opt->fixed = 0;
-		opt->pcre = 0;
-		opt->regflags |= REG_EXTENDED;
-		break;
-
-	case GREP_PATTERN_TYPE_FIXED:
-		opt->fixed = 1;
-		opt->pcre = 0;
-		opt->regflags &= ~REG_EXTENDED;
-		break;
-
-	case GREP_PATTERN_TYPE_PCRE:
-		opt->fixed = 0;
-		opt->pcre = 1;
-		opt->regflags &= ~REG_EXTENDED;
-		break;
-	}
-}
-
 static int grep_cmd_config(const char *var, const char *value, void *cb)
 {
 	int st = grep_config(var, value, cb);
@@ -798,13 +766,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			     PARSE_OPT_KEEP_DASHDASH |
 			     PARSE_OPT_STOP_AT_NON_OPTION |
 			     PARSE_OPT_NO_INTERNAL_HELP);
-
-	if (pattern_type_arg != GREP_PATTERN_TYPE_UNSPECIFIED)
-		grep_pattern_type_options(pattern_type_arg, &opt);
-	else if (opt.pattern_type_option != GREP_PATTERN_TYPE_UNSPECIFIED)
-		grep_pattern_type_options(opt.pattern_type_option, &opt);
-	else if (opt.extended_regexp_option)
-		grep_pattern_type_options(GREP_PATTERN_TYPE_ERE, &opt);
+	grep_commit_pattern_type(pattern_type_arg, &opt);
 
 	if (use_index && !startup_info->have_repository)
 		/* die the same way as if we did it at the beginning */

grep.c

@@ -137,6 +137,48 @@ void grep_init(struct grep_opt *opt, const char *prefix)
 	strcpy(opt->color_sep, def->color_sep);
 }
 
+void grep_commit_pattern_type(enum grep_pattern_type pattern_type, struct grep_opt *opt)
+{
+	if (pattern_type != GREP_PATTERN_TYPE_UNSPECIFIED)
+		grep_set_pattern_type_option(pattern_type, opt);
+	else if (opt->pattern_type_option != GREP_PATTERN_TYPE_UNSPECIFIED)
+		grep_set_pattern_type_option(opt->pattern_type_option, opt);
+	else if (opt->extended_regexp_option)
+		grep_set_pattern_type_option(GREP_PATTERN_TYPE_ERE, opt);
+}
+
+void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, struct grep_opt *opt)
+{
+	switch (pattern_type) {
+	case GREP_PATTERN_TYPE_UNSPECIFIED:
+		/* fall through */
+
+	case GREP_PATTERN_TYPE_BRE:
+		opt->fixed = 0;
+		opt->pcre = 0;
+		opt->regflags &= ~REG_EXTENDED;
+		break;
+
+	case GREP_PATTERN_TYPE_ERE:
+		opt->fixed = 0;
+		opt->pcre = 0;
+		opt->regflags |= REG_EXTENDED;
+		break;
+
+	case GREP_PATTERN_TYPE_FIXED:
+		opt->fixed = 1;
+		opt->pcre = 0;
+		opt->regflags &= ~REG_EXTENDED;
+		break;
+
+	case GREP_PATTERN_TYPE_PCRE:
+		opt->fixed = 0;
+		opt->pcre = 1;
+		opt->regflags &= ~REG_EXTENDED;
+		break;
+	}
+}
+
 static struct grep_pat *create_grep_pat(const char *pat, size_t patlen,
 					const char *origin, int no,
 					enum grep_pat_token t,

grep.h

@@ -141,6 +141,8 @@ struct grep_opt {
 extern void init_grep_defaults(void);
 extern int grep_config(const char *var, const char *value, void *);
 extern void grep_init(struct grep_opt *, const char *prefix);
+void grep_set_pattern_type_option(enum grep_pattern_type, struct grep_opt *opt);
+void grep_commit_pattern_type(enum grep_pattern_type, struct grep_opt *opt);
 
 extern void append_grep_pat(struct grep_opt *opt, const char *pat, size_t patlen, const char *origin, int no, enum grep_pat_token t);
 extern void append_grep_pattern(struct grep_opt *opt, const char *pat, const char *origin, int no, enum grep_pat_token t);