From: Explorer09 <explorer09@gmail.com>
Date: Sat, 8 Jul 2017 12:21:37 +0000 (+0800)
Subject: filter: faster is_blank_line implementation
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e784a805ef8f33ab4de544eee1876f41d2bd9dbc;p=flex

filter: faster is_blank_line implementation

Using regex_t regex_blank_line is *slow*.
---

diff --git a/src/filter.c b/src/filter.c
index fd1bb40..ccdcdd6 100644
--- a/src/filter.c
+++ b/src/filter.c
@@ -326,7 +326,9 @@ int filter_tee_header (struct filter *chain)
 
 static bool is_blank_line (const char *str)
 {
-	return (regexec (&regex_blank_line, str, 0, NULL, 0) == 0);
+	while (isspace(*str))
+		str++;
+	return (*str == '\0');
 }
 
 /** Adjust the line numbers in the #line directives of the generated scanner.
diff --git a/src/flexdef.h b/src/flexdef.h
index 9dac654..3bbaea1 100644
--- a/src/flexdef.h
+++ b/src/flexdef.h
@@ -1131,7 +1131,7 @@ extern int filter_fix_linedirs(struct filter *chain);
  * From "regex.c"
  */
 
-extern regex_t regex_linedir, regex_blank_line;
+extern regex_t regex_linedir;
 bool flex_init_regex(void);
 void flex_regcomp(regex_t *preg, const char *regex, int cflags);
 char   *regmatch_dup (regmatch_t * m, const char *src);
diff --git a/src/regex.c b/src/regex.c
index 38e658b..f4c4163 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -25,10 +25,8 @@
 
 
 static const char* REGEXP_LINEDIR = "^#line ([[:digit:]]+) \"(.*)\"";
-static const char* REGEXP_BLANK_LINE = "^[[:space:]]*$";
 
 regex_t regex_linedir; /**< matches line directives */
-regex_t regex_blank_line; /**< matches blank lines */
 
 
 /** Initialize the regular expressions.
@@ -37,8 +35,6 @@ regex_t regex_blank_line; /**< matches blank lines */
 bool flex_init_regex(void)
 {
     flex_regcomp(&regex_linedir, REGEXP_LINEDIR, REG_EXTENDED);
-    flex_regcomp(&regex_blank_line, REGEXP_BLANK_LINE, REG_EXTENDED);
-
     return true;
 }