Fix slowness with repetitive stars

Author: tidwall

match.go

@@ -16,12 +16,16 @@ import "unicode/utf8"
 // 	'\\' c      matches character c
 //
 func Match(str, pattern string) bool {
-	if pattern == "*" {
-		return true
-	}
 	return deepMatch(str, pattern)
 }
+
 func deepMatch(str, pattern string) bool {
+	if pattern == "*" {
+		return true
+	}
+	for len(pattern) > 1 && pattern[0] == '*' && pattern[1] == '*' {
+		pattern = pattern[1:]
+	}
 	for len(pattern) > 0 {
 		if pattern[0] > 0x7f {
 			return deepMatchRune(str, pattern)
@@ -52,6 +56,13 @@ func deepMatch(str, pattern string) bool {
 }
 
 func deepMatchRune(str, pattern string) bool {
+	if pattern == "*" {
+		return true
+	}
+	for len(pattern) > 1 && pattern[0] == '*' && pattern[1] == '*' {
+		pattern = pattern[1:]
+	}
+
 	var sr, pr rune
 	var srsz, prsz int
 

match_test.go

@@ -3,6 +3,7 @@ package match
 import (
 	"fmt"
 	"math/rand"
+	"strings"
 	"testing"
 	"time"
 	"unicode/utf8"
@@ -427,3 +428,17 @@ func BenchmarkUnicode(t *testing.B) {
 		}
 	}
 }
+
+func TestLotsaStars(t *testing.T) {
+	// This tests that a pattern with lots of stars will complete quickly.
+	var str, pat string
+
+	str = `,**,,**,**,**,**,**,**,`
+	pat = `,**********************************************{**",**,,**,**,` +
+		`**,**,"",**,**,**,**,**,**,**,**,**,**]`
+	Match(pat, str)
+
+	str = strings.Replace(str, ",", "情", -1)
+	pat = strings.Replace(pat, ",", "情", -1)
+	Match(pat, str)
+}