x := strings.Repeat("xxxx", 20) + "w"
	re := MustCompile("[abcdw]")
	b.StartTimer()
	for i := 0; i < b.N; i++ {
		if !re.MatchString(x) {
			b.Fatalf("no match!")
		}
	}
}

func BenchmarkMatchClass_InRange(b *testing.B) {
	b.StopTimer()
	// 'b' is between 'a' and 'c', so the charclass
	// range checking is no help here.
	x := strings.Repeat("bbbb", 20) + "c"
	re := MustCompile("[ac]")
	b.StartTimer()