gcc/libgo/go/regexp/all_test.go
Ian Lance Taylor f8d9fa9e80 libgo, compiler: Upgrade libgo to Go 1.4, except for runtime.
This upgrades all of libgo other than the runtime package to
the Go 1.4 release.  In Go 1.4 much of the runtime was
rewritten into Go.  Merging that code will take more time and
will not change the API, so I'm putting it off for now.

There are a few runtime changes anyhow, to accomodate other
packages that rely on minor modifications to the runtime
support.

The compiler changes slightly to add a one-bit flag to each
type descriptor kind that is stored directly in an interface,
which for gccgo is currently only pointer types.  Another
one-bit flag (gcprog) is reserved because it is used by the gc
compiler, but gccgo does not currently use it.

There is another error check in the compiler since I ran
across it during testing.

gotools/:
	* Makefile.am (go_cmd_go_files): Sort entries.  Add generate.go.
	* Makefile.in: Rebuild.

From-SVN: r219627
2015-01-15 00:27:56 +00:00

657 lines
18 KiB
Go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package regexp
import (
"reflect"
"regexp/syntax"
"strings"
"testing"
)
var good_re = []string{
``,
`.`,
`^.$`,
`a`,
`a*`,
`a+`,
`a?`,
`a|b`,
`a*|b*`,
`(a*|b)(c*|d)`,
`[a-z]`,
`[a-abc-c\-\]\[]`,
`[a-z]+`,
`[abc]`,
`[^1234]`,
`[^\n]`,
`\!\\`,
}
type stringError struct {
re string
err string
}
var bad_re = []stringError{
{`*`, "missing argument to repetition operator: `*`"},
{`+`, "missing argument to repetition operator: `+`"},
{`?`, "missing argument to repetition operator: `?`"},
{`(abc`, "missing closing ): `(abc`"},
{`abc)`, "unexpected ): `abc)`"},
{`x[a-z`, "missing closing ]: `[a-z`"},
{`[z-a]`, "invalid character class range: `z-a`"},
{`abc\`, "trailing backslash at end of expression"},
{`a**`, "invalid nested repetition operator: `**`"},
{`a*+`, "invalid nested repetition operator: `*+`"},
{`\x`, "invalid escape sequence: `\\x`"},
}
func compileTest(t *testing.T, expr string, error string) *Regexp {
re, err := Compile(expr)
if error == "" && err != nil {
t.Error("compiling `", expr, "`; unexpected error: ", err.Error())
}
if error != "" && err == nil {
t.Error("compiling `", expr, "`; missing error")
} else if error != "" && !strings.Contains(err.Error(), error) {
t.Error("compiling `", expr, "`; wrong error: ", err.Error(), "; want ", error)
}
return re
}
func TestGoodCompile(t *testing.T) {
for i := 0; i < len(good_re); i++ {
compileTest(t, good_re[i], "")
}
}
func TestBadCompile(t *testing.T) {
for i := 0; i < len(bad_re); i++ {
compileTest(t, bad_re[i].re, bad_re[i].err)
}
}
func matchTest(t *testing.T, test *FindTest) {
re := compileTest(t, test.pat, "")
if re == nil {
return
}
m := re.MatchString(test.text)
if m != (len(test.matches) > 0) {
t.Errorf("MatchString failure on %s: %t should be %t", test, m, len(test.matches) > 0)
}
// now try bytes
m = re.Match([]byte(test.text))
if m != (len(test.matches) > 0) {
t.Errorf("Match failure on %s: %t should be %t", test, m, len(test.matches) > 0)
}
}
func TestMatch(t *testing.T) {
for _, test := range findTests {
matchTest(t, &test)
}
}
func matchFunctionTest(t *testing.T, test *FindTest) {
m, err := MatchString(test.pat, test.text)
if err == nil {
return
}
if m != (len(test.matches) > 0) {
t.Errorf("Match failure on %s: %t should be %t", test, m, len(test.matches) > 0)
}
}
func TestMatchFunction(t *testing.T) {
for _, test := range findTests {
matchFunctionTest(t, &test)
}
}
type ReplaceTest struct {
pattern, replacement, input, output string
}
var replaceTests = []ReplaceTest{
// Test empty input and/or replacement, with pattern that matches the empty string.
{"", "", "", ""},
{"", "x", "", "x"},
{"", "", "abc", "abc"},
{"", "x", "abc", "xaxbxcx"},
// Test empty input and/or replacement, with pattern that does not match the empty string.
{"b", "", "", ""},
{"b", "x", "", ""},
{"b", "", "abc", "ac"},
{"b", "x", "abc", "axc"},
{"y", "", "", ""},
{"y", "x", "", ""},
{"y", "", "abc", "abc"},
{"y", "x", "abc", "abc"},
// Multibyte characters -- verify that we don't try to match in the middle
// of a character.
{"[a-c]*", "x", "\u65e5", "x\u65e5x"},
{"[^\u65e5]", "x", "abc\u65e5def", "xxx\u65e5xxx"},
// Start and end of a string.
{"^[a-c]*", "x", "abcdabc", "xdabc"},
{"[a-c]*$", "x", "abcdabc", "abcdx"},
{"^[a-c]*$", "x", "abcdabc", "abcdabc"},
{"^[a-c]*", "x", "abc", "x"},
{"[a-c]*$", "x", "abc", "x"},
{"^[a-c]*$", "x", "abc", "x"},
{"^[a-c]*", "x", "dabce", "xdabce"},
{"[a-c]*$", "x", "dabce", "dabcex"},
{"^[a-c]*$", "x", "dabce", "dabce"},
{"^[a-c]*", "x", "", "x"},
{"[a-c]*$", "x", "", "x"},
{"^[a-c]*$", "x", "", "x"},
{"^[a-c]+", "x", "abcdabc", "xdabc"},
{"[a-c]+$", "x", "abcdabc", "abcdx"},
{"^[a-c]+$", "x", "abcdabc", "abcdabc"},
{"^[a-c]+", "x", "abc", "x"},
{"[a-c]+$", "x", "abc", "x"},
{"^[a-c]+$", "x", "abc", "x"},
{"^[a-c]+", "x", "dabce", "dabce"},
{"[a-c]+$", "x", "dabce", "dabce"},
{"^[a-c]+$", "x", "dabce", "dabce"},
{"^[a-c]+", "x", "", ""},
{"[a-c]+$", "x", "", ""},
{"^[a-c]+$", "x", "", ""},
// Other cases.
{"abc", "def", "abcdefg", "defdefg"},
{"bc", "BC", "abcbcdcdedef", "aBCBCdcdedef"},
{"abc", "", "abcdabc", "d"},
{"x", "xXx", "xxxXxxx", "xXxxXxxXxXxXxxXxxXx"},
{"abc", "d", "", ""},
{"abc", "d", "abc", "d"},
{".+", "x", "abc", "x"},
{"[a-c]*", "x", "def", "xdxexfx"},
{"[a-c]+", "x", "abcbcdcdedef", "xdxdedef"},
{"[a-c]*", "x", "abcbcdcdedef", "xdxdxexdxexfx"},
// Substitutions
{"a+", "($0)", "banana", "b(a)n(a)n(a)"},
{"a+", "(${0})", "banana", "b(a)n(a)n(a)"},
{"a+", "(${0})$0", "banana", "b(a)an(a)an(a)a"},
{"a+", "(${0})$0", "banana", "b(a)an(a)an(a)a"},
{"hello, (.+)", "goodbye, ${1}", "hello, world", "goodbye, world"},
{"hello, (.+)", "goodbye, $1x", "hello, world", "goodbye, "},
{"hello, (.+)", "goodbye, ${1}x", "hello, world", "goodbye, worldx"},
{"hello, (.+)", "<$0><$1><$2><$3>", "hello, world", "<hello, world><world><><>"},
{"hello, (?P<noun>.+)", "goodbye, $noun!", "hello, world", "goodbye, world!"},
{"hello, (?P<noun>.+)", "goodbye, ${noun}", "hello, world", "goodbye, world"},
{"(?P<x>hi)|(?P<x>bye)", "$x$x$x", "hi", "hihihi"},
{"(?P<x>hi)|(?P<x>bye)", "$x$x$x", "bye", "byebyebye"},
{"(?P<x>hi)|(?P<x>bye)", "$xyz", "hi", ""},
{"(?P<x>hi)|(?P<x>bye)", "${x}yz", "hi", "hiyz"},
{"(?P<x>hi)|(?P<x>bye)", "hello $$x", "hi", "hello $x"},
{"a+", "${oops", "aaa", "${oops"},
{"a+", "$$", "aaa", "$"},
{"a+", "$", "aaa", "$"},
// Substitution when subexpression isn't found
{"(x)?", "$1", "123", "123"},
{"abc", "$1", "123", "123"},
}
var replaceLiteralTests = []ReplaceTest{
// Substitutions
{"a+", "($0)", "banana", "b($0)n($0)n($0)"},
{"a+", "(${0})", "banana", "b(${0})n(${0})n(${0})"},
{"a+", "(${0})$0", "banana", "b(${0})$0n(${0})$0n(${0})$0"},
{"a+", "(${0})$0", "banana", "b(${0})$0n(${0})$0n(${0})$0"},
{"hello, (.+)", "goodbye, ${1}", "hello, world", "goodbye, ${1}"},
{"hello, (?P<noun>.+)", "goodbye, $noun!", "hello, world", "goodbye, $noun!"},
{"hello, (?P<noun>.+)", "goodbye, ${noun}", "hello, world", "goodbye, ${noun}"},
{"(?P<x>hi)|(?P<x>bye)", "$x$x$x", "hi", "$x$x$x"},
{"(?P<x>hi)|(?P<x>bye)", "$x$x$x", "bye", "$x$x$x"},
{"(?P<x>hi)|(?P<x>bye)", "$xyz", "hi", "$xyz"},
{"(?P<x>hi)|(?P<x>bye)", "${x}yz", "hi", "${x}yz"},
{"(?P<x>hi)|(?P<x>bye)", "hello $$x", "hi", "hello $$x"},
{"a+", "${oops", "aaa", "${oops"},
{"a+", "$$", "aaa", "$$"},
{"a+", "$", "aaa", "$"},
}
type ReplaceFuncTest struct {
pattern string
replacement func(string) string
input, output string
}
var replaceFuncTests = []ReplaceFuncTest{
{"[a-c]", func(s string) string { return "x" + s + "y" }, "defabcdef", "defxayxbyxcydef"},
{"[a-c]+", func(s string) string { return "x" + s + "y" }, "defabcdef", "defxabcydef"},
{"[a-c]*", func(s string) string { return "x" + s + "y" }, "defabcdef", "xydxyexyfxabcydxyexyfxy"},
}
func TestReplaceAll(t *testing.T) {
for _, tc := range replaceTests {
re, err := Compile(tc.pattern)
if err != nil {
t.Errorf("Unexpected error compiling %q: %v", tc.pattern, err)
continue
}
actual := re.ReplaceAllString(tc.input, tc.replacement)
if actual != tc.output {
t.Errorf("%q.ReplaceAllString(%q,%q) = %q; want %q",
tc.pattern, tc.input, tc.replacement, actual, tc.output)
}
// now try bytes
actual = string(re.ReplaceAll([]byte(tc.input), []byte(tc.replacement)))
if actual != tc.output {
t.Errorf("%q.ReplaceAll(%q,%q) = %q; want %q",
tc.pattern, tc.input, tc.replacement, actual, tc.output)
}
}
}
func TestReplaceAllLiteral(t *testing.T) {
// Run ReplaceAll tests that do not have $ expansions.
for _, tc := range replaceTests {
if strings.Contains(tc.replacement, "$") {
continue
}
re, err := Compile(tc.pattern)
if err != nil {
t.Errorf("Unexpected error compiling %q: %v", tc.pattern, err)
continue
}
actual := re.ReplaceAllLiteralString(tc.input, tc.replacement)
if actual != tc.output {
t.Errorf("%q.ReplaceAllLiteralString(%q,%q) = %q; want %q",
tc.pattern, tc.input, tc.replacement, actual, tc.output)
}
// now try bytes
actual = string(re.ReplaceAllLiteral([]byte(tc.input), []byte(tc.replacement)))
if actual != tc.output {
t.Errorf("%q.ReplaceAllLiteral(%q,%q) = %q; want %q",
tc.pattern, tc.input, tc.replacement, actual, tc.output)
}
}
// Run literal-specific tests.
for _, tc := range replaceLiteralTests {
re, err := Compile(tc.pattern)
if err != nil {
t.Errorf("Unexpected error compiling %q: %v", tc.pattern, err)
continue
}
actual := re.ReplaceAllLiteralString(tc.input, tc.replacement)
if actual != tc.output {
t.Errorf("%q.ReplaceAllLiteralString(%q,%q) = %q; want %q",
tc.pattern, tc.input, tc.replacement, actual, tc.output)
}
// now try bytes
actual = string(re.ReplaceAllLiteral([]byte(tc.input), []byte(tc.replacement)))
if actual != tc.output {
t.Errorf("%q.ReplaceAllLiteral(%q,%q) = %q; want %q",
tc.pattern, tc.input, tc.replacement, actual, tc.output)
}
}
}
func TestReplaceAllFunc(t *testing.T) {
for _, tc := range replaceFuncTests {
re, err := Compile(tc.pattern)
if err != nil {
t.Errorf("Unexpected error compiling %q: %v", tc.pattern, err)
continue
}
actual := re.ReplaceAllStringFunc(tc.input, tc.replacement)
if actual != tc.output {
t.Errorf("%q.ReplaceFunc(%q,fn) = %q; want %q",
tc.pattern, tc.input, actual, tc.output)
}
// now try bytes
actual = string(re.ReplaceAllFunc([]byte(tc.input), func(s []byte) []byte { return []byte(tc.replacement(string(s))) }))
if actual != tc.output {
t.Errorf("%q.ReplaceFunc(%q,fn) = %q; want %q",
tc.pattern, tc.input, actual, tc.output)
}
}
}
type MetaTest struct {
pattern, output, literal string
isLiteral bool
}
var metaTests = []MetaTest{
{``, ``, ``, true},
{`foo`, `foo`, `foo`, true},
{`foo\.\$`, `foo\\\.\\\$`, `foo.$`, true}, // has meta but no operator
{`foo.\$`, `foo\.\\\$`, `foo`, false}, // has escaped operators and real operators
{`!@#$%^&*()_+-=[{]}\|,<.>/?~`, `!@#\$%\^&\*\(\)_\+-=\[\{\]\}\\\|,<\.>/\?~`, `!@#`, false},
}
func TestQuoteMeta(t *testing.T) {
for _, tc := range metaTests {
// Verify that QuoteMeta returns the expected string.
quoted := QuoteMeta(tc.pattern)
if quoted != tc.output {
t.Errorf("QuoteMeta(`%s`) = `%s`; want `%s`",
tc.pattern, quoted, tc.output)
continue
}
// Verify that the quoted string is in fact treated as expected
// by Compile -- i.e. that it matches the original, unquoted string.
if tc.pattern != "" {
re, err := Compile(quoted)
if err != nil {
t.Errorf("Unexpected error compiling QuoteMeta(`%s`): %v", tc.pattern, err)
continue
}
src := "abc" + tc.pattern + "def"
repl := "xyz"
replaced := re.ReplaceAllString(src, repl)
expected := "abcxyzdef"
if replaced != expected {
t.Errorf("QuoteMeta(`%s`).Replace(`%s`,`%s`) = `%s`; want `%s`",
tc.pattern, src, repl, replaced, expected)
}
}
}
}
func TestLiteralPrefix(t *testing.T) {
for _, tc := range metaTests {
// Literal method needs to scan the pattern.
re := MustCompile(tc.pattern)
str, complete := re.LiteralPrefix()
if complete != tc.isLiteral {
t.Errorf("LiteralPrefix(`%s`) = %t; want %t", tc.pattern, complete, tc.isLiteral)
}
if str != tc.literal {
t.Errorf("LiteralPrefix(`%s`) = `%s`; want `%s`", tc.pattern, str, tc.literal)
}
}
}
type subexpCase struct {
input string
num int
names []string
}
var subexpCases = []subexpCase{
{``, 0, nil},
{`.*`, 0, nil},
{`abba`, 0, nil},
{`ab(b)a`, 1, []string{"", ""}},
{`ab(.*)a`, 1, []string{"", ""}},
{`(.*)ab(.*)a`, 2, []string{"", "", ""}},
{`(.*)(ab)(.*)a`, 3, []string{"", "", "", ""}},
{`(.*)((a)b)(.*)a`, 4, []string{"", "", "", "", ""}},
{`(.*)(\(ab)(.*)a`, 3, []string{"", "", "", ""}},
{`(.*)(\(a\)b)(.*)a`, 3, []string{"", "", "", ""}},
{`(?P<foo>.*)(?P<bar>(a)b)(?P<foo>.*)a`, 4, []string{"", "foo", "bar", "", "foo"}},
}
func TestSubexp(t *testing.T) {
for _, c := range subexpCases {
re := MustCompile(c.input)
n := re.NumSubexp()
if n != c.num {
t.Errorf("%q: NumSubexp = %d, want %d", c.input, n, c.num)
continue
}
names := re.SubexpNames()
if len(names) != 1+n {
t.Errorf("%q: len(SubexpNames) = %d, want %d", c.input, len(names), n)
continue
}
if c.names != nil {
for i := 0; i < 1+n; i++ {
if names[i] != c.names[i] {
t.Errorf("%q: SubexpNames[%d] = %q, want %q", c.input, i, names[i], c.names[i])
}
}
}
}
}
var splitTests = []struct {
s string
r string
n int
out []string
}{
{"foo:and:bar", ":", -1, []string{"foo", "and", "bar"}},
{"foo:and:bar", ":", 1, []string{"foo:and:bar"}},
{"foo:and:bar", ":", 2, []string{"foo", "and:bar"}},
{"foo:and:bar", "foo", -1, []string{"", ":and:bar"}},
{"foo:and:bar", "bar", -1, []string{"foo:and:", ""}},
{"foo:and:bar", "baz", -1, []string{"foo:and:bar"}},
{"baabaab", "a", -1, []string{"b", "", "b", "", "b"}},
{"baabaab", "a*", -1, []string{"b", "b", "b"}},
{"baabaab", "ba*", -1, []string{"", "", "", ""}},
{"foobar", "f*b*", -1, []string{"", "o", "o", "a", "r"}},
{"foobar", "f+.*b+", -1, []string{"", "ar"}},
{"foobooboar", "o{2}", -1, []string{"f", "b", "boar"}},
{"a,b,c,d,e,f", ",", 3, []string{"a", "b", "c,d,e,f"}},
{"a,b,c,d,e,f", ",", 0, nil},
{",", ",", -1, []string{"", ""}},
{",,,", ",", -1, []string{"", "", "", ""}},
{"", ",", -1, []string{""}},
{"", ".*", -1, []string{""}},
{"", ".+", -1, []string{""}},
{"", "", -1, []string{}},
{"foobar", "", -1, []string{"f", "o", "o", "b", "a", "r"}},
{"abaabaccadaaae", "a*", 5, []string{"", "b", "b", "c", "cadaaae"}},
{":x:y:z:", ":", -1, []string{"", "x", "y", "z", ""}},
}
func TestSplit(t *testing.T) {
for i, test := range splitTests {
re, err := Compile(test.r)
if err != nil {
t.Errorf("#%d: %q: compile error: %s", i, test.r, err.Error())
continue
}
split := re.Split(test.s, test.n)
if !reflect.DeepEqual(split, test.out) {
t.Errorf("#%d: %q: got %q; want %q", i, test.r, split, test.out)
}
if QuoteMeta(test.r) == test.r {
strsplit := strings.SplitN(test.s, test.r, test.n)
if !reflect.DeepEqual(split, strsplit) {
t.Errorf("#%d: Split(%q, %q, %d): regexp vs strings mismatch\nregexp=%q\nstrings=%q", i, test.s, test.r, test.n, split, strsplit)
}
}
}
}
// Check that one-pass cutoff does trigger.
func TestOnePassCutoff(t *testing.T) {
re, err := syntax.Parse(`^x{1,1000}y{1,1000}$`, syntax.Perl)
if err != nil {
t.Fatalf("parse: %v", err)
}
p, err := syntax.Compile(re.Simplify())
if err != nil {
t.Fatalf("compile: %v", err)
}
if compileOnePass(p) != notOnePass {
t.Fatalf("makeOnePass succeeded; wanted notOnePass")
}
}
func BenchmarkLiteral(b *testing.B) {
x := strings.Repeat("x", 50) + "y"
b.StopTimer()
re := MustCompile("y")
b.StartTimer()
for i := 0; i < b.N; i++ {
if !re.MatchString(x) {
b.Fatalf("no match!")
}
}
}
func BenchmarkNotLiteral(b *testing.B) {
x := strings.Repeat("x", 50) + "y"
b.StopTimer()
re := MustCompile(".y")
b.StartTimer()
for i := 0; i < b.N; i++ {
if !re.MatchString(x) {
b.Fatalf("no match!")
}
}
}
func BenchmarkMatchClass(b *testing.B) {
b.StopTimer()
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()
for i := 0; i < b.N; i++ {
if !re.MatchString(x) {
b.Fatalf("no match!")
}
}
}
func BenchmarkReplaceAll(b *testing.B) {
x := "abcdefghijklmnopqrstuvwxyz"
b.StopTimer()
re := MustCompile("[cjrw]")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.ReplaceAllString(x, "")
}
}
func BenchmarkAnchoredLiteralShortNonMatch(b *testing.B) {
b.StopTimer()
x := []byte("abcdefghijklmnopqrstuvwxyz")
re := MustCompile("^zbc(d|e)")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}
func BenchmarkAnchoredLiteralLongNonMatch(b *testing.B) {
b.StopTimer()
x := []byte("abcdefghijklmnopqrstuvwxyz")
for i := 0; i < 15; i++ {
x = append(x, x...)
}
re := MustCompile("^zbc(d|e)")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}
func BenchmarkAnchoredShortMatch(b *testing.B) {
b.StopTimer()
x := []byte("abcdefghijklmnopqrstuvwxyz")
re := MustCompile("^.bc(d|e)")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}
func BenchmarkAnchoredLongMatch(b *testing.B) {
b.StopTimer()
x := []byte("abcdefghijklmnopqrstuvwxyz")
for i := 0; i < 15; i++ {
x = append(x, x...)
}
re := MustCompile("^.bc(d|e)")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}
func BenchmarkOnePassShortA(b *testing.B) {
b.StopTimer()
x := []byte("abcddddddeeeededd")
re := MustCompile("^.bc(d|e)*$")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}
func BenchmarkNotOnePassShortA(b *testing.B) {
b.StopTimer()
x := []byte("abcddddddeeeededd")
re := MustCompile(".bc(d|e)*$")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}
func BenchmarkOnePassShortB(b *testing.B) {
b.StopTimer()
x := []byte("abcddddddeeeededd")
re := MustCompile("^.bc(?:d|e)*$")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}
func BenchmarkNotOnePassShortB(b *testing.B) {
b.StopTimer()
x := []byte("abcddddddeeeededd")
re := MustCompile(".bc(?:d|e)*$")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}
func BenchmarkOnePassLongPrefix(b *testing.B) {
b.StopTimer()
x := []byte("abcdefghijklmnopqrstuvwxyz")
re := MustCompile("^abcdefghijklmnopqrstuvwxyz.*$")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}
func BenchmarkOnePassLongNotPrefix(b *testing.B) {
b.StopTimer()
x := []byte("abcdefghijklmnopqrstuvwxyz")
re := MustCompile("^.bcdefghijklmnopqrstuvwxyz.*$")
b.StartTimer()
for i := 0; i < b.N; i++ {
re.Match(x)
}
}