src/regexp/all_test.go - go - Git at Google

 // 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)
 	}
 }
	// 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", "fb", -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)
	}
	}