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Source file src/regexp/all_test.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 goodRe = []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 badRe = []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(goodRe); i++ {
  		compileTest(t, goodRe[i], "")
  	}
  }
  
  func TestBadCompile(t *testing.T) {
  	for i := 0; i < len(badRe); i++ {
  		compileTest(t, badRe[i].re, badRe[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)
  	}
  }
  
  func copyMatchTest(t *testing.T, test *FindTest) {
  	re := compileTest(t, test.pat, "")
  	if re == nil {
  		return
  	}
  	m1 := re.MatchString(test.text)
  	m2 := re.Copy().MatchString(test.text)
  	if m1 != m2 {
  		t.Errorf("Copied Regexp match failure on %s: original gave %t; copy gave %t; should be %t",
  			test, m1, m2, len(test.matches) > 0)
  	}
  }
  
  func TestCopyMatch(t *testing.T) {
  	for _, test := range findTests {
  		copyMatchTest(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"},
  
  	// Substitutions involving a (x){0}
  	{"(a)(b){0}(c)", ".$1|$3.", "xacxacx", "x.a|c.x.a|c.x"},
  	{"(a)(((b))){0}c", ".$1.", "xacxacx", "x.a.x.a.x"},
  	{"((a(b){0}){3}){5}(h)", "y caramb$2", "say aaaaaaaaaaaaaaaah", "say ay caramba"},
  	{"((a(b){0}){3}){5}h", "y caramb$2", "say aaaaaaaaaaaaaaaah", "say ay caramba"},
  }
  
  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},
  }
  
  var literalPrefixTests = []MetaTest{
  	// See golang.org/issue/11175.
  	// output is unused.
  	{`^0^0$`, ``, `0`, false},
  	{`^0^`, ``, ``, false},
  	{`^0$`, ``, `0`, true},
  	{`$0^`, ``, ``, false},
  	{`$0$`, ``, ``, false},
  	{`^^0$$`, ``, ``, false},
  	{`^$^$`, ``, ``, false},
  	{`$$0^^`, ``, ``, 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 append(metaTests, literalPrefixTests...) {
  		// 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)
  			}
  		}
  	}
  }
  
  // The following sequence of Match calls used to panic. See issue #12980.
  func TestParseAndCompile(t *testing.T) {
  	expr := "a$"
  	s := "a\nb"
  
  	for i, tc := range []struct {
  		reFlags  syntax.Flags
  		expMatch bool
  	}{
  		{syntax.Perl | syntax.OneLine, false},
  		{syntax.Perl &^ syntax.OneLine, true},
  	} {
  		parsed, err := syntax.Parse(expr, tc.reFlags)
  		if err != nil {
  			t.Fatalf("%d: parse: %v", i, err)
  		}
  		re, err := Compile(parsed.String())
  		if err != nil {
  			t.Fatalf("%d: compile: %v", i, err)
  		}
  		if match := re.MatchString(s); match != tc.expMatch {
  			t.Errorf("%d: %q.MatchString(%q)=%t; expected=%t", i, re, s, match, tc.expMatch)
  		}
  	}
  }
  
  // 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")
  	}
  }
  
  // Check that the same machine can be used with the standard matcher
  // and then the backtracker when there are no captures.
  func TestSwitchBacktrack(t *testing.T) {
  	re := MustCompile(`a|b`)
  	long := make([]byte, maxBacktrackVector+1)
  
  	// The following sequence of Match calls used to panic. See issue #10319.
  	re.Match(long)     // triggers standard matcher
  	re.Match(long[:1]) // triggers backtracker
  }
  
  func BenchmarkFind(b *testing.B) {
  	b.StopTimer()
  	re := MustCompile("a+b+")
  	wantSubs := "aaabb"
  	s := []byte("acbb" + wantSubs + "dd")
  	b.StartTimer()
  	b.ReportAllocs()
  	for i := 0; i < b.N; i++ {
  		subs := re.Find(s)
  		if string(subs) != wantSubs {
  			b.Fatalf("Find(%q) = %q; want %q", s, subs, wantSubs)
  		}
  	}
  }
  
  func BenchmarkFindString(b *testing.B) {
  	b.StopTimer()
  	re := MustCompile("a+b+")
  	wantSubs := "aaabb"
  	s := "acbb" + wantSubs + "dd"
  	b.StartTimer()
  	b.ReportAllocs()
  	for i := 0; i < b.N; i++ {
  		subs := re.FindString(s)
  		if subs != wantSubs {
  			b.Fatalf("FindString(%q) = %q; want %q", s, subs, wantSubs)
  		}
  	}
  }
  
  func BenchmarkFindSubmatch(b *testing.B) {
  	b.StopTimer()
  	re := MustCompile("a(a+b+)b")
  	wantSubs := "aaabb"
  	s := []byte("acbb" + wantSubs + "dd")
  	b.StartTimer()
  	b.ReportAllocs()
  	for i := 0; i < b.N; i++ {
  		subs := re.FindSubmatch(s)
  		if string(subs[0]) != wantSubs {
  			b.Fatalf("FindSubmatch(%q)[0] = %q; want %q", s, subs[0], wantSubs)
  		}
  		if string(subs[1]) != "aab" {
  			b.Fatalf("FindSubmatch(%q)[1] = %q; want %q", s, subs[1], "aab")
  		}
  	}
  }
  
  func BenchmarkFindStringSubmatch(b *testing.B) {
  	b.StopTimer()
  	re := MustCompile("a(a+b+)b")
  	wantSubs := "aaabb"
  	s := "acbb" + wantSubs + "dd"
  	b.StartTimer()
  	b.ReportAllocs()
  	for i := 0; i < b.N; i++ {
  		subs := re.FindStringSubmatch(s)
  		if subs[0] != wantSubs {
  			b.Fatalf("FindStringSubmatch(%q)[0] = %q; want %q", s, subs[0], wantSubs)
  		}
  		if subs[1] != "aab" {
  			b.Fatalf("FindStringSubmatch(%q)[1] = %q; want %q", s, subs[1], "aab")
  		}
  	}
  }
  
  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)
  	}
  }
  
  func BenchmarkMatchParallelShared(b *testing.B) {
  	x := []byte("this is a long line that contains foo bar baz")
  	re := MustCompile("foo (ba+r)? baz")
  	b.ResetTimer()
  	b.RunParallel(func(pb *testing.PB) {
  		for pb.Next() {
  			re.Match(x)
  		}
  	})
  }
  
  func BenchmarkMatchParallelCopied(b *testing.B) {
  	x := []byte("this is a long line that contains foo bar baz")
  	re := MustCompile("foo (ba+r)? baz")
  	b.ResetTimer()
  	b.RunParallel(func(pb *testing.PB) {
  		re := re.Copy()
  		for pb.Next() {
  			re.Match(x)
  		}
  	})
  }
  
  var sink string
  
  func BenchmarkQuoteMetaAll(b *testing.B) {
  	s := string(specialBytes)
  	b.SetBytes(int64(len(s)))
  	b.ResetTimer()
  	for i := 0; i < b.N; i++ {
  		sink = QuoteMeta(s)
  	}
  }
  
  func BenchmarkQuoteMetaNone(b *testing.B) {
  	s := "abcdefghijklmnopqrstuvwxyz"
  	b.SetBytes(int64(len(s)))
  	b.ResetTimer()
  	for i := 0; i < b.N; i++ {
  		sink = QuoteMeta(s)
  	}
  }
  

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