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| author | Ondřej Surý <ondrej@sury.org> | 2011-09-13 13:13:40 +0200 | 
|---|---|---|
| committer | Ondřej Surý <ondrej@sury.org> | 2011-09-13 13:13:40 +0200 | 
| commit | 5ff4c17907d5b19510a62e08fd8d3b11e62b431d (patch) | |
| tree | c0650497e988f47be9c6f2324fa692a52dea82e1 /src/pkg/exp/regexp/regexp.go | |
| parent | 80f18fc933cf3f3e829c5455a1023d69f7b86e52 (diff) | |
| download | golang-5ff4c17907d5b19510a62e08fd8d3b11e62b431d.tar.gz | |
Imported Upstream version 60upstream/60
Diffstat (limited to 'src/pkg/exp/regexp/regexp.go')
| -rw-r--r-- | src/pkg/exp/regexp/regexp.go | 795 | 
1 files changed, 795 insertions, 0 deletions
| diff --git a/src/pkg/exp/regexp/regexp.go b/src/pkg/exp/regexp/regexp.go new file mode 100644 index 000000000..1b75900f8 --- /dev/null +++ b/src/pkg/exp/regexp/regexp.go @@ -0,0 +1,795 @@ +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Package regexp implements a simple regular expression library. +// +// The syntax of the regular expressions accepted is the same +// general syntax used by Perl, Python, and other languages. +// More precisely, it is the syntax accepted by RE2 and described at +// http://code.google.com/p/re2/wiki/Syntax, except for \C. +// +// All characters are UTF-8-encoded code points. +// +// There are 16 methods of Regexp that match a regular expression and identify +// the matched text.  Their names are matched by this regular expression: +// +//	Find(All)?(String)?(Submatch)?(Index)? +// +// If 'All' is present, the routine matches successive non-overlapping +// matches of the entire expression.  Empty matches abutting a preceding +// match are ignored.  The return value is a slice containing the successive +// return values of the corresponding non-'All' routine.  These routines take +// an extra integer argument, n; if n >= 0, the function returns at most n +// matches/submatches. +// +// If 'String' is present, the argument is a string; otherwise it is a slice +// of bytes; return values are adjusted as appropriate. +// +// If 'Submatch' is present, the return value is a slice identifying the +// successive submatches of the expression.  Submatches are matches of +// parenthesized subexpressions within the regular expression, numbered from +// left to right in order of opening parenthesis.  Submatch 0 is the match of +// the entire expression, submatch 1 the match of the first parenthesized +// subexpression, and so on. +// +// If 'Index' is present, matches and submatches are identified by byte index +// pairs within the input string: result[2*n:2*n+1] identifies the indexes of +// the nth submatch.  The pair for n==0 identifies the match of the entire +// expression.  If 'Index' is not present, the match is identified by the +// text of the match/submatch.  If an index is negative, it means that +// subexpression did not match any string in the input. +// +// There is also a subset of the methods that can be applied to text read +// from a RuneReader: +// +//	MatchReader, FindReaderIndex, FindReaderSubmatchIndex +// +// This set may grow.  Note that regular expression matches may need to +// examine text beyond the text returned by a match, so the methods that +// match text from a RuneReader may read arbitrarily far into the input +// before returning. +// +// (There are a few other methods that do not match this pattern.) +// +package regexp + +import ( +	"bytes" +	"exp/regexp/syntax" +	"io" +	"os" +	"strings" +	"sync" +	"utf8" +) + +var debug = false + +// Error is the local type for a parsing error. +type Error string + +func (e Error) String() string { +	return string(e) +} + +// Regexp is the representation of a compiled regular expression. +// The public interface is entirely through methods. +// A Regexp is safe for concurrent use by multiple goroutines. +type Regexp struct { +	// read-only after Compile +	expr           string         // as passed to Compile +	prog           *syntax.Prog   // compiled program +	prefix         string         // required prefix in unanchored matches +	prefixBytes    []byte         // prefix, as a []byte +	prefixComplete bool           // prefix is the entire regexp +	prefixRune     int            // first rune in prefix +	cond           syntax.EmptyOp // empty-width conditions required at start of match + +	// cache of machines for running regexp +	mu      sync.Mutex +	machine []*machine +} + +// String returns the source text used to compile the regular expression. +func (re *Regexp) String() string { +	return re.expr +} + +// Compile parses a regular expression and returns, if successful, a Regexp +// object that can be used to match against text. +func Compile(expr string) (*Regexp, os.Error) { +	re, err := syntax.Parse(expr, syntax.Perl) +	if err != nil { +		return nil, err +	} +	prog, err := syntax.Compile(re) +	if err != nil { +		return nil, err +	} +	regexp := &Regexp{ +		expr: expr, +		prog: prog, +	} +	regexp.prefix, regexp.prefixComplete = prog.Prefix() +	if regexp.prefix != "" { +		// TODO(rsc): Remove this allocation by adding +		// IndexString to package bytes. +		regexp.prefixBytes = []byte(regexp.prefix) +		regexp.prefixRune, _ = utf8.DecodeRuneInString(regexp.prefix) +	} +	regexp.cond = prog.StartCond() +	return regexp, nil +} + +// get returns a machine to use for matching re. +// It uses the re's machine cache if possible, to avoid +// unnecessary allocation. +func (re *Regexp) get() *machine { +	re.mu.Lock() +	if n := len(re.machine); n > 0 { +		z := re.machine[n-1] +		re.machine = re.machine[:n-1] +		re.mu.Unlock() +		return z +	} +	re.mu.Unlock() +	z := progMachine(re.prog) +	z.re = re +	return z +} + +// put returns a machine to the re's machine cache. +// There is no attempt to limit the size of the cache, so it will +// grow to the maximum number of simultaneous matches +// run using re.  (The cache empties when re gets garbage collected.) +func (re *Regexp) put(z *machine) { +	re.mu.Lock() +	re.machine = append(re.machine, z) +	re.mu.Unlock() +} + +// MustCompile is like Compile but panics if the expression cannot be parsed. +// It simplifies safe initialization of global variables holding compiled regular +// expressions. +func MustCompile(str string) *Regexp { +	regexp, error := Compile(str) +	if error != nil { +		panic(`regexp: compiling "` + str + `": ` + error.String()) +	} +	return regexp +} + +// NumSubexp returns the number of parenthesized subexpressions in this Regexp. +func (re *Regexp) NumSubexp() int { +	// NumCap/2 because captures count ( and ) separately. +	// -1 because NumCap counts $0 but NumSubexp does not. +	return re.prog.NumCap/2 - 1 +} + +const endOfText = -1 + +// input abstracts different representations of the input text. It provides +// one-character lookahead. +type input interface { +	step(pos int) (rune int, width int) // advance one rune +	canCheckPrefix() bool               // can we look ahead without losing info? +	hasPrefix(re *Regexp) bool +	index(re *Regexp, pos int) int +} + +// inputString scans a string. +type inputString struct { +	str string +} + +func newInputString(str string) *inputString { +	return &inputString{str: str} +} + +func (i *inputString) step(pos int) (int, int) { +	if pos < len(i.str) { +		return utf8.DecodeRuneInString(i.str[pos:len(i.str)]) +	} +	return endOfText, 0 +} + +func (i *inputString) canCheckPrefix() bool { +	return true +} + +func (i *inputString) hasPrefix(re *Regexp) bool { +	return strings.HasPrefix(i.str, re.prefix) +} + +func (i *inputString) index(re *Regexp, pos int) int { +	return strings.Index(i.str[pos:], re.prefix) +} + +// inputBytes scans a byte slice. +type inputBytes struct { +	str []byte +} + +func newInputBytes(str []byte) *inputBytes { +	return &inputBytes{str: str} +} + +func (i *inputBytes) step(pos int) (int, int) { +	if pos < len(i.str) { +		return utf8.DecodeRune(i.str[pos:len(i.str)]) +	} +	return endOfText, 0 +} + +func (i *inputBytes) canCheckPrefix() bool { +	return true +} + +func (i *inputBytes) hasPrefix(re *Regexp) bool { +	return bytes.HasPrefix(i.str, re.prefixBytes) +} + +func (i *inputBytes) index(re *Regexp, pos int) int { +	return bytes.Index(i.str[pos:], re.prefixBytes) +} + +// inputReader scans a RuneReader. +type inputReader struct { +	r     io.RuneReader +	atEOT bool +	pos   int +} + +func newInputReader(r io.RuneReader) *inputReader { +	return &inputReader{r: r} +} + +func (i *inputReader) step(pos int) (int, int) { +	if !i.atEOT && pos != i.pos { +		return endOfText, 0 + +	} +	r, w, err := i.r.ReadRune() +	if err != nil { +		i.atEOT = true +		return endOfText, 0 +	} +	i.pos += w +	return r, w +} + +func (i *inputReader) canCheckPrefix() bool { +	return false +} + +func (i *inputReader) hasPrefix(re *Regexp) bool { +	return false +} + +func (i *inputReader) index(re *Regexp, pos int) int { +	return -1 +} + +// LiteralPrefix returns a literal string that must begin any match +// of the regular expression re.  It returns the boolean true if the +// literal string comprises the entire regular expression. +func (re *Regexp) LiteralPrefix() (prefix string, complete bool) { +	return re.prefix, re.prefixComplete +} + +// MatchReader returns whether the Regexp matches the text read by the +// RuneReader.  The return value is a boolean: true for match, false for no +// match. +func (re *Regexp) MatchReader(r io.RuneReader) bool { +	return re.doExecute(newInputReader(r), 0, 0) != nil +} + +// MatchString returns whether the Regexp matches the string s. +// The return value is a boolean: true for match, false for no match. +func (re *Regexp) MatchString(s string) bool { +	return re.doExecute(newInputString(s), 0, 0) != nil +} + +// Match returns whether the Regexp matches the byte slice b. +// The return value is a boolean: true for match, false for no match. +func (re *Regexp) Match(b []byte) bool { +	return re.doExecute(newInputBytes(b), 0, 0) != nil +} + +// MatchReader checks whether a textual regular expression matches the text +// read by the RuneReader.  More complicated queries need to use Compile and +// the full Regexp interface. +func MatchReader(pattern string, r io.RuneReader) (matched bool, error os.Error) { +	re, err := Compile(pattern) +	if err != nil { +		return false, err +	} +	return re.MatchReader(r), nil +} + +// MatchString checks whether a textual regular expression +// matches a string.  More complicated queries need +// to use Compile and the full Regexp interface. +func MatchString(pattern string, s string) (matched bool, error os.Error) { +	re, err := Compile(pattern) +	if err != nil { +		return false, err +	} +	return re.MatchString(s), nil +} + +// Match checks whether a textual regular expression +// matches a byte slice.  More complicated queries need +// to use Compile and the full Regexp interface. +func Match(pattern string, b []byte) (matched bool, error os.Error) { +	re, err := Compile(pattern) +	if err != nil { +		return false, err +	} +	return re.Match(b), nil +} + +// ReplaceAllString returns a copy of src in which all matches for the Regexp +// have been replaced by repl.  No support is provided for expressions +// (e.g. \1 or $1) in the replacement string. +func (re *Regexp) ReplaceAllString(src, repl string) string { +	return re.ReplaceAllStringFunc(src, func(string) string { return repl }) +} + +// ReplaceAllStringFunc returns a copy of src in which all matches for the +// Regexp have been replaced by the return value of of function repl (whose +// first argument is the matched string).  No support is provided for +// expressions (e.g. \1 or $1) in the replacement string. +func (re *Regexp) ReplaceAllStringFunc(src string, repl func(string) string) string { +	lastMatchEnd := 0 // end position of the most recent match +	searchPos := 0    // position where we next look for a match +	buf := new(bytes.Buffer) +	for searchPos <= len(src) { +		a := re.doExecute(newInputString(src), searchPos, 2) +		if len(a) == 0 { +			break // no more matches +		} + +		// Copy the unmatched characters before this match. +		io.WriteString(buf, src[lastMatchEnd:a[0]]) + +		// Now insert a copy of the replacement string, but not for a +		// match of the empty string immediately after another match. +		// (Otherwise, we get double replacement for patterns that +		// match both empty and nonempty strings.) +		if a[1] > lastMatchEnd || a[0] == 0 { +			io.WriteString(buf, repl(src[a[0]:a[1]])) +		} +		lastMatchEnd = a[1] + +		// Advance past this match; always advance at least one character. +		_, width := utf8.DecodeRuneInString(src[searchPos:]) +		if searchPos+width > a[1] { +			searchPos += width +		} else if searchPos+1 > a[1] { +			// This clause is only needed at the end of the input +			// string.  In that case, DecodeRuneInString returns width=0. +			searchPos++ +		} else { +			searchPos = a[1] +		} +	} + +	// Copy the unmatched characters after the last match. +	io.WriteString(buf, src[lastMatchEnd:]) + +	return buf.String() +} + +// ReplaceAll returns a copy of src in which all matches for the Regexp +// have been replaced by repl.  No support is provided for expressions +// (e.g. \1 or $1) in the replacement text. +func (re *Regexp) ReplaceAll(src, repl []byte) []byte { +	return re.ReplaceAllFunc(src, func([]byte) []byte { return repl }) +} + +// ReplaceAllFunc returns a copy of src in which all matches for the +// Regexp have been replaced by the return value of of function repl (whose +// first argument is the matched []byte).  No support is provided for +// expressions (e.g. \1 or $1) in the replacement string. +func (re *Regexp) ReplaceAllFunc(src []byte, repl func([]byte) []byte) []byte { +	lastMatchEnd := 0 // end position of the most recent match +	searchPos := 0    // position where we next look for a match +	buf := new(bytes.Buffer) +	for searchPos <= len(src) { +		a := re.doExecute(newInputBytes(src), searchPos, 2) +		if len(a) == 0 { +			break // no more matches +		} + +		// Copy the unmatched characters before this match. +		buf.Write(src[lastMatchEnd:a[0]]) + +		// Now insert a copy of the replacement string, but not for a +		// match of the empty string immediately after another match. +		// (Otherwise, we get double replacement for patterns that +		// match both empty and nonempty strings.) +		if a[1] > lastMatchEnd || a[0] == 0 { +			buf.Write(repl(src[a[0]:a[1]])) +		} +		lastMatchEnd = a[1] + +		// Advance past this match; always advance at least one character. +		_, width := utf8.DecodeRune(src[searchPos:]) +		if searchPos+width > a[1] { +			searchPos += width +		} else if searchPos+1 > a[1] { +			// This clause is only needed at the end of the input +			// string.  In that case, DecodeRuneInString returns width=0. +			searchPos++ +		} else { +			searchPos = a[1] +		} +	} + +	// Copy the unmatched characters after the last match. +	buf.Write(src[lastMatchEnd:]) + +	return buf.Bytes() +} + +var specialBytes = []byte(`\.+*?()|[]{}^$`) + +func special(b byte) bool { +	return bytes.IndexByte(specialBytes, b) >= 0 +} + +// QuoteMeta returns a string that quotes all regular expression metacharacters +// inside the argument text; the returned string is a regular expression matching +// the literal text.  For example, QuoteMeta(`[foo]`) returns `\[foo\]`. +func QuoteMeta(s string) string { +	b := make([]byte, 2*len(s)) + +	// A byte loop is correct because all metacharacters are ASCII. +	j := 0 +	for i := 0; i < len(s); i++ { +		if special(s[i]) { +			b[j] = '\\' +			j++ +		} +		b[j] = s[i] +		j++ +	} +	return string(b[0:j]) +} + +// Find matches in slice b if b is non-nil, otherwise find matches in string s. +func (re *Regexp) allMatches(s string, b []byte, n int, deliver func([]int)) { +	var end int +	if b == nil { +		end = len(s) +	} else { +		end = len(b) +	} + +	for pos, i, prevMatchEnd := 0, 0, -1; i < n && pos <= end; { +		var in input +		if b == nil { +			in = newInputString(s) +		} else { +			in = newInputBytes(b) +		} +		matches := re.doExecute(in, pos, re.prog.NumCap) +		if len(matches) == 0 { +			break +		} + +		accept := true +		if matches[1] == pos { +			// We've found an empty match. +			if matches[0] == prevMatchEnd { +				// We don't allow an empty match right +				// after a previous match, so ignore it. +				accept = false +			} +			var width int +			// TODO: use step() +			if b == nil { +				_, width = utf8.DecodeRuneInString(s[pos:end]) +			} else { +				_, width = utf8.DecodeRune(b[pos:end]) +			} +			if width > 0 { +				pos += width +			} else { +				pos = end + 1 +			} +		} else { +			pos = matches[1] +		} +		prevMatchEnd = matches[1] + +		if accept { +			deliver(matches) +			i++ +		} +	} +} + +// Find returns a slice holding the text of the leftmost match in b of the regular expression. +// A return value of nil indicates no match. +func (re *Regexp) Find(b []byte) []byte { +	a := re.doExecute(newInputBytes(b), 0, 2) +	if a == nil { +		return nil +	} +	return b[a[0]:a[1]] +} + +// FindIndex returns a two-element slice of integers defining the location of +// the leftmost match in b of the regular expression.  The match itself is at +// b[loc[0]:loc[1]]. +// A return value of nil indicates no match. +func (re *Regexp) FindIndex(b []byte) (loc []int) { +	a := re.doExecute(newInputBytes(b), 0, 2) +	if a == nil { +		return nil +	} +	return a[0:2] +} + +// FindString returns a string holding the text of the leftmost match in s of the regular +// expression.  If there is no match, the return value is an empty string, +// but it will also be empty if the regular expression successfully matches +// an empty string.  Use FindStringIndex or FindStringSubmatch if it is +// necessary to distinguish these cases. +func (re *Regexp) FindString(s string) string { +	a := re.doExecute(newInputString(s), 0, 2) +	if a == nil { +		return "" +	} +	return s[a[0]:a[1]] +} + +// FindStringIndex returns a two-element slice of integers defining the +// location of the leftmost match in s of the regular expression.  The match +// itself is at s[loc[0]:loc[1]]. +// A return value of nil indicates no match. +func (re *Regexp) FindStringIndex(s string) []int { +	a := re.doExecute(newInputString(s), 0, 2) +	if a == nil { +		return nil +	} +	return a[0:2] +} + +// FindReaderIndex returns a two-element slice of integers defining the +// location of the leftmost match of the regular expression in text read from +// the RuneReader.  The match itself is at s[loc[0]:loc[1]].  A return +// value of nil indicates no match. +func (re *Regexp) FindReaderIndex(r io.RuneReader) []int { +	a := re.doExecute(newInputReader(r), 0, 2) +	if a == nil { +		return nil +	} +	return a[0:2] +} + +// FindSubmatch returns a slice of slices holding the text of the leftmost +// match of the regular expression in b and the matches, if any, of its +// subexpressions, as defined by the 'Submatch' descriptions in the package +// comment. +// A return value of nil indicates no match. +func (re *Regexp) FindSubmatch(b []byte) [][]byte { +	a := re.doExecute(newInputBytes(b), 0, re.prog.NumCap) +	if a == nil { +		return nil +	} +	ret := make([][]byte, len(a)/2) +	for i := range ret { +		if a[2*i] >= 0 { +			ret[i] = b[a[2*i]:a[2*i+1]] +		} +	} +	return ret +} + +// FindSubmatchIndex returns a slice holding the index pairs identifying the +// leftmost match of the regular expression in b and the matches, if any, of +// its subexpressions, as defined by the 'Submatch' and 'Index' descriptions +// in the package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindSubmatchIndex(b []byte) []int { +	return re.doExecute(newInputBytes(b), 0, re.prog.NumCap) +} + +// FindStringSubmatch returns a slice of strings holding the text of the +// leftmost match of the regular expression in s and the matches, if any, of +// its subexpressions, as defined by the 'Submatch' description in the +// package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindStringSubmatch(s string) []string { +	a := re.doExecute(newInputString(s), 0, re.prog.NumCap) +	if a == nil { +		return nil +	} +	ret := make([]string, len(a)/2) +	for i := range ret { +		if a[2*i] >= 0 { +			ret[i] = s[a[2*i]:a[2*i+1]] +		} +	} +	return ret +} + +// FindStringSubmatchIndex returns a slice holding the index pairs +// identifying the leftmost match of the regular expression in s and the +// matches, if any, of its subexpressions, as defined by the 'Submatch' and +// 'Index' descriptions in the package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindStringSubmatchIndex(s string) []int { +	return re.doExecute(newInputString(s), 0, re.prog.NumCap) +} + +// FindReaderSubmatchIndex returns a slice holding the index pairs +// identifying the leftmost match of the regular expression of text read by +// the RuneReader, and the matches, if any, of its subexpressions, as defined +// by the 'Submatch' and 'Index' descriptions in the package comment.  A +// return value of nil indicates no match. +func (re *Regexp) FindReaderSubmatchIndex(r io.RuneReader) []int { +	return re.doExecute(newInputReader(r), 0, re.prog.NumCap) +} + +const startSize = 10 // The size at which to start a slice in the 'All' routines. + +// FindAll is the 'All' version of Find; it returns a slice of all successive +// matches of the expression, as defined by the 'All' description in the +// package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindAll(b []byte, n int) [][]byte { +	if n < 0 { +		n = len(b) + 1 +	} +	result := make([][]byte, 0, startSize) +	re.allMatches("", b, n, func(match []int) { +		result = append(result, b[match[0]:match[1]]) +	}) +	if len(result) == 0 { +		return nil +	} +	return result +} + +// FindAllIndex is the 'All' version of FindIndex; it returns a slice of all +// successive matches of the expression, as defined by the 'All' description +// in the package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindAllIndex(b []byte, n int) [][]int { +	if n < 0 { +		n = len(b) + 1 +	} +	result := make([][]int, 0, startSize) +	re.allMatches("", b, n, func(match []int) { +		result = append(result, match[0:2]) +	}) +	if len(result) == 0 { +		return nil +	} +	return result +} + +// FindAllString is the 'All' version of FindString; it returns a slice of all +// successive matches of the expression, as defined by the 'All' description +// in the package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindAllString(s string, n int) []string { +	if n < 0 { +		n = len(s) + 1 +	} +	result := make([]string, 0, startSize) +	re.allMatches(s, nil, n, func(match []int) { +		result = append(result, s[match[0]:match[1]]) +	}) +	if len(result) == 0 { +		return nil +	} +	return result +} + +// FindAllStringIndex is the 'All' version of FindStringIndex; it returns a +// slice of all successive matches of the expression, as defined by the 'All' +// description in the package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindAllStringIndex(s string, n int) [][]int { +	if n < 0 { +		n = len(s) + 1 +	} +	result := make([][]int, 0, startSize) +	re.allMatches(s, nil, n, func(match []int) { +		result = append(result, match[0:2]) +	}) +	if len(result) == 0 { +		return nil +	} +	return result +} + +// FindAllSubmatch is the 'All' version of FindSubmatch; it returns a slice +// of all successive matches of the expression, as defined by the 'All' +// description in the package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindAllSubmatch(b []byte, n int) [][][]byte { +	if n < 0 { +		n = len(b) + 1 +	} +	result := make([][][]byte, 0, startSize) +	re.allMatches("", b, n, func(match []int) { +		slice := make([][]byte, len(match)/2) +		for j := range slice { +			if match[2*j] >= 0 { +				slice[j] = b[match[2*j]:match[2*j+1]] +			} +		} +		result = append(result, slice) +	}) +	if len(result) == 0 { +		return nil +	} +	return result +} + +// FindAllSubmatchIndex is the 'All' version of FindSubmatchIndex; it returns +// a slice of all successive matches of the expression, as defined by the +// 'All' description in the package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindAllSubmatchIndex(b []byte, n int) [][]int { +	if n < 0 { +		n = len(b) + 1 +	} +	result := make([][]int, 0, startSize) +	re.allMatches("", b, n, func(match []int) { +		result = append(result, match) +	}) +	if len(result) == 0 { +		return nil +	} +	return result +} + +// FindAllStringSubmatch is the 'All' version of FindStringSubmatch; it +// returns a slice of all successive matches of the expression, as defined by +// the 'All' description in the package comment. +// A return value of nil indicates no match. +func (re *Regexp) FindAllStringSubmatch(s string, n int) [][]string { +	if n < 0 { +		n = len(s) + 1 +	} +	result := make([][]string, 0, startSize) +	re.allMatches(s, nil, n, func(match []int) { +		slice := make([]string, len(match)/2) +		for j := range slice { +			if match[2*j] >= 0 { +				slice[j] = s[match[2*j]:match[2*j+1]] +			} +		} +		result = append(result, slice) +	}) +	if len(result) == 0 { +		return nil +	} +	return result +} + +// FindAllStringSubmatchIndex is the 'All' version of +// FindStringSubmatchIndex; it returns a slice of all successive matches of +// the expression, as defined by the 'All' description in the package +// comment. +// A return value of nil indicates no match. +func (re *Regexp) FindAllStringSubmatchIndex(s string, n int) [][]int { +	if n < 0 { +		n = len(s) + 1 +	} +	result := make([][]int, 0, startSize) +	re.allMatches(s, nil, n, func(match []int) { +		result = append(result, match) +	}) +	if len(result) == 0 { +		return nil +	} +	return result +} | 
