Imported Upstream version 1.4upstream/1.4

1 files changed, 1120 insertions, 0 deletions

diff --git a/src/regexp/regexp.go b/src/regexp/regexp.go
new file mode 100644
index 000000000..b615acdf0
--- /dev/null
+++ b/src/regexp/regexp.go
@@ -0,0 +1,1120 @@
+// 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 implements regular expression search.
+//
+// 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.
+// For an overview of the syntax, run
+//   godoc regexp/syntax
+//
+// The regexp implementation provided by this package is
+// guaranteed to run in time linear in the size of the input.
+// (This is a property not guaranteed by most open source
+// implementations of regular expressions.) For more information
+// about this property, see
+//	http://swtch.com/~rsc/regexp/regexp1.html
+// or any book about automata theory.
+//
+// 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 (also known as capturing groups) 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"
+	"io"
+	"regexp/syntax"
+	"strconv"
+	"strings"
+	"sync"
+	"unicode"
+	"unicode/utf8"
+)
+
+var debug = false
+
+// Regexp is the representation of a compiled regular expression.
+// 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
+	onepass        *onePassProg   // onpass program or nil
+	prefix         string         // required prefix in unanchored matches
+	prefixBytes    []byte         // prefix, as a []byte
+	prefixComplete bool           // prefix is the entire regexp
+	prefixRune     rune           // first rune in prefix
+	prefixEnd      uint32         // pc for last rune in prefix
+	cond           syntax.EmptyOp // empty-width conditions required at start of match
+	numSubexp      int
+	subexpNames    []string
+	longest        bool
+
+	// 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.
+//
+// When matching against text, the regexp returns a match that
+// begins as early as possible in the input (leftmost), and among those
+// it chooses the one that a backtracking search would have found first.
+// This so-called leftmost-first matching is the same semantics
+// that Perl, Python, and other implementations use, although this
+// package implements it without the expense of backtracking.
+// For POSIX leftmost-longest matching, see CompilePOSIX.
+func Compile(expr string) (*Regexp, error) {
+	return compile(expr, syntax.Perl, false)
+}
+
+// CompilePOSIX is like Compile but restricts the regular expression
+// to POSIX ERE (egrep) syntax and changes the match semantics to
+// leftmost-longest.
+//
+// That is, when matching against text, the regexp returns a match that
+// begins as early as possible in the input (leftmost), and among those
+// it chooses a match that is as long as possible.
+// This so-called leftmost-longest matching is the same semantics
+// that early regular expression implementations used and that POSIX
+// specifies.
+//
+// However, there can be multiple leftmost-longest matches, with different
+// submatch choices, and here this package diverges from POSIX.
+// Among the possible leftmost-longest matches, this package chooses
+// the one that a backtracking search would have found first, while POSIX
+// specifies that the match be chosen to maximize the length of the first
+// subexpression, then the second, and so on from left to right.
+// The POSIX rule is computationally prohibitive and not even well-defined.
+// See http://swtch.com/~rsc/regexp/regexp2.html#posix for details.
+func CompilePOSIX(expr string) (*Regexp, error) {
+	return compile(expr, syntax.POSIX, true)
+}
+
+// Longest makes future searches prefer the leftmost-longest match.
+// That is, when matching against text, the regexp returns a match that
+// begins as early as possible in the input (leftmost), and among those
+// it chooses a match that is as long as possible.
+func (re *Regexp) Longest() {
+	re.longest = true
+}
+
+func compile(expr string, mode syntax.Flags, longest bool) (*Regexp, error) {
+	re, err := syntax.Parse(expr, mode)
+	if err != nil {
+		return nil, err
+	}
+	maxCap := re.MaxCap()
+	capNames := re.CapNames()
+
+	re = re.Simplify()
+	prog, err := syntax.Compile(re)
+	if err != nil {
+		return nil, err
+	}
+	regexp := &Regexp{
+		expr:        expr,
+		prog:        prog,
+		onepass:     compileOnePass(prog),
+		numSubexp:   maxCap,
+		subexpNames: capNames,
+		cond:        prog.StartCond(),
+		longest:     longest,
+	}
+	if regexp.onepass == notOnePass {
+		regexp.prefix, regexp.prefixComplete = prog.Prefix()
+	} else {
+		regexp.prefix, regexp.prefixComplete, regexp.prefixEnd = onePassPrefix(prog)
+	}
+	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)
+	}
+	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, re.onepass)
+	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: Compile(` + quote(str) + `): ` + error.Error())
+	}
+	return regexp
+}
+
+// MustCompilePOSIX is like CompilePOSIX but panics if the expression cannot be parsed.
+// It simplifies safe initialization of global variables holding compiled regular
+// expressions.
+func MustCompilePOSIX(str string) *Regexp {
+	regexp, error := CompilePOSIX(str)
+	if error != nil {
+		panic(`regexp: CompilePOSIX(` + quote(str) + `): ` + error.Error())
+	}
+	return regexp
+}
+
+func quote(s string) string {
+	if strconv.CanBackquote(s) {
+		return "`" + s + "`"
+	}
+	return strconv.Quote(s)
+}
+
+// NumSubexp returns the number of parenthesized subexpressions in this Regexp.
+func (re *Regexp) NumSubexp() int {
+	return re.numSubexp
+}
+
+// SubexpNames returns the names of the parenthesized subexpressions
+// in this Regexp.  The name for the first sub-expression is names[1],
+// so that if m is a match slice, the name for m[i] is SubexpNames()[i].
+// Since the Regexp as a whole cannot be named, names[0] is always
+// the empty string.  The slice should not be modified.
+func (re *Regexp) SubexpNames() []string {
+	return re.subexpNames
+}
+
+const endOfText rune = -1
+
+// input abstracts different representations of the input text. It provides
+// one-character lookahead.
+type input interface {
+	step(pos int) (r rune, width int) // advance one rune
+	canCheckPrefix() bool             // can we look ahead without losing info?
+	hasPrefix(re *Regexp) bool
+	index(re *Regexp, pos int) int
+	context(pos int) syntax.EmptyOp
+}
+
+// inputString scans a string.
+type inputString struct {
+	str string
+}
+
+func (i *inputString) step(pos int) (rune, int) {
+	if pos < len(i.str) {
+		c := i.str[pos]
+		if c < utf8.RuneSelf {
+			return rune(c), 1
+		}
+		return utf8.DecodeRuneInString(i.str[pos:])
+	}
+	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)
+}
+
+func (i *inputString) context(pos int) syntax.EmptyOp {
+	r1, r2 := endOfText, endOfText
+	if pos > 0 && pos <= len(i.str) {
+		r1, _ = utf8.DecodeLastRuneInString(i.str[:pos])
+	}
+	if pos < len(i.str) {
+		r2, _ = utf8.DecodeRuneInString(i.str[pos:])
+	}
+	return syntax.EmptyOpContext(r1, r2)
+}
+
+// inputBytes scans a byte slice.
+type inputBytes struct {
+	str []byte
+}
+
+func (i *inputBytes) step(pos int) (rune, int) {
+	if pos < len(i.str) {
+		c := i.str[pos]
+		if c < utf8.RuneSelf {
+			return rune(c), 1
+		}
+		return utf8.DecodeRune(i.str[pos:])
+	}
+	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)
+}
+
+func (i *inputBytes) context(pos int) syntax.EmptyOp {
+	r1, r2 := endOfText, endOfText
+	if pos > 0 && pos <= len(i.str) {
+		r1, _ = utf8.DecodeLastRune(i.str[:pos])
+	}
+	if pos < len(i.str) {
+		r2, _ = utf8.DecodeRune(i.str[pos:])
+	}
+	return syntax.EmptyOpContext(r1, r2)
+}
+
+// inputReader scans a RuneReader.
+type inputReader struct {
+	r     io.RuneReader
+	atEOT bool
+	pos   int
+}
+
+func (i *inputReader) step(pos int) (rune, 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
+}
+
+func (i *inputReader) context(pos int) syntax.EmptyOp {
+	return 0
+}
+
+// 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 reports whether the Regexp matches the text read by the
+// RuneReader.
+func (re *Regexp) MatchReader(r io.RuneReader) bool {
+	return re.doExecute(r, nil, "", 0, 0) != nil
+}
+
+// MatchString reports whether the Regexp matches the string s.
+func (re *Regexp) MatchString(s string) bool {
+	return re.doExecute(nil, nil, s, 0, 0) != nil
+}
+
+// Match reports whether the Regexp matches the byte slice b.
+func (re *Regexp) Match(b []byte) bool {
+	return re.doExecute(nil, 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, err 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, err 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, err error) {
+	re, err := Compile(pattern)
+	if err != nil {
+		return false, err
+	}
+	return re.Match(b), nil
+}
+
+// ReplaceAllString returns a copy of src, replacing matches of the Regexp
+// with the replacement string repl.  Inside repl, $ signs are interpreted as
+// in Expand, so for instance $1 represents the text of the first submatch.
+func (re *Regexp) ReplaceAllString(src, repl string) string {
+	n := 2
+	if strings.Index(repl, "$") >= 0 {
+		n = 2 * (re.numSubexp + 1)
+	}
+	b := re.replaceAll(nil, src, n, func(dst []byte, match []int) []byte {
+		return re.expand(dst, repl, nil, src, match)
+	})
+	return string(b)
+}
+
+// ReplaceAllLiteralString returns a copy of src, replacing matches of the Regexp
+// with the replacement string repl.  The replacement repl is substituted directly,
+// without using Expand.
+func (re *Regexp) ReplaceAllLiteralString(src, repl string) string {
+	return string(re.replaceAll(nil, src, 2, func(dst []byte, match []int) []byte {
+		return append(dst, repl...)
+	}))
+}
+
+// ReplaceAllStringFunc returns a copy of src in which all matches of the
+// Regexp have been replaced by the return value of function repl applied
+// to the matched substring.  The replacement returned by repl is substituted
+// directly, without using Expand.
+func (re *Regexp) ReplaceAllStringFunc(src string, repl func(string) string) string {
+	b := re.replaceAll(nil, src, 2, func(dst []byte, match []int) []byte {
+		return append(dst, repl(src[match[0]:match[1]])...)
+	})
+	return string(b)
+}
+
+func (re *Regexp) replaceAll(bsrc []byte, src string, nmatch int, repl func(dst []byte, m []int) []byte) []byte {
+	lastMatchEnd := 0 // end position of the most recent match
+	searchPos := 0    // position where we next look for a match
+	var buf []byte
+	var endPos int
+	if bsrc != nil {
+		endPos = len(bsrc)
+	} else {
+		endPos = len(src)
+	}
+	for searchPos <= endPos {
+		a := re.doExecute(nil, bsrc, src, searchPos, nmatch)
+		if len(a) == 0 {
+			break // no more matches
+		}
+
+		// Copy the unmatched characters before this match.
+		if bsrc != nil {
+			buf = append(buf, bsrc[lastMatchEnd:a[0]]...)
+		} else {
+			buf = append(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 {
+			buf = repl(buf, a)
+		}
+		lastMatchEnd = a[1]
+
+		// Advance past this match; always advance at least one character.
+		var width int
+		if bsrc != nil {
+			_, width = utf8.DecodeRune(bsrc[searchPos:])
+		} else {
+			_, 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.
+	if bsrc != nil {
+		buf = append(buf, bsrc[lastMatchEnd:]...)
+	} else {
+		buf = append(buf, src[lastMatchEnd:]...)
+	}
+
+	return buf
+}
+
+// ReplaceAll returns a copy of src, replacing matches of the Regexp
+// with the replacement text repl.  Inside repl, $ signs are interpreted as
+// in Expand, so for instance $1 represents the text of the first submatch.
+func (re *Regexp) ReplaceAll(src, repl []byte) []byte {
+	n := 2
+	if bytes.IndexByte(repl, '$') >= 0 {
+		n = 2 * (re.numSubexp + 1)
+	}
+	srepl := ""
+	b := re.replaceAll(src, "", n, func(dst []byte, match []int) []byte {
+		if len(srepl) != len(repl) {
+			srepl = string(repl)
+		}
+		return re.expand(dst, srepl, src, "", match)
+	})
+	return b
+}
+
+// ReplaceAllLiteral returns a copy of src, replacing matches of the Regexp
+// with the replacement bytes repl.  The replacement repl is substituted directly,
+// without using Expand.
+func (re *Regexp) ReplaceAllLiteral(src, repl []byte) []byte {
+	return re.replaceAll(src, "", 2, func(dst []byte, match []int) []byte {
+		return append(dst, repl...)
+	})
+}
+
+// ReplaceAllFunc returns a copy of src in which all matches of the
+// Regexp have been replaced by the return value of function repl applied
+// to the matched byte slice.  The replacement returned by repl is substituted
+// directly, without using Expand.
+func (re *Regexp) ReplaceAllFunc(src []byte, repl func([]byte) []byte) []byte {
+	return re.replaceAll(src, "", 2, func(dst []byte, match []int) []byte {
+		return append(dst, repl(src[match[0]:match[1]])...)
+	})
+}
+
+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])
+}
+
+// The number of capture values in the program may correspond
+// to fewer capturing expressions than are in the regexp.
+// For example, "(a){0}" turns into an empty program, so the
+// maximum capture in the program is 0 but we need to return
+// an expression for \1.  Pad appends -1s to the slice a as needed.
+func (re *Regexp) pad(a []int) []int {
+	if a == nil {
+		// No match.
+		return nil
+	}
+	n := (1 + re.numSubexp) * 2
+	for len(a) < n {
+		a = append(a, -1)
+	}
+	return a
+}
+
+// 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; {
+		matches := re.doExecute(nil, b, s, 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(re.pad(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(nil, 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(nil, 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(nil, nil, 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) (loc []int) {
+	a := re.doExecute(nil, nil, 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 text was found in the input stream at
+// byte offset loc[0] through loc[1]-1.
+// A return value of nil indicates no match.
+func (re *Regexp) FindReaderIndex(r io.RuneReader) (loc []int) {
+	a := re.doExecute(r, nil, "", 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(nil, b, "", 0, re.prog.NumCap)
+	if a == nil {
+		return nil
+	}
+	ret := make([][]byte, 1+re.numSubexp)
+	for i := range ret {
+		if 2*i < len(a) && a[2*i] >= 0 {
+			ret[i] = b[a[2*i]:a[2*i+1]]
+		}
+	}
+	return ret
+}
+
+// Expand appends template to dst and returns the result; during the
+// append, Expand replaces variables in the template with corresponding
+// matches drawn from src.  The match slice should have been returned by
+// FindSubmatchIndex.
+//
+// In the template, a variable is denoted by a substring of the form
+// $name or ${name}, where name is a non-empty sequence of letters,
+// digits, and underscores.  A purely numeric name like $1 refers to
+// the submatch with the corresponding index; other names refer to
+// capturing parentheses named with the (?P<name>...) syntax.  A
+// reference to an out of range or unmatched index or a name that is not
+// present in the regular expression is replaced with an empty slice.
+//
+// In the $name form, name is taken to be as long as possible: $1x is
+// equivalent to ${1x}, not ${1}x, and, $10 is equivalent to ${10}, not ${1}0.
+//
+// To insert a literal $ in the output, use $$ in the template.
+func (re *Regexp) Expand(dst []byte, template []byte, src []byte, match []int) []byte {
+	return re.expand(dst, string(template), src, "", match)
+}
+
+// ExpandString is like Expand but the template and source are strings.
+// It appends to and returns a byte slice in order to give the calling
+// code control over allocation.
+func (re *Regexp) ExpandString(dst []byte, template string, src string, match []int) []byte {
+	return re.expand(dst, template, nil, src, match)
+}
+
+func (re *Regexp) expand(dst []byte, template string, bsrc []byte, src string, match []int) []byte {
+	for len(template) > 0 {
+		i := strings.Index(template, "$")
+		if i < 0 {
+			break
+		}
+		dst = append(dst, template[:i]...)
+		template = template[i:]
+		if len(template) > 1 && template[1] == '$' {
+			// Treat $$ as $.
+			dst = append(dst, '$')
+			template = template[2:]
+			continue
+		}
+		name, num, rest, ok := extract(template)
+		if !ok {
+			// Malformed; treat $ as raw text.
+			dst = append(dst, '$')
+			template = template[1:]
+			continue
+		}
+		template = rest
+		if num >= 0 {
+			if 2*num+1 < len(match) && match[2*num] >= 0 {
+				if bsrc != nil {
+					dst = append(dst, bsrc[match[2*num]:match[2*num+1]]...)
+				} else {
+					dst = append(dst, src[match[2*num]:match[2*num+1]]...)
+				}
+			}
+		} else {
+			for i, namei := range re.subexpNames {
+				if name == namei && 2*i+1 < len(match) && match[2*i] >= 0 {
+					if bsrc != nil {
+						dst = append(dst, bsrc[match[2*i]:match[2*i+1]]...)
+					} else {
+						dst = append(dst, src[match[2*i]:match[2*i+1]]...)
+					}
+					break
+				}
+			}
+		}
+	}
+	dst = append(dst, template...)
+	return dst
+}
+
+// extract returns the name from a leading "$name" or "${name}" in str.
+// If it is a number, extract returns num set to that number; otherwise num = -1.
+func extract(str string) (name string, num int, rest string, ok bool) {
+	if len(str) < 2 || str[0] != '$' {
+		return
+	}
+	brace := false
+	if str[1] == '{' {
+		brace = true
+		str = str[2:]
+	} else {
+		str = str[1:]
+	}
+	i := 0
+	for i < len(str) {
+		rune, size := utf8.DecodeRuneInString(str[i:])
+		if !unicode.IsLetter(rune) && !unicode.IsDigit(rune) && rune != '_' {
+			break
+		}
+		i += size
+	}
+	if i == 0 {
+		// empty name is not okay
+		return
+	}
+	name = str[:i]
+	if brace {
+		if i >= len(str) || str[i] != '}' {
+			// missing closing brace
+			return
+		}
+		i++
+	}
+
+	// Parse number.
+	num = 0
+	for i := 0; i < len(name); i++ {
+		if name[i] < '0' || '9' < name[i] || num >= 1e8 {
+			num = -1
+			break
+		}
+		num = num*10 + int(name[i]) - '0'
+	}
+	// Disallow leading zeros.
+	if name[0] == '0' && len(name) > 1 {
+		num = -1
+	}
+
+	rest = str[i:]
+	ok = true
+	return
+}
+
+// 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.pad(re.doExecute(nil, 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(nil, nil, s, 0, re.prog.NumCap)
+	if a == nil {
+		return nil
+	}
+	ret := make([]string, 1+re.numSubexp)
+	for i := range ret {
+		if 2*i < len(a) && 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.pad(re.doExecute(nil, nil, 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.pad(re.doExecute(r, nil, "", 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
+}
+
+// Split slices s into substrings separated by the expression and returns a slice of
+// the substrings between those expression matches.
+//
+// The slice returned by this method consists of all the substrings of s
+// not contained in the slice returned by FindAllString. When called on an expression
+// that contains no metacharacters, it is equivalent to strings.SplitN.
+//
+// Example:
+//   s := regexp.MustCompile("a*").Split("abaabaccadaaae", 5)
+//   // s: ["", "b", "b", "c", "cadaaae"]
+//
+// The count determines the number of substrings to return:
+//   n > 0: at most n substrings; the last substring will be the unsplit remainder.
+//   n == 0: the result is nil (zero substrings)
+//   n < 0: all substrings
+func (re *Regexp) Split(s string, n int) []string {
+
+	if n == 0 {
+		return nil
+	}
+
+	if len(re.expr) > 0 && len(s) == 0 {
+		return []string{""}
+	}
+
+	matches := re.FindAllStringIndex(s, n)
+	strings := make([]string, 0, len(matches))
+
+	beg := 0
+	end := 0
+	for _, match := range matches {
+		if n > 0 && len(strings) >= n-1 {
+			break
+		}
+
+		end = match[0]
+		if match[1] != 0 {
+			strings = append(strings, s[beg:end])
+		}
+		beg = match[1]
+	}
+
+	if end != len(s) {
+		strings = append(strings, s[beg:])
+	}
+
+	return strings
+}