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-rw-r--r--src/pkg/regexp/all_test.go65
-rw-r--r--src/pkg/regexp/example_test.go4
-rw-r--r--src/pkg/regexp/exec.go121
-rw-r--r--src/pkg/regexp/onepass.go582
-rw-r--r--src/pkg/regexp/onepass_test.go208
-rw-r--r--src/pkg/regexp/regexp.go20
-rw-r--r--src/pkg/regexp/syntax/doc.go4
-rwxr-xr-xsrc/pkg/regexp/syntax/make_perl_groups.pl4
-rw-r--r--src/pkg/regexp/syntax/parse.go3
-rw-r--r--src/pkg/regexp/syntax/parse_test.go4
-rw-r--r--src/pkg/regexp/syntax/perl_groups.go4
-rw-r--r--src/pkg/regexp/syntax/prog.go54
-rw-r--r--src/pkg/regexp/syntax/prog_test.go4
13 files changed, 1049 insertions, 28 deletions
diff --git a/src/pkg/regexp/all_test.go b/src/pkg/regexp/all_test.go
index e914a7ccb..301a1dfcd 100644
--- a/src/pkg/regexp/all_test.go
+++ b/src/pkg/regexp/all_test.go
@@ -473,6 +473,11 @@ func TestSplit(t *testing.T) {
}
}
+// This ran out of stack before issue 7608 was fixed.
+func TestOnePassCutoff(t *testing.T) {
+ MustCompile(`^(?:x{1,1000}){1,1000}$`)
+}
+
func BenchmarkLiteral(b *testing.B) {
x := strings.Repeat("x", 50) + "y"
b.StopTimer()
@@ -578,3 +583,63 @@ func BenchmarkAnchoredLongMatch(b *testing.B) {
re.Match(x)
}
}
+
+func BenchmarkOnePassShortA(b *testing.B) {
+ b.StopTimer()
+ x := []byte("abcddddddeeeededd")
+ re := MustCompile("^.bc(d|e)*$")
+ 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)
+ }
+}
diff --git a/src/pkg/regexp/example_test.go b/src/pkg/regexp/example_test.go
index b0ad9d340..a4e0da8ea 100644
--- a/src/pkg/regexp/example_test.go
+++ b/src/pkg/regexp/example_test.go
@@ -1,3 +1,7 @@
+// Copyright 2013 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_test
import (
diff --git a/src/pkg/regexp/exec.go b/src/pkg/regexp/exec.go
index 333ca2554..c4cb201f6 100644
--- a/src/pkg/regexp/exec.go
+++ b/src/pkg/regexp/exec.go
@@ -37,6 +37,7 @@ type thread struct {
type machine struct {
re *Regexp // corresponding Regexp
p *syntax.Prog // compiled program
+ op *onePassProg // compiled onepass program, or notOnePass
q0, q1 queue // two queues for runq, nextq
pool []*thread // pool of available threads
matched bool // whether a match was found
@@ -66,8 +67,8 @@ func (m *machine) newInputReader(r io.RuneReader) input {
}
// progMachine returns a new machine running the prog p.
-func progMachine(p *syntax.Prog) *machine {
- m := &machine{p: p}
+func progMachine(p *syntax.Prog, op *onePassProg) *machine {
+ m := &machine{p: p, op: op}
n := len(m.p.Inst)
m.q0 = queue{make([]uint32, n), make([]entry, 0, n)}
m.q1 = queue{make([]uint32, n), make([]entry, 0, n)}
@@ -312,6 +313,105 @@ func (m *machine) add(q *queue, pc uint32, pos int, cap []int, cond syntax.Empty
return t
}
+// onepass runs the machine over the input starting at pos.
+// It reports whether a match was found.
+// If so, m.matchcap holds the submatch information.
+func (m *machine) onepass(i input, pos int) bool {
+ startCond := m.re.cond
+ if startCond == ^syntax.EmptyOp(0) { // impossible
+ return false
+ }
+ m.matched = false
+ for i := range m.matchcap {
+ m.matchcap[i] = -1
+ }
+ r, r1 := endOfText, endOfText
+ width, width1 := 0, 0
+ r, width = i.step(pos)
+ if r != endOfText {
+ r1, width1 = i.step(pos + width)
+ }
+ var flag syntax.EmptyOp
+ if pos == 0 {
+ flag = syntax.EmptyOpContext(-1, r)
+ } else {
+ flag = i.context(pos)
+ }
+ pc := m.op.Start
+ inst := m.op.Inst[pc]
+ // If there is a simple literal prefix, skip over it.
+ if pos == 0 && syntax.EmptyOp(inst.Arg)&^flag == 0 &&
+ len(m.re.prefix) > 0 && i.canCheckPrefix() {
+ // Match requires literal prefix; fast search for it.
+ if i.hasPrefix(m.re) {
+ pos += len(m.re.prefix)
+ r, width = i.step(pos)
+ r1, width1 = i.step(pos + width)
+ flag = i.context(pos)
+ pc = int(m.re.prefixEnd)
+ } else {
+ return m.matched
+ }
+ }
+ for {
+ inst = m.op.Inst[pc]
+ pc = int(inst.Out)
+ switch inst.Op {
+ default:
+ panic("bad inst")
+ case syntax.InstMatch:
+ m.matched = true
+ if len(m.matchcap) > 0 {
+ m.matchcap[0] = 0
+ m.matchcap[1] = pos
+ }
+ return m.matched
+ case syntax.InstRune:
+ if !inst.MatchRune(r) {
+ return m.matched
+ }
+ case syntax.InstRune1:
+ if r != inst.Rune[0] {
+ return m.matched
+ }
+ case syntax.InstRuneAny:
+ // Nothing
+ case syntax.InstRuneAnyNotNL:
+ if r == '\n' {
+ return m.matched
+ }
+ // peek at the input rune to see which branch of the Alt to take
+ case syntax.InstAlt, syntax.InstAltMatch:
+ pc = int(onePassNext(&inst, r))
+ continue
+ case syntax.InstFail:
+ return m.matched
+ case syntax.InstNop:
+ continue
+ case syntax.InstEmptyWidth:
+ if syntax.EmptyOp(inst.Arg)&^flag != 0 {
+ return m.matched
+ }
+ continue
+ case syntax.InstCapture:
+ if int(inst.Arg) < len(m.matchcap) {
+ m.matchcap[inst.Arg] = pos
+ }
+ continue
+ }
+ if width == 0 {
+ break
+ }
+ flag = syntax.EmptyOpContext(r, r1)
+ pos += width
+ r, width = r1, width1
+ if r != endOfText {
+ r1, width1 = i.step(pos + width)
+ }
+ }
+ return m.matched
+}
+
// empty is a non-nil 0-element slice,
// so doExecute can avoid an allocation
// when 0 captures are requested from a successful match.
@@ -329,16 +429,23 @@ func (re *Regexp) doExecute(r io.RuneReader, b []byte, s string, pos int, ncap i
} else {
i = m.newInputString(s)
}
- m.init(ncap)
- if !m.match(i, pos) {
- re.put(m)
- return nil
+ if m.op != notOnePass {
+ if !m.onepass(i, pos) {
+ re.put(m)
+ return nil
+ }
+ } else {
+ m.init(ncap)
+ if !m.match(i, pos) {
+ re.put(m)
+ return nil
+ }
}
if ncap == 0 {
re.put(m)
return empty // empty but not nil
}
- cap := make([]int, ncap)
+ cap := make([]int, len(m.matchcap))
copy(cap, m.matchcap)
re.put(m)
return cap
diff --git a/src/pkg/regexp/onepass.go b/src/pkg/regexp/onepass.go
new file mode 100644
index 000000000..501fb28af
--- /dev/null
+++ b/src/pkg/regexp/onepass.go
@@ -0,0 +1,582 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+
+package regexp
+
+import (
+ "bytes"
+ "regexp/syntax"
+ "sort"
+ "unicode"
+)
+
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// "One-pass" regexp execution.
+// Some regexps can be analyzed to determine that they never need
+// backtracking: they are guaranteed to run in one pass over the string
+// without bothering to save all the usual NFA state.
+// Detect those and execute them more quickly.
+
+// A onePassProg is a compiled one-pass regular expression program.
+// It is the same as syntax.Prog except for the use of onePassInst.
+type onePassProg struct {
+ Inst []onePassInst
+ Start int // index of start instruction
+ NumCap int // number of InstCapture insts in re
+}
+
+// A onePassInst is a single instruction in a one-pass regular expression program.
+// It is the same as syntax.Inst except for the new 'Next' field.
+type onePassInst struct {
+ syntax.Inst
+ Next []uint32
+}
+
+// OnePassPrefix returns a literal string that all matches for the
+// regexp must start with. Complete is true if the prefix
+// is the entire match. Pc is the index of the last rune instruction
+// in the string. The OnePassPrefix skips over the mandatory
+// EmptyBeginText
+func onePassPrefix(p *syntax.Prog) (prefix string, complete bool, pc uint32) {
+ i := &p.Inst[p.Start]
+ if i.Op != syntax.InstEmptyWidth || (syntax.EmptyOp(i.Arg))&syntax.EmptyBeginText == 0 {
+ return "", i.Op == syntax.InstMatch, uint32(p.Start)
+ }
+ pc = i.Out
+ i = &p.Inst[pc]
+ for i.Op == syntax.InstNop {
+ pc = i.Out
+ i = &p.Inst[pc]
+ }
+ // Avoid allocation of buffer if prefix is empty.
+ if iop(i) != syntax.InstRune || len(i.Rune) != 1 {
+ return "", i.Op == syntax.InstMatch, uint32(p.Start)
+ }
+
+ // Have prefix; gather characters.
+ var buf bytes.Buffer
+ for iop(i) == syntax.InstRune && len(i.Rune) == 1 && syntax.Flags(i.Arg)&syntax.FoldCase == 0 {
+ buf.WriteRune(i.Rune[0])
+ pc, i = i.Out, &p.Inst[i.Out]
+ }
+ return buf.String(), i.Op == syntax.InstEmptyWidth && (syntax.EmptyOp(i.Arg))&syntax.EmptyBeginText != 0, pc
+}
+
+// OnePassNext selects the next actionable state of the prog, based on the input character.
+// It should only be called when i.Op == InstAlt or InstAltMatch, and from the one-pass machine.
+// One of the alternates may ultimately lead without input to end of line. If the instruction
+// is InstAltMatch the path to the InstMatch is in i.Out, the normal node in i.Next.
+func onePassNext(i *onePassInst, r rune) uint32 {
+ next := i.MatchRunePos(r)
+ if next >= 0 {
+ return i.Next[next]
+ }
+ if i.Op == syntax.InstAltMatch {
+ return i.Out
+ }
+ return 0
+}
+
+func iop(i *syntax.Inst) syntax.InstOp {
+ op := i.Op
+ switch op {
+ case syntax.InstRune1, syntax.InstRuneAny, syntax.InstRuneAnyNotNL:
+ op = syntax.InstRune
+ }
+ return op
+}
+
+// Sparse Array implementation is used as a queueOnePass.
+type queueOnePass struct {
+ sparse []uint32
+ dense []uint32
+ size, nextIndex uint32
+}
+
+func (q *queueOnePass) empty() bool {
+ return q.nextIndex >= q.size
+}
+
+func (q *queueOnePass) next() (n uint32) {
+ n = q.dense[q.nextIndex]
+ q.nextIndex++
+ return
+}
+
+func (q *queueOnePass) clear() {
+ q.size = 0
+ q.nextIndex = 0
+}
+
+func (q *queueOnePass) reset() {
+ q.nextIndex = 0
+}
+
+func (q *queueOnePass) contains(u uint32) bool {
+ if u >= uint32(len(q.sparse)) {
+ return false
+ }
+ return q.sparse[u] < q.size && q.dense[q.sparse[u]] == u
+}
+
+func (q *queueOnePass) insert(u uint32) {
+ if !q.contains(u) {
+ q.insertNew(u)
+ }
+}
+
+func (q *queueOnePass) insertNew(u uint32) {
+ if u >= uint32(len(q.sparse)) {
+ return
+ }
+ q.sparse[u] = q.size
+ q.dense[q.size] = u
+ q.size++
+}
+
+func newQueue(size int) (q *queueOnePass) {
+ return &queueOnePass{
+ sparse: make([]uint32, size),
+ dense: make([]uint32, size),
+ }
+}
+
+// mergeRuneSets merges two non-intersecting runesets, and returns the merged result,
+// and a NextIp array. The idea is that if a rune matches the OnePassRunes at index
+// i, NextIp[i/2] is the target. If the input sets intersect, an empty runeset and a
+// NextIp array with the single element mergeFailed is returned.
+// The code assumes that both inputs contain ordered and non-intersecting rune pairs.
+const mergeFailed = uint32(0xffffffff)
+
+var (
+ noRune = []rune{}
+ noNext = []uint32{mergeFailed}
+)
+
+func mergeRuneSets(leftRunes, rightRunes *[]rune, leftPC, rightPC uint32) ([]rune, []uint32) {
+ leftLen := len(*leftRunes)
+ rightLen := len(*rightRunes)
+ if leftLen&0x1 != 0 || rightLen&0x1 != 0 {
+ panic("mergeRuneSets odd length []rune")
+ }
+ var (
+ lx, rx int
+ )
+ merged := make([]rune, 0)
+ next := make([]uint32, 0)
+ ok := true
+ defer func() {
+ if !ok {
+ merged = nil
+ next = nil
+ }
+ }()
+
+ ix := -1
+ extend := func(newLow *int, newArray *[]rune, pc uint32) bool {
+ if ix > 0 && (*newArray)[*newLow] <= merged[ix] {
+ return false
+ }
+ merged = append(merged, (*newArray)[*newLow], (*newArray)[*newLow+1])
+ *newLow += 2
+ ix += 2
+ next = append(next, pc)
+ return true
+ }
+
+ for lx < leftLen || rx < rightLen {
+ switch {
+ case rx >= rightLen:
+ ok = extend(&lx, leftRunes, leftPC)
+ case lx >= leftLen:
+ ok = extend(&rx, rightRunes, rightPC)
+ case (*rightRunes)[rx] < (*leftRunes)[lx]:
+ ok = extend(&rx, rightRunes, rightPC)
+ default:
+ ok = extend(&lx, leftRunes, leftPC)
+ }
+ if !ok {
+ return noRune, noNext
+ }
+ }
+ return merged, next
+}
+
+// cleanupOnePass drops working memory, and restores certain shortcut instructions.
+func cleanupOnePass(prog *onePassProg, original *syntax.Prog) {
+ for ix, instOriginal := range original.Inst {
+ switch instOriginal.Op {
+ case syntax.InstAlt, syntax.InstAltMatch, syntax.InstRune:
+ case syntax.InstCapture, syntax.InstEmptyWidth, syntax.InstNop, syntax.InstMatch, syntax.InstFail:
+ prog.Inst[ix].Next = nil
+ case syntax.InstRune1, syntax.InstRuneAny, syntax.InstRuneAnyNotNL:
+ prog.Inst[ix].Next = nil
+ prog.Inst[ix] = onePassInst{Inst: instOriginal}
+ }
+ }
+}
+
+// onePassCopy creates a copy of the original Prog, as we'll be modifying it
+func onePassCopy(prog *syntax.Prog) *onePassProg {
+ p := &onePassProg{
+ Start: prog.Start,
+ NumCap: prog.NumCap,
+ }
+ for _, inst := range prog.Inst {
+ p.Inst = append(p.Inst, onePassInst{Inst: inst})
+ }
+
+ // rewrites one or more common Prog constructs that enable some otherwise
+ // non-onepass Progs to be onepass. A:BD (for example) means an InstAlt at
+ // ip A, that points to ips B & C.
+ // A:BC + B:DA => A:BC + B:CD
+ // A:BC + B:DC => A:DC + B:DC
+ for pc := range p.Inst {
+ switch p.Inst[pc].Op {
+ default:
+ continue
+ case syntax.InstAlt, syntax.InstAltMatch:
+ // A:Bx + B:Ay
+ p_A_Other := &p.Inst[pc].Out
+ p_A_Alt := &p.Inst[pc].Arg
+ // make sure a target is another Alt
+ instAlt := p.Inst[*p_A_Alt]
+ if !(instAlt.Op == syntax.InstAlt || instAlt.Op == syntax.InstAltMatch) {
+ p_A_Alt, p_A_Other = p_A_Other, p_A_Alt
+ instAlt = p.Inst[*p_A_Alt]
+ if !(instAlt.Op == syntax.InstAlt || instAlt.Op == syntax.InstAltMatch) {
+ continue
+ }
+ }
+ instOther := p.Inst[*p_A_Other]
+ // Analyzing both legs pointing to Alts is for another day
+ if instOther.Op == syntax.InstAlt || instOther.Op == syntax.InstAltMatch {
+ // too complicated
+ continue
+ }
+ // simple empty transition loop
+ // A:BC + B:DA => A:BC + B:DC
+ p_B_Alt := &p.Inst[*p_A_Alt].Out
+ p_B_Other := &p.Inst[*p_A_Alt].Arg
+ patch := false
+ if instAlt.Out == uint32(pc) {
+ patch = true
+ } else if instAlt.Arg == uint32(pc) {
+ patch = true
+ p_B_Alt, p_B_Other = p_B_Other, p_B_Alt
+ }
+ if patch {
+ *p_B_Alt = *p_A_Other
+ }
+
+ // empty transition to common target
+ // A:BC + B:DC => A:DC + B:DC
+ if *p_A_Other == *p_B_Alt {
+ *p_A_Alt = *p_B_Other
+ }
+ }
+ }
+ return p
+}
+
+// runeSlice exists to permit sorting the case-folded rune sets.
+type runeSlice []rune
+
+func (p runeSlice) Len() int { return len(p) }
+func (p runeSlice) Less(i, j int) bool { return p[i] < p[j] }
+func (p runeSlice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
+
+// Sort is a convenience method.
+func (p runeSlice) Sort() {
+ sort.Sort(p)
+}
+
+var anyRuneNotNL = []rune{0, '\n' - 1, '\n' + 1, unicode.MaxRune}
+var anyRune = []rune{0, unicode.MaxRune}
+
+// makeOnePass creates a onepass Prog, if possible. It is possible if at any alt,
+// the match engine can always tell which branch to take. The routine may modify
+// p if it is turned into a onepass Prog. If it isn't possible for this to be a
+// onepass Prog, the Prog notOnePass is returned. makeOnePass is recursive
+// to the size of the Prog.
+func makeOnePass(p *onePassProg) *onePassProg {
+ // If the machine is very long, it's not worth the time to check if we can use one pass.
+ if len(p.Inst) >= 1000 {
+ return notOnePass
+ }
+
+ var (
+ instQueue = newQueue(len(p.Inst))
+ visitQueue = newQueue(len(p.Inst))
+ build func(uint32, *queueOnePass)
+ check func(uint32, map[uint32]bool) bool
+ onePassRunes = make([][]rune, len(p.Inst))
+ )
+ build = func(pc uint32, q *queueOnePass) {
+ if q.contains(pc) {
+ return
+ }
+ inst := p.Inst[pc]
+ switch inst.Op {
+ case syntax.InstAlt, syntax.InstAltMatch:
+ q.insert(inst.Out)
+ build(inst.Out, q)
+ q.insert(inst.Arg)
+ case syntax.InstMatch, syntax.InstFail:
+ default:
+ q.insert(inst.Out)
+ }
+ }
+
+ // check that paths from Alt instructions are unambiguous, and rebuild the new
+ // program as a onepass program
+ check = func(pc uint32, m map[uint32]bool) (ok bool) {
+ ok = true
+ inst := &p.Inst[pc]
+ if visitQueue.contains(pc) {
+ return
+ }
+ visitQueue.insert(pc)
+ switch inst.Op {
+ case syntax.InstAlt, syntax.InstAltMatch:
+ ok = check(inst.Out, m) && check(inst.Arg, m)
+ // check no-input paths to InstMatch
+ matchOut := m[inst.Out]
+ matchArg := m[inst.Arg]
+ if matchOut && matchArg {
+ ok = false
+ break
+ }
+ // Match on empty goes in inst.Out
+ if matchArg {
+ inst.Out, inst.Arg = inst.Arg, inst.Out
+ matchOut, matchArg = matchArg, matchOut
+ }
+ if matchOut {
+ m[pc] = true
+ inst.Op = syntax.InstAltMatch
+ }
+
+ // build a dispatch operator from the two legs of the alt.
+ onePassRunes[pc], inst.Next = mergeRuneSets(
+ &onePassRunes[inst.Out], &onePassRunes[inst.Arg], inst.Out, inst.Arg)
+ if len(inst.Next) > 0 && inst.Next[0] == mergeFailed {
+ ok = false
+ break
+ }
+ case syntax.InstCapture, syntax.InstNop:
+ ok = check(inst.Out, m)
+ m[pc] = m[inst.Out]
+ // pass matching runes back through these no-ops.
+ onePassRunes[pc] = append([]rune{}, onePassRunes[inst.Out]...)
+ inst.Next = []uint32{}
+ for i := len(onePassRunes[pc]) / 2; i >= 0; i-- {
+ inst.Next = append(inst.Next, inst.Out)
+ }
+ case syntax.InstEmptyWidth:
+ ok = check(inst.Out, m)
+ m[pc] = m[inst.Out]
+ onePassRunes[pc] = append([]rune{}, onePassRunes[inst.Out]...)
+ inst.Next = []uint32{}
+ for i := len(onePassRunes[pc]) / 2; i >= 0; i-- {
+ inst.Next = append(inst.Next, inst.Out)
+ }
+ case syntax.InstMatch, syntax.InstFail:
+ m[pc] = inst.Op == syntax.InstMatch
+ break
+ case syntax.InstRune:
+ ok = check(inst.Out, m)
+ m[pc] = false
+ if len(inst.Next) > 0 {
+ break
+ }
+ if len(inst.Rune) == 0 {
+ onePassRunes[pc] = []rune{}
+ inst.Next = []uint32{inst.Out}
+ break
+ }
+ runes := make([]rune, 0)
+ if len(inst.Rune) == 1 && syntax.Flags(inst.Arg)&syntax.FoldCase != 0 {
+ r0 := inst.Rune[0]
+ runes = append(runes, r0, r0)
+ for r1 := unicode.SimpleFold(r0); r1 != r0; r1 = unicode.SimpleFold(r1) {
+ runes = append(runes, r1, r1)
+ }
+ sort.Sort(runeSlice(runes))
+ } else {
+ runes = append(runes, inst.Rune...)
+ }
+ onePassRunes[pc] = runes
+ inst.Next = []uint32{}
+ for i := len(onePassRunes[pc]) / 2; i >= 0; i-- {
+ inst.Next = append(inst.Next, inst.Out)
+ }
+ inst.Op = syntax.InstRune
+ case syntax.InstRune1:
+ ok = check(inst.Out, m)
+ m[pc] = false
+ if len(inst.Next) > 0 {
+ break
+ }
+ runes := []rune{}
+ // expand case-folded runes
+ if syntax.Flags(inst.Arg)&syntax.FoldCase != 0 {
+ r0 := inst.Rune[0]
+ runes = append(runes, r0, r0)
+ for r1 := unicode.SimpleFold(r0); r1 != r0; r1 = unicode.SimpleFold(r1) {
+ runes = append(runes, r1, r1)
+ }
+ sort.Sort(runeSlice(runes))
+ } else {
+ runes = append(runes, inst.Rune[0], inst.Rune[0])
+ }
+ onePassRunes[pc] = runes
+ inst.Next = []uint32{}
+ for i := len(onePassRunes[pc]) / 2; i >= 0; i-- {
+ inst.Next = append(inst.Next, inst.Out)
+ }
+ inst.Op = syntax.InstRune
+ case syntax.InstRuneAny:
+ ok = check(inst.Out, m)
+ m[pc] = false
+ if len(inst.Next) > 0 {
+ break
+ }
+ onePassRunes[pc] = append([]rune{}, anyRune...)
+ inst.Next = []uint32{inst.Out}
+ case syntax.InstRuneAnyNotNL:
+ ok = check(inst.Out, m)
+ m[pc] = false
+ if len(inst.Next) > 0 {
+ break
+ }
+ onePassRunes[pc] = append([]rune{}, anyRuneNotNL...)
+ inst.Next = []uint32{}
+ for i := len(onePassRunes[pc]) / 2; i >= 0; i-- {
+ inst.Next = append(inst.Next, inst.Out)
+ }
+ }
+ return
+ }
+
+ instQueue.clear()
+ instQueue.insert(uint32(p.Start))
+ m := make(map[uint32]bool, len(p.Inst))
+ for !instQueue.empty() {
+ pc := instQueue.next()
+ inst := p.Inst[pc]
+ visitQueue.clear()
+ if !check(uint32(pc), m) {
+ p = notOnePass
+ break
+ }
+ switch inst.Op {
+ case syntax.InstAlt, syntax.InstAltMatch:
+ instQueue.insert(inst.Out)
+ instQueue.insert(inst.Arg)
+ case syntax.InstCapture, syntax.InstEmptyWidth, syntax.InstNop:
+ instQueue.insert(inst.Out)
+ case syntax.InstMatch:
+ case syntax.InstFail:
+ case syntax.InstRune, syntax.InstRune1, syntax.InstRuneAny, syntax.InstRuneAnyNotNL:
+ default:
+ }
+ }
+ if p != notOnePass {
+ for i, _ := range p.Inst {
+ p.Inst[i].Rune = onePassRunes[i]
+ }
+ }
+ return p
+}
+
+// walk visits each Inst in the prog once, and applies the argument
+// function(ip, next), in pre-order.
+func walk(prog *syntax.Prog, funcs ...func(ip, next uint32)) {
+ var walk1 func(uint32)
+ progQueue := newQueue(len(prog.Inst))
+ walk1 = func(ip uint32) {
+ if progQueue.contains(ip) {
+ return
+ }
+ progQueue.insert(ip)
+ inst := prog.Inst[ip]
+ switch inst.Op {
+ case syntax.InstAlt, syntax.InstAltMatch:
+ for _, f := range funcs {
+ f(ip, inst.Out)
+ f(ip, inst.Arg)
+ }
+ walk1(inst.Out)
+ walk1(inst.Arg)
+ default:
+ for _, f := range funcs {
+ f(ip, inst.Out)
+ }
+ walk1(inst.Out)
+ }
+ }
+ walk1(uint32(prog.Start))
+}
+
+// find returns the Insts that match the argument predicate function
+func find(prog *syntax.Prog, f func(*syntax.Prog, int) bool) (matches []uint32) {
+ matches = []uint32{}
+
+ for ip := range prog.Inst {
+ if f(prog, ip) {
+ matches = append(matches, uint32(ip))
+ }
+ }
+ return
+}
+
+var notOnePass *onePassProg = nil
+
+// compileOnePass returns a new *syntax.Prog suitable for onePass execution if the original Prog
+// can be recharacterized as a one-pass regexp program, or syntax.notOnePass if the
+// Prog cannot be converted. For a one pass prog, the fundamental condition that must
+// be true is: at any InstAlt, there must be no ambiguity about what branch to take.
+func compileOnePass(prog *syntax.Prog) (p *onePassProg) {
+ if prog.Start == 0 {
+ return notOnePass
+ }
+ // onepass regexp is anchored
+ if prog.Inst[prog.Start].Op != syntax.InstEmptyWidth ||
+ syntax.EmptyOp(prog.Inst[prog.Start].Arg)&syntax.EmptyBeginText != syntax.EmptyBeginText {
+ return notOnePass
+ }
+ // every instruction leading to InstMatch must be EmptyEndText
+ for _, inst := range prog.Inst {
+ opOut := prog.Inst[inst.Out].Op
+ switch inst.Op {
+ default:
+ if opOut == syntax.InstMatch {
+ return notOnePass
+ }
+ case syntax.InstAlt, syntax.InstAltMatch:
+ if opOut == syntax.InstMatch || prog.Inst[inst.Arg].Op == syntax.InstMatch {
+ return notOnePass
+ }
+ case syntax.InstEmptyWidth:
+ if opOut == syntax.InstMatch {
+ if syntax.EmptyOp(inst.Arg)&syntax.EmptyEndText == syntax.EmptyEndText {
+ continue
+ }
+ return notOnePass
+ }
+ }
+ }
+ // Creates a slightly optimized copy of the original Prog
+ // that cleans up some Prog idioms that block valid onepass programs
+ p = onePassCopy(prog)
+
+ // checkAmbiguity on InstAlts, build onepass Prog if possible
+ p = makeOnePass(p)
+
+ if p != notOnePass {
+ cleanupOnePass(p, prog)
+ }
+ return p
+}
diff --git a/src/pkg/regexp/onepass_test.go b/src/pkg/regexp/onepass_test.go
new file mode 100644
index 000000000..7b2beea67
--- /dev/null
+++ b/src/pkg/regexp/onepass_test.go
@@ -0,0 +1,208 @@
+// Copyright 2014 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"
+ "testing"
+)
+
+var runeMergeTests = []struct {
+ left, right, merged []rune
+ next []uint32
+ leftPC, rightPC uint32
+}{
+ {
+ // empty rhs
+ []rune{69, 69},
+ []rune{},
+ []rune{69, 69},
+ []uint32{1},
+ 1, 2,
+ },
+ {
+ // identical runes, identical targets
+ []rune{69, 69},
+ []rune{69, 69},
+ []rune{},
+ []uint32{mergeFailed},
+ 1, 1,
+ },
+ {
+ // identical runes, different targets
+ []rune{69, 69},
+ []rune{69, 69},
+ []rune{},
+ []uint32{mergeFailed},
+ 1, 2,
+ },
+ {
+ // append right-first
+ []rune{69, 69},
+ []rune{71, 71},
+ []rune{69, 69, 71, 71},
+ []uint32{1, 2},
+ 1, 2,
+ },
+ {
+ // append, left-first
+ []rune{71, 71},
+ []rune{69, 69},
+ []rune{69, 69, 71, 71},
+ []uint32{2, 1},
+ 1, 2,
+ },
+ {
+ // successful interleave
+ []rune{60, 60, 71, 71, 101, 101},
+ []rune{69, 69, 88, 88},
+ []rune{60, 60, 69, 69, 71, 71, 88, 88, 101, 101},
+ []uint32{1, 2, 1, 2, 1},
+ 1, 2,
+ },
+ {
+ // left surrounds right
+ []rune{69, 74},
+ []rune{71, 71},
+ []rune{},
+ []uint32{mergeFailed},
+ 1, 2,
+ },
+ {
+ // right surrounds left
+ []rune{69, 74},
+ []rune{68, 75},
+ []rune{},
+ []uint32{mergeFailed},
+ 1, 2,
+ },
+ {
+ // overlap at interval begin
+ []rune{69, 74},
+ []rune{74, 75},
+ []rune{},
+ []uint32{mergeFailed},
+ 1, 2,
+ },
+ {
+ // overlap ar interval end
+ []rune{69, 74},
+ []rune{65, 69},
+ []rune{},
+ []uint32{mergeFailed},
+ 1, 2,
+ },
+ {
+ // overlap from above
+ []rune{69, 74},
+ []rune{71, 74},
+ []rune{},
+ []uint32{mergeFailed},
+ 1, 2,
+ },
+ {
+ // overlap from below
+ []rune{69, 74},
+ []rune{65, 71},
+ []rune{},
+ []uint32{mergeFailed},
+ 1, 2,
+ },
+ {
+ // out of order []rune
+ []rune{69, 74, 60, 65},
+ []rune{66, 67},
+ []rune{},
+ []uint32{mergeFailed},
+ 1, 2,
+ },
+}
+
+func TestMergeRuneSet(t *testing.T) {
+ for ix, test := range runeMergeTests {
+ merged, next := mergeRuneSets(&test.left, &test.right, test.leftPC, test.rightPC)
+ if !reflect.DeepEqual(merged, test.merged) {
+ t.Errorf("mergeRuneSet :%d (%v, %v) merged\n have\n%v\nwant\n%v", ix, test.left, test.right, merged, test.merged)
+ }
+ if !reflect.DeepEqual(next, test.next) {
+ t.Errorf("mergeRuneSet :%d(%v, %v) next\n have\n%v\nwant\n%v", ix, test.left, test.right, next, test.next)
+ }
+ }
+}
+
+const noStr = `!`
+
+var onePass = &onePassProg{}
+
+var onePassTests = []struct {
+ re string
+ onePass *onePassProg
+ prog string
+}{
+ {`^(?:a|(?:a*))$`, notOnePass, noStr},
+ {`^(?:(a)|(?:a*))$`, notOnePass, noStr},
+ {`^(?:(?:(?:.(?:$))?))$`, onePass, `a`},
+ {`^abcd$`, onePass, `abcd`},
+ {`^abcd$`, onePass, `abcde`},
+ {`^(?:(?:a{0,})*?)$`, onePass, `a`},
+ {`^(?:(?:a+)*)$`, onePass, ``},
+ {`^(?:(?:a|(?:aa)))$`, onePass, ``},
+ {`^(?:[^\s\S])$`, onePass, ``},
+ {`^(?:(?:a{3,4}){0,})$`, notOnePass, `aaaaaa`},
+ {`^(?:(?:a+)*)$`, onePass, `a`},
+ {`^(?:(?:(?:a*)+))$`, onePass, noStr},
+ {`^(?:(?:a+)*)$`, onePass, ``},
+ {`^[a-c]+$`, onePass, `abc`},
+ {`^[a-c]*$`, onePass, `abcdabc`},
+ {`^(?:a*)$`, onePass, `aaaaaaa`},
+ {`^(?:(?:aa)|a)$`, onePass, `a`},
+ {`^[a-c]*`, notOnePass, `abcdabc`},
+ {`^[a-c]*$`, onePass, `abc`},
+ {`^...$`, onePass, ``},
+ {`^(?:a|(?:aa))$`, onePass, `a`},
+ {`^[a-c]*`, notOnePass, `abcabc`},
+ {`^a((b))c$`, onePass, noStr},
+ {`^a.[l-nA-Cg-j]?e$`, onePass, noStr},
+ {`^a((b))$`, onePass, noStr},
+ {`^a(?:(b)|(c))c$`, onePass, noStr},
+ {`^a(?:(b*)|(c))c$`, notOnePass, noStr},
+ {`^a(?:b|c)$`, onePass, noStr},
+ {`^a(?:b?|c)$`, onePass, noStr},
+ {`^a(?:b?|c?)$`, notOnePass, noStr},
+ {`^a(?:b?|c+)$`, onePass, noStr},
+ {`^a(?:b+|(bc))d$`, notOnePass, noStr},
+ {`^a(?:bc)+$`, onePass, noStr},
+ {`^a(?:[bcd])+$`, onePass, noStr},
+ {`^a((?:[bcd])+)$`, onePass, noStr},
+ {`^a(:?b|c)*d$`, onePass, `abbbccbbcbbd"`},
+ {`^.bc(d|e)*$`, onePass, `abcddddddeeeededd`},
+ {`^(?:(?:aa)|.)$`, notOnePass, `a`},
+ {`^(?:(?:a{1,2}){1,2})$`, notOnePass, `aaaa`},
+}
+
+func TestCompileOnePass(t *testing.T) {
+ var (
+ p *syntax.Prog
+ re *syntax.Regexp
+ err error
+ )
+ for _, test := range onePassTests {
+ if re, err = syntax.Parse(test.re, syntax.Perl); err != nil {
+ t.Errorf("Parse(%q) got err:%s, want success", test.re, err)
+ continue
+ }
+ // needs to be done before compile...
+ re = re.Simplify()
+ if p, err = syntax.Compile(re); err != nil {
+ t.Errorf("Compile(%q) got err:%s, want success", test.re, err)
+ continue
+ }
+ onePass = compileOnePass(p)
+ if (onePass == notOnePass) != (test.onePass == notOnePass) {
+ t.Errorf("CompileOnePass(%q) got %v, expected %v", test.re, onePass, test.onePass)
+ }
+ }
+}
diff --git a/src/pkg/regexp/regexp.go b/src/pkg/regexp/regexp.go
index 0046026ea..0b8336a04 100644
--- a/src/pkg/regexp/regexp.go
+++ b/src/pkg/regexp/regexp.go
@@ -11,6 +11,14 @@
// 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
@@ -70,16 +78,17 @@ import (
var debug = false
// 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
+ 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
@@ -156,12 +165,17 @@ func compile(expr string, mode syntax.Flags, longest bool) (*Regexp, error) {
regexp := &Regexp{
expr: expr,
prog: prog,
+ onepass: compileOnePass(prog),
numSubexp: maxCap,
subexpNames: capNames,
cond: prog.StartCond(),
longest: longest,
}
- regexp.prefix, regexp.prefixComplete = prog.Prefix()
+ 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.
@@ -183,7 +197,7 @@ func (re *Regexp) get() *machine {
return z
}
re.mu.Unlock()
- z := progMachine(re.prog)
+ z := progMachine(re.prog, re.onepass)
z.re = re
return z
}
diff --git a/src/pkg/regexp/syntax/doc.go b/src/pkg/regexp/syntax/doc.go
index e52632ef7..8e72c90d3 100644
--- a/src/pkg/regexp/syntax/doc.go
+++ b/src/pkg/regexp/syntax/doc.go
@@ -46,6 +46,10 @@ Repetitions:
x{n,}? n or more x, prefer fewer
x{n}? exactly n x
+Implementation restriction: The counting forms x{n} etc. (but not the other
+forms x* etc.) have an upper limit of n=1000. Negative or higher explicit
+counts yield the parse error ErrInvalidRepeatSize.
+
Grouping:
(re) numbered capturing group (submatch)
(?P<name>re) named & numbered capturing group (submatch)
diff --git a/src/pkg/regexp/syntax/make_perl_groups.pl b/src/pkg/regexp/syntax/make_perl_groups.pl
index d024f5090..90040fcb4 100755
--- a/src/pkg/regexp/syntax/make_perl_groups.pl
+++ b/src/pkg/regexp/syntax/make_perl_groups.pl
@@ -92,6 +92,10 @@ sub PrintClasses($@) {
}
print <<EOF;
+// Copyright 2013 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.
+
// GENERATED BY make_perl_groups.pl; DO NOT EDIT.
// make_perl_groups.pl >perl_groups.go
diff --git a/src/pkg/regexp/syntax/parse.go b/src/pkg/regexp/syntax/parse.go
index 42d0bf4a1..cb25dca39 100644
--- a/src/pkg/regexp/syntax/parse.go
+++ b/src/pkg/regexp/syntax/parse.go
@@ -668,7 +668,6 @@ func Parse(s string, flags Flags) (*Regexp, error) {
c rune
op Op
lastRepeat string
- min, max int
)
p.flags = flags
p.wholeRegexp = s
@@ -740,7 +739,7 @@ func Parse(s string, flags Flags) (*Regexp, error) {
op = OpQuest
}
after := t[1:]
- if after, err = p.repeat(op, min, max, before, after, lastRepeat); err != nil {
+ if after, err = p.repeat(op, 0, 0, before, after, lastRepeat); err != nil {
return nil, err
}
repeat = before
diff --git a/src/pkg/regexp/syntax/parse_test.go b/src/pkg/regexp/syntax/parse_test.go
index 269d6c3b8..f3089294c 100644
--- a/src/pkg/regexp/syntax/parse_test.go
+++ b/src/pkg/regexp/syntax/parse_test.go
@@ -100,12 +100,12 @@ var parseTests = []parseTest{
{`\P{Braille}`, `cc{0x0-0x27ff 0x2900-0x10ffff}`},
{`\p{^Braille}`, `cc{0x0-0x27ff 0x2900-0x10ffff}`},
{`\P{^Braille}`, `cc{0x2800-0x28ff}`},
- {`\pZ`, `cc{0x20 0xa0 0x1680 0x180e 0x2000-0x200a 0x2028-0x2029 0x202f 0x205f 0x3000}`},
+ {`\pZ`, `cc{0x20 0xa0 0x1680 0x2000-0x200a 0x2028-0x2029 0x202f 0x205f 0x3000}`},
{`[\p{Braille}]`, `cc{0x2800-0x28ff}`},
{`[\P{Braille}]`, `cc{0x0-0x27ff 0x2900-0x10ffff}`},
{`[\p{^Braille}]`, `cc{0x0-0x27ff 0x2900-0x10ffff}`},
{`[\P{^Braille}]`, `cc{0x2800-0x28ff}`},
- {`[\pZ]`, `cc{0x20 0xa0 0x1680 0x180e 0x2000-0x200a 0x2028-0x2029 0x202f 0x205f 0x3000}`},
+ {`[\pZ]`, `cc{0x20 0xa0 0x1680 0x2000-0x200a 0x2028-0x2029 0x202f 0x205f 0x3000}`},
{`\p{Lu}`, mkCharClass(unicode.IsUpper)},
{`[\p{Lu}]`, mkCharClass(unicode.IsUpper)},
{`(?i)[\p{Lu}]`, mkCharClass(isUpperFold)},
diff --git a/src/pkg/regexp/syntax/perl_groups.go b/src/pkg/regexp/syntax/perl_groups.go
index 1a11ca62f..effe4e686 100644
--- a/src/pkg/regexp/syntax/perl_groups.go
+++ b/src/pkg/regexp/syntax/perl_groups.go
@@ -1,3 +1,7 @@
+// Copyright 2013 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.
+
// GENERATED BY make_perl_groups.pl; DO NOT EDIT.
// make_perl_groups.pl >perl_groups.go
diff --git a/src/pkg/regexp/syntax/prog.go b/src/pkg/regexp/syntax/prog.go
index a482a82f2..29bd282d0 100644
--- a/src/pkg/regexp/syntax/prog.go
+++ b/src/pkg/regexp/syntax/prog.go
@@ -37,6 +37,27 @@ const (
InstRuneAnyNotNL
)
+var instOpNames = []string{
+ "InstAlt",
+ "InstAltMatch",
+ "InstCapture",
+ "InstEmptyWidth",
+ "InstMatch",
+ "InstFail",
+ "InstNop",
+ "InstRune",
+ "InstRune1",
+ "InstRuneAny",
+ "InstRuneAnyNotNL",
+}
+
+func (i InstOp) String() string {
+ if uint(i) >= uint(len(instOpNames)) {
+ return ""
+ }
+ return instOpNames[i]
+}
+
// An EmptyOp specifies a kind or mixture of zero-width assertions.
type EmptyOp uint8
@@ -103,13 +124,13 @@ func (p *Prog) String() string {
// skipNop follows any no-op or capturing instructions
// and returns the resulting pc.
-func (p *Prog) skipNop(pc uint32) *Inst {
+func (p *Prog) skipNop(pc uint32) (*Inst, uint32) {
i := &p.Inst[pc]
for i.Op == InstNop || i.Op == InstCapture {
pc = i.Out
i = &p.Inst[pc]
}
- return i
+ return i, pc
}
// op returns i.Op but merges all the Rune special cases into InstRune
@@ -126,7 +147,7 @@ func (i *Inst) op() InstOp {
// regexp must start with. Complete is true if the prefix
// is the entire match.
func (p *Prog) Prefix() (prefix string, complete bool) {
- i := p.skipNop(uint32(p.Start))
+ i, _ := p.skipNop(uint32(p.Start))
// Avoid allocation of buffer if prefix is empty.
if i.op() != InstRune || len(i.Rune) != 1 {
@@ -137,7 +158,7 @@ func (p *Prog) Prefix() (prefix string, complete bool) {
var buf bytes.Buffer
for i.op() == InstRune && len(i.Rune) == 1 && Flags(i.Arg)&FoldCase == 0 {
buf.WriteRune(i.Rune[0])
- i = p.skipNop(i.Out)
+ i, _ = p.skipNop(i.Out)
}
return buf.String(), i.Op == InstMatch
}
@@ -166,35 +187,46 @@ Loop:
return flag
}
+const noMatch = -1
+
// MatchRune returns true if the instruction matches (and consumes) r.
// It should only be called when i.Op == InstRune.
func (i *Inst) MatchRune(r rune) bool {
+ return i.MatchRunePos(r) != noMatch
+}
+
+// MatchRunePos checks whether the instruction matches (and consumes) r.
+// If so, MatchRunePos returns the index of the matching rune pair
+// (or, when len(i.Rune) == 1, rune singleton).
+// If not, MatchRunePos returns -1.
+// MatchRunePos should only be called when i.Op == InstRune.
+func (i *Inst) MatchRunePos(r rune) int {
rune := i.Rune
// Special case: single-rune slice is from literal string, not char class.
if len(rune) == 1 {
r0 := rune[0]
if r == r0 {
- return true
+ return 0
}
if Flags(i.Arg)&FoldCase != 0 {
for r1 := unicode.SimpleFold(r0); r1 != r0; r1 = unicode.SimpleFold(r1) {
if r == r1 {
- return true
+ return 0
}
}
}
- return false
+ return noMatch
}
// Peek at the first few pairs.
// Should handle ASCII well.
for j := 0; j < len(rune) && j <= 8; j += 2 {
if r < rune[j] {
- return false
+ return noMatch
}
if r <= rune[j+1] {
- return true
+ return j / 2
}
}
@@ -205,14 +237,14 @@ func (i *Inst) MatchRune(r rune) bool {
m := lo + (hi-lo)/2
if c := rune[2*m]; c <= r {
if r <= rune[2*m+1] {
- return true
+ return m
}
lo = m + 1
} else {
hi = m
}
}
- return false
+ return noMatch
}
// As per re2's Prog::IsWordChar. Determines whether rune is an ASCII word char.
diff --git a/src/pkg/regexp/syntax/prog_test.go b/src/pkg/regexp/syntax/prog_test.go
index cd71abc2a..50bfa3d4b 100644
--- a/src/pkg/regexp/syntax/prog_test.go
+++ b/src/pkg/regexp/syntax/prog_test.go
@@ -4,9 +4,7 @@
package syntax
-import (
- "testing"
-)
+import "testing"
var compileTests = []struct {
Regexp string
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-23 13:46:57 +0000