summaryrefslogtreecommitdiff
path: root/src/pkg/regexp/exec.go
diff options
context:
space:
mode:
Diffstat (limited to 'src/pkg/regexp/exec.go')
-rw-r--r--src/pkg/regexp/exec.go452
1 files changed, 0 insertions, 452 deletions
diff --git a/src/pkg/regexp/exec.go b/src/pkg/regexp/exec.go
deleted file mode 100644
index c4cb201f6..000000000
--- a/src/pkg/regexp/exec.go
+++ /dev/null
@@ -1,452 +0,0 @@
-// Copyright 2011 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 (
- "io"
- "regexp/syntax"
-)
-
-// A queue is a 'sparse array' holding pending threads of execution.
-// See http://research.swtch.com/2008/03/using-uninitialized-memory-for-fun-and.html
-type queue struct {
- sparse []uint32
- dense []entry
-}
-
-// A entry is an entry on a queue.
-// It holds both the instruction pc and the actual thread.
-// Some queue entries are just place holders so that the machine
-// knows it has considered that pc. Such entries have t == nil.
-type entry struct {
- pc uint32
- t *thread
-}
-
-// A thread is the state of a single path through the machine:
-// an instruction and a corresponding capture array.
-// See http://swtch.com/~rsc/regexp/regexp2.html
-type thread struct {
- inst *syntax.Inst
- cap []int
-}
-
-// A machine holds all the state during an NFA simulation for p.
-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
- matchcap []int // capture information for the match
-
- // cached inputs, to avoid allocation
- inputBytes inputBytes
- inputString inputString
- inputReader inputReader
-}
-
-func (m *machine) newInputBytes(b []byte) input {
- m.inputBytes.str = b
- return &m.inputBytes
-}
-
-func (m *machine) newInputString(s string) input {
- m.inputString.str = s
- return &m.inputString
-}
-
-func (m *machine) newInputReader(r io.RuneReader) input {
- m.inputReader.r = r
- m.inputReader.atEOT = false
- m.inputReader.pos = 0
- return &m.inputReader
-}
-
-// progMachine returns a new machine running the prog 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)}
- ncap := p.NumCap
- if ncap < 2 {
- ncap = 2
- }
- m.matchcap = make([]int, ncap)
- return m
-}
-
-func (m *machine) init(ncap int) {
- for _, t := range m.pool {
- t.cap = t.cap[:ncap]
- }
- m.matchcap = m.matchcap[:ncap]
-}
-
-// alloc allocates a new thread with the given instruction.
-// It uses the free pool if possible.
-func (m *machine) alloc(i *syntax.Inst) *thread {
- var t *thread
- if n := len(m.pool); n > 0 {
- t = m.pool[n-1]
- m.pool = m.pool[:n-1]
- } else {
- t = new(thread)
- t.cap = make([]int, len(m.matchcap), cap(m.matchcap))
- }
- t.inst = i
- return t
-}
-
-// free returns t to the free pool.
-func (m *machine) free(t *thread) {
- m.inputBytes.str = nil
- m.inputString.str = ""
- m.inputReader.r = nil
- m.pool = append(m.pool, t)
-}
-
-// match 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) match(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
- }
- runq, nextq := &m.q0, &m.q1
- 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)
- }
- for {
- if len(runq.dense) == 0 {
- if startCond&syntax.EmptyBeginText != 0 && pos != 0 {
- // Anchored match, past beginning of text.
- break
- }
- if m.matched {
- // Have match; finished exploring alternatives.
- break
- }
- if len(m.re.prefix) > 0 && r1 != m.re.prefixRune && i.canCheckPrefix() {
- // Match requires literal prefix; fast search for it.
- advance := i.index(m.re, pos)
- if advance < 0 {
- break
- }
- pos += advance
- r, width = i.step(pos)
- r1, width1 = i.step(pos + width)
- }
- }
- if !m.matched {
- if len(m.matchcap) > 0 {
- m.matchcap[0] = pos
- }
- m.add(runq, uint32(m.p.Start), pos, m.matchcap, flag, nil)
- }
- flag = syntax.EmptyOpContext(r, r1)
- m.step(runq, nextq, pos, pos+width, r, flag)
- if width == 0 {
- break
- }
- if len(m.matchcap) == 0 && m.matched {
- // Found a match and not paying attention
- // to where it is, so any match will do.
- break
- }
- pos += width
- r, width = r1, width1
- if r != endOfText {
- r1, width1 = i.step(pos + width)
- }
- runq, nextq = nextq, runq
- }
- m.clear(nextq)
- return m.matched
-}
-
-// clear frees all threads on the thread queue.
-func (m *machine) clear(q *queue) {
- for _, d := range q.dense {
- if d.t != nil {
- // m.free(d.t)
- m.pool = append(m.pool, d.t)
- }
- }
- q.dense = q.dense[:0]
-}
-
-// step executes one step of the machine, running each of the threads
-// on runq and appending new threads to nextq.
-// The step processes the rune c (which may be endOfText),
-// which starts at position pos and ends at nextPos.
-// nextCond gives the setting for the empty-width flags after c.
-func (m *machine) step(runq, nextq *queue, pos, nextPos int, c rune, nextCond syntax.EmptyOp) {
- longest := m.re.longest
- for j := 0; j < len(runq.dense); j++ {
- d := &runq.dense[j]
- t := d.t
- if t == nil {
- continue
- }
- if longest && m.matched && len(t.cap) > 0 && m.matchcap[0] < t.cap[0] {
- // m.free(t)
- m.pool = append(m.pool, t)
- continue
- }
- i := t.inst
- add := false
- switch i.Op {
- default:
- panic("bad inst")
-
- case syntax.InstMatch:
- if len(t.cap) > 0 && (!longest || !m.matched || m.matchcap[1] < pos) {
- t.cap[1] = pos
- copy(m.matchcap, t.cap)
- }
- if !longest {
- // First-match mode: cut off all lower-priority threads.
- for _, d := range runq.dense[j+1:] {
- if d.t != nil {
- // m.free(d.t)
- m.pool = append(m.pool, d.t)
- }
- }
- runq.dense = runq.dense[:0]
- }
- m.matched = true
-
- case syntax.InstRune:
- add = i.MatchRune(c)
- case syntax.InstRune1:
- add = c == i.Rune[0]
- case syntax.InstRuneAny:
- add = true
- case syntax.InstRuneAnyNotNL:
- add = c != '\n'
- }
- if add {
- t = m.add(nextq, i.Out, nextPos, t.cap, nextCond, t)
- }
- if t != nil {
- // m.free(t)
- m.pool = append(m.pool, t)
- }
- }
- runq.dense = runq.dense[:0]
-}
-
-// add adds an entry to q for pc, unless the q already has such an entry.
-// It also recursively adds an entry for all instructions reachable from pc by following
-// empty-width conditions satisfied by cond. pos gives the current position
-// in the input.
-func (m *machine) add(q *queue, pc uint32, pos int, cap []int, cond syntax.EmptyOp, t *thread) *thread {
- if pc == 0 {
- return t
- }
- if j := q.sparse[pc]; j < uint32(len(q.dense)) && q.dense[j].pc == pc {
- return t
- }
-
- j := len(q.dense)
- q.dense = q.dense[:j+1]
- d := &q.dense[j]
- d.t = nil
- d.pc = pc
- q.sparse[pc] = uint32(j)
-
- i := &m.p.Inst[pc]
- switch i.Op {
- default:
- panic("unhandled")
- case syntax.InstFail:
- // nothing
- case syntax.InstAlt, syntax.InstAltMatch:
- t = m.add(q, i.Out, pos, cap, cond, t)
- t = m.add(q, i.Arg, pos, cap, cond, t)
- case syntax.InstEmptyWidth:
- if syntax.EmptyOp(i.Arg)&^cond == 0 {
- t = m.add(q, i.Out, pos, cap, cond, t)
- }
- case syntax.InstNop:
- t = m.add(q, i.Out, pos, cap, cond, t)
- case syntax.InstCapture:
- if int(i.Arg) < len(cap) {
- opos := cap[i.Arg]
- cap[i.Arg] = pos
- m.add(q, i.Out, pos, cap, cond, nil)
- cap[i.Arg] = opos
- } else {
- t = m.add(q, i.Out, pos, cap, cond, t)
- }
- case syntax.InstMatch, syntax.InstRune, syntax.InstRune1, syntax.InstRuneAny, syntax.InstRuneAnyNotNL:
- if t == nil {
- t = m.alloc(i)
- } else {
- t.inst = i
- }
- if len(cap) > 0 && &t.cap[0] != &cap[0] {
- copy(t.cap, cap)
- }
- d.t = t
- t = nil
- }
- 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.
-var empty = make([]int, 0)
-
-// doExecute finds the leftmost match in the input and returns
-// the position of its subexpressions.
-func (re *Regexp) doExecute(r io.RuneReader, b []byte, s string, pos int, ncap int) []int {
- m := re.get()
- var i input
- if r != nil {
- i = m.newInputReader(r)
- } else if b != nil {
- i = m.newInputBytes(b)
- } else {
- i = m.newInputString(s)
- }
- 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, len(m.matchcap))
- copy(cap, m.matchcap)
- re.put(m)
- return cap
-}
generated by cgit v1.2.3 (git 2.39.1) at 2025-04-29 09:00:35 +0000