Permalink
Switch branches/tags
weekly.2012-03-27 weekly.2012-03-22 weekly.2012-03-13 weekly.2012-03-04 weekly.2012-02-22 weekly.2012-02-14 weekly.2012-02-07 weekly.2012-01-27 weekly.2012-01-20 weekly.2012-01-15 weekly.2011-12-22 weekly.2011-12-14 weekly.2011-12-06 weekly.2011-12-02 weekly.2011-12-01 weekly.2011-11-18 weekly.2011-11-09 weekly.2011-11-08 weekly.2011-11-02 weekly.2011-11-01 weekly.2011-10-26 weekly.2011-10-25 weekly.2011-10-18 weekly.2011-10-06 weekly.2011-09-21 weekly.2011-09-16 weekly.2011-09-07 weekly.2011-09-01 weekly.2011-08-17 weekly.2011-08-10 weekly.2011-07-29 weekly.2011-07-19 weekly.2011-07-07 weekly.2011-06-23 weekly.2011-06-16 weekly.2011-06-09 weekly.2011-06-02 weekly.2011-05-22 weekly.2011-04-27 weekly.2011-04-13 weekly.2011-04-04 weekly.2011-03-28 weekly.2011-03-15 weekly.2011-03-07.1 weekly.2011-03-07 weekly.2011-02-24 weekly.2011-02-15 weekly.2011-02-01.1 weekly.2011-02-01 weekly.2011-01-20 weekly.2011-01-19 weekly.2011-01-12 weekly.2011-01-06 weekly.2010-12-22 weekly.2010-12-15.1 weekly.2010-12-15 weekly.2010-12-08 weekly.2010-12-02 weekly.2010-11-23 weekly.2010-11-10 weekly.2010-11-02 weekly.2010-10-27 weekly.2010-10-20 weekly.2010-10-13.1 weekly.2010-10-13 weekly.2010-09-29 weekly.2010-09-22 weekly.2010-09-15 weekly.2010-09-06 weekly.2010-08-25 weekly.2010-08-11 weekly.2010-08-04 weekly.2010-07-29 weekly.2010-07-14 weekly.2010-07-01 weekly.2010-06-21 weekly.2010-06-09 weekly.2010-05-27 weekly.2010-05-04 weekly.2010-04-27 weekly.2010-04-13 weekly.2010-03-30 weekly.2010-03-22 weekly.2010-03-15 weekly.2010-03-04 weekly.2010-02-23 weekly.2010-02-17 weekly.2010-02-04 weekly.2010-01-27 weekly.2010-01-13 weekly.2010-01-05 weekly.2009-12-22 weekly.2009-12-09 weekly.2009-12-07 weekly.2009-11-17 weekly.2009-11-12 weekly.2009-11-10.1 weekly.2009-11-10 weekly.2009-11-06 weekly
Nothing to show
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
347 lines (312 sloc) 7.48 KB
// 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 syntax
import (
"strconv"
"strings"
"unicode"
)
// Compiled program.
// May not belong in this package, but convenient for now.
// A Prog is a compiled regular expression program.
type Prog struct {
Inst []Inst
Start int // index of start instruction
NumCap int // number of InstCapture insts in re
}
// An InstOp is an instruction opcode.
type InstOp uint8
const (
InstAlt InstOp = iota
InstAltMatch
InstCapture
InstEmptyWidth
InstMatch
InstFail
InstNop
InstRune
InstRune1
InstRuneAny
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
const (
EmptyBeginLine EmptyOp = 1 << iota
EmptyEndLine
EmptyBeginText
EmptyEndText
EmptyWordBoundary
EmptyNoWordBoundary
)
// EmptyOpContext returns the zero-width assertions
// satisfied at the position between the runes r1 and r2.
// Passing r1 == -1 indicates that the position is
// at the beginning of the text.
// Passing r2 == -1 indicates that the position is
// at the end of the text.
func EmptyOpContext(r1, r2 rune) EmptyOp {
var op EmptyOp = EmptyNoWordBoundary
var boundary byte
switch {
case IsWordChar(r1):
boundary = 1
case r1 == '\n':
op |= EmptyBeginLine
case r1 < 0:
op |= EmptyBeginText | EmptyBeginLine
}
switch {
case IsWordChar(r2):
boundary ^= 1
case r2 == '\n':
op |= EmptyEndLine
case r2 < 0:
op |= EmptyEndText | EmptyEndLine
}
if boundary != 0 { // IsWordChar(r1) != IsWordChar(r2)
op ^= (EmptyWordBoundary | EmptyNoWordBoundary)
}
return op
}
// IsWordChar reports whether r is consider a ``word character''
// during the evaluation of the \b and \B zero-width assertions.
// These assertions are ASCII-only: the word characters are [A-Za-z0-9_].
func IsWordChar(r rune) bool {
return 'A' <= r && r <= 'Z' || 'a' <= r && r <= 'z' || '0' <= r && r <= '9' || r == '_'
}
// An Inst is a single instruction in a regular expression program.
type Inst struct {
Op InstOp
Out uint32 // all but InstMatch, InstFail
Arg uint32 // InstAlt, InstAltMatch, InstCapture, InstEmptyWidth
Rune []rune
}
func (p *Prog) String() string {
var b strings.Builder
dumpProg(&b, p)
return b.String()
}
// skipNop follows any no-op or capturing instructions.
func (p *Prog) skipNop(pc uint32) *Inst {
i := &p.Inst[pc]
for i.Op == InstNop || i.Op == InstCapture {
i = &p.Inst[i.Out]
}
return i
}
// op returns i.Op but merges all the Rune special cases into InstRune
func (i *Inst) op() InstOp {
op := i.Op
switch op {
case InstRune1, InstRuneAny, InstRuneAnyNotNL:
op = InstRune
}
return op
}
// Prefix returns a literal string that all matches for the
// 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))
// Avoid allocation of buffer if prefix is empty.
if i.op() != InstRune || len(i.Rune) != 1 {
return "", i.Op == InstMatch
}
// Have prefix; gather characters.
var buf strings.Builder
for i.op() == InstRune && len(i.Rune) == 1 && Flags(i.Arg)&FoldCase == 0 {
buf.WriteRune(i.Rune[0])
i = p.skipNop(i.Out)
}
return buf.String(), i.Op == InstMatch
}
// StartCond returns the leading empty-width conditions that must
// be true in any match. It returns ^EmptyOp(0) if no matches are possible.
func (p *Prog) StartCond() EmptyOp {
var flag EmptyOp
pc := uint32(p.Start)
i := &p.Inst[pc]
Loop:
for {
switch i.Op {
case InstEmptyWidth:
flag |= EmptyOp(i.Arg)
case InstFail:
return ^EmptyOp(0)
case InstCapture, InstNop:
// skip
default:
break Loop
}
pc = i.Out
i = &p.Inst[pc]
}
return flag
}
const noMatch = -1
// MatchRune reports whether 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
switch len(rune) {
case 0:
return noMatch
case 1:
// Special case: single-rune slice is from literal string, not char class.
r0 := rune[0]
if r == r0 {
return 0
}
if Flags(i.Arg)&FoldCase != 0 {
for r1 := unicode.SimpleFold(r0); r1 != r0; r1 = unicode.SimpleFold(r1) {
if r == r1 {
return 0
}
}
}
return noMatch
case 2:
if r >= rune[0] && r <= rune[1] {
return 0
}
return noMatch
case 4, 6, 8:
// Linear search for a few pairs.
// Should handle ASCII well.
for j := 0; j < len(rune); j += 2 {
if r < rune[j] {
return noMatch
}
if r <= rune[j+1] {
return j / 2
}
}
return noMatch
}
// Otherwise binary search.
lo := 0
hi := len(rune) / 2
for lo < hi {
m := lo + (hi-lo)/2
if c := rune[2*m]; c <= r {
if r <= rune[2*m+1] {
return m
}
lo = m + 1
} else {
hi = m
}
}
return noMatch
}
// MatchEmptyWidth reports whether the instruction matches
// an empty string between the runes before and after.
// It should only be called when i.Op == InstEmptyWidth.
func (i *Inst) MatchEmptyWidth(before rune, after rune) bool {
switch EmptyOp(i.Arg) {
case EmptyBeginLine:
return before == '\n' || before == -1
case EmptyEndLine:
return after == '\n' || after == -1
case EmptyBeginText:
return before == -1
case EmptyEndText:
return after == -1
case EmptyWordBoundary:
return IsWordChar(before) != IsWordChar(after)
case EmptyNoWordBoundary:
return IsWordChar(before) == IsWordChar(after)
}
panic("unknown empty width arg")
}
func (i *Inst) String() string {
var b strings.Builder
dumpInst(&b, i)
return b.String()
}
func bw(b *strings.Builder, args ...string) {
for _, s := range args {
b.WriteString(s)
}
}
func dumpProg(b *strings.Builder, p *Prog) {
for j := range p.Inst {
i := &p.Inst[j]
pc := strconv.Itoa(j)
if len(pc) < 3 {
b.WriteString(" "[len(pc):])
}
if j == p.Start {
pc += "*"
}
bw(b, pc, "\t")
dumpInst(b, i)
bw(b, "\n")
}
}
func u32(i uint32) string {
return strconv.FormatUint(uint64(i), 10)
}
func dumpInst(b *strings.Builder, i *Inst) {
switch i.Op {
case InstAlt:
bw(b, "alt -> ", u32(i.Out), ", ", u32(i.Arg))
case InstAltMatch:
bw(b, "altmatch -> ", u32(i.Out), ", ", u32(i.Arg))
case InstCapture:
bw(b, "cap ", u32(i.Arg), " -> ", u32(i.Out))
case InstEmptyWidth:
bw(b, "empty ", u32(i.Arg), " -> ", u32(i.Out))
case InstMatch:
bw(b, "match")
case InstFail:
bw(b, "fail")
case InstNop:
bw(b, "nop -> ", u32(i.Out))
case InstRune:
if i.Rune == nil {
// shouldn't happen
bw(b, "rune <nil>")
}
bw(b, "rune ", strconv.QuoteToASCII(string(i.Rune)))
if Flags(i.Arg)&FoldCase != 0 {
bw(b, "/i")
}
bw(b, " -> ", u32(i.Out))
case InstRune1:
bw(b, "rune1 ", strconv.QuoteToASCII(string(i.Rune)), " -> ", u32(i.Out))
case InstRuneAny:
bw(b, "any -> ", u32(i.Out))
case InstRuneAnyNotNL:
bw(b, "anynotnl -> ", u32(i.Out))
}
}