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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [regexp/] [syntax/] [prog.go] - Blame information for rev 747

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// 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 (
        "bytes"
        "strconv"
        "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
)
 
// 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
        if r1 < 0 {
                op |= EmptyBeginText | EmptyBeginLine
        }
        if r1 == '\n' {
                op |= EmptyBeginLine
        }
        if r2 < 0 {
                op |= EmptyEndText | EmptyEndLine
        }
        if r2 == '\n' {
                op |= EmptyEndLine
        }
        if IsWordChar(r1) != IsWordChar(r2) {
                op |= EmptyWordBoundary
        } else {
                op |= 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 bytes.Buffer
        dumpProg(&b, p)
        return b.String()
}
 
// skipNop follows any no-op or capturing instructions
// and returns the resulting pc.
func (p *Prog) skipNop(pc uint32) *Inst {
        i := &p.Inst[pc]
        for i.Op == InstNop || i.Op == InstCapture {
                pc = i.Out
                i = &p.Inst[pc]
        }
        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 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)
        }
        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
}
 
// 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 {
        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
                }
                if Flags(i.Arg)&FoldCase != 0 {
                        for r1 := unicode.SimpleFold(r0); r1 != r0; r1 = unicode.SimpleFold(r1) {
                                if r == r1 {
                                        return true
                                }
                        }
                }
                return false
        }
 
        // 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
                }
                if r <= rune[j+1] {
                        return true
                }
        }
 
        // 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 true
                        }
                        lo = m + 1
                } else {
                        hi = m
                }
        }
        return false
}
 
// As per re2's Prog::IsWordChar. Determines whether rune is an ASCII word char.
// Since we act on runes, it would be easy to support Unicode here.
func wordRune(r rune) bool {
        return r == '_' ||
                ('A' <= r && r <= 'Z') ||
                ('a' <= r && r <= 'z') ||
                ('0' <= r && r <= '9')
}
 
// MatchEmptyWidth returns true if 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 wordRune(before) != wordRune(after)
        case EmptyNoWordBoundary:
                return wordRune(before) == wordRune(after)
        }
        panic("unknown empty width arg")
}
 
func (i *Inst) String() string {
        var b bytes.Buffer
        dumpInst(&b, i)
        return b.String()
}
 
func bw(b *bytes.Buffer, args ...string) {
        for _, s := range args {
                b.WriteString(s)
        }
}
 
func dumpProg(b *bytes.Buffer, 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 *bytes.Buffer, 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 ")
                }
                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))
        }
}

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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [regexp/] [syntax/] [prog.go] - Blame information for rev 747

Line No.	Rev	Author	Line
1	747	jeremybenn	`// Copyright 2011 The Go Authors. All rights reserved.`
2			`// Use of this source code is governed by a BSD-style`
3			`// license that can be found in the LICENSE file.`
4
5			`package syntax`
6
7			`import (`
8			`"bytes"`
9			`"strconv"`
10			`"unicode"`
11			`)`
12
13			`// Compiled program.`
14			`// May not belong in this package, but convenient for now.`
15
16			`// A Prog is a compiled regular expression program.`
17			`type Prog struct {`
18			`Inst []Inst`
19			`Start int // index of start instruction`
20			`NumCap int // number of InstCapture insts in re`
21			`}`
22
23			`// An InstOp is an instruction opcode.`
24			`type InstOp uint8`
25
26			`const (`
27			`InstAlt InstOp = iota`
28			`InstAltMatch`
29			`InstCapture`
30			`InstEmptyWidth`
31			`InstMatch`
32			`InstFail`
33			`InstNop`
34			`InstRune`
35			`InstRune1`
36			`InstRuneAny`
37			`InstRuneAnyNotNL`
38			`)`
39
40			`// An EmptyOp specifies a kind or mixture of zero-width assertions.`
41			`type EmptyOp uint8`
42
43			`const (`
44			`EmptyBeginLine EmptyOp = 1 << iota`
45			`EmptyEndLine`
46			`EmptyBeginText`
47			`EmptyEndText`
48			`EmptyWordBoundary`
49			`EmptyNoWordBoundary`
50			`)`
51
52			`// EmptyOpContext returns the zero-width assertions`
53			`// satisfied at the position between the runes r1 and r2.`
54			`// Passing r1 == -1 indicates that the position is`
55			`// at the beginning of the text.`
56			`// Passing r2 == -1 indicates that the position is`
57			`// at the end of the text.`
58			`func EmptyOpContext(r1, r2 rune) EmptyOp {`
59			`var op EmptyOp`
60			`if r1 < 0 {`
61			`op \|= EmptyBeginText \| EmptyBeginLine`
62			`}`
63			`if r1 == '\n' {`
64			`op \|= EmptyBeginLine`
65			`}`
66			`if r2 < 0 {`
67			`op \|= EmptyEndText \| EmptyEndLine`
68			`}`
69			`if r2 == '\n' {`
70			`op \|= EmptyEndLine`
71			`}`
72			`if IsWordChar(r1) != IsWordChar(r2) {`
73			`op \|= EmptyWordBoundary`
74			`} else {`
75			`op \|= EmptyNoWordBoundary`
76			`}`
77			`return op`
78			`}`
79
80			// IsWordChar reports whether r is consider a ``word character''
81			`// during the evaluation of the \b and \B zero-width assertions.`
82			`// These assertions are ASCII-only: the word characters are [A-Za-z0-9_].`
83			`func IsWordChar(r rune) bool {`
84			`return 'A' <= r && r <= 'Z' \|\| 'a' <= r && r <= 'z' \|\| '0' <= r && r <= '9' \|\| r == '_'`
85			`}`
86
87			`// An Inst is a single instruction in a regular expression program.`
88			`type Inst struct {`
89			`Op InstOp`
90			`Out uint32 // all but InstMatch, InstFail`
91			`Arg uint32 // InstAlt, InstAltMatch, InstCapture, InstEmptyWidth`
92			`Rune []rune`
93			`}`
94
95			`func (p *Prog) String() string {`
96			`var b bytes.Buffer`
97			`dumpProg(&b, p)`
98			`return b.String()`
99			`}`
100
101			`// skipNop follows any no-op or capturing instructions`
102			`// and returns the resulting pc.`
103			`func (p Prog) skipNop(pc uint32) Inst {`
104			`i := &p.Inst[pc]`
105			`for i.Op == InstNop \|\| i.Op == InstCapture {`
106			`pc = i.Out`
107			`i = &p.Inst[pc]`
108			`}`
109			`return i`
110			`}`
111
112			`// op returns i.Op but merges all the Rune special cases into InstRune`
113			`func (i *Inst) op() InstOp {`
114			`op := i.Op`
115			`switch op {`
116			`case InstRune1, InstRuneAny, InstRuneAnyNotNL:`
117			`op = InstRune`
118			`}`
119			`return op`
120			`}`
121
122			`// Prefix returns a literal string that all matches for the`
123			`// regexp must start with. Complete is true if the prefix`
124			`// is the entire match.`
125			`func (p *Prog) Prefix() (prefix string, complete bool) {`
126			`i := p.skipNop(uint32(p.Start))`
127
128			`// Avoid allocation of buffer if prefix is empty.`
129			`if i.op() != InstRune \|\| len(i.Rune) != 1 {`
130			`return "", i.Op == InstMatch`
131			`}`
132
133			`// Have prefix; gather characters.`
134			`var buf bytes.Buffer`
135			`for i.op() == InstRune && len(i.Rune) == 1 && Flags(i.Arg)&FoldCase == 0 {`
136			`buf.WriteRune(i.Rune[0])`
137			`i = p.skipNop(i.Out)`
138			`}`
139			`return buf.String(), i.Op == InstMatch`
140			`}`
141
142			`// StartCond returns the leading empty-width conditions that must`
143			`// be true in any match. It returns ^EmptyOp(0) if no matches are possible.`
144			`func (p *Prog) StartCond() EmptyOp {`
145			`var flag EmptyOp`
146			`pc := uint32(p.Start)`
147			`i := &p.Inst[pc]`
148			`Loop:`
149			`for {`
150			`switch i.Op {`
151			`case InstEmptyWidth:`
152			`flag \|= EmptyOp(i.Arg)`
153			`case InstFail:`
154			`return ^EmptyOp(0)`
155			`case InstCapture, InstNop:`
156			`// skip`
157			`default:`
158			`break Loop`
159			`}`
160			`pc = i.Out`
161			`i = &p.Inst[pc]`
162			`}`
163			`return flag`
164			`}`
165
166			`// MatchRune returns true if the instruction matches (and consumes) r.`
167			`// It should only be called when i.Op == InstRune.`
168			`func (i *Inst) MatchRune(r rune) bool {`
169			`rune := i.Rune`
170
171			`// Special case: single-rune slice is from literal string, not char class.`
172			`if len(rune) == 1 {`
173			`r0 := rune[0]`
174			`if r == r0 {`
175			`return true`
176			`}`
177			`if Flags(i.Arg)&FoldCase != 0 {`
178			`for r1 := unicode.SimpleFold(r0); r1 != r0; r1 = unicode.SimpleFold(r1) {`
179			`if r == r1 {`
180			`return true`
181			`}`
182			`}`
183			`}`
184			`return false`
185			`}`
186
187			`// Peek at the first few pairs.`
188			`// Should handle ASCII well.`
189			`for j := 0; j < len(rune) && j <= 8; j += 2 {`
190			`if r < rune[j] {`
191			`return false`
192			`}`
193			`if r <= rune[j+1] {`
194			`return true`
195			`}`
196			`}`
197
198			`// Otherwise binary search.`
199			`lo := 0`
200			`hi := len(rune) / 2`
201			`for lo < hi {`
202			`m := lo + (hi-lo)/2`
203			`if c := rune[2*m]; c <= r {`
204			`if r <= rune[2*m+1] {`
205			`return true`
206			`}`
207			`lo = m + 1`
208			`} else {`
209			`hi = m`
210			`}`
211			`}`
212			`return false`
213			`}`
214
215			`// As per re2's Prog::IsWordChar. Determines whether rune is an ASCII word char.`
216			`// Since we act on runes, it would be easy to support Unicode here.`
217			`func wordRune(r rune) bool {`
218			`return r == '_' \|\|`
219			`('A' <= r && r <= 'Z') \|\|`
220			`('a' <= r && r <= 'z') \|\|`
221			`('0' <= r && r <= '9')`
222			`}`
223
224			`// MatchEmptyWidth returns true if the instruction matches`
225			`// an empty string between the runes before and after.`
226			`// It should only be called when i.Op == InstEmptyWidth.`
227			`func (i *Inst) MatchEmptyWidth(before rune, after rune) bool {`
228			`switch EmptyOp(i.Arg) {`
229			`case EmptyBeginLine:`
230			`return before == '\n' \|\| before == -1`
231			`case EmptyEndLine:`
232			`return after == '\n' \|\| after == -1`
233			`case EmptyBeginText:`
234			`return before == -1`
235			`case EmptyEndText:`
236			`return after == -1`
237			`case EmptyWordBoundary:`
238			`return wordRune(before) != wordRune(after)`
239			`case EmptyNoWordBoundary:`
240			`return wordRune(before) == wordRune(after)`
241			`}`
242			`panic("unknown empty width arg")`
243			`}`
244
245			`func (i *Inst) String() string {`
246			`var b bytes.Buffer`
247			`dumpInst(&b, i)`
248			`return b.String()`
249			`}`
250
251			`func bw(b *bytes.Buffer, args ...string) {`
252			`for _, s := range args {`
253			`b.WriteString(s)`
254			`}`
255			`}`
256
257			`func dumpProg(b bytes.Buffer, p Prog) {`
258			`for j := range p.Inst {`
259			`i := &p.Inst[j]`
260			`pc := strconv.Itoa(j)`
261			`if len(pc) < 3 {`
262			`b.WriteString(" "[len(pc):])`
263			`}`
264			`if j == p.Start {`
265			`pc += "*"`
266			`}`
267			`bw(b, pc, "\t")`
268			`dumpInst(b, i)`
269			`bw(b, "\n")`
270			`}`
271			`}`
272
273			`func u32(i uint32) string {`
274			`return strconv.FormatUint(uint64(i), 10)`
275			`}`
276
277			`func dumpInst(b bytes.Buffer, i Inst) {`
278			`switch i.Op {`
279			`case InstAlt:`
280			`bw(b, "alt -> ", u32(i.Out), ", ", u32(i.Arg))`
281			`case InstAltMatch:`
282			`bw(b, "altmatch -> ", u32(i.Out), ", ", u32(i.Arg))`
283			`case InstCapture:`
284			`bw(b, "cap ", u32(i.Arg), " -> ", u32(i.Out))`
285			`case InstEmptyWidth:`
286			`bw(b, "empty ", u32(i.Arg), " -> ", u32(i.Out))`
287			`case InstMatch:`
288			`bw(b, "match")`
289			`case InstFail:`
290			`bw(b, "fail")`
291			`case InstNop:`
292			`bw(b, "nop -> ", u32(i.Out))`
293			`case InstRune:`
294			`if i.Rune == nil {`
295			`// shouldn't happen`
296			`bw(b, "rune ")`
297			`}`
298			`bw(b, "rune ", strconv.QuoteToASCII(string(i.Rune)))`
299			`if Flags(i.Arg)&FoldCase != 0 {`
300			`bw(b, "/i")`
301			`}`
302			`bw(b, " -> ", u32(i.Out))`
303			`case InstRune1:`
304			`bw(b, "rune1 ", strconv.QuoteToASCII(string(i.Rune)), " -> ", u32(i.Out))`
305			`case InstRuneAny:`
306			`bw(b, "any -> ", u32(i.Out))`
307			`case InstRuneAnyNotNL:`
308			`bw(b, "anynotnl -> ", u32(i.Out))`
309			`}`
310			`}`