mirror of
https://github.com/golang/go
synced 2024-11-21 13:44:45 -07:00
regexp: speed up by about 30%.
The code used interfaces in a pretty, pedagogical way but not efficiently. Remove unnecessary interface code for significant speedups. Before: regexp.BenchmarkLiteral 1000000 2629 ns/op regexp.BenchmarkNotLiteral 100000 18131 ns/op regexp.BenchmarkMatchClass 100000 26647 ns/op regexp.BenchmarkMatchClass_InRange 100000 27092 ns/op regexp.BenchmarkReplaceAll 100000 27014 ns/op After: regexp.BenchmarkLiteral 1000000 2077 ns/op regexp.BenchmarkNotLiteral 100000 13738 ns/op regexp.BenchmarkMatchClass 100000 20418 ns/op regexp.BenchmarkMatchClass_InRange 100000 20999 ns/op regexp.BenchmarkReplaceAll 100000 21825 ns/op There's likely more to do without major surgery, but this is a simple, significant step. R=rsc CC=golang-dev https://golang.org/cl/3572042
This commit is contained in:
parent
3fb6d62e3a
commit
8bb9e616ed
@ -89,114 +89,82 @@ var (
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ErrBadBackslash = Error("illegal backslash escape")
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)
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const (
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iStart = iota // beginning of program
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iEnd // end of program: success
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iBOT // '^' beginning of text
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iEOT // '$' end of text
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iChar // 'a' regular character
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iCharClass // [a-z] character class
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iAny // '.' any character including newline
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iNotNL // [^\n] special case: any character but newline
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iBra // '(' parenthesized expression
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iEbra // ')'; end of '(' parenthesized expression
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iAlt // '|' alternation
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iNop // do nothing; makes it easy to link without patching
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)
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// An instruction executed by the NFA
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type instr interface {
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kind() int // the type of this instruction: _CHAR, _ANY, etc.
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next() instr // the instruction to execute after this one
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setNext(i instr)
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index() int
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setIndex(i int)
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print()
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type instr struct {
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kind int // the type of this instruction: iChar, iAny, etc.
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index int // used only in debugging; could be eliminated
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next *instr // the instruction to execute after this one
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// Special fields valid only for some items.
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char int // iChar
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braNum int // iBra, iEbra
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cclass *charClass // iCharClass
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left *instr // iAlt, other branch
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}
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// Fields and methods common to all instructions
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type common struct {
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_next instr
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_index int
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func (i *instr) print() {
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switch i.kind {
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case iStart:
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print("start")
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case iEnd:
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print("end")
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case iBOT:
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print("bot")
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case iEOT:
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print("eot")
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case iChar:
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print("char ", string(i.char))
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case iCharClass:
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i.cclass.print()
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case iAny:
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print("any")
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case iNotNL:
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print("notnl")
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case iBra:
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print("bra", i.braNum)
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case iEbra:
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print("ebra", i.braNum)
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case iAlt:
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print("alt(", i.left.index, ")")
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case iNop:
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print("nop")
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}
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}
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func (c *common) next() instr { return c._next }
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func (c *common) setNext(i instr) { c._next = i }
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func (c *common) index() int { return c._index }
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func (c *common) setIndex(i int) { c._index = i }
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// Regexp is the representation of a compiled regular expression.
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// The public interface is entirely through methods.
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type Regexp struct {
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expr string // the original expression
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prefix string // initial plain text string
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prefixBytes []byte // initial plain text bytes
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inst []instr
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start instr // first instruction of machine
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prefixStart instr // where to start if there is a prefix
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nbra int // number of brackets in expression, for subexpressions
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inst []*instr
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start *instr // first instruction of machine
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prefixStart *instr // where to start if there is a prefix
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nbra int // number of brackets in expression, for subexpressions
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}
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const (
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_START = iota // beginning of program
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_END // end of program: success
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_BOT // '^' beginning of text
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_EOT // '$' end of text
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_CHAR // 'a' regular character
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_CHARCLASS // [a-z] character class
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_ANY // '.' any character including newline
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_NOTNL // [^\n] special case: any character but newline
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_BRA // '(' parenthesized expression
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_EBRA // ')'; end of '(' parenthesized expression
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_ALT // '|' alternation
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_NOP // do nothing; makes it easy to link without patching
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)
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// --- START start of program
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type _Start struct {
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common
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}
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func (start *_Start) kind() int { return _START }
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func (start *_Start) print() { print("start") }
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// --- END end of program
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type _End struct {
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common
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}
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func (end *_End) kind() int { return _END }
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func (end *_End) print() { print("end") }
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// --- BOT beginning of text
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type _Bot struct {
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common
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}
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func (bot *_Bot) kind() int { return _BOT }
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func (bot *_Bot) print() { print("bot") }
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// --- EOT end of text
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type _Eot struct {
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common
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}
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func (eot *_Eot) kind() int { return _EOT }
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func (eot *_Eot) print() { print("eot") }
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// --- CHAR a regular character
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type _Char struct {
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common
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char int
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}
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func (char *_Char) kind() int { return _CHAR }
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func (char *_Char) print() { print("char ", string(char.char)) }
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func newChar(char int) *_Char {
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c := new(_Char)
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c.char = char
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return c
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}
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// --- CHARCLASS [a-z]
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type _CharClass struct {
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common
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type charClass struct {
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negate bool // is character class negated? ([^a-z])
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// slice of int, stored pairwise: [a-z] is (a,z); x is (x,x):
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ranges []int
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cmin, cmax int
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}
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func (cclass *_CharClass) kind() int { return _CHARCLASS }
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func (cclass *_CharClass) print() {
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func (cclass *charClass) print() {
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print("charclass")
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if cclass.negate {
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print(" (negated)")
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@ -212,7 +180,7 @@ func (cclass *_CharClass) print() {
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}
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}
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func (cclass *_CharClass) addRange(a, b int) {
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func (cclass *charClass) addRange(a, b int) {
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// range is a through b inclusive
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cclass.ranges = append(cclass.ranges, a, b)
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if a < cclass.cmin {
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@ -223,7 +191,7 @@ func (cclass *_CharClass) addRange(a, b int) {
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}
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}
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func (cclass *_CharClass) matches(c int) bool {
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func (cclass *charClass) matches(c int) bool {
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if c < cclass.cmin || c > cclass.cmax {
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return cclass.negate
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}
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@ -236,67 +204,17 @@ func (cclass *_CharClass) matches(c int) bool {
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return cclass.negate
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}
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func newCharClass() *_CharClass {
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c := new(_CharClass)
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c.ranges = make([]int, 0, 4)
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c.cmin = 0x10FFFF + 1 // MaxRune + 1
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c.cmax = -1
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return c
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func newCharClass() *instr {
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i := &instr{kind: iCharClass}
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i.cclass = new(charClass)
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i.cclass.ranges = make([]int, 0, 4)
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i.cclass.cmin = 0x10FFFF + 1 // MaxRune + 1
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i.cclass.cmax = -1
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return i
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}
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// --- ANY any character
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type _Any struct {
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common
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}
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func (any *_Any) kind() int { return _ANY }
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func (any *_Any) print() { print("any") }
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// --- NOTNL any character but newline
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type _NotNl struct {
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common
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}
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func (notnl *_NotNl) kind() int { return _NOTNL }
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func (notnl *_NotNl) print() { print("notnl") }
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// --- BRA parenthesized expression
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type _Bra struct {
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common
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n int // subexpression number
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}
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func (bra *_Bra) kind() int { return _BRA }
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func (bra *_Bra) print() { print("bra", bra.n) }
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// --- EBRA end of parenthesized expression
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type _Ebra struct {
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common
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n int // subexpression number
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}
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func (ebra *_Ebra) kind() int { return _EBRA }
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func (ebra *_Ebra) print() { print("ebra ", ebra.n) }
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// --- ALT alternation
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type _Alt struct {
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common
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left instr // other branch
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}
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func (alt *_Alt) kind() int { return _ALT }
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func (alt *_Alt) print() { print("alt(", alt.left.index(), ")") }
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// --- NOP no operation
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type _Nop struct {
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common
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}
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func (nop *_Nop) kind() int { return _NOP }
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func (nop *_Nop) print() { print("nop") }
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func (re *Regexp) add(i instr) instr {
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i.setIndex(len(re.inst))
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func (re *Regexp) add(i *instr) *instr {
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i.index = len(re.inst)
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re.inst = append(re.inst, i)
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return i
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}
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@ -364,8 +282,9 @@ func escape(c int) int {
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return -1
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}
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func (p *parser) charClass() instr {
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cc := newCharClass()
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func (p *parser) charClass() *instr {
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i := newCharClass()
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cc := i.cclass
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if p.c() == '^' {
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cc.negate = true
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p.nextc()
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@ -380,18 +299,18 @@ func (p *parser) charClass() instr {
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// Is it [^\n]?
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if cc.negate && len(cc.ranges) == 2 &&
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cc.ranges[0] == '\n' && cc.ranges[1] == '\n' {
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nl := new(_NotNl)
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nl := &instr{kind: iNotNL}
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p.re.add(nl)
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return nl
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}
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// Special common case: "[a]" -> "a"
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if !cc.negate && len(cc.ranges) == 2 && cc.ranges[0] == cc.ranges[1] {
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c := newChar(cc.ranges[0])
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c := &instr{kind: iChar, char: cc.ranges[0]}
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p.re.add(c)
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return c
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}
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p.re.add(cc)
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return cc
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p.re.add(i)
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return i
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case '-': // do this before backslash processing
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p.error(ErrBadRange)
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case '\\':
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@ -428,7 +347,7 @@ func (p *parser) charClass() instr {
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return nil
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}
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func (p *parser) term() (start, end instr) {
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func (p *parser) term() (start, end *instr) {
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switch c := p.c(); c {
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case '|', endOfFile:
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return nil, nil
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@ -443,15 +362,15 @@ func (p *parser) term() (start, end instr) {
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p.error(ErrUnmatchedRbkt)
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case '^':
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p.nextc()
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start = p.re.add(new(_Bot))
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start = p.re.add(&instr{kind: iBOT})
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return start, start
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case '$':
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p.nextc()
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start = p.re.add(new(_Eot))
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start = p.re.add(&instr{kind: iEOT})
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return start, start
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case '.':
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p.nextc()
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start = p.re.add(new(_Any))
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start = p.re.add(&instr{kind: iAny})
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return start, start
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case '[':
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p.nextc()
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@ -472,12 +391,12 @@ func (p *parser) term() (start, end instr) {
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}
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p.nlpar--
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p.nextc()
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bra := new(_Bra)
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bra := &instr{kind: iBra}
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p.re.add(bra)
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ebra := new(_Ebra)
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ebra := &instr{kind: iEbra}
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p.re.add(ebra)
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bra.n = nbra
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ebra.n = nbra
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bra.braNum = nbra
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ebra.braNum = nbra
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if start == nil {
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if end == nil {
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p.error(ErrInternal)
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@ -485,9 +404,9 @@ func (p *parser) term() (start, end instr) {
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}
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start = ebra
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} else {
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end.setNext(ebra)
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end.next = ebra
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}
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bra.setNext(start)
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bra.next = start
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return bra, ebra
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case '\\':
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c = p.nextc()
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@ -504,14 +423,14 @@ func (p *parser) term() (start, end instr) {
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fallthrough
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default:
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p.nextc()
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start = newChar(c)
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start = &instr{kind: iChar, char: c}
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p.re.add(start)
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return start, start
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}
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panic("unreachable")
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}
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func (p *parser) closure() (start, end instr) {
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func (p *parser) closure() (start, end *instr) {
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start, end = p.term()
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if start == nil {
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return
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@ -519,28 +438,28 @@ func (p *parser) closure() (start, end instr) {
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switch p.c() {
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case '*':
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// (start,end)*:
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alt := new(_Alt)
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alt := &instr{kind: iAlt}
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p.re.add(alt)
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end.setNext(alt) // after end, do alt
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end.next = alt // after end, do alt
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alt.left = start // alternate brach: return to start
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start = alt // alt becomes new (start, end)
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end = alt
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case '+':
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// (start,end)+:
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alt := new(_Alt)
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alt := &instr{kind: iAlt}
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p.re.add(alt)
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end.setNext(alt) // after end, do alt
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end.next = alt // after end, do alt
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alt.left = start // alternate brach: return to start
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end = alt // start is unchanged; end is alt
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case '?':
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// (start,end)?:
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alt := new(_Alt)
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alt := &instr{kind: iAlt}
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p.re.add(alt)
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nop := new(_Nop)
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nop := &instr{kind: iNop}
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p.re.add(nop)
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alt.left = start // alternate branch is start
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alt.setNext(nop) // follow on to nop
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end.setNext(nop) // after end, go to nop
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alt.next = nop // follow on to nop
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end.next = nop // after end, go to nop
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start = alt // start is now alt
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end = nop // end is nop pointed to by both branches
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default:
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@ -553,27 +472,27 @@ func (p *parser) closure() (start, end instr) {
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return
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}
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func (p *parser) concatenation() (start, end instr) {
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func (p *parser) concatenation() (start, end *instr) {
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for {
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nstart, nend := p.closure()
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switch {
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case nstart == nil: // end of this concatenation
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if start == nil { // this is the empty string
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nop := p.re.add(new(_Nop))
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nop := p.re.add(&instr{kind: iNop})
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return nop, nop
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}
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return
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case start == nil: // this is first element of concatenation
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start, end = nstart, nend
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default:
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end.setNext(nstart)
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end.next = nstart
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end = nend
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}
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}
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panic("unreachable")
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}
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func (p *parser) regexp() (start, end instr) {
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func (p *parser) regexp() (start, end *instr) {
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start, end = p.concatenation()
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for {
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switch p.c() {
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@ -582,36 +501,35 @@ func (p *parser) regexp() (start, end instr) {
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case '|':
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p.nextc()
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nstart, nend := p.concatenation()
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alt := new(_Alt)
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alt := &instr{kind: iAlt}
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p.re.add(alt)
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alt.left = start
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alt.setNext(nstart)
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nop := new(_Nop)
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alt.next = nstart
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nop := &instr{kind: iNop}
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p.re.add(nop)
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end.setNext(nop)
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nend.setNext(nop)
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end.next = nop
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nend.next = nop
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start, end = alt, nop
|
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}
|
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}
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panic("unreachable")
|
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}
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|
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func unNop(i instr) instr {
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||||
for i.kind() == _NOP {
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i = i.next()
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func unNop(i *instr) *instr {
|
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for i.kind == iNop {
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i = i.next
|
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}
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return i
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}
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|
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func (re *Regexp) eliminateNops() {
|
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for _, inst := range re.inst {
|
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if inst.kind() == _END {
|
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if inst.kind == iEnd {
|
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continue
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}
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inst.setNext(unNop(inst.next()))
|
||||
if inst.kind() == _ALT {
|
||||
alt := inst.(*_Alt)
|
||||
alt.left = unNop(alt.left)
|
||||
inst.next = unNop(inst.next)
|
||||
if inst.kind == iAlt {
|
||||
inst.left = unNop(inst.left)
|
||||
}
|
||||
}
|
||||
}
|
||||
@ -619,10 +537,10 @@ func (re *Regexp) eliminateNops() {
|
||||
func (re *Regexp) dump() {
|
||||
print("prefix <", re.prefix, ">\n")
|
||||
for _, inst := range re.inst {
|
||||
print(inst.index(), ": ")
|
||||
print(inst.index, ": ")
|
||||
inst.print()
|
||||
if inst.kind() != _END {
|
||||
print(" -> ", inst.next().index())
|
||||
if inst.kind != iEnd {
|
||||
print(" -> ", inst.next.index)
|
||||
}
|
||||
print("\n")
|
||||
}
|
||||
@ -630,12 +548,12 @@ func (re *Regexp) dump() {
|
||||
|
||||
func (re *Regexp) doParse() {
|
||||
p := newParser(re)
|
||||
start := new(_Start)
|
||||
start := &instr{kind: iStart}
|
||||
re.add(start)
|
||||
s, e := p.regexp()
|
||||
start.setNext(s)
|
||||
start.next = s
|
||||
re.start = start
|
||||
e.setNext(re.add(new(_End)))
|
||||
e.next = re.add(&instr{kind: iEnd})
|
||||
|
||||
if debug {
|
||||
re.dump()
|
||||
@ -659,27 +577,25 @@ func (re *Regexp) doParse() {
|
||||
func (re *Regexp) setPrefix() {
|
||||
var b []byte
|
||||
var utf = make([]byte, utf8.UTFMax)
|
||||
var inst *instr
|
||||
// First instruction is start; skip that.
|
||||
i := re.inst[0].next().index()
|
||||
Loop:
|
||||
for i < len(re.inst) {
|
||||
inst := re.inst[i]
|
||||
for inst = re.inst[0].next; inst.kind != iEnd; inst = inst.next {
|
||||
// stop if this is not a char
|
||||
if inst.kind() != _CHAR {
|
||||
if inst.kind != iChar {
|
||||
break
|
||||
}
|
||||
// stop if this char can be followed by a match for an empty string,
|
||||
// which includes closures, ^, and $.
|
||||
switch re.inst[inst.next().index()].kind() {
|
||||
case _BOT, _EOT, _ALT:
|
||||
switch inst.next.kind {
|
||||
case iBOT, iEOT, iAlt:
|
||||
break Loop
|
||||
}
|
||||
n := utf8.EncodeRune(utf, inst.(*_Char).char)
|
||||
n := utf8.EncodeRune(utf, inst.char)
|
||||
b = append(b, utf[0:n]...)
|
||||
i = inst.next().index()
|
||||
}
|
||||
// point prefixStart instruction to first non-CHAR after prefix
|
||||
re.prefixStart = re.inst[i]
|
||||
re.prefixStart = inst
|
||||
re.prefixBytes = b
|
||||
re.prefix = string(b)
|
||||
}
|
||||
@ -696,7 +612,7 @@ func Compile(str string) (regexp *Regexp, error os.Error) {
|
||||
}
|
||||
}()
|
||||
regexp.expr = str
|
||||
regexp.inst = make([]instr, 0, 10)
|
||||
regexp.inst = make([]*instr, 0, 10)
|
||||
regexp.doParse()
|
||||
return
|
||||
}
|
||||
@ -772,52 +688,51 @@ func (a *matchArena) noMatch() *matchVec {
|
||||
}
|
||||
|
||||
type state struct {
|
||||
inst instr // next instruction to execute
|
||||
prefixed bool // this match began with a fixed prefix
|
||||
inst *instr // next instruction to execute
|
||||
prefixed bool // this match began with a fixed prefix
|
||||
match *matchVec
|
||||
}
|
||||
|
||||
// Append new state to to-do list. Leftmost-longest wins so avoid
|
||||
// adding a state that's already active. The matchVec will be inc-ref'ed
|
||||
// if it is assigned to a state.
|
||||
func (a *matchArena) addState(s []state, inst instr, prefixed bool, match *matchVec, pos, end int) []state {
|
||||
switch inst.kind() {
|
||||
case _BOT:
|
||||
func (a *matchArena) addState(s []state, inst *instr, prefixed bool, match *matchVec, pos, end int) []state {
|
||||
switch inst.kind {
|
||||
case iBOT:
|
||||
if pos == 0 {
|
||||
s = a.addState(s, inst.next(), prefixed, match, pos, end)
|
||||
s = a.addState(s, inst.next, prefixed, match, pos, end)
|
||||
}
|
||||
return s
|
||||
case _EOT:
|
||||
case iEOT:
|
||||
if pos == end {
|
||||
s = a.addState(s, inst.next(), prefixed, match, pos, end)
|
||||
s = a.addState(s, inst.next, prefixed, match, pos, end)
|
||||
}
|
||||
return s
|
||||
case _BRA:
|
||||
n := inst.(*_Bra).n
|
||||
case iBra:
|
||||
n := inst.braNum
|
||||
match.m[2*n] = pos
|
||||
s = a.addState(s, inst.next(), prefixed, match, pos, end)
|
||||
s = a.addState(s, inst.next, prefixed, match, pos, end)
|
||||
return s
|
||||
case _EBRA:
|
||||
n := inst.(*_Ebra).n
|
||||
case iEbra:
|
||||
n := inst.braNum
|
||||
match.m[2*n+1] = pos
|
||||
s = a.addState(s, inst.next(), prefixed, match, pos, end)
|
||||
s = a.addState(s, inst.next, prefixed, match, pos, end)
|
||||
return s
|
||||
}
|
||||
index := inst.index()
|
||||
l := len(s)
|
||||
// States are inserted in order so it's sufficient to see if we have the same
|
||||
// instruction; no need to see if existing match is earlier (it is).
|
||||
for i := 0; i < l; i++ {
|
||||
if s[i].inst.index() == index {
|
||||
if s[i].inst == inst {
|
||||
return s
|
||||
}
|
||||
}
|
||||
s = append(s, state{inst, prefixed, match})
|
||||
match.ref++
|
||||
if inst.kind() == _ALT {
|
||||
s = a.addState(s, inst.(*_Alt).left, prefixed, a.copy(match), pos, end)
|
||||
if inst.kind == iAlt {
|
||||
s = a.addState(s, inst.left, prefixed, a.copy(match), pos, end)
|
||||
// give other branch a copy of this match vector
|
||||
s = a.addState(s, inst.next(), prefixed, a.copy(match), pos, end)
|
||||
s = a.addState(s, inst.next, prefixed, a.copy(match), pos, end)
|
||||
}
|
||||
return s
|
||||
}
|
||||
@ -860,7 +775,7 @@ func (re *Regexp) doExecute(str string, bytestr []byte, pos int) []int {
|
||||
s[out] = arena.addState(s[out], re.prefixStart, true, match, pos, end)
|
||||
prefixed = false // next iteration should start at beginning of machine.
|
||||
} else {
|
||||
s[out] = arena.addState(s[out], re.start.next(), false, match, pos, end)
|
||||
s[out] = arena.addState(s[out], re.start.next, false, match, pos, end)
|
||||
}
|
||||
arena.free(match) // if addState saved it, ref was incremented
|
||||
}
|
||||
@ -886,29 +801,29 @@ func (re *Regexp) doExecute(str string, bytestr []byte, pos int) []int {
|
||||
}
|
||||
pos += charwidth
|
||||
for _, st := range s[in] {
|
||||
switch st.inst.kind() {
|
||||
case _BOT:
|
||||
case _EOT:
|
||||
case _CHAR:
|
||||
if c == st.inst.(*_Char).char {
|
||||
s[out] = arena.addState(s[out], st.inst.next(), st.prefixed, st.match, pos, end)
|
||||
switch st.inst.kind {
|
||||
case iBOT:
|
||||
case iEOT:
|
||||
case iChar:
|
||||
if c == st.inst.char {
|
||||
s[out] = arena.addState(s[out], st.inst.next, st.prefixed, st.match, pos, end)
|
||||
}
|
||||
case _CHARCLASS:
|
||||
if st.inst.(*_CharClass).matches(c) {
|
||||
s[out] = arena.addState(s[out], st.inst.next(), st.prefixed, st.match, pos, end)
|
||||
case iCharClass:
|
||||
if st.inst.cclass.matches(c) {
|
||||
s[out] = arena.addState(s[out], st.inst.next, st.prefixed, st.match, pos, end)
|
||||
}
|
||||
case _ANY:
|
||||
case iAny:
|
||||
if c != endOfFile {
|
||||
s[out] = arena.addState(s[out], st.inst.next(), st.prefixed, st.match, pos, end)
|
||||
s[out] = arena.addState(s[out], st.inst.next, st.prefixed, st.match, pos, end)
|
||||
}
|
||||
case _NOTNL:
|
||||
case iNotNL:
|
||||
if c != endOfFile && c != '\n' {
|
||||
s[out] = arena.addState(s[out], st.inst.next(), st.prefixed, st.match, pos, end)
|
||||
s[out] = arena.addState(s[out], st.inst.next, st.prefixed, st.match, pos, end)
|
||||
}
|
||||
case _BRA:
|
||||
case _EBRA:
|
||||
case _ALT:
|
||||
case _END:
|
||||
case iBra:
|
||||
case iEbra:
|
||||
case iAlt:
|
||||
case iEnd:
|
||||
// choose leftmost longest
|
||||
if !found || // first
|
||||
st.match.m[0] < final.match.m[0] || // leftmost
|
||||
|
Loading…
Reference in New Issue
Block a user