mirror of
https://github.com/golang/go
synced 2024-11-25 03:57:56 -07:00
beginnings of regular expression library.
will move elsewhere when more complete. parses, does not execute. no character classes yet. R=rsc DELTA=522 (522 added, 0 deleted, 0 changed) OCL=16863 CL=16874
This commit is contained in:
Rob Pike
parent
583dac04e3
commit
8f5b277cac
20
usr/r/regexp/Makefile
Normal file
20
usr/r/regexp/Makefile
Normal file
@ -0,0 +1,20 @@
|
||||
# Copyright 2009 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.
|
||||
|
||||
A=6
|
||||
G=$(A)g
|
||||
L=$(A)l
|
||||
|
||||
all: main
|
||||
|
||||
main: main.6
|
||||
$L -o main main.6
|
||||
|
||||
main.6: regexp.6
|
||||
|
||||
clean:
|
||||
rm -f *.6 main
|
||||
|
||||
%.6: %.go
|
||||
$G $<
|
||||
22
usr/r/regexp/main.go
Normal file
22
usr/r/regexp/main.go
Normal file
@ -0,0 +1,22 @@
|
||||
// Copyright 2009 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 main
|
||||
|
||||
import (
|
||||
"os";
|
||||
"regexp";
|
||||
)
|
||||
|
||||
func main() {
|
||||
str := "a*b*c*";
|
||||
if sys.argc() > 1 {
|
||||
str = sys.argv(1);
|
||||
}
|
||||
re, err := regexp.Compile(str);
|
||||
if err != nil {
|
||||
print("error: ", err.String(), "\n");
|
||||
sys.exit(1);
|
||||
}
|
||||
}
|
||||
489
usr/r/regexp/regexp.go
Normal file
489
usr/r/regexp/regexp.go
Normal file
@ -0,0 +1,489 @@
|
||||
// Copyright 2009 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.
|
||||
|
||||
// Regular expression library.
|
||||
|
||||
package regexp
|
||||
|
||||
import os "os"
|
||||
|
||||
export var ErrUnimplemented = os.NewError("unimplemented");
|
||||
export var ErrInternal = os.NewError("internal error");
|
||||
export var ErrUnmatchedLpar = os.NewError("unmatched '('");
|
||||
export var ErrUnmatchedRpar = os.NewError("unmatched ')'");
|
||||
export var ErrExtraneousBackslash = os.NewError("extraneous backslash");
|
||||
export var ErrEmpty = os.NewError("empty subexpression or alternation");
|
||||
export var ErrBadClosure = os.NewError("repeated closure (**, ++, etc.)");
|
||||
export var ErrBareClosure = os.NewError("closure applies to nothing");
|
||||
export var ErrBadBackslash = os.NewError("illegal backslash escape");
|
||||
|
||||
// An instruction executed by the NFA
|
||||
type Inst interface {
|
||||
Type() int; // the type of this instruction: CHAR, ANY, etc.
|
||||
This() int; // the index of this instruction
|
||||
Next() int; // the index of the instruction to execute after this one
|
||||
SetThis(i int);
|
||||
SetNext(i int);
|
||||
Print(ind string);
|
||||
}
|
||||
|
||||
type RE struct {
|
||||
expr string; // the original expression
|
||||
ch *chan<- *RE; // reply channel when we're done
|
||||
error *os.Error; // compile- or run-time error; nil if OK
|
||||
ninst int;
|
||||
inst *[]Inst;
|
||||
start Inst;
|
||||
}
|
||||
|
||||
const (
|
||||
START // beginning of program: marker to start
|
||||
= iota;
|
||||
END; // end of program: success
|
||||
BOT; // '^' beginning of text
|
||||
EOT; // '$' end of text
|
||||
CHAR; // 'a' regular character
|
||||
ANY; // '.' any character
|
||||
BRA; // '(' parenthesized expression
|
||||
EBRA; // ')'; end of '(' parenthesized expression
|
||||
ALT; // '|' alternation
|
||||
NOP; // do nothing; makes it easy to link without patching
|
||||
)
|
||||
|
||||
// --- START start of program
|
||||
type Start struct {
|
||||
this int;
|
||||
next int;
|
||||
}
|
||||
|
||||
func (start *Start) Type() int { return START }
|
||||
func (start *Start) This() int { return start.this }
|
||||
func (start *Start) Next() int { return start.next }
|
||||
func (start *Start) SetThis(i int) { start.this = i }
|
||||
func (start *Start) SetNext(i int) { start.next = i }
|
||||
func (start *Start) Print(ind string) { print(ind, "start") }
|
||||
|
||||
// --- END end of program
|
||||
type End struct {
|
||||
this int;
|
||||
next int;
|
||||
}
|
||||
|
||||
func (end *End) Type() int { return END }
|
||||
func (end *End) This() int { return end.this }
|
||||
func (end *End) Next() int { return end.next }
|
||||
func (end *End) SetThis(i int) { end.this = i }
|
||||
func (end *End) SetNext(i int) { end.next = i }
|
||||
func (end *End) Print(ind string) { print(ind, "end") }
|
||||
|
||||
// --- BOT beginning of text
|
||||
type Bot struct {
|
||||
this int;
|
||||
next int;
|
||||
}
|
||||
|
||||
func (bot *Bot) Type() int { return BOT }
|
||||
func (bot *Bot) This() int { return bot.this }
|
||||
func (bot *Bot) Next() int { return bot.next }
|
||||
func (bot *Bot) SetThis(i int) { bot.this = i }
|
||||
func (bot *Bot) SetNext(i int) { bot.next = i }
|
||||
func (bot *Bot) Print(ind string) { print(ind, "bot") }
|
||||
|
||||
// --- EOT end of text
|
||||
type Eot struct {
|
||||
this int;
|
||||
next int;
|
||||
}
|
||||
|
||||
func (eot *Eot) Type() int { return EOT }
|
||||
func (eot *Eot) This() int { return eot.this }
|
||||
func (eot *Eot) Next() int { return eot.next }
|
||||
func (eot *Eot) SetThis(i int) { eot.this = i }
|
||||
func (eot *Eot) SetNext(i int) { eot.next = i }
|
||||
func (eot *Eot) Print(ind string) { print(ind, "eot") }
|
||||
|
||||
// --- CHAR a regular character
|
||||
type Char struct {
|
||||
this int;
|
||||
next int;
|
||||
char int;
|
||||
set bool;
|
||||
}
|
||||
|
||||
func (char *Char) Type() int { return CHAR }
|
||||
func (char *Char) This() int { return char.this }
|
||||
func (char *Char) Next() int { return char.next }
|
||||
func (char *Char) SetThis(i int) { char.this = i }
|
||||
func (char *Char) SetNext(i int) { char.next = i }
|
||||
func (char *Char) Print(ind string) { print(ind, "char ", string(char.char)) }
|
||||
|
||||
func NewChar(char int) *Char {
|
||||
c := new(Char);
|
||||
c.char = char;
|
||||
return c;
|
||||
}
|
||||
|
||||
// --- ANY any character
|
||||
type Any struct {
|
||||
this int;
|
||||
next int;
|
||||
}
|
||||
|
||||
func (any *Any) Type() int { return ANY }
|
||||
func (any *Any) This() int { return any.this }
|
||||
func (any *Any) Next() int { return any.next }
|
||||
func (any *Any) SetThis(i int) { any.this = i }
|
||||
func (any *Any) SetNext(i int) { any.next = i }
|
||||
func (any *Any) Print(ind string) { print(ind, "any") }
|
||||
|
||||
// --- BRA parenthesized expression
|
||||
type Bra struct {
|
||||
this int;
|
||||
next int;
|
||||
}
|
||||
|
||||
func (bra *Bra) Type() int { return BRA }
|
||||
func (bra *Bra) This() int { return bra.this }
|
||||
func (bra *Bra) Next() int { return bra.next }
|
||||
func (bra *Bra) SetThis(i int) { bra.this = i }
|
||||
func (bra *Bra) SetNext(i int) { bra.next = i }
|
||||
func (bra *Bra) Print(ind string) { print(ind , "bra"); }
|
||||
|
||||
// --- EBRA end of parenthesized expression
|
||||
type Ebra struct {
|
||||
this int;
|
||||
next int;
|
||||
n int; // subexpression number
|
||||
}
|
||||
|
||||
func (ebra *Ebra) Type() int { return BRA }
|
||||
func (ebra *Ebra) This() int { return ebra.this }
|
||||
func (ebra *Ebra) Next() int { return ebra.next }
|
||||
func (ebra *Ebra) SetThis(i int) { ebra.this = i }
|
||||
func (ebra *Ebra) SetNext(i int) { ebra.next = i }
|
||||
func (ebra *Ebra) Print(ind string) { print(ind , "ebra ", ebra.n); }
|
||||
|
||||
// --- ALT alternation
|
||||
type Alt struct {
|
||||
this int;
|
||||
next int;
|
||||
left int; // other branch
|
||||
}
|
||||
|
||||
func (alt *Alt) Type() int { return ALT }
|
||||
func (alt *Alt) This() int { return alt.this }
|
||||
func (alt *Alt) Next() int { return alt.next }
|
||||
func (alt *Alt) SetThis(i int) { alt.this = i }
|
||||
func (alt *Alt) SetNext(i int) { alt.next = i }
|
||||
func (alt *Alt) Print(ind string) { print(ind , "alt(", alt.left, ")"); }
|
||||
|
||||
// --- NOP no operation
|
||||
type Nop struct {
|
||||
this int;
|
||||
next int;
|
||||
}
|
||||
|
||||
func (nop *Nop) Type() int { return NOP }
|
||||
func (nop *Nop) This() int { return nop.this }
|
||||
func (nop *Nop) Next() int { return nop.next }
|
||||
func (nop *Nop) SetThis(i int) { nop.this = i }
|
||||
func (nop *Nop) SetNext(i int) { nop.next = i }
|
||||
func (nop *Nop) Print(ind string) { print(ind, "nop") }
|
||||
|
||||
|
||||
func (re *RE) AddInst(inst Inst) int {
|
||||
if re.ninst >= cap(re.inst) {
|
||||
panic("write the code to grow inst")
|
||||
}
|
||||
re.inst[re.ninst] = inst;
|
||||
i := re.ninst;
|
||||
inst.SetThis(re.ninst);
|
||||
re.ninst++;
|
||||
inst.SetNext(re.ninst);
|
||||
return i;
|
||||
}
|
||||
|
||||
// report error and exit compiling/executing goroutine
|
||||
func (re *RE) Error(err *os.Error) {
|
||||
re.error = err;
|
||||
re.ch <- re;
|
||||
sys.goexit();
|
||||
}
|
||||
|
||||
type Parser struct {
|
||||
re *RE;
|
||||
nbra int;
|
||||
pos int;
|
||||
ch int;
|
||||
}
|
||||
|
||||
const EOF = -1
|
||||
|
||||
func (p *Parser) c() int {
|
||||
return p.ch;
|
||||
}
|
||||
|
||||
func (p *Parser) nextc() int {
|
||||
if p.pos >= len(p.re.expr) {
|
||||
p.ch = EOF
|
||||
} else {
|
||||
c, w := sys.stringtorune(p.re.expr, p.pos); // TODO: stringotorune shoudl take a string*
|
||||
p.ch = c;
|
||||
p.pos += w;
|
||||
}
|
||||
return p.ch;
|
||||
}
|
||||
|
||||
func NewParser(re *RE) *Parser {
|
||||
parser := new(Parser);
|
||||
parser.re = re;
|
||||
parser.nextc(); // load p.ch
|
||||
return parser;
|
||||
}
|
||||
|
||||
/*
|
||||
|
||||
Grammar:
|
||||
regexp:
|
||||
concatenation { '|' concatenation }
|
||||
concatenation:
|
||||
{ closure }
|
||||
closure:
|
||||
term { '*' | '+' | '?' }
|
||||
term:
|
||||
'.'
|
||||
character
|
||||
characterclass
|
||||
'(' regexp ')'
|
||||
|
||||
*/
|
||||
|
||||
func (p *Parser) Regexp() (start, end int)
|
||||
|
||||
const NULL = -1
|
||||
|
||||
func special(c int) bool {
|
||||
s := `\.+*?()|[-]`;
|
||||
for i := 0; i < len(s); i++ {
|
||||
if c == int(s[i]) {
|
||||
return true
|
||||
}
|
||||
}
|
||||
return false
|
||||
}
|
||||
|
||||
func (p *Parser) Term() (start, end int) {
|
||||
switch c := p.c(); c {
|
||||
case ')', '|', EOF:
|
||||
return NULL, NULL;
|
||||
case '*', '+', '|':
|
||||
p.re.Error(ErrBareClosure);
|
||||
case '.':
|
||||
p.nextc();
|
||||
start = p.re.AddInst(new(Any));
|
||||
return start, start;
|
||||
case '(':
|
||||
p.nextc();
|
||||
start, end = p.Regexp();
|
||||
if p.c() != ')' {
|
||||
p.re.Error(ErrUnmatchedLpar);
|
||||
}
|
||||
p.nextc();
|
||||
p.nbra++;
|
||||
bra := new(Bra);
|
||||
brai := p.re.AddInst(bra);
|
||||
ebra := new(Ebra);
|
||||
ebrai := p.re.AddInst(ebra);
|
||||
ebra.n = p.nbra;
|
||||
if start == NULL {
|
||||
if end != NULL { p.re.Error(ErrInternal) }
|
||||
start = ebrai
|
||||
} else {
|
||||
p.re.inst[end].SetNext(ebrai);
|
||||
}
|
||||
bra.SetNext(start);
|
||||
return brai, ebrai;
|
||||
case '\\':
|
||||
c = p.nextc();
|
||||
switch {
|
||||
case c == EOF:
|
||||
p.re.Error(ErrExtraneousBackslash);
|
||||
case c == 'n':
|
||||
c = '\n';
|
||||
case special(c):
|
||||
// c is as delivered
|
||||
default:
|
||||
p.re.Error(ErrBadBackslash);
|
||||
}
|
||||
fallthrough;
|
||||
default:
|
||||
p.nextc();
|
||||
start = p.re.AddInst(NewChar(c));
|
||||
return start, start
|
||||
}
|
||||
panic("unreachable");
|
||||
}
|
||||
|
||||
func (p *Parser) Closure() (start, end int) {
|
||||
start, end = p.Term();
|
||||
if start == NULL {
|
||||
return start, end
|
||||
}
|
||||
switch p.c() {
|
||||
case '*':
|
||||
// (start,end)*:
|
||||
alt := new(Alt);
|
||||
alti := p.re.AddInst(alt);
|
||||
p.re.inst[end].SetNext(alti); // after end, do alt
|
||||
alt.left = start; // alternate brach: return to start
|
||||
start = alti; // alt becomes new (start, end)
|
||||
end = alti;
|
||||
case '+':
|
||||
// (start,end)+:
|
||||
alt := new(Alt);
|
||||
alti := p.re.AddInst(alt);
|
||||
p.re.inst[end].SetNext(alti); // after end, do alt
|
||||
alt.left = start; // alternate brach: return to start
|
||||
end = alti; // start is unchanged; end is alt
|
||||
case '?':
|
||||
// (start,end)?:
|
||||
alt := new(Alt);
|
||||
alti := p.re.AddInst(alt);
|
||||
nop := new(Nop);
|
||||
nopi := p.re.AddInst(nop);
|
||||
alt.left = start; // alternate branch is start
|
||||
alt.next = nopi; // follow on to nop
|
||||
p.re.inst[end].SetNext(nopi); // after end, go to nop
|
||||
start = alti; // start is now alt
|
||||
end = nopi; // end is nop pointed to by both branches
|
||||
default:
|
||||
return start, end;
|
||||
}
|
||||
switch p.nextc() {
|
||||
case '*', '+', '?':
|
||||
p.re.Error(ErrBadClosure);
|
||||
}
|
||||
return start, end;
|
||||
}
|
||||
|
||||
func (p *Parser) Concatenation() (start, end int) {
|
||||
start, end = NULL, NULL;
|
||||
for {
|
||||
nstart, nend := p.Closure();
|
||||
switch {
|
||||
case nstart == NULL: // end of this concatenation
|
||||
return start, end;
|
||||
case start == NULL: // this is first element of concatenation
|
||||
start, end = nstart, nend;
|
||||
default:
|
||||
p.re.inst[end].SetNext(nstart);
|
||||
end = nend;
|
||||
}
|
||||
}
|
||||
panic("unreachable");
|
||||
}
|
||||
|
||||
func (p *Parser) Regexp() (start, end int) {
|
||||
start, end = p.Concatenation();
|
||||
if start == NULL {
|
||||
return NULL, NULL
|
||||
}
|
||||
for {
|
||||
switch p.c() {
|
||||
default:
|
||||
return start, end;
|
||||
case '|':
|
||||
p.nextc();
|
||||
nstart, nend := p.Concatenation();
|
||||
// xyz|(nothing) is xyz or nop
|
||||
if nstart == NULL {
|
||||
nopi := p.re.AddInst(new(Nop));
|
||||
nstart, nend = nopi, nopi;
|
||||
}
|
||||
alt := new(Alt);
|
||||
alti := p.re.AddInst(alt);
|
||||
alt.left = start;
|
||||
alt.next = nstart;
|
||||
nop := new(Nop);
|
||||
nopi := p.re.AddInst(nop);
|
||||
p.re.inst[end].SetNext(nopi);
|
||||
p.re.inst[nend].SetNext(nopi);
|
||||
start, end = alti, nopi;
|
||||
}
|
||||
}
|
||||
panic("unreachable");
|
||||
}
|
||||
|
||||
func (re *RE) UnNop(i int) int {
|
||||
for re.inst[i].Type() == NOP {
|
||||
i = re.inst[i].Next()
|
||||
}
|
||||
return i
|
||||
}
|
||||
|
||||
func (re *RE) EliminateNops() {
|
||||
for i := 0; i < re.ninst - 1; i++ { // last one is END
|
||||
inst := re.inst[i];
|
||||
inst.SetNext(re.UnNop(inst.Next()));
|
||||
if inst.Type() == ALT {
|
||||
alt := inst.(*Alt);
|
||||
alt.left = re.UnNop(alt.left)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func (re *RE) DoParse() {
|
||||
parser := NewParser(re);
|
||||
start := new(Start);
|
||||
starti := re.AddInst(start);
|
||||
s, e := parser.Regexp();
|
||||
if s == NULL {
|
||||
if e != NULL { re.Error(ErrInternal) }
|
||||
e = starti;
|
||||
}
|
||||
start.next = s;
|
||||
re.inst[e].SetNext(re.AddInst(new(End)));
|
||||
|
||||
for i := 0; i < re.ninst; i++ {
|
||||
inst := re.inst[i];
|
||||
print(i, ":\t");
|
||||
inst.Print("\t");
|
||||
print(" -> ", inst.Next(), "\n");
|
||||
}
|
||||
println();
|
||||
|
||||
re.EliminateNops();
|
||||
|
||||
for i := 0; i < re.ninst; i++ {
|
||||
inst := re.inst[i];
|
||||
print(i, ":\t");
|
||||
inst.Print("\t");
|
||||
print(" -> ", inst.Next(), "\n");
|
||||
}
|
||||
println();
|
||||
|
||||
re.Error(ErrUnimplemented);
|
||||
}
|
||||
|
||||
func Compiler(str string, ch *chan *RE) {
|
||||
re := new(RE);
|
||||
re.inst = new([]Inst, 100);
|
||||
re.expr = str;
|
||||
re.ch = ch;
|
||||
re.DoParse();
|
||||
ch <- re;
|
||||
}
|
||||
|
||||
// Public interface has only execute functionality (not yet implemented)
|
||||
export type Regexp interface {
|
||||
// Execute() bool
|
||||
}
|
||||
|
||||
// compile in separate goroutine; wait for result
|
||||
export func Compile(str string) (regexp Regexp, error *os.Error) {
|
||||
ch := new(chan *RE);
|
||||
go Compiler(str, ch);
|
||||
re := <-ch;
|
||||
return re, re.error
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user