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Commit 0f0648d3 authored by Rob Pike's avatar Rob Pike
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convert from integer indexes to interface variables. 

update printing.

R=rsc
DELTA=194  (60 added, 41 deleted, 93 changed)
OCL=16942
CL=16945
parent b5e0cc7e
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Showing with 148 additions and 129 deletions
usr/r/regexp/regexp.go
View file @ 0f0648d3
......@@ -21,8 +21,8 @@ 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.
Next() int; // the index of the instruction to execute after this one
SetNext(i int);
Next() Inst; // the instruction to execute after this one
SetNext(i Inst);
Print(ind string);
}
......@@ -30,8 +30,6 @@ 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;
}
......@@ -51,59 +49,54 @@ const (
// --- START start of program
type Start struct {
this int;
next int;
next Inst;
}
func (start *Start) Type() int { return START }
func (start *Start) Next() int { return start.next }
func (start *Start) SetNext(i int) { start.next = i }
func (start *Start) Next() Inst { return start.next }
func (start *Start) SetNext(i Inst) { start.next = i }
func (start *Start) Print(ind string) { print(ind, "start") }
// --- END end of program
type End struct {
this int;
next int;
next Inst;
}
func (end *End) Type() int { return END }
func (end *End) Next() int { return end.next }
func (end *End) SetNext(i int) { end.next = i }
func (end *End) Next() Inst { return end.next }
func (end *End) SetNext(i Inst) { end.next = i }
func (end *End) Print(ind string) { print(ind, "end") }
// --- BOT beginning of text
type Bot struct {
this int;
next int;
next Inst;
}
func (bot *Bot) Type() int { return BOT }
func (bot *Bot) Next() int { return bot.next }
func (bot *Bot) SetNext(i int) { bot.next = i }
func (bot *Bot) Next() Inst { return bot.next }
func (bot *Bot) SetNext(i Inst) { bot.next = i }
func (bot *Bot) Print(ind string) { print(ind, "bot") }
// --- EOT end of text
type Eot struct {
this int;
next int;
next Inst;
}
func (eot *Eot) Type() int { return EOT }
func (eot *Eot) Next() int { return eot.next }
func (eot *Eot) SetNext(i int) { eot.next = i }
func (eot *Eot) Next() Inst { return eot.next }
func (eot *Eot) SetNext(i Inst) { eot.next = i }
func (eot *Eot) Print(ind string) { print(ind, "eot") }
// --- CHAR a regular character
type Char struct {
this int;
next int;
next Inst;
char int;
set bool;
}
func (char *Char) Type() int { return CHAR }
func (char *Char) Next() int { return char.next }
func (char *Char) SetNext(i int) { char.next = i }
func (char *Char) Next() Inst { return char.next }
func (char *Char) SetNext(i Inst) { char.next = i }
func (char *Char) Print(ind string) { print(ind, "char ", string(char.char)) }
func NewChar(char int) *Char {
......@@ -114,73 +107,57 @@ func NewChar(char int) *Char {
// --- ANY any character
type Any struct {
this int;
next int;
next Inst;
}
func (any *Any) Type() int { return ANY }
func (any *Any) Next() int { return any.next }
func (any *Any) SetNext(i int) { any.next = i }
func (any *Any) Next() Inst { return any.next }
func (any *Any) SetNext(i Inst) { any.next = i }
func (any *Any) Print(ind string) { print(ind, "any") }
// --- BRA parenthesized expression
type Bra struct {
this int;
next int;
next Inst;
n int; // subexpression number
}
func (bra *Bra) Type() int { return BRA }
func (bra *Bra) Next() int { return bra.next }
func (bra *Bra) SetNext(i int) { bra.next = i }
func (bra *Bra) Next() Inst { return bra.next }
func (bra *Bra) SetNext(i Inst) { bra.next = i }
func (bra *Bra) Print(ind string) { print(ind , "bra"); }
// --- EBRA end of parenthesized expression
type Ebra struct {
this int;
next int;
next Inst;
n int; // subexpression number
}
func (ebra *Ebra) Type() int { return BRA }
func (ebra *Ebra) Next() int { return ebra.next }
func (ebra *Ebra) SetNext(i int) { ebra.next = i }
func (ebra *Ebra) Next() Inst { return ebra.next }
func (ebra *Ebra) SetNext(i Inst) { 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
next Inst;
left Inst; // other branch
}
func (alt *Alt) Type() int { return ALT }
func (alt *Alt) Next() int { return alt.next }
func (alt *Alt) SetNext(i int) { alt.next = i }
func (alt *Alt) Next() Inst { return alt.next }
func (alt *Alt) SetNext(i Inst) { alt.next = i }
func (alt *Alt) Print(ind string) { print(ind , "alt(", alt.left, ")"); }
// --- NOP no operation
type Nop struct {
this int;
next int;
next Inst;
}
func (nop *Nop) Type() int { return NOP }
func (nop *Nop) Next() int { return nop.next }
func (nop *Nop) SetNext(i int) { nop.next = i }
func (nop *Nop) Next() Inst { return nop.next }
func (nop *Nop) SetNext(i Inst) { 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;
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;
......@@ -190,7 +167,8 @@ func (re *RE) Error(err *os.Error) {
type Parser struct {
re *RE;
nbra int;
nbra int; // number of brackets in expression, for subexpressions
nlpar int; // number of unclosed lpars
pos int;
ch int;
}
......@@ -236,9 +214,20 @@ Grammar:
*/
func (p *Parser) Regexp() (start, end int)
func (p *Parser) Regexp() (start, end Inst)
var NULL Inst
type BUGinter interface{}
const NULL = -1
// same as i == NULL. TODO: remove when 6g lets me do i == NULL
func isNULL(i Inst) bool {
return sys.BUG_intereq(i.(BUGinter), NULL.(BUGinter))
}
// same as i == j. TODO: remove when 6g lets me do i == j
func isEQ(i,j Inst) bool {
return sys.BUG_intereq(i.(BUGinter), j.(BUGinter))
}
func special(c int) bool {
s := `\.+*?()|[-]`;
......@@ -250,39 +239,43 @@ func special(c int) bool {
return false
}
func (p *Parser) Term() (start, end int) {
func (p *Parser) Term() (start, end Inst) {
switch c := p.c(); c {
case '|', EOF:
return NULL, NULL;
case '*', '+', '|':
p.re.Error(ErrBareClosure);
case ')':
p.re.Error(ErrUnmatchedRpar);
if p.nlpar == 0 {
p.re.Error(ErrUnmatchedRpar);
}
return NULL, NULL;
case '.':
p.nextc();
start = p.re.AddInst(new(Any));
start = new(Any);
return start, start;
case '(':
p.nextc();
p.nlpar++;
start, end = p.Regexp();
if p.c() != ')' {
p.re.Error(ErrUnmatchedLpar);
}
p.nlpar--;
p.nextc();
p.nbra++;
bra := new(Bra);
brai := p.re.AddInst(bra);
ebra := new(Ebra);
ebrai := p.re.AddInst(ebra);
bra.n = p.nbra;
ebra.n = p.nbra;
if start == NULL {
if end != NULL { p.re.Error(ErrInternal) }
start = ebrai
if isNULL(start) {
if !isNULL(end) { p.re.Error(ErrInternal) }
start = ebra
} else {
p.re.inst[end].SetNext(ebrai);
end.SetNext(ebra);
}
bra.SetNext(start);
return brai, ebrai;
return bra, ebra;
case '\\':
c = p.nextc();
switch {
......@@ -298,44 +291,40 @@ func (p *Parser) Term() (start, end int) {
fallthrough;
default:
p.nextc();
start = p.re.AddInst(NewChar(c));
start = NewChar(c);
return start, start
}
panic("unreachable");
}
func (p *Parser) Closure() (start, end int) {
func (p *Parser) Closure() (start, end Inst) {
start, end = p.Term();
if start == NULL {
if isNULL(start) {
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
end.SetNext(alt); // after end, do alt
alt.left = start; // alternate brach: return to start
start = alti; // alt becomes new (start, end)
end = alti;
start = alt; // alt becomes new (start, end)
end = alt;
case '+':
// (start,end)+:
alt := new(Alt);
alti := p.re.AddInst(alt);
p.re.inst[end].SetNext(alti); // after end, do alt
end.SetNext(alt); // after end, do alt
alt.left = start; // alternate brach: return to start
end = alti; // start is unchanged; end is alt
end = alt; // 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
alt.next = nop; // follow on to nop
end.SetNext(nop); // after end, go to nop
start = alt; // start is now alt
end = nop; // end is nop pointed to by both branches
default:
return start, end;
}
......@@ -346,26 +335,34 @@ func (p *Parser) Closure() (start, end int) {
return start, end;
}
func (p *Parser) Concatenation() (start, end int) {
func (p *Parser) Concatenation() (start, end Inst) {
start, end = NULL, NULL;
for {
switch p.c() {
case '|', ')', EOF:
if isNULL(start) { // this is the empty string
nop := new(Nop);
return nop, nop;
}
return start, end;
}
nstart, nend := p.Closure();
switch {
case nstart == NULL: // end of this concatenation
case isNULL(nstart): // end of this concatenation
return start, end;
case start == NULL: // this is first element of concatenation
case isNULL(start): // this is first element of concatenation
start, end = nstart, nend;
default:
p.re.inst[end].SetNext(nstart);
end.SetNext(nstart);
end = nend;
}
}
panic("unreachable");
}
func (p *Parser) Regexp() (start, end int) {
func (p *Parser) Regexp() (start, end Inst) {
start, end = p.Concatenation();
if start == NULL {
if isNULL(start) {
return NULL, NULL
}
for {
......@@ -376,70 +373,93 @@ func (p *Parser) Regexp() (start, end int) {
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;
if isNULL(nstart) {
nop := new(Nop);
nstart, nend = nop, nop;
}
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;
end.SetNext(nop);
nend.SetNext(nop);
start, end = alt, nop;
}
}
panic("unreachable");
}
func (re *RE) UnNop(i int) int {
for re.inst[i].Type() == NOP {
i = re.inst[i].Next()
func UnNop(i Inst) Inst {
for i.Type() == NOP {
i = 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) EliminateNops(start Inst) {
for i := start; i.Type() != END; i = i.Next() { // last one is END
i.SetNext(UnNop(i.Next()));
if i.Type() == ALT {
alt := i.(*Alt);
alt.left = UnNop(alt.left);
re.EliminateNops(alt.left);
}
}
}
// use a 'done' array to know where we've already printed.
// the output is not pretty but it is serviceable.
func (re *RE) Dump(ind string, inst Inst, done *[]Inst) {
// see if we've been here, and mark it
for i := 0; i < len(done); i++ {
if isEQ(inst, done[i]) {
print(ind, inst, ": -> ", inst.Next(), "...\n");
return;
}
}
slot := len(done);
done= done[0:slot+1];
done[slot] = inst;
if isNULL(inst) {
println("NULL");
return;
}
if inst.Type() == END { print(inst, ": END\n"); return }
print(ind, inst, ": ");
inst.Print("");
print(" -> ", inst.Next(), "\n");
switch inst.Type() {
case END:
return;
case ALT:
re.Dump(ind + "\t", inst.(*Alt).left, done);
}
re.Dump(ind, inst.Next(), done);
}
func (re *RE) DumpAll() {
re.Dump("", re.start, new([]Inst, 1000)[0:0]);
}
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;
if isNULL(s) {
if !isNULL(e) { re.Error(ErrInternal) }
e = start;
}
start.next = s;
re.inst[e].SetNext(re.AddInst(new(End)));
re.start = start;
e.SetNext(new(End));
for i := 0; i < re.ninst; i++ {
inst := re.inst[i];
print(i, ":\t");
inst.Print("\t");
print(" -> ", inst.Next(), "\n");
}
re.DumpAll();
println();
re.EliminateNops();
re.EliminateNops(re.start);
for i := 0; i < re.ninst; i++ {
inst := re.inst[i];
print(i, ":\t");
inst.Print("\t");
print(" -> ", inst.Next(), "\n");
}
re.DumpAll();
println();
re.Error(ErrUnimplemented);
......@@ -447,7 +467,6 @@ func (re *RE) DoParse() {
func Compiler(str string, ch *chan *RE) {
re := new(RE);
re.inst = new([]Inst, 100);
re.expr = str;
re.ch = ch;
re.DoParse();
......
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