ref: a8d00e5d56b261376410c3c87c46327362763bd8
dir: /sys/src/cmd/sam/regexp.c/
#include "sam.h"
Rangeset sel;
String lastregexp;
/*
* Machine Information
*/
typedef struct Inst Inst;
struct Inst
{
long type; /* <= Runemax ==> literal, otherwise action */
union {
int rsid;
int rsubid;
int class;
struct Inst *rother;
struct Inst *rright;
} r;
union{
struct Inst *lleft;
struct Inst *lnext;
} l;
};
#define sid r.rsid
#define subid r.rsubid
#define rclass r.class
#define other r.rother
#define right r.rright
#define left l.lleft
#define next l.lnext
#define NPROG 1024
Inst program[NPROG];
Inst *progp;
Inst *startinst; /* First inst. of program; might not be program[0] */
Inst *bstartinst; /* same for backwards machine */
typedef struct Ilist Ilist;
struct Ilist
{
Inst *inst; /* Instruction of the thread */
Rangeset se;
Posn startp; /* first char of match */
};
#define NLIST 127
Ilist *tl, *nl; /* This list, next list */
Ilist list[2][NLIST+1]; /* +1 for trailing null */
static Rangeset sempty;
/*
* Actions and Tokens
*
* 0x100xx are operators, value == precedence
* 0x200xx are tokens, i.e. operands for operators
*/
enum {
OPERATOR = Runemask+1, /* Bitmask of all operators */
START = OPERATOR, /* Start, used for marker on stack */
RBRA, /* Right bracket, ) */
LBRA, /* Left bracket, ( */
OR, /* Alternation, | */
CAT, /* Concatentation, implicit operator */
STAR, /* Closure, * */
PLUS, /* a+ == aa* */
QUEST, /* a? == a|nothing, i.e. 0 or 1 a's */
ANY = OPERATOR<<1, /* Any character but newline, . */
NOP, /* No operation, internal use only */
BOL, /* Beginning of line, ^ */
EOL, /* End of line, $ */
CCLASS, /* Character class, [] */
NCCLASS, /* Negated character class, [^] */
END, /* Terminate: match found */
ISATOR = OPERATOR,
ISAND = OPERATOR<<1,
};
/*
* Parser Information
*/
typedef struct Node Node;
struct Node
{
Inst *first;
Inst *last;
};
#define NSTACK 20
Node andstack[NSTACK];
Node *andp;
int atorstack[NSTACK];
int *atorp;
int lastwasand; /* Last token was operand */
int cursubid;
int subidstack[NSTACK];
int *subidp;
int backwards;
int nbra;
Rune *exprp; /* pointer to next character in source expression */
#define DCLASS 10 /* allocation increment */
int nclass; /* number active */
int Nclass; /* high water mark */
Rune **class;
int negateclass;
int addinst(Ilist *l, Inst *inst, Rangeset *sep);
void newmatch(Rangeset*);
void bnewmatch(Rangeset*);
void pushand(Inst*, Inst*);
void pushator(int);
Node *popand(int);
int popator(void);
void startlex(Rune*);
int lex(void);
void operator(int);
void operand(int);
void evaluntil(int);
void optimize(Inst*);
void bldcclass(void);
void
regerror(Err e)
{
Strzero(&lastregexp);
error(e);
}
void
regerror_c(Err e, int c)
{
Strzero(&lastregexp);
error_c(e, c);
}
Inst *
newinst(int t)
{
if(progp >= &program[NPROG])
regerror(Etoolong);
progp->type = t;
progp->left = 0;
progp->right = 0;
return progp++;
}
Inst *
realcompile(Rune *s)
{
int token;
startlex(s);
atorp = atorstack;
andp = andstack;
subidp = subidstack;
cursubid = 0;
lastwasand = FALSE;
/* Start with a low priority operator to prime parser */
pushator(START-1);
while((token=lex()) != END){
if((token&ISATOR) == OPERATOR)
operator(token);
else
operand(token);
}
/* Close with a low priority operator */
evaluntil(START);
/* Force END */
operand(END);
evaluntil(START);
if(nbra)
regerror(Eleftpar);
--andp; /* points to first and only operand */
return andp->first;
}
void
compile(String *s)
{
int i;
Inst *oprogp;
if(Strcmp(s, &lastregexp)==0)
return;
for(i=0; i<nclass; i++)
free(class[i]);
nclass = 0;
progp = program;
backwards = FALSE;
startinst = realcompile(s->s);
optimize(program);
oprogp = progp;
backwards = TRUE;
bstartinst = realcompile(s->s);
optimize(oprogp);
Strduplstr(&lastregexp, s);
}
void
operand(int t)
{
Inst *i;
if(lastwasand)
operator(CAT); /* catenate is implicit */
i = newinst(t);
if(t == CCLASS){
if(negateclass)
i->type = NCCLASS; /* UGH */
i->rclass = nclass-1; /* UGH */
}
pushand(i, i);
lastwasand = TRUE;
}
void
operator(int t)
{
if(t==RBRA && --nbra<0)
regerror(Erightpar);
if(t==LBRA){
/*
* if(++cursubid >= NSUBEXP)
* regerror(Esubexp);
*/
cursubid++; /* silently ignored */
nbra++;
if(lastwasand)
operator(CAT);
}else
evaluntil(t);
if(t!=RBRA)
pushator(t);
lastwasand = FALSE;
if(t==STAR || t==QUEST || t==PLUS || t==RBRA)
lastwasand = TRUE; /* these look like operands */
}
void
cant(char *s)
{
char buf[100];
sprint(buf, "regexp: can't happen: %s", s);
panic(buf);
}
void
pushand(Inst *f, Inst *l)
{
if(andp >= &andstack[NSTACK])
cant("operand stack overflow");
andp->first = f;
andp->last = l;
andp++;
}
void
pushator(int t)
{
if(atorp >= &atorstack[NSTACK])
cant("operator stack overflow");
*atorp++=t;
if(cursubid >= NSUBEXP)
*subidp++= -1;
else
*subidp++=cursubid;
}
Node *
popand(int op)
{
if(andp <= &andstack[0])
if(op)
regerror_c(Emissop, op);
else
regerror(Ebadregexp);
return --andp;
}
int
popator(void)
{
if(atorp <= &atorstack[0])
cant("operator stack underflow");
--subidp;
return *--atorp;
}
void
evaluntil(int pri)
{
Node *op1, *op2, *t;
Inst *inst1, *inst2;
while(pri==RBRA || atorp[-1]>=pri){
switch(popator()){
case LBRA:
op1 = popand('(');
inst2 = newinst(RBRA);
inst2->subid = *subidp;
op1->last->next = inst2;
inst1 = newinst(LBRA);
inst1->subid = *subidp;
inst1->next = op1->first;
pushand(inst1, inst2);
return; /* must have been RBRA */
default:
panic("unknown regexp operator");
break;
case OR:
op2 = popand('|');
op1 = popand('|');
inst2 = newinst(NOP);
op2->last->next = inst2;
op1->last->next = inst2;
inst1 = newinst(OR);
inst1->right = op1->first;
inst1->left = op2->first;
pushand(inst1, inst2);
break;
case CAT:
op2 = popand(0);
op1 = popand(0);
if(backwards && op2->first->type!=END)
t = op1, op1 = op2, op2 = t;
op1->last->next = op2->first;
pushand(op1->first, op2->last);
break;
case STAR:
op2 = popand('*');
inst1 = newinst(OR);
op2->last->next = inst1;
inst1->right = op2->first;
pushand(inst1, inst1);
break;
case PLUS:
op2 = popand('+');
inst1 = newinst(OR);
op2->last->next = inst1;
inst1->right = op2->first;
pushand(op2->first, inst1);
break;
case QUEST:
op2 = popand('?');
inst1 = newinst(OR);
inst2 = newinst(NOP);
inst1->left = inst2;
inst1->right = op2->first;
op2->last->next = inst2;
pushand(inst1, inst2);
break;
}
}
}
void
optimize(Inst *start)
{
Inst *inst, *target;
for(inst=start; inst->type!=END; inst++){
target = inst->next;
while(target->type == NOP)
target = target->next;
inst->next = target;
}
}
#ifdef DEBUG
void
dumpstack(void){
Node *stk;
int *ip;
dprint("operators\n");
for(ip = atorstack; ip<atorp; ip++)
dprint("0%o\n", *ip);
dprint("operands\n");
for(stk = andstack; stk<andp; stk++)
dprint("0%o\t0%o\n", stk->first->type, stk->last->type);
}
void
dump(void){
Inst *l;
l = program;
do{
dprint("%d:\t0%o\t%d\t%d\n", l-program, l->type,
l->left-program, l->right-program);
}while(l++->type);
}
#endif
void
startlex(Rune *s)
{
exprp = s;
nbra = 0;
}
int
lex(void){
int c= *exprp++;
switch(c){
case '\\':
if(*exprp)
if((c= *exprp++)=='n')
c='\n';
break;
case 0:
c = END;
--exprp; /* In case we come here again */
break;
case '*':
c = STAR;
break;
case '?':
c = QUEST;
break;
case '+':
c = PLUS;
break;
case '|':
c = OR;
break;
case '.':
c = ANY;
break;
case '(':
c = LBRA;
break;
case ')':
c = RBRA;
break;
case '^':
c = BOL;
break;
case '$':
c = EOL;
break;
case '[':
c = CCLASS;
bldcclass();
break;
}
return c;
}
long
nextrec(void){
if(exprp[0]==0 || (exprp[0]=='\\' && exprp[1]==0))
regerror(Ebadclass);
if(exprp[0] == '\\'){
exprp++;
if(*exprp=='n'){
exprp++;
return '\n';
}
return *exprp++|(Runemask+1);
}
return *exprp++;
}
void
bldcclass(void)
{
long c1, c2, n, na;
Rune *classp;
classp = emalloc(DCLASS*RUNESIZE);
n = 0;
na = DCLASS;
/* we have already seen the '[' */
if(*exprp == '^'){
classp[n++] = '\n'; /* don't match newline in negate case */
negateclass = TRUE;
exprp++;
}else
negateclass = FALSE;
while((c1 = nextrec()) != ']'){
if(c1 == '-'){
Error:
free(classp);
regerror(Ebadclass);
}
if(n+4 >= na){ /* 3 runes plus NUL */
na += DCLASS;
classp = erealloc(classp, na*RUNESIZE);
}
if(*exprp == '-'){
exprp++; /* eat '-' */
if((c2 = nextrec()) == ']')
goto Error;
classp[n+0] = Runemax;
classp[n+1] = c1 & Runemask;
classp[n+2] = c2 & Runemask;
n += 3;
}else
classp[n++] = c1 & Runemask;
}
classp[n] = 0;
if(nclass == Nclass){
Nclass += DCLASS;
class = erealloc(class, Nclass*sizeof(Rune*));
}
class[nclass++] = classp;
}
int
classmatch(int classno, int c, int negate)
{
Rune *p;
p = class[classno];
while(*p){
if(*p == Runemax){
if(p[1]<=c && c<=p[2])
return !negate;
p += 3;
}else if(*p++ == c)
return !negate;
}
return negate;
}
/*
* Note optimization in addinst:
* *l must be pending when addinst called; if *l has been looked
* at already, the optimization is a bug.
*/
int
addinst(Ilist *l, Inst *inst, Rangeset *sep)
{
Ilist *p;
for(p = l; p->inst; p++){
if(p->inst==inst){
if((sep)->p[0].p1 < p->se.p[0].p1)
p->se= *sep; /* this would be bug */
return 0; /* It's already there */
}
}
p->inst = inst;
p->se= *sep;
(p+1)->inst = 0;
return 1;
}
int
execute(File *f, Posn startp, Posn eof)
{
int flag = 0;
Inst *inst;
Ilist *tlp;
Posn p = startp;
int nnl = 0, ntl;
int c;
int wrapped = 0;
int startchar = startinst->type<OPERATOR? startinst->type : 0;
list[0][0].inst = list[1][0].inst = 0;
sel.p[0].p1 = -1;
/* Execute machine once for each character */
for(;;p++){
doloop:
c = filereadc(f, p);
if(p>=eof || c<0){
switch(wrapped++){
case 0: /* let loop run one more click */
case 2:
break;
case 1: /* expired; wrap to beginning */
if(sel.p[0].p1>=0 || eof!=INFINITY)
goto Return;
list[0][0].inst = list[1][0].inst = 0;
p = 0;
goto doloop;
default:
goto Return;
}
}else if(((wrapped && p>=startp) || sel.p[0].p1>0) && nnl==0)
break;
/* fast check for first char */
if(startchar && nnl==0 && c!=startchar)
continue;
tl = list[flag];
nl = list[flag^=1];
nl->inst = 0;
ntl = nnl;
nnl = 0;
if(sel.p[0].p1<0 && (!wrapped || p<startp || startp==eof)){
/* Add first instruction to this list */
sempty.p[0].p1 = p;
if(addinst(tl, startinst, &sempty))
if(++ntl >= NLIST)
Overflow:
error(Eoverflow);
}
/* Execute machine until this list is empty */
for(tlp = tl; inst = tlp->inst; tlp++){ /* assignment = */
Switchstmt:
switch(inst->type){
default: /* regular character */
if(inst->type==c){
Addinst:
if(addinst(nl, inst->next, &tlp->se))
if(++nnl >= NLIST)
goto Overflow;
}
break;
case LBRA:
if(inst->subid>=0)
tlp->se.p[inst->subid].p1 = p;
inst = inst->next;
goto Switchstmt;
case RBRA:
if(inst->subid>=0)
tlp->se.p[inst->subid].p2 = p;
inst = inst->next;
goto Switchstmt;
case ANY:
if(c!='\n')
goto Addinst;
break;
case BOL:
if(p==0 || filereadc(f, p - 1)=='\n'){
Step:
inst = inst->next;
goto Switchstmt;
}
break;
case EOL:
if(c == '\n')
goto Step;
break;
case CCLASS:
if(c>=0 && classmatch(inst->rclass, c, 0))
goto Addinst;
break;
case NCCLASS:
if(c>=0 && classmatch(inst->rclass, c, 1))
goto Addinst;
break;
case OR:
/* evaluate right choice later */
if(addinst(tlp, inst->right, &tlp->se))
if(++ntl >= NLIST)
goto Overflow;
/* efficiency: advance and re-evaluate */
inst = inst->left;
goto Switchstmt;
case END: /* Match! */
tlp->se.p[0].p2 = p;
newmatch(&tlp->se);
break;
}
}
}
Return:
return sel.p[0].p1>=0;
}
void
newmatch(Rangeset *sp)
{
int i;
if(sel.p[0].p1<0 || sp->p[0].p1<sel.p[0].p1 ||
(sp->p[0].p1==sel.p[0].p1 && sp->p[0].p2>sel.p[0].p2))
for(i = 0; i<NSUBEXP; i++)
sel.p[i] = sp->p[i];
}
int
bexecute(File *f, Posn startp)
{
int flag = 0;
Inst *inst;
Ilist *tlp;
Posn p = startp;
int nnl = 0, ntl;
int c;
int wrapped = 0;
int startchar = bstartinst->type<OPERATOR? bstartinst->type : 0;
list[0][0].inst = list[1][0].inst = 0;
sel.p[0].p1= -1;
/* Execute machine once for each character, including terminal NUL */
for(;;--p){
doloop:
if((c = filereadc(f, p - 1))==-1){
switch(wrapped++){
case 0: /* let loop run one more click */
case 2:
break;
case 1: /* expired; wrap to end */
if(sel.p[0].p1>=0)
case 3:
goto Return;
list[0][0].inst = list[1][0].inst = 0;
p = f->nc;
goto doloop;
default:
goto Return;
}
}else if(((wrapped && p<=startp) || sel.p[0].p1>0) && nnl==0)
break;
/* fast check for first char */
if(startchar && nnl==0 && c!=startchar)
continue;
tl = list[flag];
nl = list[flag^=1];
nl->inst = 0;
ntl = nnl;
nnl = 0;
if(sel.p[0].p1<0 && (!wrapped || p>startp)){
/* Add first instruction to this list */
/* the minus is so the optimizations in addinst work */
sempty.p[0].p1 = -p;
if(addinst(tl, bstartinst, &sempty))
if(++ntl >= NLIST)
Overflow:
error(Eoverflow);
}
/* Execute machine until this list is empty */
for(tlp = tl; inst = tlp->inst; tlp++){ /* assignment = */
Switchstmt:
switch(inst->type){
default: /* regular character */
if(inst->type == c){
Addinst:
if(addinst(nl, inst->next, &tlp->se))
if(++nnl >= NLIST)
goto Overflow;
}
break;
case LBRA:
if(inst->subid>=0)
tlp->se.p[inst->subid].p1 = p;
inst = inst->next;
goto Switchstmt;
case RBRA:
if(inst->subid >= 0)
tlp->se.p[inst->subid].p2 = p;
inst = inst->next;
goto Switchstmt;
case ANY:
if(c != '\n')
goto Addinst;
break;
case BOL:
if(c=='\n' || p==0){
Step:
inst = inst->next;
goto Switchstmt;
}
break;
case EOL:
if(p==f->nc || filereadc(f, p)=='\n')
goto Step;
break;
case CCLASS:
if(c>=0 && classmatch(inst->rclass, c, 0))
goto Addinst;
break;
case NCCLASS:
if(c>=0 && classmatch(inst->rclass, c, 1))
goto Addinst;
break;
case OR:
/* evaluate right choice later */
if(addinst(tl, inst->right, &tlp->se))
if(++ntl >= NLIST)
goto Overflow;
/* efficiency: advance and re-evaluate */
inst = inst->left;
goto Switchstmt;
case END: /* Match! */
tlp->se.p[0].p1 = -tlp->se.p[0].p1; /* minus sign */
tlp->se.p[0].p2 = p;
bnewmatch(&tlp->se);
break;
}
}
}
Return:
return sel.p[0].p1>=0;
}
void
bnewmatch(Rangeset *sp)
{
int i;
if(sel.p[0].p1<0 || sp->p[0].p1>sel.p[0].p2 || (sp->p[0].p1==sel.p[0].p2 && sp->p[0].p2<sel.p[0].p1))
for(i = 0; i<NSUBEXP; i++){ /* note the reversal; p1<=p2 */
sel.p[i].p1 = sp->p[i].p2;
sel.p[i].p2 = sp->p[i].p1;
}
}