/*
** When joining 'ktables', constants from one of the subpatterns must
** be renumbered; 'correctkeys' corrects their indices (adding 'n'
** to each of them)
*/
static void correctkeys (TTree *tree, int n) {
if (n == 0) return; /* no correction? */
tailcall:
switch (tree->tag) {
case TOpenCall: case TCall: case TRunTime: case TRule: {
if (tree->key > 0)
tree->key += n;
break;
}
case TCapture: {
if (tree->key > 0 && tree->cap != Carg && tree->cap != Cnum)
tree->key += n;
break;
}
default: break;
}
switch (numsiblings[tree->tag]) {
case 1: /* correctkeys(sib1(tree), n); */
tree = sib1(tree); goto tailcall;
case 2:
correctkeys(sib1(tree), n);
tree = sib2(tree); goto tailcall; /* correctkeys(sib2(tree), n); */
default: assert(numsiblings[tree->tag] == 0); break;
}
}
/*
** Make final adjustments in a tree. Fix open calls in tree 't',
** making them refer to their respective rules or raising appropriate
** errors (if not inside a grammar). Correct associativity of associative
** constructions (making them right associative). Assume that tree's
** ktable is at the top of the stack (for error messages).
*/
static void finalfix (lua_State *L, int postable, TTree *g, TTree *t) {
tailcall:
switch (t->tag) {
case TGrammar: /* subgrammars were already fixed */
return;
case TOpenCall: {
if (g != NULL) /* inside a grammar? */
fixonecall(L, postable, g, t);
else { /* open call outside grammar */
lua_rawgeti(L, -1, t->key);
luaL_error(L, "rule '%s' used outside a grammar", val2str(L, -1));
}
break;
}
case TSeq: case TChoice:
correctassociativity(t);
break;
}
switch (numsiblings[t->tag]) {
case 1: /* finalfix(L, postable, g, sib1(t)); */
t = sib1(t); goto tailcall;
case 2:
finalfix(L, postable, g, sib1(t));
t = sib2(t); goto tailcall; /* finalfix(L, postable, g, sib2(t)); */
default: assert(numsiblings[t->tag] == 0); break;
}
}
/*
** Constant capture
*/
static int lp_constcapture (lua_State *L) {
int i;
int n = lua_gettop(L); /* number of values */
if (n == 0) /* no values? */
newleaf(L, TTrue); /* no capture */
else if (n == 1)
newemptycapkey(L, Cconst, 1); /* single constant capture */
else { /* create a group capture with all values */
TTree *tree = newtree(L, 1 + 3 * (n - 1) + 2);
newktable(L, n); /* create a 'ktable' for new tree */
tree->tag = TCapture;
tree->cap = Cgroup;
tree->key = 0;
tree = sib1(tree);
for (i = 1; i <= n - 1; i++) {
tree->tag = TSeq;
tree->u.ps = 3; /* skip TCapture and its sibling */
auxemptycap(sib1(tree), Cconst);
sib1(tree)->key = addtoktable(L, i);
tree = sib2(tree);
}
auxemptycap(tree, Cconst);
tree->key = addtoktable(L, i);
}
return 1;
}
static void verifygrammar (lua_State *L, TTree *grammar) {
int passed[MAXRULES];
TTree *rule;
/* check left-recursive rules */
for (rule = sib1(grammar); rule->tag == TRule; rule = sib2(rule)) {
if (rule->key == 0) continue; /* unused rule */
verifyrule(L, sib1(rule), passed, 0, 0);
}
assert(rule->tag == TTrue);
/* check infinite loops inside rules */
for (rule = sib1(grammar); rule->tag == TRule; rule = sib2(rule)) {
if (rule->key == 0) continue; /* unused rule */
if (checkloops(sib1(rule))) {
lua_rawgeti(L, -1, rule->key); /* get rule's key */
luaL_error(L, "empty loop in rule '%s'", val2str(L, -1));
}
}
assert(rule->tag == TTrue);
}
/*
** Build a sequence of 'n' nodes, each with tag 'tag' and 'u.n' got
** from the array 's' (or 0 if array is NULL). (TSeq is binary, so it
** must build a sequence of sequence of sequence...)
*/
static void fillseq (TTree *tree, int tag, int n, const char *s) {
int i;
for (i = 0; i < n - 1; i++) { /* initial n-1 copies of Seq tag; Seq ... */
tree->tag = TSeq; tree->u.ps = 2;
sib1(tree)->tag = tag;
sib1(tree)->u.n = s ? (byte)s[i] : 0;
tree = sib2(tree);
}
tree->tag = tag; /* last one does not need TSeq */
tree->u.n = s ? (byte)s[i] : 0;
}
/*
** Check whether a rule can be left recursive; raise an error in that
** case; otherwise return 1 iff pattern is nullable. Assume ktable at
** the top of the stack.
*/
static int verifyrule (lua_State *L, TTree *tree, int *passed, int npassed,
int nullable) {
tailcall:
switch (tree->tag) {
case TChar: case TSet: case TAny:
case TFalse:
return nullable; /* cannot pass from here */
case TTrue:
case TBehind: /* look-behind cannot have calls */
return 1;
case TNot: case TAnd: case TRep:
/* return verifyrule(L, sib1(tree), passed, npassed, 1); */
tree = sib1(tree); nullable = 1; goto tailcall;
case TCapture: case TRunTime:
/* return verifyrule(L, sib1(tree), passed, npassed); */
tree = sib1(tree); goto tailcall;
case TCall:
/* return verifyrule(L, sib2(tree), passed, npassed); */
tree = sib2(tree); goto tailcall;
case TSeq: /* only check 2nd child if first is nullable */
if (!verifyrule(L, sib1(tree), passed, npassed, 0))
return nullable;
/* else return verifyrule(L, sib2(tree), passed, npassed); */
tree = sib2(tree); goto tailcall;
case TChoice: /* must check both children */
nullable = verifyrule(L, sib1(tree), passed, npassed, nullable);
/* return verifyrule(L, sib2(tree), passed, npassed, nullable); */
tree = sib2(tree); goto tailcall;
case TRule:
if (npassed >= MAXRULES)
return verifyerror(L, passed, npassed);
else {
passed[npassed++] = tree->key;
/* return verifyrule(L, sib1(tree), passed, npassed); */
tree = sib1(tree); goto tailcall;
}
case TGrammar:
return nullable(tree); /* sub-grammar cannot be left recursive */
default: assert(0); return 0;
}
}
static void buildgrammar (lua_State *L, TTree *grammar, int frule, int n) {
int i;
TTree *nd = sib1(grammar); /* auxiliary pointer to traverse the tree */
for (i = 0; i < n; i++) { /* add each rule into new tree */
int ridx = frule + 2*i + 1; /* index of i-th rule */
int rulesize;
TTree *rn = gettree(L, ridx, &rulesize);
nd->tag = TRule;
nd->key = 0;
nd->cap = i; /* rule number */
nd->u.ps = rulesize + 1; /* point to next rule */
memcpy(sib1(nd), rn, rulesize * sizeof(TTree)); /* copy rule */
mergektable(L, ridx, sib1(nd)); /* merge its ktable into new one */
nd = sib2(nd); /* move to next rule */
}
nd->tag = TTrue; /* finish list of rules */
}
/*
** Check whether a tree has potential infinite loops
*/
static int checkloops (TTree *tree) {
tailcall:
if (tree->tag == TRep && nullable(sib1(tree)))
return 1;
else if (tree->tag == TGrammar)
return 0; /* sub-grammars already checked */
else {
switch (numsiblings[tree->tag]) {
case 1: /* return checkloops(sib1(tree)); */
tree = sib1(tree); goto tailcall;
case 2:
if (checkloops(sib1(tree))) return 1;
/* else return checkloops(sib2(tree)); */
tree = sib2(tree); goto tailcall;
default: assert(numsiblings[tree->tag] == 0); return 0;
}
}
}
/*
** [t1 - t2] == Seq (Not t2) t1
** If t1 and t2 are charsets, make their difference.
*/
static int lp_sub (lua_State *L) {
Charset st1, st2;
int s1, s2;
TTree *t1 = getpatt(L, 1, &s1);
TTree *t2 = getpatt(L, 2, &s2);
if (tocharset(t1, &st1) && tocharset(t2, &st2)) {
TTree *t = newcharset(L);
loopset(i, treebuffer(t)[i] = st1.cs[i] & ~st2.cs[i]);
}
else {
TTree *tree = newtree(L, 2 + s1 + s2);
tree->tag = TSeq; /* sequence of... */
tree->u.ps = 2 + s2;
sib1(tree)->tag = TNot; /* ...not... */
memcpy(sib1(sib1(tree)), t2, s2 * sizeof(TTree)); /* ...t2 */
memcpy(sib2(tree), t1, s1 * sizeof(TTree)); /* ... and t1 */
joinktables(L, 1, sib1(tree), 2);
}
return 1;
}
/*
** add to tree a sequence where first sibling is 'sib' (with size
** 'sibsize'); returns position for second sibling
*/
static TTree *seqaux (TTree *tree, TTree *sib, int sibsize) {
tree->tag = TSeq; tree->u.ps = sibsize + 1;
memcpy(sib1(tree), sib, sibsize * sizeof(TTree));
return sib2(tree);
}
