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#include "cnfbuild.h"
struct stck {
struct boolexpr **stack;
size_t size, pos;
};
struct stck *stack_create();
void stack_push(struct stck *s, struct boolexpr *b);
struct boolexpr *stack_pop(struct stck *s);
void cnf_and(struct symlist *sl, struct boolexpr *bl);
void cnf_or(struct symlist *sl, struct boolexpr *bl);
void cnf_not(struct symlist *sl, struct boolexpr *bl);
void cnf_boolexpr(struct symlist *sl, struct boolexpr *bl) {
if (bl->type == BT_TRUE) {
// Term is always true. No write required.
return;
} else if (bl->type == BT_FALSE) {
fprintf(stderr,
"E: Trying to write false term. This shouldn't happen.\n");
exit(6);
}
struct stck *stack = stack_create();
while (bl != NULL) {
switch (bl->type) {
case BT_NOT:
if (bl->left->id != 0) {
cnf_not(sl, bl);
bl = stack_pop(stack);
} else {
stack_push(stack, bl);
bl = bl->left;
}
break;
case BT_AND:
case BT_OR:
if (bl->left->id != 0) {
if (bl->right->id != 0) {
if (bl->type == BT_OR) {
cnf_or(sl, bl);
bl = stack_pop(stack);
} else { /* BT_AND */
cnf_and(sl, bl);
bl = stack_pop(stack);
}
} else {
stack_push(stack, bl);
bl = bl->right;
}
} else {
stack_push(stack, bl);
bl = bl->left;
}
break;
default:
bl = stack_pop(stack);
break;
}
}
}
struct stck *stack_create() {
struct stck *rtn;
rtn = malloc(sizeof(struct stck));
rtn->size = 2;
rtn->pos = 0;
rtn->stack = malloc(rtn->size * sizeof(struct boolexpr *));
return rtn;
}
void stack_push(struct stck *s, struct boolexpr *b) {
if (++(s->pos) >= s->size) {
s->size *= 2;
s->stack = realloc(s->stack, s->size * sizeof(struct boolexpr *));
}
s->stack[s->pos - 1] = b;
}
inline struct boolexpr *stack_pop(struct stck *s) {
if (s->pos > 0)
return s->stack[--(s->pos)];
else
return NULL;
}
void cnf_and(struct symlist *sl, struct boolexpr *bl) {
if (bl->id != 0)
return;
bl->id = symlist_adddummy(sl);
// bl->id <-> (bl->left->id && bl->right->id)
//
// (bl->id || !bl->left->id || !bl->right->id) &&
// (!bl->id || bl->left->id) &&
// (!bl->id || bl->right->id)
output_rules_symbol((int) bl->id);
output_rules_symbol(-(int) bl->left->id);
output_rules_symbol(-(int) bl->right->id);
output_rules_endterm();
output_rules_symbol(-(int) bl->id);
output_rules_symbol((int) bl->left->id);
output_rules_endterm();
output_rules_symbol(-(int) bl->id);
output_rules_symbol((int) bl->right->id);
output_rules_endterm();
}
void cnf_or(struct symlist *sl, struct boolexpr *bl) {
if (bl->id != 0)
return;
bl->id = symlist_adddummy(sl);
// bl->id <-> (bl->left->id || bl->right->id)
//
// (!bl->id || bl->left->id || bl->right->id) &&
// (bl->id || !bl->left->id) &&
// (bl->id || !bl->right->id)
output_rules_symbol(-(int) bl->id);
output_rules_symbol((int) bl->left->id);
output_rules_symbol((int) bl->right->id);
output_rules_endterm();
output_rules_symbol((int) bl->id);
output_rules_symbol(-(int) bl->left->id);
output_rules_endterm();
output_rules_symbol((int) bl->id);
output_rules_symbol(-(int) bl->right->id);
output_rules_endterm();
}
void cnf_not(struct symlist *sl, struct boolexpr *bl) {
if (bl->id != 0)
return;
bl->id = symlist_adddummy(sl);
// bl->id <-> !bl->left->id
// (bl->id || bl->left->id) && (!bl->id || !bl->left->id)
output_rules_symbol((int) bl->id);
output_rules_symbol((int) bl->left->id);
output_rules_endterm();
output_rules_symbol(-(int) bl->id);
output_rules_symbol(-(int) bl->left->id);
output_rules_endterm();
}
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