예제 #1
0
void Expr::partial_eval_primitive_application() {
	Expr* lhs = arg1;
	Expr* rhs = arg2->drop_i1();

	// arg1 and arg2 are now uninitialized space

	switch (lhs->type) {
	case K:
		type = K1;
		arg1 = rhs;
		arg2 = 0;
		break;
	case K1:
		type = I1;
		arg1 = lhs->arg1->dup();
		arg2 = 0;
		rhs->deref();
		break;
	case S:
		type = S1;
		arg1 = rhs;
		arg2 = 0;
		break;
	case S1:
		type = S2;
		arg1 = lhs->arg1->dup();
		arg2 = rhs;
		break;
	case LazyRead:
		lhs->type = S2;
		lhs->arg1 = new Expr(S2, I.dup(), new Expr(K1, make_church_char(getchar())));
		lhs->arg2 = new Expr(K1, new Expr(LazyRead));
		// fall thru
	case S2:
		//type = A;
		arg1 = partial_apply(lhs->arg1->dup(), rhs->dup());
		arg2 = partial_apply(lhs->arg2->dup(), rhs);
		break;
	case Inc:
		rhs = rhs->partial_eval();
		type = Num;
		numeric_arg1 = rhs->to_number() + 1;
		if (numeric_arg1 == 0) {
			fputs("Runtime error: invalid output format (attempted to apply inc to a non-number)\n", stderr);
			exit(3);
		}
		arg2 = 0;
		break;
	case Num:
		fputs("Runtime error: invalid output format (attempted to apply a number)\n", stderr);
		exit(3);
	default:
		fprintf(stderr, "INTERNAL ERROR: invalid type in partial_eval_primitive_application (%d)\n", lhs->type);
		exit(4);
	}
	lhs->deref();
}
예제 #2
0
Expr* Expr::partial_eval() {
	Expr* prev = 0;
	Expr* cur = this;
	for (;;) {
		cur = cur->drop_i1();
		while (cur->type == A) {
			Expr* next = cur->arg1->drop_i1();
			cur->arg1 = prev;
			prev = cur; cur = next;
		}
		if (!prev) {
			return cur;
		}
		Expr* next = cur; cur = prev;
		prev = cur->arg1;
		cur->arg1 = next;
		cur->partial_eval_primitive_application();
	}
}