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();
}
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();
}
}