/*
* Apply s to an offset equality x = y + offset
*/
static void subst_eq(substitution_t *s, offset_equality_t *e) {
offset_pair_t aux1, aux2;
aux1.var = e->lhs;
aux1.delta = 0;
subst_var(s, &aux1);
aux2.var = e->rhs;
aux2.delta = 0;
subst_var(s, &aux2);
e->lhs = aux1.var;
e->rhs = aux2.var;
e->offset -= aux1.delta;
e->offset += aux2.delta;
}
/*
* Apply s to a monomial array mono
* - store the result in buffer b
*/
static void subst_poly(substitution_t *s, poly_buffer_t *b, monomial_t *mono) {
offset_pair_t aux;
rational_t q;
int32_t x;
q_init(&q);
reset_poly_buffer(b);
x = mono->var;
while (x != max_idx) {
if (x == const_idx) {
poly_buffer_add_const(b, &mono->coeff);
} else {
aux.var = x;
aux.delta = 0;
subst_var(s, &aux); // aux constains S[x] = y + delta
// add a * y + a * delta to b
if (aux.var > 0) {
poly_buffer_add_monomial(b, aux.var, &mono->coeff);
}
q_set32(&q, aux.delta);
poly_buffer_addmul_monomial(b, const_idx, &mono->coeff, &q);
}
mono ++;
x = mono->var;
}
normalize_poly_buffer(b);
q_clear(&q);
}
Expr*
subst(Expr* e, const Subst& sub) {
switch (e->kind) {
case id_expr: return e;
case unit_term: return e;
case true_term: return e;
case false_term: return e;
case if_term: return subst_ternary_term(as<If>(e), sub);
case int_term: return e;
case and_term: return subst_binary_term(as<And>(e), sub);
case or_term: return subst_binary_term(as<Or>(e), sub);
case equals_term: return subst_binary_term(as<Equals>(e), sub);
case less_term: return subst_binary_term(as<Less>(e), sub);
case not_term: return subst_unary_term(as<Not>(e), sub);
case succ_term: return subst_unary_term(as<Succ>(e), sub);
case pred_term: return subst_unary_term(as<Pred>(e), sub);
case iszero_term: return subst_unary_term(as<Iszero>(e), sub);
case var_term: return subst_var(as<Var>(e), sub);
case abs_term: return subst_binary_term(as<Abs>(e), sub);
case app_term: return subst_binary_term(as<App>(e), sub);
case ref_term: return subst_ref(as<Ref>(e), sub);
case mem_term: return subst_mem(as<Mem>(e), sub);
case kind_type: return e;
case unit_type: return e;
case bool_type: return e;
case nat_type: return e;
case arrow_type: return e;
case record_term: return e;
default: break;
}
lang_unreachable(format("substitution into unkown term '{}'", node_name(e)));
}