union.cpp

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#include "mim/union.h"
 
#include <algorithm>
 
#include "mim/check.h"
#include "mim/lam.h"
 
namespace mim {
 
DefVec Match::cases(const Def* scrutinee) {
    auto type = scrutinee->unfold_type();
    if (!type) return {};
    if (auto join = type->isa<Join>()) return DefVec(join->ops().begin(), join->ops().end());
    if (auto variant = type->isa<Variant>()) return DefVec(variant->ops().begin(), variant->ops().end());
    return DefVec{type};
}
 
bool Match::accepts(const Def* arm, const Def* c, bool infer) {
    auto alpha = [infer](const Def* a, const Def* b) { return infer ? Check::alpha(a, b) : Check::test_alpha(a, b); };
 
    auto pi = arm->isa_type<Pi>();
    if (!pi) return false;
    if (alpha(pi->dom(), c)) return true;
    if (auto join = pi->dom()->isa_imm<Join>())
        return std::ranges::any_of(join->ops(), [&](const Def* op) { return alpha(op, c); });
    return false;
}
 
} // namespace mim