//===- TypeSwitchTest.cpp - TypeSwitch unit tests -------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "llvm/ADT/TypeSwitch.h"
#include "gtest/gtest.h"

using namespace llvm;

namespace {
/// Utility classes to setup casting functionality.
struct Base {
  enum Kind { DerivedA, DerivedB, DerivedC, DerivedD, DerivedE };
  Kind kind;
};
template <Base::Kind DerivedKind> struct DerivedImpl : Base {
  DerivedImpl() : Base{DerivedKind} {}
  static bool classof(const Base *base) { return base->kind == DerivedKind; }
};
struct DerivedA : public DerivedImpl<Base::DerivedA> {};
struct DerivedB : public DerivedImpl<Base::DerivedB> {};
struct DerivedC : public DerivedImpl<Base::DerivedC> {};
struct DerivedD : public DerivedImpl<Base::DerivedD> {};
struct DerivedE : public DerivedImpl<Base::DerivedE> {};
} // end anonymous namespace

TEST(TypeSwitchTest, CaseResult) {
  auto translate = [](auto value) {
    return TypeSwitch<Base *, int>(&value)
        .Case<DerivedA>([](DerivedA *) { return 0; })
        .Case([](DerivedB *) { return 1; })
        .Case([](DerivedC *) { return 2; })
        .Default([](Base *) { return -1; });
  };
  EXPECT_EQ(0, translate(DerivedA()));
  EXPECT_EQ(1, translate(DerivedB()));
  EXPECT_EQ(2, translate(DerivedC()));
  EXPECT_EQ(-1, translate(DerivedD()));
}

TEST(TypeSwitchTest, CasesResult) {
  auto translate = [](auto value) {
    return TypeSwitch<Base *, int>(&value)
        .Case<DerivedA, DerivedB, DerivedD>([](auto *) { return 0; })
        .Case([](DerivedC *) { return 1; })
        .Default(-1);
  };
  EXPECT_EQ(0, translate(DerivedA()));
  EXPECT_EQ(0, translate(DerivedB()));
  EXPECT_EQ(1, translate(DerivedC()));
  EXPECT_EQ(0, translate(DerivedD()));
  EXPECT_EQ(-1, translate(DerivedE()));
}

TEST(TypeSwitchTest, CaseVoid) {
  auto translate = [](auto value) {
    int result = -2;
    TypeSwitch<Base *>(&value)
        .Case([&](DerivedA *) { result = 0; })
        .Case([&](DerivedB *) { result = 1; })
        .Case([&](DerivedC *) { result = 2; })
        .Default([&](Base *) { result = -1; });
    return result;
  };
  EXPECT_EQ(0, translate(DerivedA()));
  EXPECT_EQ(1, translate(DerivedB()));
  EXPECT_EQ(2, translate(DerivedC()));
  EXPECT_EQ(-1, translate(DerivedD()));
}

TEST(TypeSwitchTest, CasesVoid) {
  auto translate = [](auto value) {
    int result = -1;
    TypeSwitch<Base *>(&value)
        .Case<DerivedA, DerivedB, DerivedD>([&](auto *) { result = 0; })
        .Case([&](DerivedC *) { result = 1; });
    return result;
  };
  EXPECT_EQ(0, translate(DerivedA()));
  EXPECT_EQ(0, translate(DerivedB()));
  EXPECT_EQ(1, translate(DerivedC()));
  EXPECT_EQ(0, translate(DerivedD()));
  EXPECT_EQ(-1, translate(DerivedE()));
}

TEST(TypeSwitchTest, CaseOptional) {
  auto translate = [](auto value) {
    return TypeSwitch<Base *, std::optional<int>>(&value)
        .Case([](DerivedA *) { return 0; })
        .Case([](DerivedC *) { return std::nullopt; })
        .Default([](Base *) { return -1; });
  };
  EXPECT_EQ(0, translate(DerivedA()));
  EXPECT_EQ(std::nullopt, translate(DerivedC()));
  EXPECT_EQ(-1, translate(DerivedD()));
  EXPECT_EQ(std::nullopt,
            (TypeSwitch<Base *, std::optional<int>>(nullptr).Default(
                [](Base *) { return std::nullopt; })));
}

TEST(TypeSwitchTest, CasesOptional) {
  auto translate = [](auto value) {
    return TypeSwitch<Base *, std::optional<int>>(&value)
        .Case<DerivedB, DerivedC>([](auto *) { return std::nullopt; })
        .Case([](DerivedA *) { return 0; })
        .Default([](Base *) { return -1; });
  };
  EXPECT_EQ(0, translate(DerivedA()));
  EXPECT_EQ(std::nullopt, translate(DerivedB()));
  EXPECT_EQ(std::nullopt, translate(DerivedC()));
  EXPECT_EQ(-1, translate(DerivedD()));
}

TEST(TypeSwitchTest, DefaultUnreachableWithValue) {
  auto translate = [](auto value) {
    return TypeSwitch<Base *, int>(&value)
        .Case([](DerivedA *) { return 0; })
        .DefaultUnreachable("Unhandled type");
  };
  EXPECT_EQ(0, translate(DerivedA()));

#if defined(GTEST_HAS_DEATH_TEST) && !defined(NDEBUG)
  EXPECT_DEATH((void)translate(DerivedD()), "Unhandled type");
#endif
}

TEST(TypeSwitchTest, DefaultUnreachableWithVoid) {
  auto translate = [](auto value) {
    int result = -1;
    TypeSwitch<Base *>(&value)
        .Case([&result](DerivedA *) { result = 0; })
        .DefaultUnreachable("Unhandled type");
    return result;
  };
  EXPECT_EQ(0, translate(DerivedA()));

#if defined(GTEST_HAS_DEATH_TEST) && !defined(NDEBUG)
  EXPECT_DEATH((void)translate(DerivedD()), "Unhandled type");
#endif
}

TEST(TypeSwitchTest, DefaultNullopt) {
  auto translate = [](auto value) {
    return TypeSwitch<Base *, std::optional<int>>(&value)
        .Case([](DerivedA *) { return 0; })
        .Default(std::nullopt);
  };
  EXPECT_EQ(0, translate(DerivedA()));
  EXPECT_EQ(std::nullopt, translate(DerivedD()));
}

TEST(TypeSwitchTest, DefaultNullptr) {
  float foo = 0.0f;
  auto translate = [&](auto value) {
    return TypeSwitch<Base *, float *>(&value)
        .Case([&](DerivedA *) { return &foo; })
        .Default(nullptr);
  };
  EXPECT_EQ(&foo, translate(DerivedA()));
  EXPECT_EQ(nullptr, translate(DerivedD()));
}

TEST(TypeSwitchTest, DefaultNullptrForPointerLike) {
  struct Value {
    void *ptr;
    Value(const Value &other) = default;
    Value(std::nullptr_t) : ptr(nullptr) {}
    Value() : Value(nullptr) {}
  };

  float foo = 0.0f;
  Value fooVal;
  fooVal.ptr = &foo;
  auto translate = [&](auto value) {
    return TypeSwitch<Base *, Value>(&value)
        .Case([&](DerivedA *) { return fooVal; })
        .Default(nullptr);
  };
  EXPECT_EQ(&foo, translate(DerivedA()).ptr);
  EXPECT_EQ(nullptr, translate(DerivedD()).ptr);
}