llvm/unittests/ADT/STLExtrasTest.cpp

//===- STLExtrasTest.cpp - Unit tests for STL extras ----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

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

#include <vector>

using namespace llvm;

namespace {

int f(rank<0>) { return 0; }
int f(rank<1>) { return 1; }
int f(rank<2>) { return 2; }
int f(rank<4>) { return 4; }

TEST(STLExtrasTest, Rank) {
  // We shouldn't get ambiguities and should select the overload of the same
  // rank as the argument.
  EXPECT_EQ(0, f(rank<0>()));
  EXPECT_EQ(1, f(rank<1>()));
  EXPECT_EQ(2, f(rank<2>()));

  // This overload is missing so we end up back at 2.
  EXPECT_EQ(2, f(rank<3>()));

  // But going past 3 should work fine.
  EXPECT_EQ(4, f(rank<4>()));

  // And we can even go higher and just fall back to the last overload.
  EXPECT_EQ(4, f(rank<5>()));
  EXPECT_EQ(4, f(rank<6>()));
}

TEST(STLExtrasTest, EnumerateLValue) {
  // Test that a simple LValue can be enumerated and gives correct results with
  // multiple types, including the empty container.
  std::vector<char> foo = {'a', 'b', 'c'};
  std::vector<std::pair<std::size_t, char>> CharResults;

  for (auto X : llvm::enumerate(foo)) {
    CharResults.emplace_back(X.Index, X.Value);
  }
  ASSERT_EQ(3u, CharResults.size());
  EXPECT_EQ(std::make_pair(0u, 'a'), CharResults[0]);
  EXPECT_EQ(std::make_pair(1u, 'b'), CharResults[1]);
  EXPECT_EQ(std::make_pair(2u, 'c'), CharResults[2]);

  // Test a const range of a different type.
  std::vector<std::pair<std::size_t, int>> IntResults;
  const std::vector<int> bar = {1, 2, 3};
  for (auto X : llvm::enumerate(bar)) {
    IntResults.emplace_back(X.Index, X.Value);
  }
  ASSERT_EQ(3u, IntResults.size());
  EXPECT_EQ(std::make_pair(0u, 1), IntResults[0]);
  EXPECT_EQ(std::make_pair(1u, 2), IntResults[1]);
  EXPECT_EQ(std::make_pair(2u, 3), IntResults[2]);

  // Test an empty range.
  IntResults.clear();
  const std::vector<int> baz;
  for (auto X : llvm::enumerate(baz)) {
    IntResults.emplace_back(X.Index, X.Value);
  }
  EXPECT_TRUE(IntResults.empty());
}

TEST(STLExtrasTest, EnumerateModifyLValue) {
  // Test that you can modify the underlying entries of an lvalue range through
  // the enumeration iterator.
  std::vector<char> foo = {'a', 'b', 'c'};

  for (auto X : llvm::enumerate(foo)) {
    ++X.Value;
  }
  EXPECT_EQ('b', foo[0]);
  EXPECT_EQ('c', foo[1]);
  EXPECT_EQ('d', foo[2]);
}

TEST(STLExtrasTest, EnumerateRValueRef) {
  // Test that an rvalue can be enumerated.
  std::vector<std::pair<std::size_t, int>> Results;

  auto Enumerator = llvm::enumerate(std::vector<int>{1, 2, 3});

  for (auto X : llvm::enumerate(std::vector<int>{1, 2, 3})) {
    Results.emplace_back(X.Index, X.Value);
  }

  ASSERT_EQ(3u, Results.size());
  EXPECT_EQ(std::make_pair(0u, 1), Results[0]);
  EXPECT_EQ(std::make_pair(1u, 2), Results[1]);
  EXPECT_EQ(std::make_pair(2u, 3), Results[2]);
}

TEST(STLExtrasTest, EnumerateModifyRValue) {
  // Test that when enumerating an rvalue, modification still works (even if
  // this isn't terribly useful, it at least shows that we haven't snuck an
  // extra const in there somewhere.
  std::vector<std::pair<std::size_t, char>> Results;

  for (auto X : llvm::enumerate(std::vector<char>{'1', '2', '3'})) {
    ++X.Value;
    Results.emplace_back(X.Index, X.Value);
  }

  ASSERT_EQ(3u, Results.size());
  EXPECT_EQ(std::make_pair(0u, '2'), Results[0]);
  EXPECT_EQ(std::make_pair(1u, '3'), Results[1]);
  EXPECT_EQ(std::make_pair(2u, '4'), Results[2]);
}

template <bool B> struct CanMove {};
template <> struct CanMove<false> {
  CanMove(CanMove &&) = delete;

  CanMove() = default;
  CanMove(const CanMove &) = default;
};

template <bool B> struct CanCopy {};
template <> struct CanCopy<false> {
  CanCopy(const CanCopy &) = delete;

  CanCopy() = default;
  CanCopy(CanCopy &&) = default;
};

template <bool Moveable, bool Copyable>
struct Range : CanMove<Moveable>, CanCopy<Copyable> {
  explicit Range(int &C, int &M, int &D) : C(C), M(M), D(D) {}
  Range(const Range &R) : CanCopy<Copyable>(R), C(R.C), M(R.M), D(R.D) { ++C; }
  Range(Range &&R) : CanMove<Moveable>(std::move(R)), C(R.C), M(R.M), D(R.D) {
    ++M;
  }
  ~Range() { ++D; }

  int &C;
  int &M;
  int &D;

  int *begin() { return nullptr; }
  int *end() { return nullptr; }
};

TEST(STLExtrasTest, EnumerateLifetimeSemantics) {
  // Test that when enumerating lvalues and rvalues, there are no surprise
  // copies or moves.

  // With an rvalue, it should not be destroyed until the end of the scope.
  int Copies = 0;
  int Moves = 0;
  int Destructors = 0;
  {
    auto E1 = enumerate(Range<true, false>(Copies, Moves, Destructors));
    // Doesn't compile.  rvalue ranges must be moveable.
    // auto E2 = enumerate(Range<false, true>(Copies, Moves, Destructors));
    EXPECT_EQ(0, Copies);
    EXPECT_EQ(1, Moves);
    EXPECT_EQ(1, Destructors);
  }
  EXPECT_EQ(0, Copies);
  EXPECT_EQ(1, Moves);
  EXPECT_EQ(2, Destructors);

  Copies = Moves = Destructors = 0;
  // With an lvalue, it should not be destroyed even after the end of the scope.
  // lvalue ranges need be neither copyable nor moveable.
  Range<false, false> R(Copies, Moves, Destructors);
  {
    auto Enumerator = enumerate(R);
    (void)Enumerator;
    EXPECT_EQ(0, Copies);
    EXPECT_EQ(0, Moves);
    EXPECT_EQ(0, Destructors);
  }
  EXPECT_EQ(0, Copies);
  EXPECT_EQ(0, Moves);
  EXPECT_EQ(0, Destructors);
}
}