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Commit 70e45912 authored by Dominik Laskowski's avatar Dominik Laskowski
Browse files

FTL: Fix SmallMap<K, V, 0>::try_emplace 

SmallVector<T, N>::emplace_back returns a reference, whereas
SmallVector<T, 0>::emplace_back returns an iterator (because
its API must be compatible with StaticVector).

Bug: 185536303
Test: ftl_test
Change-Id: I6bdcd983c0bb2d2a326f79906997f85e89d7df44
parent 1b685dd3

include/ftl/small_map.h

+18 −4
Original line number Diff line number Diff line
@@ -107,12 +107,20 @@ class SmallMap final { 
  template <typename Q, typename W, std::size_t M, typename E>

  SmallMap(SmallMap<Q, W, M, E> other) : map_(std::move(other.map_)) {}



  static constexpr size_type static_capacity() { return N; }



  size_type max_size() const { return map_.max_size(); }

  size_type size() const { return map_.size(); }

  bool empty() const { return map_.empty(); }



  // Returns whether the map is backed by static or dynamic storage.

  bool dynamic() const { return map_.dynamic(); }

  bool dynamic() const {

    if constexpr (static_capacity() > 0) {

      return map_.dynamic();

    } else {

      return true;

    }

  }



  iterator begin() { return map_.begin(); }

  const_iterator begin() const { return cbegin(); }
@@ -171,9 +179,15 @@ class SmallMap final { 
      return {it, false};

    }



    auto& ref = map_.emplace_back(std::piecewise_construct, std::forward_as_tuple(key),

    decltype(auto) ref_or_it =

        map_.emplace_back(std::piecewise_construct, std::forward_as_tuple(key),

                          std::forward_as_tuple(std::forward<Args>(args)...));

    return {&ref, true};



    if constexpr (static_capacity() > 0) {

      return {&ref_or_it, true};

    } else {

      return {ref_or_it, true};

    }

  }



  // Replaces a mapping if it exists, and returns an iterator to it. Returns the end() iterator

libs/ftl/small_map_test.cpp

+42 −13
Original line number Diff line number Diff line
@@ -189,9 +189,20 @@ TEST(SmallMap, Get) { 
  }

}



TEST(SmallMap, TryEmplace) {

  SmallMap<int, std::string, 3> map;

  using Pair = decltype(map)::value_type;

template <typename Capacity>

struct SmallMapTest : testing::Test {

  static constexpr std::size_t kCapacity = Capacity{}();

};



template <std::size_t N>

using Capacity = std::integral_constant<std::size_t, N>;



using Capacities = testing::Types<Capacity<3>, Capacity<0>>;

TYPED_TEST_SUITE(SmallMapTest, Capacities, );



TYPED_TEST(SmallMapTest, TryEmplace) {

  SmallMap<int, std::string, TestFixture::kCapacity> map;

  using Pair = typename decltype(map)::value_type;



  {

    const auto [it, ok] = map.try_emplace(123, "abc");
@@ -207,14 +218,22 @@ TEST(SmallMap, TryEmplace) { 
    const auto [it, ok] = map.try_emplace(-1);

    ASSERT_TRUE(ok);

    EXPECT_EQ(*it, Pair(-1, std::string()));

    if constexpr (map.static_capacity() > 0) {

      EXPECT_FALSE(map.dynamic());

    } else {

      EXPECT_TRUE(map.dynamic());

    }

  }

  {

    // Insertion fails if mapping exists.

    const auto [it, ok] = map.try_emplace(42, "!!!");

    EXPECT_FALSE(ok);

    EXPECT_EQ(*it, Pair(42, "???"));

    if constexpr (map.static_capacity() > 0) {

      EXPECT_FALSE(map.dynamic());

    } else {

      EXPECT_TRUE(map.dynamic());

    }

  }

  {

    // Insertion at capacity promotes the map.
@@ -240,9 +259,9 @@ struct String { 


}  // namespace



TEST(SmallMap, TryReplace) {

  SmallMap<int, String, 3> map = ftl::init::map(1, "a")(2, "B");

  using Pair = decltype(map)::value_type;

TYPED_TEST(SmallMapTest, TryReplace) {

  SmallMap<int, String, TestFixture::kCapacity> map = ftl::init::map(1, "a")(2, "B");

  using Pair = typename decltype(map)::value_type;



  {

    // Replacing fails unless mapping exists.
@@ -260,7 +279,12 @@ TEST(SmallMap, TryReplace) { 
    EXPECT_EQ(*it, Pair(2, "b"));

  }



  if constexpr (map.static_capacity() > 0) {

    EXPECT_FALSE(map.dynamic());

  } else {

    EXPECT_TRUE(map.dynamic());

  }



  EXPECT_TRUE(map.try_emplace(3, "abc").second);

  EXPECT_TRUE(map.try_emplace(4, "d").second);

  EXPECT_TRUE(map.dynamic());
@@ -284,9 +308,9 @@ TEST(SmallMap, TryReplace) { 
  EXPECT_EQ(map, SmallMap(ftl::init::map(4, "d"s)(3, "c"s)(2, "b"s)(1, "a"s)));

}



TEST(SmallMap, EmplaceOrReplace) {

  SmallMap<int, String, 3> map = ftl::init::map(1, "a")(2, "B");

  using Pair = decltype(map)::value_type;

TYPED_TEST(SmallMapTest, EmplaceOrReplace) {

  SmallMap<int, String, TestFixture::kCapacity> map = ftl::init::map(1, "a")(2, "B");

  using Pair = typename decltype(map)::value_type;



  {

    // New mapping is emplaced.
@@ -305,7 +329,12 @@ TEST(SmallMap, EmplaceOrReplace) { 
    EXPECT_EQ(*it, Pair(2, "b"));

  }



  if constexpr (map.static_capacity() > 0) {

    EXPECT_FALSE(map.dynamic());

  } else {

    EXPECT_TRUE(map.dynamic());

  }



  EXPECT_FALSE(map.emplace_or_replace(3, "abc").second);  // Replace.

  EXPECT_TRUE(map.emplace_or_replace(4, "d").second);     // Emplace.

  EXPECT_TRUE(map.dynamic());