FTL: Add SmallVector<T, N>
SmallVector is a StaticVector that promotes to std::vector when full.
It will serve as a base for SmallMap.
Bug: 160012986
Test: ftl_test
Change-Id: Id223a6fc169d792746220d2dde1f9f1a0e87a0cc
diff --git a/libs/ftl/Android.bp b/libs/ftl/Android.bp
index e11be57..fb32382 100644
--- a/libs/ftl/Android.bp
+++ b/libs/ftl/Android.bp
@@ -5,6 +5,7 @@
address: true,
},
srcs: [
+ "SmallVector_test.cpp",
"StaticVector_test.cpp",
],
cflags: [
diff --git a/libs/ftl/SmallVector_test.cpp b/libs/ftl/SmallVector_test.cpp
new file mode 100644
index 0000000..c41e622
--- /dev/null
+++ b/libs/ftl/SmallVector_test.cpp
@@ -0,0 +1,455 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <ftl/SmallVector.h>
+#include <gtest/gtest.h>
+
+#include <algorithm>
+#include <iterator>
+#include <string>
+#include <utility>
+
+using namespace std::string_literals;
+
+namespace android::test {
+
+using ftl::SmallVector;
+
+// Keep in sync with example usage in header file.
+TEST(SmallVector, Example) {
+ ftl::SmallVector<char, 3> vector;
+ EXPECT_TRUE(vector.empty());
+ EXPECT_FALSE(vector.dynamic());
+
+ vector = {'a', 'b', 'c'};
+ EXPECT_EQ(vector.size(), 3u);
+ EXPECT_FALSE(vector.dynamic());
+
+ vector.push_back('d');
+ EXPECT_TRUE(vector.dynamic());
+
+ vector.unstable_erase(vector.begin());
+ EXPECT_EQ(vector, (ftl::SmallVector{'d', 'b', 'c'}));
+
+ vector.pop_back();
+ EXPECT_EQ(vector.back(), 'b');
+ EXPECT_TRUE(vector.dynamic());
+
+ const char array[] = "hi";
+ vector = ftl::SmallVector(array);
+ EXPECT_EQ(vector, (ftl::SmallVector{'h', 'i', '\0'}));
+ EXPECT_FALSE(vector.dynamic());
+}
+
+TEST(SmallVector, Construct) {
+ {
+ // Default constructor.
+ SmallVector<std::string, 2> vector;
+
+ EXPECT_TRUE(vector.empty());
+ EXPECT_FALSE(vector.dynamic());
+ }
+ {
+ // Array constructor.
+ const float kFloats[] = {.1f, .2f, .3f};
+ SmallVector vector(kFloats);
+
+ EXPECT_EQ(vector, (SmallVector{.1f, .2f, .3f}));
+ EXPECT_FALSE(vector.dynamic());
+ }
+ {
+ // Iterator constructor.
+ const char chars[] = "abcdef";
+ std::string string(chars);
+ SmallVector<char, sizeof(chars)> vector(string.begin(), string.end());
+
+ EXPECT_STREQ(vector.begin(), chars);
+ EXPECT_FALSE(vector.dynamic());
+ }
+ {
+ // Variadic constructor with same types.
+ SmallVector vector = {1, 2, 3};
+
+ static_assert(std::is_same_v<decltype(vector), SmallVector<int, 3>>);
+ EXPECT_EQ(vector, (SmallVector{1, 2, 3}));
+ EXPECT_FALSE(vector.dynamic());
+ }
+ {
+ // Variadic constructor with different types.
+ const auto copy = "quince"s;
+ auto move = "tart"s;
+ SmallVector vector = {copy, std::move(move)};
+
+ static_assert(std::is_same_v<decltype(vector), SmallVector<std::string, 2>>);
+ EXPECT_EQ(vector, (SmallVector{"quince"s, "tart"s}));
+ EXPECT_FALSE(vector.dynamic());
+ }
+ {
+ // In-place constructor with same types.
+ SmallVector vector(std::in_place_type<std::string>, "red", "velvet", "cake");
+
+ static_assert(std::is_same_v<decltype(vector), SmallVector<std::string, 3>>);
+ EXPECT_EQ(vector, (SmallVector{"red"s, "velvet"s, "cake"s}));
+ EXPECT_FALSE(vector.dynamic());
+ }
+ {
+ // In-place constructor with different types.
+ const auto copy = "red"s;
+ auto move = "velvet"s;
+ std::initializer_list<char> list = {'c', 'a', 'k', 'e'};
+ SmallVector vector(std::in_place_type<std::string>, copy.c_str(), std::move(move), list);
+
+ static_assert(std::is_same_v<decltype(vector), SmallVector<std::string, 3>>);
+ EXPECT_EQ(vector, (SmallVector{"red"s, "velvet"s, "cake"s}));
+ EXPECT_FALSE(vector.dynamic());
+ }
+ {
+ // Conversion from StaticVector.
+ ftl::StaticVector doubles = {.1, .2, .3};
+ SmallVector vector = std::move(doubles);
+ EXPECT_TRUE(doubles.empty());
+
+ static_assert(std::is_same_v<decltype(vector), SmallVector<double, 3>>);
+ EXPECT_EQ(vector, (SmallVector{.1, .2, .3}));
+ EXPECT_FALSE(vector.dynamic());
+ }
+}
+
+TEST(SmallVector, String) {
+ SmallVector<char, 10> chars;
+ char c = 'a';
+ std::generate_n(std::back_inserter(chars), chars.max_size(), [&c] { return c++; });
+ chars.push_back('\0');
+
+ EXPECT_TRUE(chars.dynamic());
+ EXPECT_EQ(chars.size(), 11u);
+ EXPECT_STREQ(chars.begin(), "abcdefghij");
+
+ // Constructor takes iterator range.
+ const char kString[] = "123456";
+ SmallVector<char, 10> string(std::begin(kString), std::end(kString));
+
+ EXPECT_FALSE(string.dynamic());
+ EXPECT_STREQ(string.begin(), "123456");
+ EXPECT_EQ(string.size(), 7u);
+
+ // Similar to emplace, but replaces rather than inserts.
+ string.replace(string.begin() + 5, '\0');
+ EXPECT_STREQ(string.begin(), "12345");
+
+ swap(chars, string);
+
+ EXPECT_STREQ(chars.begin(), "12345");
+ EXPECT_STREQ(string.begin(), "abcdefghij");
+
+ EXPECT_FALSE(chars.dynamic());
+ EXPECT_TRUE(string.dynamic());
+}
+
+TEST(SmallVector, CopyableElement) {
+ struct Pair {
+ // Needed because std::vector emplace does not use uniform initialization.
+ Pair(int a, int b) : a(a), b(b) {}
+
+ const int a, b;
+ bool operator==(Pair p) const { return p.a == a && p.b == b; }
+ };
+
+ SmallVector<Pair, 5> pairs;
+
+ EXPECT_TRUE(pairs.empty());
+ EXPECT_EQ(pairs.max_size(), 5u);
+
+ for (size_t i = 0; i < pairs.max_size(); ++i) {
+ EXPECT_EQ(pairs.size(), i);
+
+ const int a = static_cast<int>(i) * 2;
+ EXPECT_EQ(pairs.emplace_back(a, a + 1), Pair(a, a + 1));
+ }
+
+ EXPECT_EQ(pairs.size(), 5u);
+ EXPECT_FALSE(pairs.dynamic());
+
+ // The vector is promoted when full.
+ EXPECT_EQ(pairs.emplace_back(10, 11), Pair(10, 11));
+ EXPECT_TRUE(pairs.dynamic());
+
+ EXPECT_EQ(pairs,
+ (SmallVector{Pair{0, 1}, Pair{2, 3}, Pair{4, 5}, Pair{6, 7}, Pair{8, 9},
+ Pair{10, 11}}));
+
+ // Constructor takes at most N elements.
+ SmallVector<int, 6> sums = {0, 0, 0, 0, 0, 0};
+ EXPECT_FALSE(sums.dynamic());
+
+ // Random-access iterators comply with standard.
+ std::transform(pairs.begin(), pairs.end(), sums.begin(), [](Pair p) { return p.a + p.b; });
+ EXPECT_EQ(sums, (SmallVector{1, 5, 9, 13, 17, 21}));
+
+ sums.pop_back();
+ std::reverse(sums.begin(), sums.end());
+
+ EXPECT_EQ(sums, (SmallVector{17, 13, 9, 5, 1}));
+}
+
+TEST(SmallVector, MovableElement) {
+ // Construct std::string elements in-place from C-style strings. Without std::in_place_type, the
+ // element type would be deduced from the first element, i.e. const char*.
+ SmallVector strings(std::in_place_type<std::string>, "", "", "", "cake", "velvet", "red", "");
+ strings.pop_back();
+
+ EXPECT_EQ(strings.max_size(), 7u);
+ EXPECT_EQ(strings.size(), 6u);
+
+ // Erase "cake" and append a substring copy.
+ {
+ const auto it = std::find_if(strings.begin(), strings.end(),
+ [](const auto& s) { return !s.empty(); });
+ ASSERT_FALSE(it == strings.end());
+ EXPECT_EQ(*it, "cake");
+
+ strings.unstable_erase(it);
+ EXPECT_EQ(strings.emplace_back("cakewalk", 4u), "cake"s);
+ }
+
+ strings[1] = "quince"s;
+
+ // Replace last empty string with "tart".
+ {
+ const auto rit = std::find(strings.rbegin(), strings.rend(), std::string());
+ ASSERT_FALSE(rit == strings.rend());
+
+ std::initializer_list<char> list = {'t', 'a', 'r', 't'};
+ strings.replace(rit.base() - 1, list);
+ }
+
+ strings.front().assign("pie");
+
+ EXPECT_EQ(strings, (SmallVector{"pie"s, "quince"s, "tart"s, "red"s, "velvet"s, "cake"s}));
+
+ strings.push_back("nougat");
+ strings.push_back("oreo");
+ EXPECT_TRUE(strings.dynamic());
+
+ std::rotate(strings.begin(), strings.end() - 2, strings.end());
+
+ EXPECT_EQ(strings,
+ (SmallVector{"nougat"s, "oreo"s, "pie"s, "quince"s, "tart"s, "red"s, "velvet"s,
+ "cake"s}));
+}
+
+TEST(SmallVector, Replace) {
+ // Replacing does not require a copy/move assignment operator.
+ struct Word {
+ explicit Word(std::string str) : str(std::move(str)) {}
+ const std::string str;
+
+ bool operator==(const Word& other) const { return other.str == str; }
+ };
+
+ SmallVector words(std::in_place_type<Word>, "colored", "velour");
+
+ // The replaced element can be referenced by the replacement.
+ {
+ const Word& word = words.replace(words.last(), words.back().str.substr(0, 3) + "vet");
+ EXPECT_EQ(word, Word("velvet"));
+ }
+
+ // The vector is not promoted if replacing while full.
+ EXPECT_FALSE(words.dynamic());
+
+ words.emplace_back("cake");
+ EXPECT_TRUE(words.dynamic());
+
+ {
+ const Word& word = words.replace(words.begin(), words.front().str.substr(4));
+ EXPECT_EQ(word, Word("red"));
+ }
+
+ EXPECT_EQ(words, (SmallVector{Word("red"), Word("velvet"), Word("cake")}));
+}
+
+TEST(SmallVector, ReverseAppend) {
+ SmallVector strings = {"red"s, "velvet"s, "cake"s};
+ EXPECT_FALSE(strings.dynamic());
+
+ auto rit = strings.rbegin();
+ while (rit != strings.rend()) {
+ // Iterator and reference are invalidated on insertion.
+ const auto i = std::distance(strings.begin(), rit.base());
+ std::string s = *rit;
+
+ strings.push_back(std::move(s));
+ rit = std::make_reverse_iterator(strings.begin() + i) + 1;
+ }
+
+ EXPECT_EQ(strings, (SmallVector{"red"s, "velvet"s, "cake"s, "cake"s, "velvet"s, "red"s}));
+ EXPECT_TRUE(strings.dynamic());
+}
+
+TEST(SmallVector, Sort) {
+ SmallVector strings(std::in_place_type<std::string>, "pie", "quince", "tart", "red", "velvet");
+ strings.push_back("cake"s);
+
+ auto sorted = std::move(strings);
+ EXPECT_TRUE(strings.empty());
+
+ EXPECT_TRUE(sorted.dynamic());
+ EXPECT_TRUE(strings.dynamic());
+
+ std::sort(sorted.begin(), sorted.end());
+ EXPECT_EQ(sorted, (SmallVector{"cake"s, "pie"s, "quince"s, "red"s, "tart"s, "velvet"s}));
+
+ // Constructor takes array reference.
+ {
+ const char* kStrings[] = {"cake", "lie"};
+ strings = SmallVector(kStrings);
+ EXPECT_FALSE(strings.dynamic());
+ }
+
+ EXPECT_GT(sorted, strings);
+ swap(sorted, strings);
+ EXPECT_LT(sorted, strings);
+
+ EXPECT_FALSE(sorted.dynamic());
+ EXPECT_TRUE(strings.dynamic());
+
+ // Append remaining elements, such that "pie" is the only difference.
+ for (const char* str : {"quince", "red", "tart", "velvet"}) {
+ sorted.emplace_back(str);
+ }
+ EXPECT_TRUE(sorted.dynamic());
+
+ EXPECT_NE(sorted, strings);
+
+ // Replace second element with "pie".
+ const auto it = sorted.begin() + 1;
+ EXPECT_EQ(sorted.replace(it, 'p' + it->substr(1)), "pie");
+
+ EXPECT_EQ(sorted, strings);
+}
+
+namespace {
+
+struct DestroyCounts {
+ DestroyCounts(int& live, int& dead) : counts{live, dead} {}
+ DestroyCounts(const DestroyCounts& other) : counts(other.counts) {}
+ DestroyCounts(DestroyCounts&& other) : counts(other.counts) { other.alive = false; }
+ ~DestroyCounts() { ++(alive ? counts.live : counts.dead); }
+
+ struct {
+ int& live;
+ int& dead;
+ } counts;
+
+ bool alive = true;
+};
+
+void swap(DestroyCounts& lhs, DestroyCounts& rhs) {
+ std::swap(lhs.alive, rhs.alive);
+}
+
+} // namespace
+
+TEST(SmallVector, Destroy) {
+ int live = 0;
+ int dead = 0;
+
+ { SmallVector<DestroyCounts, 3> counts; }
+ EXPECT_EQ(0, live);
+ EXPECT_EQ(0, dead);
+
+ {
+ SmallVector<DestroyCounts, 3> counts;
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+
+ EXPECT_FALSE(counts.dynamic());
+ }
+ EXPECT_EQ(3, live);
+ EXPECT_EQ(0, dead);
+
+ live = 0;
+ {
+ SmallVector<DestroyCounts, 3> counts;
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+
+ EXPECT_TRUE(counts.dynamic());
+ }
+ EXPECT_EQ(4, live);
+ EXPECT_EQ(3, dead);
+
+ live = dead = 0;
+ {
+ SmallVector<DestroyCounts, 2> counts;
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+
+ auto copy = counts;
+ EXPECT_TRUE(copy.dynamic());
+ }
+ EXPECT_EQ(6, live);
+ EXPECT_EQ(2, dead);
+
+ live = dead = 0;
+ {
+ SmallVector<DestroyCounts, 2> counts;
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+
+ auto move = std::move(counts);
+ EXPECT_TRUE(move.dynamic());
+ }
+ EXPECT_EQ(3, live);
+ EXPECT_EQ(2, dead);
+
+ live = dead = 0;
+ {
+ SmallVector<DestroyCounts, 2> counts1;
+ counts1.emplace_back(live, dead);
+ counts1.emplace_back(live, dead);
+ counts1.emplace_back(live, dead);
+
+ EXPECT_TRUE(counts1.dynamic());
+ EXPECT_EQ(2, dead);
+ dead = 0;
+
+ SmallVector<DestroyCounts, 2> counts2;
+ counts2.emplace_back(live, dead);
+
+ EXPECT_FALSE(counts2.dynamic());
+
+ swap(counts1, counts2);
+
+ EXPECT_FALSE(counts1.dynamic());
+ EXPECT_TRUE(counts2.dynamic());
+
+ EXPECT_EQ(0, live);
+ EXPECT_EQ(1, dead);
+
+ dead = 0;
+ }
+ EXPECT_EQ(4, live);
+ EXPECT_EQ(0, dead);
+}
+
+} // namespace android::test