FTL: Add StaticVector<T, N>
FTL is a template library shared by SurfaceFlinger and InputFlinger.
StaticVector is a hybrid of std::array and std::vector, a statically
allocated container with fixed capacity. It will serve as a base for
SmallVector and SmallMap.
Bug: 160012986
Test: ftl_test
Test: Apply ag/12919186 and compare assembly
Change-Id: I821c736f3411e970402faf19d9238b68c056ca93
diff --git a/libs/ftl/Android.bp b/libs/ftl/Android.bp
new file mode 100644
index 0000000..e11be57
--- /dev/null
+++ b/libs/ftl/Android.bp
@@ -0,0 +1,16 @@
+cc_test {
+ name: "ftl_test",
+ test_suites: ["device-tests"],
+ sanitize: {
+ address: true,
+ },
+ srcs: [
+ "StaticVector_test.cpp",
+ ],
+ cflags: [
+ "-Wall",
+ "-Werror",
+ "-Wextra",
+ "-Wpedantic",
+ ],
+}
diff --git a/libs/ftl/StaticVector_test.cpp b/libs/ftl/StaticVector_test.cpp
new file mode 100644
index 0000000..06e4659
--- /dev/null
+++ b/libs/ftl/StaticVector_test.cpp
@@ -0,0 +1,347 @@
+/*
+ * 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/StaticVector.h>
+#include <gtest/gtest.h>
+
+#include <algorithm>
+#include <iterator>
+#include <string>
+#include <utility>
+
+using namespace std::string_literals;
+
+namespace android::test {
+
+using ftl::StaticVector;
+
+// Keep in sync with example usage in header file.
+TEST(StaticVector, Example) {
+ ftl::StaticVector<char, 3> vector;
+ EXPECT_TRUE(vector.empty());
+
+ vector = {'a', 'b'};
+ EXPECT_EQ(vector.size(), 2u);
+
+ vector.push_back('c');
+ EXPECT_TRUE(vector.full());
+
+ EXPECT_FALSE(vector.push_back('d'));
+ EXPECT_EQ(vector.size(), 3u);
+
+ vector.unstable_erase(vector.begin());
+ EXPECT_EQ(vector, (ftl::StaticVector{'c', 'b'}));
+
+ vector.pop_back();
+ EXPECT_EQ(vector.back(), 'c');
+
+ const char array[] = "hi";
+ vector = ftl::StaticVector(array);
+ EXPECT_EQ(vector, (ftl::StaticVector{'h', 'i', '\0'}));
+}
+
+TEST(StaticVector, Construct) {
+ {
+ // Default constructor.
+ StaticVector<std::string, 2> vector;
+ EXPECT_TRUE(vector.empty());
+ }
+ {
+ // Array constructor.
+ const float kFloats[] = {.1f, .2f, .3f};
+ StaticVector vector(kFloats);
+ EXPECT_EQ(vector, (StaticVector{.1f, .2f, .3f}));
+ }
+ {
+ // Iterator constructor.
+ const char chars[] = "abcdef";
+ std::string string(chars);
+ StaticVector<char, sizeof(chars)> vector(string.begin(), string.end());
+
+ EXPECT_STREQ(vector.begin(), chars);
+ }
+ {
+ // Variadic constructor with same types.
+ StaticVector vector = {1, 2, 3};
+
+ static_assert(std::is_same_v<decltype(vector), StaticVector<int, 3>>);
+ EXPECT_EQ(vector, (StaticVector{1, 2, 3}));
+ }
+ {
+ // Variadic constructor with different types.
+ const auto copy = "quince"s;
+ auto move = "tart"s;
+ StaticVector vector = {copy, std::move(move)};
+
+ static_assert(std::is_same_v<decltype(vector), StaticVector<std::string, 2>>);
+ EXPECT_EQ(vector, (StaticVector{"quince"s, "tart"s}));
+ }
+ {
+ // In-place constructor with same types.
+ StaticVector vector(std::in_place_type<std::string>, "red", "velvet", "cake");
+
+ static_assert(std::is_same_v<decltype(vector), StaticVector<std::string, 3>>);
+ EXPECT_EQ(vector, (StaticVector{"red"s, "velvet"s, "cake"s}));
+ }
+ {
+ // In-place constructor with different types.
+ const auto copy = "red"s;
+ auto move = "velvet"s;
+ std::initializer_list<char> list = {'c', 'a', 'k', 'e'};
+ StaticVector vector(std::in_place_type<std::string>, copy.c_str(), std::move(move), list);
+
+ static_assert(std::is_same_v<decltype(vector), StaticVector<std::string, 3>>);
+ EXPECT_EQ(vector, (StaticVector{"red"s, "velvet"s, "cake"s}));
+ }
+}
+
+TEST(StaticVector, String) {
+ StaticVector<char, 10> chars;
+ char c = 'a';
+ std::generate_n(std::back_inserter(chars), chars.max_size(), [&c] { return c++; });
+ chars.back() = '\0';
+
+ EXPECT_STREQ(chars.begin(), "abcdefghi");
+
+ // Constructor takes iterator range.
+ const char kString[] = "123456";
+ StaticVector<char, 10> string(std::begin(kString), std::end(kString));
+
+ EXPECT_STREQ(string.begin(), "123456");
+ EXPECT_EQ(string.size(), 7u);
+
+ // Similar to emplace, but replaces rather than inserts.
+ const auto it = string.replace(string.begin() + 5, '\0');
+ EXPECT_NE(it, string.end());
+ EXPECT_STREQ(string.begin(), "12345");
+
+ swap(chars, string);
+
+ EXPECT_STREQ(chars.begin(), "12345");
+ EXPECT_STREQ(string.begin(), "abcdefghi");
+}
+
+TEST(StaticVector, CopyableElement) {
+ struct Pair {
+ const int a, b;
+ bool operator==(Pair p) const { return p.a == a && p.b == b; }
+ };
+
+ StaticVector<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;
+ const auto it = pairs.emplace_back(a, a + 1);
+ ASSERT_NE(it, pairs.end());
+ EXPECT_EQ(*it, (Pair{a, a + 1}));
+ }
+
+ EXPECT_TRUE(pairs.full());
+ EXPECT_EQ(pairs.size(), 5u);
+
+ // Insertion fails if the vector is full.
+ const auto it = pairs.emplace_back(10, 11);
+ EXPECT_EQ(it, pairs.end());
+
+ EXPECT_EQ(pairs, (StaticVector{Pair{0, 1}, Pair{2, 3}, Pair{4, 5}, Pair{6, 7}, Pair{8, 9}}));
+
+ // Constructor takes at most N elements.
+ StaticVector<int, 6> sums = {0, 0, 0, 0, 0, -1};
+ EXPECT_TRUE(sums.full());
+
+ // Random-access iterators comply with standard.
+ std::transform(pairs.begin(), pairs.end(), sums.begin(), [](Pair p) { return p.a + p.b; });
+ EXPECT_EQ(sums, (StaticVector{1, 5, 9, 13, 17, -1}));
+
+ sums.pop_back();
+ std::reverse(sums.begin(), sums.end());
+
+ EXPECT_EQ(sums, (StaticVector{17, 13, 9, 5, 1}));
+}
+
+TEST(StaticVector, 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*.
+ StaticVector 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.
+ {
+ 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);
+
+ // Construct std::string from first 4 characters of C-style string.
+ it = strings.emplace_back("cakewalk", 4u);
+ ASSERT_NE(it, strings.end());
+ EXPECT_EQ(*it, "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'};
+ const auto it = strings.replace(rit.base() - 1, list);
+ EXPECT_NE(it, strings.end());
+ }
+
+ strings.front().assign("pie");
+
+ EXPECT_EQ(strings, (StaticVector{"pie"s, "quince"s, "tart"s, "red"s, "velvet"s, "cake"s}));
+}
+
+TEST(StaticVector, ReverseTruncate) {
+ StaticVector<std::string, 10> strings("pie", "quince", "tart", "red", "velvet", "cake");
+ EXPECT_FALSE(strings.full());
+
+ for (auto it = strings.begin(); it != strings.end(); ++it) {
+ strings.replace(it, strings.back());
+ strings.pop_back();
+ }
+
+ EXPECT_EQ(strings, (StaticVector{"cake"s, "velvet"s, "red"s}));
+}
+
+TEST(StaticVector, Sort) {
+ StaticVector<std::string, 7> strings("pie", "quince", "tart", "red", "velvet", "cake");
+ EXPECT_FALSE(strings.full());
+
+ auto sorted = std::move(strings);
+ EXPECT_TRUE(strings.empty());
+
+ std::sort(sorted.begin(), sorted.end());
+ EXPECT_EQ(sorted, (StaticVector{"cake"s, "pie"s, "quince"s, "red"s, "tart"s, "velvet"s}));
+
+ // Constructor takes array reference.
+ {
+ const char* kStrings[] = {"cake", "lie"};
+ strings = StaticVector(kStrings);
+ }
+
+ EXPECT_GT(sorted, strings);
+ swap(sorted, strings);
+ EXPECT_LT(sorted, strings);
+
+ // Append remaining elements, such that "pie" is the only difference.
+ sorted.replace(sorted.end(), "quince");
+ for (const char* str : {"red", "tart", "velvet"}) sorted.emplace_back(str);
+
+ EXPECT_NE(sorted, strings);
+
+ sorted.replace(sorted.begin() + 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(StaticVector, Destroy) {
+ int live = 0;
+ int dead = 0;
+
+ { StaticVector<DestroyCounts, 5> counts; }
+ EXPECT_EQ(0, live);
+ EXPECT_EQ(0, dead);
+
+ {
+ StaticVector<DestroyCounts, 5> counts;
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+ }
+ EXPECT_EQ(3, live);
+ EXPECT_EQ(0, dead);
+
+ live = 0;
+ {
+ StaticVector<DestroyCounts, 5> counts;
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+
+ auto copy = counts;
+ }
+ EXPECT_EQ(6, live);
+ EXPECT_EQ(0, dead);
+
+ live = 0;
+ {
+ StaticVector<DestroyCounts, 5> counts;
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+ counts.emplace_back(live, dead);
+
+ auto move = std::move(counts);
+ }
+ EXPECT_EQ(3, live);
+ EXPECT_EQ(3, dead);
+
+ live = dead = 0;
+ {
+ StaticVector<DestroyCounts, 5> counts1;
+ counts1.emplace_back(live, dead);
+ counts1.emplace_back(live, dead);
+ counts1.emplace_back(live, dead);
+
+ StaticVector<DestroyCounts, 5> counts2;
+ counts2.emplace_back(live, dead);
+
+ swap(counts1, counts2);
+
+ EXPECT_EQ(0, live);
+ EXPECT_EQ(2, dead);
+
+ dead = 0;
+ }
+ EXPECT_EQ(4, live);
+ EXPECT_EQ(0, dead);
+}
+
+} // namespace android::test