Add constexpr_vector class

lib/fizzy/CMakeLists.txt

@@ -8,6 +8,7 @@ add_library(fizzy::fizzy ALIAS fizzy)
 target_sources(
     fizzy PRIVATE
     bytes.hpp
+    constexpr_vector.hpp
     execute.cpp
     execute.hpp
     instructions.cpp

lib/fizzy/constexpr_vector.hpp

@@ -0,0 +1,35 @@
+// Fizzy: A fast WebAssembly interpreter
+// Copyright 2019-2020 The Fizzy Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include <utility>
+
+namespace fizzy
+{
+/// Constexpr vector is used to represent compile time constant value lists.
+/// It allows to have a collection (constexpr array) of such lists, where list lengths vary across
+/// the collection, but each length is still known at compile time (and doesn't exceed Capacity
+/// limit).
+template <typename T, std::size_t Capacity>
+class constexpr_vector
+{
+private:
+    const T m_array[Capacity];
+    const std::size_t m_size;
+
+public:
+    template <typename... U>
+    constexpr constexpr_vector(U&&... u) noexcept
+      : m_array{std::forward<U>(u)...}, m_size(sizeof...(U))
+    {}
+
+    constexpr const T* data() const noexcept { return m_array; }
+    constexpr std::size_t size() const noexcept { return m_size; }
+
+    constexpr const T* begin() const noexcept { return m_array; }
+    constexpr const T* end() const noexcept { return m_array + m_size; }
+};
+
+}  // namespace fizzy

test/unittests/CMakeLists.txt

@@ -10,6 +10,7 @@ target_link_libraries(fizzy-unittests PRIVATE fizzy::fizzy fizzy::test-utils GTe
 target_sources(
     fizzy-unittests PRIVATE
     api_test.cpp
+    constexpr_vector_test.cpp
     end_to_end_test.cpp
     execute_call_test.cpp
     execute_control_test.cpp

test/unittests/constexpr_vector_test.cpp

@@ -0,0 +1,61 @@
+// Fizzy: A fast WebAssembly interpreter
+// Copyright 2019-2020 The Fizzy Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+#include "constexpr_vector.hpp"
+#include "span.hpp"
+#include <gmock/gmock.h>
+#include <vector>
+
+using namespace fizzy;
+using namespace testing;
+
+static_assert(constexpr_vector<int, 5>{1, 2, 3}.size() == 3);
+static_assert(*constexpr_vector<int, 5>{1, 2, 3}.data() == 1);
+
+TEST(constexpr_vector, size)
+{
+    constexpr constexpr_vector<int, 5> v1 = {};
+    EXPECT_EQ(v1.size(), 0);
+
+    constexpr constexpr_vector<int, 5> v2 = {1, 2, 3};
+    EXPECT_EQ(v2.size(), 3);
+    EXPECT_EQ(*v2.data(), 1);
+
+    constexpr constexpr_vector<int, 5> v3 = {1, 2, 3, 4, 5};
+    EXPECT_EQ(v3.size(), 5);
+    EXPECT_EQ(*v3.data(), 1);
+}
+
+TEST(constexpr_vector, iterator)
+{
+    constexpr constexpr_vector<int, 5> v = {1, 2, 3};
+    int expected = 1;
+    for (const auto i : v)
+    {
+        EXPECT_EQ(i, expected);
+        ++expected;
+    }
+    EXPECT_EQ(expected, 4);
+}
+
+TEST(constexpr_vector, span)
+{
+    constexpr constexpr_vector<int, 5> v = {1, 2, 3};
+    int expected = 1;
+    for (const auto i : span<const int>(v))
+    {
+        EXPECT_EQ(i, expected);
+        ++expected;
+    }
+    EXPECT_EQ(expected, 4);
+}
+
+TEST(constexpr_vector, array)
+{
+    constexpr constexpr_vector<int, 5> arr[] = {{1, 2, 3}, {4, 5, 6, 7, 8}, {9}, {}};
+    EXPECT_THAT(std::vector<int>(arr[0].begin(), arr[0].end()), ElementsAre(1, 2, 3));
+    EXPECT_THAT(std::vector<int>(arr[1].begin(), arr[1].end()), ElementsAre(4, 5, 6, 7, 8));
+    EXPECT_THAT(std::vector<int>(arr[2].begin(), arr[2].end()), ElementsAre(9));
+    EXPECT_THAT(std::vector<int>(arr[3].begin(), arr[3].end()), IsEmpty());
+}