AK: Add Array<T, Size> template.

AK/Array.h

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Iterator.h>
+#include <AK/Span.h>
+
+namespace AK {
+
+template<typename T, size_t Size>
+struct Array {
+    constexpr const T* data() const { return __data; }
+    constexpr T* data() { return __data; }
+
+    constexpr size_t size() const { return Size; }
+
+    constexpr Span<const T> span() const { return { __data, Size }; }
+    constexpr Span<T> span() { return { __data, Size }; }
+
+    constexpr const T& at(size_t index) const
+    {
+        ASSERT(index < size());
+        return (*this)[index];
+    }
+    constexpr T& at(size_t index)
+    {
+        ASSERT(index < size());
+        return (*this)[index];
+    }
+
+    constexpr const T& front() const { return at(0); }
+    constexpr T& front() { return at(0); }
+
+    constexpr const T& back() const { return at(max(1, size()) - 1); }
+    constexpr T& back() { return at(max(1, size()) - 1); }
+
+    constexpr bool is_empty() const { return size() == 0; }
+
+    constexpr const T& operator[](size_t index) const { return __data[index]; }
+    constexpr T& operator[](size_t index) { return __data[index]; }
+
+    using ConstIterator = SimpleIterator<const Array, const T>;
+    using Iterator = SimpleIterator<Array, T>;
+
+    constexpr ConstIterator begin() const { return ConstIterator::begin(*this); }
+    constexpr Iterator begin() { return Iterator::begin(*this); }
+
+    constexpr ConstIterator end() const { return ConstIterator::end(*this); }
+    constexpr Iterator end() { return Iterator::end(*this); }
+
+    constexpr operator Span<const T>() const { return span(); }
+    constexpr operator Span<T>() { return span(); }
+
+    T __data[Size];
+};
+
+}
+
+using AK::Array;

AK/Forward.h

@@ -61,7 +61,7 @@ class CircularDuplexStream;
 template<typename T>
 class Span;
 
-template<typename T>
+template<typename T, size_t Size>
 class Array;
 
 template<typename Container, typename ValueType>

AK/Tests/TestArray.cpp

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/TestSuite.h>
+
+#include <AK/Array.h>
+
+// FIXME: Use Span<const int> as soon as Span has all the constexpr stuff too.
+template<size_t Size>
+static constexpr int constexpr_sum(const Array<int, Size>& array)
+{
+    int sum = 0;
+    for (auto value : array)
+        sum += value;
+
+    return sum;
+}
+
+TEST_CASE(compile_time_contructible)
+{
+    constexpr Array<int, 4> array = { 0, 1, 2, 3 };
+    static_assert(array.size() == 4);
+}
+
+TEST_CASE(compile_time_iterable)
+{
+    constexpr Array<int, 8> array = { 0, 1, 2, 3, 4, 5, 6, 7 };
+    static_assert(constexpr_sum(array) == 28);
+}
+
+TEST_MAIN(Array)