add macOS implementation

macos/include/utils/Slice.h

@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef TNT_UTILS_SLICE_H
+#define TNT_UTILS_SLICE_H
+
+#include <utils/compiler.h>
+
+#include <utility>
+
+#include <assert.h>
+#include <stddef.h>
+
+namespace utils {
+
+/*
+ * A fixed-size slice of a container
+ */
+template <typename T>
+class Slice {
+public:
+    using iterator = T*;
+    using const_iterator = T const*;
+    using value_type = T;
+    using reference = T&;
+    using const_reference = T const&;
+    using pointer = T*;
+    using const_pointer = T const*;
+    using size_type = size_t;
+
+    Slice() noexcept = default;
+
+    Slice(const_iterator begin, const_iterator end) noexcept
+            : mBegin(const_cast<iterator>(begin)),
+              mEnd(const_cast<iterator>(end)) {
+    }
+
+    Slice(const_pointer begin, size_type count) noexcept
+            : mBegin(const_cast<iterator>(begin)),
+              mEnd(mBegin + count) {
+    }
+
+    Slice(Slice const& rhs) noexcept = default;
+    Slice(Slice&& rhs) noexcept = default;
+    Slice& operator=(Slice const& rhs) noexcept = default;
+    Slice& operator=(Slice&& rhs) noexcept = default;
+
+    void set(pointer begin, size_type count) UTILS_RESTRICT noexcept {
+        mBegin = begin;
+        mEnd = begin + count;
+    }
+
+    void set(iterator begin, iterator end) UTILS_RESTRICT noexcept {
+        mBegin = begin;
+        mEnd = end;
+    }
+
+    void swap(Slice& rhs) UTILS_RESTRICT noexcept {
+        std::swap(mBegin, rhs.mBegin);
+        std::swap(mEnd, rhs.mEnd);
+    }
+
+    void clear() UTILS_RESTRICT noexcept {
+        mBegin = nullptr;
+        mEnd = nullptr;
+    }
+
+    // size
+    size_t size() const UTILS_RESTRICT noexcept { return mEnd - mBegin; }
+    size_t sizeInBytes() const UTILS_RESTRICT noexcept { return size() * sizeof(T); }
+    bool empty() const UTILS_RESTRICT noexcept { return size() == 0; }
+
+    // iterators
+    iterator begin() UTILS_RESTRICT noexcept { return mBegin; }
+    const_iterator begin() const UTILS_RESTRICT noexcept { return mBegin; }
+    const_iterator cbegin() const UTILS_RESTRICT noexcept { return this->begin(); }
+    iterator end() UTILS_RESTRICT noexcept { return mEnd; }
+    const_iterator end() const UTILS_RESTRICT noexcept { return mEnd; }
+    const_iterator cend() const UTILS_RESTRICT noexcept { return this->end(); }
+
+    // data access
+    reference operator[](size_t n) UTILS_RESTRICT noexcept {
+        assert(n < size());
+        return mBegin[n];
+    }
+
+    const_reference operator[](size_t n) const UTILS_RESTRICT noexcept {
+        assert(n < size());
+        return mBegin[n];
+    }
+
+    reference at(size_t n) UTILS_RESTRICT noexcept {
+        return operator[](n);
+    }
+
+    const_reference at(size_t n) const UTILS_RESTRICT noexcept {
+        return operator[](n);
+    }
+
+    reference front() UTILS_RESTRICT noexcept {
+        assert(!empty());
+        return *mBegin;
+    }
+
+    const_reference front() const UTILS_RESTRICT noexcept {
+        assert(!empty());
+        return *mBegin;
+    }
+
+    reference back() UTILS_RESTRICT noexcept {
+        assert(!empty());
+        return *(this->end() - 1);
+    }
+
+    const_reference back() const UTILS_RESTRICT noexcept {
+        assert(!empty());
+        return *(this->end() - 1);
+    }
+
+    pointer data() UTILS_RESTRICT noexcept {
+        return this->begin();
+    }
+
+    const_pointer data() const UTILS_RESTRICT noexcept {
+        return this->begin();
+    }
+
+protected:
+    iterator mBegin = nullptr;
+    iterator mEnd = nullptr;
+};
+
+} // namespace utils
+
+#endif // TNT_UTILS_SLICE_H