upload android base code part3

android/art/runtime/base/transform_array_ref.h

@@ -0,0 +1,196 @@
+/*
+ * Copyright (C) 2016 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 ART_RUNTIME_BASE_TRANSFORM_ARRAY_REF_H_
+#define ART_RUNTIME_BASE_TRANSFORM_ARRAY_REF_H_
+
+#include <type_traits>
+
+#include "base/array_ref.h"
+#include "base/transform_iterator.h"
+
+namespace art {
+
+/**
+ * @brief An ArrayRef<> wrapper that uses a transformation function for element access.
+ */
+template <typename BaseType, typename Function>
+class TransformArrayRef {
+ private:
+  using Iter = TransformIterator<typename ArrayRef<BaseType>::iterator, Function>;
+
+  // The Function may take a non-const reference, so const_iterator may not exist.
+  using FallbackConstIter = std::iterator<std::random_access_iterator_tag, void, void, void, void>;
+  using PreferredConstIter =
+      TransformIterator<typename ArrayRef<BaseType>::const_iterator, Function>;
+  template <typename F, typename = typename std::result_of<F(const BaseType&)>::type>
+  static PreferredConstIter ConstIterHelper(int&);
+  template <typename F>
+  static FallbackConstIter ConstIterHelper(const int&);
+
+  using ConstIter = decltype(ConstIterHelper<Function>(*reinterpret_cast<int*>(0)));
+
+ public:
+  using value_type = typename Iter::value_type;
+  using reference = typename Iter::reference;
+  using const_reference = typename ConstIter::reference;
+  using pointer = typename Iter::pointer;
+  using const_pointer = typename ConstIter::pointer;
+  using iterator = Iter;
+  using const_iterator = typename std::conditional<
+      std::is_same<ConstIter, FallbackConstIter>::value,
+      void,
+      ConstIter>::type;
+  using reverse_iterator = std::reverse_iterator<Iter>;
+  using const_reverse_iterator = typename std::conditional<
+      std::is_same<ConstIter, FallbackConstIter>::value,
+      void,
+      std::reverse_iterator<ConstIter>>::type;
+  using difference_type = typename ArrayRef<BaseType>::difference_type;
+  using size_type = typename ArrayRef<BaseType>::size_type;
+
+  // Constructors.
+
+  TransformArrayRef(const TransformArrayRef& other) = default;
+
+  template <typename OtherBT>
+  TransformArrayRef(const ArrayRef<OtherBT>& base, Function fn)
+      : data_(base, fn) { }
+
+  template <typename OtherBT,
+            typename = typename std::enable_if<std::is_same<BaseType, const OtherBT>::value>::type>
+  TransformArrayRef(const TransformArrayRef<OtherBT, Function>& other)  // NOLINT, implicit
+      : TransformArrayRef(other.base(), other.GetFunction()) { }
+
+  // Assignment operators.
+
+  TransformArrayRef& operator=(const TransformArrayRef& other) = default;
+
+  template <typename OtherBT,
+            typename = typename std::enable_if<std::is_same<BaseType, const OtherBT>::value>::type>
+  TransformArrayRef& operator=(const TransformArrayRef<OtherBT, Function>& other) {
+    return *this = TransformArrayRef(other.base(), other.GetFunction());
+  }
+
+  // Destructor.
+  ~TransformArrayRef() = default;
+
+  // Iterators.
+  iterator begin() { return MakeIterator(base().begin()); }
+  const_iterator begin() const { return MakeIterator(base().cbegin()); }
+  const_iterator cbegin() const { return MakeIterator(base().cbegin()); }
+  iterator end() { return MakeIterator(base().end()); }
+  const_iterator end() const { MakeIterator(base().cend()); }
+  const_iterator cend() const { return MakeIterator(base().cend()); }
+  reverse_iterator rbegin() { return reverse_iterator(end()); }
+  const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
+  const_reverse_iterator crbegin() const { return const_reverse_iterator(cend()); }
+  reverse_iterator rend() { return reverse_iterator(begin()); }
+  const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
+  const_reverse_iterator crend() const { return const_reverse_iterator(cbegin()); }
+
+  // Size.
+  size_type size() const { return base().size(); }
+  bool empty() const { return base().empty(); }
+
+  // Element access. NOTE: Not providing data().
+
+  reference operator[](size_type n) { return GetFunction()(base()[n]); }
+  const_reference operator[](size_type n) const { return GetFunction()(base()[n]); }
+
+  reference front() { return GetFunction()(base().front()); }
+  const_reference front() const { return GetFunction()(base().front()); }
+
+  reference back() { return GetFunction()(base().back()); }
+  const_reference back() const { return GetFunction()(base().back()); }
+
+  TransformArrayRef SubArray(size_type pos) {
+    return TransformArrayRef(base().subarray(pos), GetFunction());
+  }
+  TransformArrayRef SubArray(size_type pos) const {
+    return TransformArrayRef(base().subarray(pos), GetFunction());
+  }
+  TransformArrayRef SubArray(size_type pos, size_type length) const {
+    return TransformArrayRef(base().subarray(pos, length), GetFunction());
+  }
+
+  // Retrieve the base ArrayRef<>.
+  ArrayRef<BaseType> base() {
+    return data_.base_;
+  }
+  ArrayRef<const BaseType> base() const {
+    return ArrayRef<const BaseType>(data_.base_);
+  }
+
+ private:
+  // Allow EBO for state-less Function.
+  struct Data : Function {
+   public:
+    Data(ArrayRef<BaseType> base, Function fn) : Function(fn), base_(base) { }
+
+    ArrayRef<BaseType> base_;
+  };
+
+  const Function& GetFunction() const {
+    return static_cast<const Function&>(data_);
+  }
+
+  template <typename BaseIterator>
+  auto MakeIterator(BaseIterator base) const {
+    return MakeTransformIterator(base, GetFunction());
+  }
+
+  Data data_;
+
+  template <typename OtherBT, typename OtherFunction>
+  friend class TransformArrayRef;
+};
+
+template <typename BaseType, typename Function>
+bool operator==(const TransformArrayRef<BaseType, Function>& lhs,
+                const TransformArrayRef<BaseType, Function>& rhs) {
+  return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin());
+}
+
+template <typename BaseType, typename Function>
+bool operator!=(const TransformArrayRef<BaseType, Function>& lhs,
+                const TransformArrayRef<BaseType, Function>& rhs) {
+  return !(lhs == rhs);
+}
+
+template <typename ValueType, typename Function>
+TransformArrayRef<ValueType, Function> MakeTransformArrayRef(
+    ArrayRef<ValueType> container, Function f) {
+  return TransformArrayRef<ValueType, Function>(container, f);
+}
+
+template <typename Container, typename Function>
+TransformArrayRef<typename Container::value_type, Function> MakeTransformArrayRef(
+    Container& container, Function f) {
+  return TransformArrayRef<typename Container::value_type, Function>(
+      ArrayRef<typename Container::value_type>(container.data(), container.size()), f);
+}
+
+template <typename Container, typename Function>
+TransformArrayRef<const typename Container::value_type, Function> MakeTransformArrayRef(
+    const Container& container, Function f) {
+  return TransformArrayRef<const typename Container::value_type, Function>(
+      ArrayRef<const typename Container::value_type>(container.data(), container.size()), f);
+}
+
+}  // namespace art
+
+#endif  // ART_RUNTIME_BASE_TRANSFORM_ARRAY_REF_H_