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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_NODE_SET_VIEW_H_
#define COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_NODE_SET_VIEW_H_
#include <iterator>
#include <type_traits>
#include <vector>
#include "base/memory/raw_ref.h"
#include "base/notreached.h"
#include "components/performance_manager/public/graph/node.h"
namespace performance_manager {
// A view over a NodeSet. Provides an iterable view where elements are casted to
// the requested type using NodeView::FromNode.
template <class UnderlyingSet, class NodeViewPtr>
class NodeSetView {
public:
using value_type = NodeViewPtr;
using NodeView = std::remove_pointer_t<NodeViewPtr>;
class Iterator {
public:
using value_type = NodeViewPtr;
using difference_type = std::ptrdiff_t;
using pointer = value_type*;
using reference = value_type&;
// Need a default constructor to pass the static_assert below.
Iterator() { NOTREACHED(); }
explicit Iterator(UnderlyingSet::const_iterator iterator)
: iterator_(iterator) {}
value_type operator*() const { return NodeView::FromNode(*iterator_); }
Iterator& operator++() {
++iterator_;
return *this;
}
Iterator operator++(int) {
Iterator old(*this);
++iterator_;
return old;
}
bool operator==(const Iterator& other) const {
return iterator_ == other.iterator_;
}
private:
UnderlyingSet::const_iterator iterator_;
};
// Make sure the implementation conforms to a standard forward iterator.
static_assert(std::forward_iterator<Iterator>);
explicit NodeSetView(const UnderlyingSet& node_set) : node_set_(node_set) {}
~NodeSetView() = default;
// Standard iterator interface.
Iterator begin() const { return Iterator(node_set_->begin()); }
Iterator end() const { return Iterator(node_set_->end()); }
bool empty() const { return node_set_->empty(); }
size_t size() const { return node_set_->size(); }
// Helper method to generate a vector containing all the elements.
std::vector<NodeViewPtr> AsVector() {
return std::vector<NodeViewPtr>(begin(), end());
}
private:
raw_ref<const UnderlyingSet> node_set_;
};
} // namespace performance_manager
#endif // COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_NODE_SET_VIEW_H_
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