LinkedStack.h

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 * in the documentation and/or other materials provided with the
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#ifndef LinkedStack_h
#define LinkedStack_h

#include "wtf/Allocator.h"
#include "wtf/PtrUtil.h"
#include <memory>

namespace WTF {

template <typename T>
class LinkedStack {
  USING_FAST_MALLOC(LinkedStack);

 public:
  LinkedStack() : m_size(0) {}

  // Iterative cleanup to prevent stack overflow problems.
  ~LinkedStack() {
    std::unique_ptr<Node> ptr = m_head.release();
    while (ptr)
      ptr = ptr->m_next.release();
  }

  bool isEmpty();

  void push(const T&);
  const T& peek();
  void pop();

  size_t size();

 private:
  class Node {
    USING_FAST_MALLOC(LinkedStack::Node);

   public:
    Node(const T&, std::unique_ptr<Node> next);

    T m_data;
    std::unique_ptr<Node> m_next;
  };

  std::unique_ptr<Node> m_head;
  size_t m_size;
};

template <typename T>
LinkedStack<T>::Node::Node(const T& data, std::unique_ptr<Node> next)
    : m_data(data), m_next(next) {}

template <typename T>
inline bool LinkedStack<T>::isEmpty() {
  return !m_head;
}

template <typename T>
inline void LinkedStack<T>::push(const T& data) {
  m_head = WTF::wrapUnique(new Node(data, m_head.release()));
  ++m_size;
}

template <typename T>
inline const T& LinkedStack<T>::peek() {
  return m_head->m_data;
}

template <typename T>
inline void LinkedStack<T>::pop() {
  DCHECK(m_head);
  DCHECK(m_size);
  m_head = m_head->m_next.release();
  --m_size;
}

template <typename T>
inline size_t LinkedStack<T>::size() {
  return m_size;
}

}  // namespace WTF

using WTF::LinkedStack;

#endif