Migrate the IndexedDB backend from Blink to Chromium

content/browser/indexed_db/list_set.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_BROWSER_INDEXED_DB_LIST_SET_H_
+#define CONTENT_BROWSER_INDEXED_DB_LIST_SET_H_
+
+#include <algorithm>
+#include <iterator>
+#include <list>
+#include <set>
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+
+//
+// A container class that provides fast containment test (like a set)
+// but maintains insertion order for iteration (like list).
+//
+// Member types of value (primitives and objects by value), raw pointers
+// and scoped_refptr<> are supported.
+//
+template <typename T> class list_set {
+ public:
+  list_set() {}
+  list_set(const list_set<T>& other) : list_(other.list_), set_(other.set_) {}
+  list_set& operator=(const list_set<T>& other) {
+    list_ = other.list_;
+    set_ = other.set_;
+    return *this;
+  }
+
+  void insert(const T& elem) {
+    if (set_.find(elem) != set_.end())
+      return;
+    set_.insert(elem);
+    list_.push_back(elem);
+  }
+
+  void erase(const T& elem) {
+    if (set_.find(elem) == set_.end())
+      return;
+    set_.erase(elem);
+    typename std::list<T>::iterator it =
+        std::find(list_.begin(), list_.end(), elem);
+    DCHECK(it != list_.end());
+    list_.erase(it);
+  }
+
+  bool has(const T& elem) { return set_.find(elem) != set_.end(); }
+
+  size_t size() const {
+    DCHECK_EQ(list_.size(), set_.size());
+    return set_.size();
+  }
+
+  bool empty() const {
+    DCHECK_EQ(list_.empty(), set_.empty());
+    return set_.empty();
+  }
+
+  class const_iterator;
+
+  class iterator {
+   public:
+    typedef iterator self_type;
+    typedef T value_type;
+    typedef T& reference;
+    typedef T* pointer;
+    typedef std::bidirectional_iterator_tag iterator_category;
+    typedef std::ptrdiff_t difference_type;
+
+    inline iterator(typename std::list<T>::iterator it) : it_(it) {}
+    inline self_type& operator++() {
+      ++it_;
+      return *this;
+    }
+    inline self_type operator++(int) {
+      self_type result(*this);
+      ++(*this);
+      return result;
+    }
+    inline self_type& operator--() {
+      --it_;
+      return *this;
+    }
+    inline self_type operator--(int) {
+      self_type result(*this);
+      --(*this);
+      return result;
+    }
+    inline value_type& operator*() { return *it_; }
+    inline value_type* operator->() { return &(*it_); }
+    inline bool operator==(const iterator& rhs) const { return it_ == rhs.it_; }
+    inline bool operator!=(const iterator& rhs) const { return it_ != rhs.it_; }
+
+    inline operator const_iterator() const { return const_iterator(it_); }
+
+   private:
+    typename std::list<T>::iterator it_;
+  };
+
+  class const_iterator {
+   public:
+    typedef const_iterator self_type;
+    typedef T value_type;
+    typedef T& reference;
+    typedef T* pointer;
+    typedef std::bidirectional_iterator_tag iterator_category;
+    typedef std::ptrdiff_t difference_type;
+
+    inline const_iterator(typename std::list<T>::const_iterator it) : it_(it) {}
+    inline self_type& operator++() {
+      ++it_;
+      return *this;
+    }
+    inline self_type operator++(int) {
+      self_type result(*this);
+      ++(*this);
+      return result;
+    }
+    inline self_type& operator--() {
+      --it_;
+      return *this;
+    }
+    inline self_type operator--(int) {
+      self_type result(*this);
+      --(*this);
+      return result;
+    }
+    inline const value_type& operator*() { return *it_; }
+    inline const value_type* operator->() { return &(*it_); }
+    inline bool operator==(const const_iterator& rhs) const {
+      return it_ == rhs.it_;
+    }
+    inline bool operator!=(const const_iterator& rhs) const {
+      return it_ != rhs.it_;
+    }
+
+   private:
+    typename std::list<T>::const_iterator it_;
+  };
+
+  iterator begin() { return iterator(list_.begin()); }
+  iterator end() { return iterator(list_.end()); }
+  const_iterator begin() const { return const_iterator(list_.begin()); }
+  const_iterator end() const { return const_iterator(list_.end()); }
+
+ private:
+  std::list<T> list_;
+  std::set<T> set_;
+};
+
+// Prevent instantiation of list_set<scoped_ptr<T>> as the current
+// implementation would fail.
+// TODO(jsbell): Support scoped_ptr through specialization.
+template <typename T> class list_set<scoped_ptr<T> >;
+
+#endif  // CONTENT_BROWSER_INDEXED_DB_LIST_SET_H_