Home | History | Annotate | Download | only in media 
      1 // Copyright 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_RENDERER_MEDIA_TAGGED_LIST_H_
      6 #define CONTENT_RENDERER_MEDIA_TAGGED_LIST_H_
      7 
      8 #include <algorithm>
      9 #include <list>
     10 
     11 #include "base/logging.h"
     12 #include "base/memory/ref_counted.h"
     13 
     14 namespace content {
     15 
     16 // Implements the pattern of a list of items, where added items are
     17 // tagged, you can tag all items, and you can retrieve the list of
     18 // items that are tagged, which removes the tag.
     19 //
     20 // For thread safety, operations on this object should be under an
     21 // external lock. An internally-locked version could be created, but
     22 // is not needed at the moment as users already lock.
     23 template <class ItemType>
     24 class TaggedList {
     25  public:
     26   typedef std::list<scoped_refptr<ItemType> > ItemList;
     27 
     28   TaggedList() {}
     29 
     30   void AddAndTag(ItemType* item) {
     31     items_.push_back(item);
     32     tagged_items_.push_back(item);
     33   }
     34 
     35   void TagAll() {
     36     tagged_items_ = items_;
     37   }
     38 
     39   const ItemList& Items() const {
     40     return items_;
     41   }
     42 
     43   // Retrieves the list of items with tags, and removes their tags.
     44   //
     45   // |dest| should be empty.
     46   void RetrieveAndClearTags(ItemList* dest) {
     47     DCHECK(dest->empty());
     48     dest->swap(tagged_items_);
     49   }
     50 
     51   // Remove an item that matches a predicate. Will return a reference
     52   // to it if it is found.
     53   template <class UnaryPredicate>
     54   scoped_refptr<ItemType> Remove(UnaryPredicate predicate) {
     55     tagged_items_.remove_if(predicate);
     56 
     57     typename ItemList::iterator it = std::find_if(
     58         items_.begin(), items_.end(), predicate);
     59     if (it != items_.end()) {
     60       scoped_refptr<ItemType> removed_item = *it;
     61       items_.erase(it);
     62       return removed_item;
     63     }
     64 
     65     return NULL;
     66   }
     67 
     68   template <class UnaryPredicate>
     69   bool Contains(UnaryPredicate predicate) const {
     70     return std::find_if(items_.begin(), items_.end(), predicate) !=
     71         items_.end();
     72   }
     73 
     74   void Clear() {
     75     items_.clear();
     76     tagged_items_.clear();
     77   }
     78 
     79   bool IsEmpty() const {
     80     bool is_empty = items_.empty();
     81     DCHECK(!is_empty || tagged_items_.empty());
     82     return is_empty;
     83   }
     84 
     85  private:
     86   ItemList items_;
     87   ItemList tagged_items_;
     88 
     89   DISALLOW_COPY_AND_ASSIGN(TaggedList);
     90 };
     91 
     92 }  // namespace content
     93 
     94 #endif  // CONTENT_RENDERER_MEDIA_TAGGED_LIST_H_
     95