The Tor Browser: xpcom/glue/nsTObserverArray.h@6474c204b198 (annotated)

xpcom/glue/nsTObserverArray.h@6474c204b198 (annotated)

xpcom/glue/nsTObserverArray.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef nsTObserverArray_h___
 #define nsTObserverArray_h___
 #include "mozilla/MemoryReporting.h"
 #include "nsTArray.h"
 #include "nsCycleCollectionNoteChild.h"
 /**
  * An array of observers. Like a normal array, but supports iterators that are
  * stable even if the array is modified during iteration.
  * The template parameter T is the observer type the array will hold;
  * N is the number of built-in storage slots that come with the array.
  * NOTE: You probably want to use nsTObserverArray, unless you specifically
  * want built-in storage. See below.
  * @see nsTObserverArray, nsTArray
  */
 class NS_COM_GLUE nsTObserverArray_base {
   public:
     typedef uint32_t index_type;
     typedef uint32_t size_type;
     typedef int32_t  diff_type;
   protected:
     class Iterator_base {
       protected:
         friend class nsTObserverArray_base;
         Iterator_base(index_type aPosition, Iterator_base* aNext)
           : mPosition(aPosition),
             mNext(aNext) {
         }
         // The current position of the iterator. Its exact meaning differs
         // depending on iterator. See nsTObserverArray<T>::ForwardIterator.
         index_type mPosition;
         // The next iterator currently iterating the same array
         Iterator_base* mNext;
     };
     nsTObserverArray_base()
       : mIterators(nullptr) {
     }
     ~nsTObserverArray_base() {
       NS_ASSERTION(mIterators == nullptr, "iterators outlasting array");
     }
     /**
      * Adjusts iterators after an element has been inserted or removed
      * from the array.
      * @param modPos     Position where elements were added or removed.
      * @param adjustment -1 if an element was removed, 1 if an element was
      *                   added.
      */
     void AdjustIterators(index_type aModPos, diff_type aAdjustment);
     /**
      * Clears iterators when the array is destroyed.
      */
     void ClearIterators();
     mutable Iterator_base* mIterators;
 };
 template<class T, uint32_t N>
 class nsAutoTObserverArray : protected nsTObserverArray_base {
   public:
     typedef T           elem_type;
     typedef nsTArray<T> array_type;
     nsAutoTObserverArray() {
     }
     //
     // Accessor methods
     //
     // @return The number of elements in the array.
     size_type Length() const {
       return mArray.Length();
     }
     // @return True if the array is empty or false otherwise.
     bool IsEmpty() const {
       return mArray.IsEmpty();
     }
     // This method provides direct access to the i'th element of the array.
     // The given index must be within the array bounds. If the underlying array
     // may change during iteration, use an iterator instead of this function.
     // @param i  The index of an element in the array.
     // @return   A reference to the i'th element of the array.
     elem_type& ElementAt(index_type i) {
       return mArray.ElementAt(i);
     }
     // Same as above, but readonly.
     const elem_type& ElementAt(index_type i) const {
       return mArray.ElementAt(i);
     }
     // This method provides direct access to the i'th element of the array in
     // a bounds safe manner. If the requested index is out of bounds the
     // provided default value is returned.
     // @param i  The index of an element in the array.
     // @param def The value to return if the index is out of bounds.
     elem_type& SafeElementAt(index_type i, elem_type& def) {
       return mArray.SafeElementAt(i, def);
     }
     // Same as above, but readonly.
     const elem_type& SafeElementAt(index_type i, const elem_type& def) const {
       return mArray.SafeElementAt(i, def);
     }
     // No operator[] is provided because the point of this class is to support
     // allow modifying the array during iteration, and ElementAt() is not safe
     // in those conditions.
     //
     // Search methods
     //
     // This method searches, starting from the beginning of the array,
     // for the first element in this array that is equal to the given element.
     // 'operator==' must be defined for elem_type.
     // @param item   The item to search for.
     // @return       true if the element was found.
     template<class Item>
     bool Contains(const Item& item) const {
       return IndexOf(item) != array_type::NoIndex;
     }
     // This method searches for the offset of the first element in this
     // array that is equal to the given element.
     // 'operator==' must be defined for elem_type.
     // @param item   The item to search for.
     // @param start  The index to start from.
     // @return       The index of the found element or NoIndex if not found.
     template<class Item>
     index_type IndexOf(const Item& item, index_type start = 0) const {
       return mArray.IndexOf(item, start);
     }
     //
     // Mutation methods
     //
     // Insert a given element at the given index.
     // @param index  The index at which to insert item.
     // @param item   The item to insert,
     // @return       A pointer to the newly inserted element, or a null on DOM
     template<class Item>
     elem_type *InsertElementAt(index_type aIndex, const Item& aItem) {
       elem_type* item = mArray.InsertElementAt(aIndex, aItem);
       AdjustIterators(aIndex, 1);
       return item;
     }
     // Same as above but without copy constructing.
     // This is useful to avoid temporaries.
     elem_type* InsertElementAt(index_type aIndex) {
       elem_type* item = mArray.InsertElementAt(aIndex);
       AdjustIterators(aIndex, 1);
       return item;
     }
     // Prepend an element to the array unless it already exists in the array.
     // 'operator==' must be defined for elem_type.
     // @param item   The item to prepend.
     // @return       true if the element was found, or inserted successfully.
     template<class Item>
     bool PrependElementUnlessExists(const Item& item) {
       if (Contains(item)) {
         return true;
       }
       bool inserted = mArray.InsertElementAt(0, item) != nullptr;
       AdjustIterators(0, 1);
       return inserted;
     }
     // Append an element to the array.
     // @param item   The item to append.
     // @return A pointer to the newly appended element, or null on OOM.
     template<class Item>
     elem_type* AppendElement(const Item& item) {
       return mArray.AppendElement(item);
     }
     // Same as above, but without copy-constructing. This is useful to avoid
     // temporaries.
     elem_type* AppendElement() {
       return mArray.AppendElement();
     }
     // Append an element to the array unless it already exists in the array.
     // 'operator==' must be defined for elem_type.
     // @param item   The item to append.
     // @return       true if the element was found, or inserted successfully.
     template<class Item>
     bool AppendElementUnlessExists(const Item& item) {
       return Contains(item) || AppendElement(item) != nullptr;
     }
     // Remove an element from the array.
     // @param index  The index of the item to remove.
     void RemoveElementAt(index_type index) {
       NS_ASSERTION(index < mArray.Length(), "invalid index");
       mArray.RemoveElementAt(index);
       AdjustIterators(index, -1);
     }
     // This helper function combines IndexOf with RemoveElementAt to "search
     // and destroy" the first element that is equal to the given element.
     // 'operator==' must be defined for elem_type.
     // @param item  The item to search for.
     // @return true if the element was found and removed.
     template<class Item>
     bool RemoveElement(const Item& item) {
       index_type index = mArray.IndexOf(item, 0);
       if (index == array_type::NoIndex)
         return false;
       mArray.RemoveElementAt(index);
       AdjustIterators(index, -1);
       return true;
     }
     // Removes all observers and collapses all iterators to the beginning of
     // the array. The result is that forward iterators will see all elements
     // in the array.
     void Clear() {
       mArray.Clear();
       ClearIterators();
     }
     // Returns the number of bytes on the heap taken up by this object, not
     // including sizeof(*this).
     size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
       return mArray.SizeOfExcludingThis(mallocSizeOf);
     }
     //
     // Iterators
     //
     // Base class for iterators. Do not use this directly.
     class Iterator : public Iterator_base {
       protected:
         friend class nsAutoTObserverArray;
         typedef nsAutoTObserverArray<T, N> array_type;
         Iterator(index_type aPosition, const array_type& aArray)
           : Iterator_base(aPosition, aArray.mIterators),
             mArray(const_cast<array_type&>(aArray)) {
           aArray.mIterators = this;
         }
         ~Iterator() {
           NS_ASSERTION(mArray.mIterators == this,
                        "Iterators must currently be destroyed in opposite order "
                        "from the construction order. It is suggested that you "
                        "simply put them on the stack");
           mArray.mIterators = mNext;
         }
         // The array we're iterating
         array_type& mArray;
     };
     // Iterates the array forward from beginning to end. mPosition points
     // to the element that will be returned on next call to GetNext.
     // Elements:
     // - prepended to the array during iteration *will not* be traversed
     // - appended during iteration *will* be traversed
     // - removed during iteration *will not* be traversed.
     // @see EndLimitedIterator
     class ForwardIterator : protected Iterator {
       public:
         typedef nsAutoTObserverArray<T, N> array_type;
         typedef Iterator                   base_type;
         ForwardIterator(const array_type& aArray)
           : Iterator(0, aArray) {
         }
         ForwardIterator(const array_type& aArray, index_type aPos)
           : Iterator(aPos, aArray) {
         }
         bool operator <(const ForwardIterator& aOther) const {
           NS_ASSERTION(&this->mArray == &aOther.mArray,
                        "not iterating the same array");
           return base_type::mPosition < aOther.mPosition;
         }
         // Returns true if there are more elements to iterate.
         // This must precede a call to GetNext(). If false is
         // returned, GetNext() must not be called.
         bool HasMore() const {
           return base_type::mPosition < base_type::mArray.Length();
         }
         // Returns the next element and steps one step. This must
         // be preceded by a call to HasMore().
         // @return The next observer.
         elem_type& GetNext() {
           NS_ASSERTION(HasMore(), "iterating beyond end of array");
           return base_type::mArray.ElementAt(base_type::mPosition++);
         }
     };
     // EndLimitedIterator works like ForwardIterator, but will not iterate new
     // observers appended to the array after the iterator was created.
     class EndLimitedIterator : protected ForwardIterator {
       public:
         typedef nsAutoTObserverArray<T, N> array_type;
         typedef Iterator                   base_type;
         EndLimitedIterator(const array_type& aArray)
           : ForwardIterator(aArray),
             mEnd(aArray, aArray.Length()) {
         }
         // Returns true if there are more elements to iterate.
         // This must precede a call to GetNext(). If false is
         // returned, GetNext() must not be called.
         bool HasMore() const {
           return *this < mEnd;
         }
         // Returns the next element and steps one step. This must
         // be preceded by a call to HasMore().
         // @return The next observer.
         elem_type& GetNext() {
           NS_ASSERTION(HasMore(), "iterating beyond end of array");
           return base_type::mArray.ElementAt(base_type::mPosition++);
         }
       private:
         ForwardIterator mEnd;
     };
   protected:
     nsAutoTArray<T, N> mArray;
 };
 template<class T>
 class nsTObserverArray : public nsAutoTObserverArray<T, 0> {
   public:
     typedef nsAutoTObserverArray<T, 0>       base_type;
     typedef nsTObserverArray_base::size_type size_type;
     //
     // Initialization methods
     //
     nsTObserverArray() {}
     // Initialize this array and pre-allocate some number of elements.
     explicit nsTObserverArray(size_type capacity) {
       base_type::mArray.SetCapacity(capacity);
     }
 };
 template <typename T, uint32_t N>
 inline void
 ImplCycleCollectionUnlink(nsAutoTObserverArray<T, N>& aField)
 {
   aField.Clear();
 }
 template <typename T, uint32_t N>
 inline void
 ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
                             nsAutoTObserverArray<T, N>& aField,
                             const char* aName,
                             uint32_t aFlags = 0)
 {
   aFlags |= CycleCollectionEdgeNameArrayFlag;
   uint32_t length = aField.Length();
   for (uint32_t i = 0; i < length; ++i) {
     ImplCycleCollectionTraverse(aCallback, aField.ElementAt(i), aName, aFlags);
   }
 }
 // XXXbz I wish I didn't have to pass in the observer type, but I
 // don't see a way to get it out of array_.
 // Note that this macro only works if the array holds pointers to XPCOM objects.
 #define NS_OBSERVER_ARRAY_NOTIFY_XPCOM_OBSERVERS(array_, obstype_, func_, params_) \
   PR_BEGIN_MACRO                                                             \
     nsTObserverArray<obstype_ *>::ForwardIterator iter_(array_);             \
     nsRefPtr<obstype_> obs_;                                                 \
     while (iter_.HasMore()) {                                                 \
       obs_ = iter_.GetNext();                                                \
       obs_ -> func_ params_ ;                                                \
     }                                                                        \
   PR_END_MACRO
 // Note that this macro only works if the array holds pointers to XPCOM objects.
 #define NS_OBSERVER_ARRAY_NOTIFY_OBSERVERS(array_, obstype_, func_, params_) \
   PR_BEGIN_MACRO                                                             \
     nsTObserverArray<obstype_ *>::ForwardIterator iter_(array_);             \
     obstype_* obs_;                                                          \
     while (iter_.HasMore()) {                                                \
       obs_ = iter_.GetNext();                                                \
       obs_ -> func_ params_ ;                                                \
     }                                                                        \
   PR_END_MACRO
 #endif // nsTObserverArray_h___

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xpcom/glue/nsTObserverArray.h@6474c204b198 (annotated)

xpcom/glue/nsTObserverArray.h