The Tor Browser: comparison xpcom/glue/nsTObserverArray.h

--1:000000000000
+:21ef098d02e0
+/* -*- 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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comparison: xpcom/glue/nsTObserverArray.h

xpcom/glue/nsTObserverArray.h