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+/*
+ * Copyright (C) 2005 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//
+// Templated list class. Normally we'd use STL, but we don't have that.
+// This class mimics STL's interfaces.
+//
+// Objects are copied into the list with the '=' operator or with copy-
+// construction, so if the compiler's auto-generated versions won't work for
+// you, define your own.
+//
+// The only class you want to use from here is "List".
+//
+#ifndef _LIBS_UTILS_LIST_H
+#define _LIBS_UTILS_LIST_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+namespace android {
+
+/*
+ * Doubly-linked list. Instantiate with "List<MyClass> myList".
+ *
+ * Objects added to the list are copied using the assignment operator,
+ * so this must be defined.
+ */
+template<typename T>
+class List
+{
+protected:
+ /*
+ * One element in the list.
+ */
+ class _Node {
+ public:
+ explicit _Node(const T& val) : mVal(val) {}
+ ~_Node() {}
+ inline T& getRef() { return mVal; }
+ inline const T& getRef() const { return mVal; }
+ inline _Node* getPrev() const { return mpPrev; }
+ inline _Node* getNext() const { return mpNext; }
+ inline void setVal(const T& val) { mVal = val; }
+ inline void setPrev(_Node* ptr) { mpPrev = ptr; }
+ inline void setNext(_Node* ptr) { mpNext = ptr; }
+ private:
+ friend class List;
+ friend class _ListIterator;
+ T mVal;
+ _Node* mpPrev;
+ _Node* mpNext;
+ };
+
+ /*
+ * Iterator for walking through the list.
+ */
+
+ template <typename TYPE>
+ struct CONST_ITERATOR {
+ typedef _Node const * NodePtr;
+ typedef const TYPE Type;
+ };
+
+ template <typename TYPE>
+ struct NON_CONST_ITERATOR {
+ typedef _Node* NodePtr;
+ typedef TYPE Type;
+ };
+
+ template<
+ typename U,
+ template <class> class Constness
+ >
+ class _ListIterator {
+ typedef _ListIterator<U, Constness> _Iter;
+ typedef typename Constness<U>::NodePtr _NodePtr;
+ typedef typename Constness<U>::Type _Type;
+
+ explicit _ListIterator(_NodePtr ptr) : mpNode(ptr) {}
+
+ public:
+ _ListIterator() {}
+ _ListIterator(const _Iter& rhs) : mpNode(rhs.mpNode) {}
+ ~_ListIterator() {}
+
+ // this will handle conversions from iterator to const_iterator
+ // (and also all convertible iterators)
+ // Here, in this implementation, the iterators can be converted
+ // if the nodes can be converted
+ template<typename V> explicit
+ _ListIterator(const V& rhs) : mpNode(rhs.mpNode) {}
+
+
+ /*
+ * Dereference operator. Used to get at the juicy insides.
+ */
+ _Type& operator*() const { return mpNode->getRef(); }
+ _Type* operator->() const { return &(mpNode->getRef()); }
+
+ /*
+ * Iterator comparison.
+ */
+ inline bool operator==(const _Iter& right) const {
+ return mpNode == right.mpNode; }
+
+ inline bool operator!=(const _Iter& right) const {
+ return mpNode != right.mpNode; }
+
+ /*
+ * handle comparisons between iterator and const_iterator
+ */
+ template<typename OTHER>
+ inline bool operator==(const OTHER& right) const {
+ return mpNode == right.mpNode; }
+
+ template<typename OTHER>
+ inline bool operator!=(const OTHER& right) const {
+ return mpNode != right.mpNode; }
+
+ /*
+ * Incr/decr, used to move through the list.
+ */
+ inline _Iter& operator++() { // pre-increment
+ mpNode = mpNode->getNext();
+ return *this;
+ }
+ const _Iter operator++(int) { // post-increment
+ _Iter tmp(*this);
+ mpNode = mpNode->getNext();
+ return tmp;
+ }
+ inline _Iter& operator--() { // pre-increment
+ mpNode = mpNode->getPrev();
+ return *this;
+ }
+ const _Iter operator--(int) { // post-increment
+ _Iter tmp(*this);
+ mpNode = mpNode->getPrev();
+ return tmp;
+ }
+
+ inline _NodePtr getNode() const { return mpNode; }
+
+ _NodePtr mpNode; /* should be private, but older gcc fails */
+ private:
+ friend class List;
+ };
+
+public:
+ List() {
+ prep();
+ }
+ List(const List<T>& src) { // copy-constructor
+ prep();
+ insert(begin(), src.begin(), src.end());
+ }
+ virtual ~List() {
+ clear();
+ delete[] (unsigned char*) mpMiddle;
+ }
+
+ typedef _ListIterator<T, NON_CONST_ITERATOR> iterator;
+ typedef _ListIterator<T, CONST_ITERATOR> const_iterator;
+
+ List<T>& operator=(const List<T>& right);
+
+ /* returns true if the list is empty */
+ inline bool empty() const { return mpMiddle->getNext() == mpMiddle; }
+
+ /* return #of elements in list */
+ size_t size() const {
+ return size_t(distance(begin(), end()));
+ }
+
+ /*
+ * Return the first element or one past the last element. The
+ * _Node* we're returning is converted to an "iterator" by a
+ * constructor in _ListIterator.
+ */
+ inline iterator begin() {
+ return iterator(mpMiddle->getNext());
+ }
+ inline const_iterator begin() const {
+ return const_iterator(const_cast<_Node const*>(mpMiddle->getNext()));
+ }
+ inline iterator end() {
+ return iterator(mpMiddle);
+ }
+ inline const_iterator end() const {
+ return const_iterator(const_cast<_Node const*>(mpMiddle));
+ }
+
+ /* add the object to the head or tail of the list */
+ void push_front(const T& val) { insert(begin(), val); }
+ void push_back(const T& val) { insert(end(), val); }
+
+ /* insert before the current node; returns iterator at new node */
+ iterator insert(iterator posn, const T& val)
+ {
+ _Node* newNode = new _Node(val); // alloc & copy-construct
+ newNode->setNext(posn.getNode());
+ newNode->setPrev(posn.getNode()->getPrev());
+ posn.getNode()->getPrev()->setNext(newNode);
+ posn.getNode()->setPrev(newNode);
+ return iterator(newNode);
+ }
+
+ /* insert a range of elements before the current node */
+ void insert(iterator posn, const_iterator first, const_iterator last) {
+ for ( ; first != last; ++first)
+ insert(posn, *first);
+ }
+
+ /* remove one entry; returns iterator at next node */
+ iterator erase(iterator posn) {
+ _Node* pNext = posn.getNode()->getNext();
+ _Node* pPrev = posn.getNode()->getPrev();
+ pPrev->setNext(pNext);
+ pNext->setPrev(pPrev);
+ delete posn.getNode();
+ return iterator(pNext);
+ }
+
+ /* remove a range of elements */
+ iterator erase(iterator first, iterator last) {
+ while (first != last)
+ erase(first++); // don't erase than incr later!
+ return iterator(last);
+ }
+
+ /* remove all contents of the list */
+ void clear() {
+ _Node* pCurrent = mpMiddle->getNext();
+ _Node* pNext;
+
+ while (pCurrent != mpMiddle) {
+ pNext = pCurrent->getNext();
+ delete pCurrent;
+ pCurrent = pNext;
+ }
+ mpMiddle->setPrev(mpMiddle);
+ mpMiddle->setNext(mpMiddle);
+ }
+
+ /*
+ * Measure the distance between two iterators. On exist, "first"
+ * will be equal to "last". The iterators must refer to the same
+ * list.
+ *
+ * FIXME: This is actually a generic iterator function. It should be a
+ * template function at the top-level with specializations for things like
+ * vector<>, which can just do pointer math). Here we limit it to
+ * _ListIterator of the same type but different constness.
+ */
+ template<
+ typename U,
+ template <class> class CL,
+ template <class> class CR
+ >
+ ptrdiff_t distance(
+ _ListIterator<U, CL> first, _ListIterator<U, CR> last) const
+ {
+ ptrdiff_t count = 0;
+ while (first != last) {
+ ++first;
+ ++count;
+ }
+ return count;
+ }
+
+private:
+ /*
+ * I want a _Node but don't need it to hold valid data. More
+ * to the point, I don't want T's constructor to fire, since it
+ * might have side-effects or require arguments. So, we do this
+ * slightly uncouth storage alloc.
+ */
+ void prep() {
+ mpMiddle = (_Node*) new unsigned char[sizeof(_Node)];
+ mpMiddle->setPrev(mpMiddle);
+ mpMiddle->setNext(mpMiddle);
+ }
+
+ /*
+ * This node plays the role of "pointer to head" and "pointer to tail".
+ * It sits in the middle of a circular list of nodes. The iterator
+ * runs around the circle until it encounters this one.
+ */
+ _Node* mpMiddle;
+};
+
+/*
+ * Assignment operator.
+ *
+ * The simplest way to do this would be to clear out the target list and
+ * fill it with the source. However, we can speed things along by
+ * re-using existing elements.
+ */
+template<class T>
+List<T>& List<T>::operator=(const List<T>& right)
+{
+ if (this == &right)
+ return *this; // self-assignment
+ iterator firstDst = begin();
+ iterator lastDst = end();
+ const_iterator firstSrc = right.begin();
+ const_iterator lastSrc = right.end();
+ while (firstSrc != lastSrc && firstDst != lastDst)
+ *firstDst++ = *firstSrc++;
+ if (firstSrc == lastSrc) // ran out of elements in source?
+ erase(firstDst, lastDst); // yes, erase any extras
+ else
+ insert(lastDst, firstSrc, lastSrc); // copy remaining over
+ return *this;
+}
+
+}; // namespace android
+
+#endif // _LIBS_UTILS_LIST_H
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