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