00001 /* 00002 * Copyright (c) 2000, 2020, Oracle and/or its affiliates. 00003 * 00004 * Licensed under the Universal Permissive License v 1.0 as shown at 00005 * http://oss.oracle.com/licenses/upl. 00006 */ 00007 #ifndef COH_LIST_ITERATOR_HPP 00008 #define COH_LIST_ITERATOR_HPP 00009 00010 #include "coherence/lang.ns" 00011 00012 #include "coherence/util/Iterator.hpp" 00013 00014 COH_OPEN_NAMESPACE2(coherence,util) 00015 00016 00017 /** 00018 * An iterator for lists that allows the programmer to traverse the list in 00019 * either direction, modify the list during iteration, and obtain the 00020 * iterator's current position in the list. A ListIterator has no current 00021 * element; its cursor position always lies between the element that would be 00022 * returned by a call to previous() and the element that would be returned 00023 * by a call to next(). In a list of length n, there are n+1 valid index 00024 * values, from 0 to n, inclusive. 00025 * 00026 * @author nsa 2008.01.28 00027 */ 00028 class COH_EXPORT ListIterator 00029 : public interface_spec<ListIterator, 00030 implements<Iterator> > 00031 { 00032 // ----- ListIterator interface ----------------------------------------- 00033 00034 public: 00035 /** 00036 * Return the index of the next element to be returned from a call to 00037 * next(). 00038 * 00039 * @return the index of the next element, or the list size if the 00040 * iterator has reached the end of the list 00041 */ 00042 virtual size32_t nextIndex() const = 0; 00043 00044 /** 00045 * Return the index of the element to be returned from a call to 00046 * previous(). 00047 * 00048 * @return the index of the element that would be returned from a call 00049 * to previous, or List::npos if the iterator is at the start 00050 * of the list. 00051 */ 00052 virtual size32_t previousIndex() const = 0; 00053 00054 /** 00055 * Returns true if this list iterator has more elements when 00056 * traversing the list in the reverse direction. 00057 * 00058 * @return true if this list iterator has more elements when 00059 * traversing the list in the reverse direction 00060 */ 00061 virtual bool hasPrevious() const = 0; 00062 00063 /** 00064 * Returns the previous element in the list. 00065 * 00066 * @return the previous element in the list 00067 */ 00068 virtual Object::Holder previous() = 0; 00069 }; 00070 00071 COH_CLOSE_NAMESPACE2 00072 00073 #endif // COH_LIST_ITERATOR_HPP