universe@494: /*
universe@494:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
universe@494:  *
universe@494:  * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
universe@494:  *
universe@494:  * Redistribution and use in source and binary forms, with or without
universe@494:  * modification, are permitted provided that the following conditions are met:
universe@494:  *
universe@494:  *   1. Redistributions of source code must retain the above copyright
universe@494:  *      notice, this list of conditions and the following disclaimer.
universe@494:  *
universe@494:  *   2. Redistributions in binary form must reproduce the above copyright
universe@494:  *      notice, this list of conditions and the following disclaimer in the
universe@494:  *      documentation and/or other materials provided with the distribution.
universe@494:  *
universe@494:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
universe@494:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
universe@494:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
universe@494:  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
universe@494:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
universe@494:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
universe@494:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
universe@494:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
universe@494:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
universe@494:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
universe@494:  * POSSIBILITY OF SUCH DAMAGE.
universe@494:  */
universe@494: /**
universe@494:  * \file iterator.h
universe@494:  * \brief Interface for iterator implementations.
universe@494:  * \author Mike Becker
universe@494:  * \author Olaf Wintermann
universe@494:  * \version 3.0
universe@494:  * \copyright 2-Clause BSD License
universe@494:  */
universe@494: 
universe@494: #ifndef UCX_ITERATOR_H
universe@494: #define UCX_ITERATOR_H
universe@494: 
universe@494: #include "common.h"
universe@494: 
universe@494: /**
universe@494:  * Internal iterator struct - use CxIterator.
universe@494:  */
universe@494: struct cx_iterator_s {
universe@494:     /**
universe@494:      * True iff the iterator points to valid data.
universe@494:      */
universe@500:     bool (*valid)(struct cx_iterator_s const *) __attribute__ ((__nonnull__));
universe@494: 
universe@494:     /**
universe@494:      * Returns a pointer to the current element.
universe@494:      */
universe@500:     void *(*current)(struct cx_iterator_s const *) __attribute__ ((__nonnull__));
universe@494: 
universe@494:     /**
universe@494:      * Advances the iterator.
universe@494:      */
universe@500:     void (*next)(struct cx_iterator_s *) __attribute__ ((__nonnull__));
universe@495: 
universe@495:     /**
universe@495:      * Handle for the current element, if required.
universe@495:      */
universe@495:     void *elem_handle;
universe@495: 
universe@495:     /**
universe@495:      * Handle for the source collection, if any.
universe@495:      */
universe@495:     void *src_handle;
universe@495: 
universe@495:     /**
universe@495:      * If the iterator is position-aware, contains the index of the element in the underlying collection.
universe@495:      * Otherwise, this field is usually uninitialized.
universe@495:      */
universe@495:     size_t index;
universe@495: 
universe@495:     /**
universe@495:      * Users may set this to true, if the current element shall be removed from the underlying collection
universe@495:      * when the iterator advances.
universe@495:      * Has no effect on iterators that are not based on a collection.
universe@495:      */
universe@495:     bool remove;
universe@494: };
universe@494: 
universe@494: /**
universe@500:  * Iterator value type.
universe@500:  * An iterator points to a certain element in an (possibly unbounded) chain of elements.
universe@500:  * Iterators that are based on collections (which have a defined "first" element), are supposed
universe@500:  * to be "position-aware", which means that they keep track of the current index within the collection.
universe@500:  *
universe@500:  * @note Objects that are pointed to by an iterator are mutable through that iterator. However, if the
universe@500:  * iterator is based on a collection and the underlying collection is mutated (elements added or removed),
universe@500:  * the iterator becomes invalid (regardless of what cxIteratorValid() returns) and MUST be re-obtained
universe@500:  * from the collection.
universe@500:  */
universe@500: typedef struct cx_iterator_s CxIterator;
universe@500: 
universe@500: /**
universe@494:  * Checks if the iterator points to valid data.
universe@494:  *
universe@494:  * This is especially false for past-the-end iterators.
universe@494:  *
universe@496:  * @param iter a pointer to the iterator
universe@494:  * @return true iff the iterator points to valid data
universe@494:  */
universe@494: __attribute__ ((__nonnull__))
universe@494: static inline bool cxIteratorValid(CxIterator const *iter) {
universe@494:     return iter->valid(iter);
universe@494: }
universe@494: 
universe@494: /**
universe@494:  * Returns a pointer to the current element.
universe@494:  *
universe@494:  * The behavior is undefined if this iterator is invalid.
universe@494:  *
universe@496:  * @param iter a pointer to the iterator
universe@494:  * @return a pointer to the current element
universe@494:  */
universe@494: __attribute__ ((__nonnull__))
universe@494: static inline void *cxIteratorCurrent(CxIterator const *iter) {
universe@494:     return iter->current(iter);
universe@494: }
universe@494: 
universe@494: /**
universe@494:  * Advances the iterator to the next element.
universe@494:  *
universe@496:  * @param iter a pointer to the iterator
universe@494:  */
universe@494: __attribute__ ((__nonnull__))
universe@494: static inline void cxIteratorNext(CxIterator *iter) {
universe@494:     iter->next(iter);
universe@494: }
universe@494: 
universe@496: /**
universe@496:  * Loops over an iterator.
universe@496:  * @param type the type of the elements
universe@496:  * @param elem the name of the iteration variable
universe@496:  * @param iter the iterator
universe@496:  */
universe@496: #define cx_foreach(type, elem, iter) \
universe@497: for (type elem; cxIteratorValid(&iter) && (elem = cxIteratorCurrent(&iter)) != NULL ; cxIteratorNext(&iter)) // NOLINT(bugprone-macro-parentheses)
universe@496: 
universe@494: #endif /* UCX_ITERATOR_H */