ucx: src/cx/iterator.h@6ce8cfa10a96

     1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

     3  *

     4  * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.

     5  *

     6  * Redistribution and use in source and binary forms, with or without

     7  * modification, are permitted provided that the following conditions are met:

     8  *

     9  *   1. Redistributions of source code must retain the above copyright

    10  *      notice, this list of conditions and the following disclaimer.

    11  *

    12  *   2. Redistributions in binary form must reproduce the above copyright

    13  *      notice, this list of conditions and the following disclaimer in the

    14  *      documentation and/or other materials provided with the distribution.

    15  *

    16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    26  * POSSIBILITY OF SUCH DAMAGE.

    27  */

    28 /**

    29  * \file iterator.h

    30  * \brief Interface for iterator implementations.

    31  * \author Mike Becker

    32  * \author Olaf Wintermann

    33  * \version 3.0

    34  * \copyright 2-Clause BSD License

    35  */

    37 #ifndef UCX_ITERATOR_H

    38 #define UCX_ITERATOR_H

    40 #include "common.h"

    42 /**

    43  * Iterator value type.

    44  * An iterator points to a certain element in an (possibly unbounded) chain of elements.

    45  * Iterators that are based on collections (which have a defined "first" element), are supposed

    46  * to be "position-aware", which means that they keep track of the current index within the collection.

    47  *

    48  * @note Objects that are pointed to by an iterator are mutable through that iterator. However, if the

    49  * iterator is based on a collection and the underlying collection is mutated (elements added or removed),

    50  * the iterator becomes invalid (regardless of what cxIteratorValid() returns) and MUST be re-obtained

    51  * from the collection.

    52  */

    53 typedef struct cx_iterator_s CxIterator;

    55 /**

    56  * Internal iterator struct - use CxIterator.

    57  */

    58 struct cx_iterator_s {

    59     /**

    60      * If the iterator is position-aware, contains the index of the element in the underlying collection.

    61      * Otherwise, this field is usually uninitialized.

    62      */

    63     size_t index;

    64     /**

    65      * Internal data.

    66      */

    67     void *data;

    69     /**

    70      * True iff the iterator points to valid data.

    71      */

    72     bool (*valid)(CxIterator const *) __attribute__ ((__nonnull__));

    74     /**

    75      * Returns a pointer to the current element.

    76      */

    77     void *(*current)(CxIterator const *) __attribute__ ((__nonnull__));

    79     /**

    80      * Advances the iterator.

    81      */

    82     void (*next)(CxIterator *) __attribute__ ((__nonnull__));

    83 };

    85 /**

    86  * Checks if the iterator points to valid data.

    87  *

    88  * This is especially false for past-the-end iterators.

    89  *

    90  * @param iter the iterator

    91  * @return true iff the iterator points to valid data

    92  */

    93 __attribute__ ((__nonnull__))

    94 static inline bool cxIteratorValid(CxIterator const *iter) {

    95     return iter->valid(iter);

    96 }

    98 /**

    99  * Returns a pointer to the current element.

   100  *

   101  * The behavior is undefined if this iterator is invalid.

   102  *

   103  * @param iter the iterator

   104  * @return a pointer to the current element

   105  */

   106 __attribute__ ((__nonnull__))

   107 static inline void *cxIteratorCurrent(CxIterator const *iter) {

   108     return iter->current(iter);

   109 }

   111 /**

   112  * Advances the iterator to the next element.

   113  *

   114  * @param iter the iterator

   115  */

   116 __attribute__ ((__nonnull__))

   117 static inline void cxIteratorNext(CxIterator *iter) {

   118     iter->next(iter);

   119 }

   121 #endif /* UCX_ITERATOR_H */

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