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:  * \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@854: struct cx_iterator_base_s {
universe@854:     /**
universe@854:      * True iff the iterator points to valid data.
universe@854:      */
universe@854:     __attribute__ ((__nonnull__))
universe@854:     bool (*valid)(void const *);
universe@854: 
universe@854:     /**
universe@854:      * Returns a pointer to the current element.
universe@854:      *
universe@854:      * When valid returns false, the behavior of this function is undefined.
universe@854:      */
universe@854:     __attribute__ ((__nonnull__))
universe@854:     void *(*current)(void const *);
universe@854: 
universe@854:     /**
universe@854:      * Original implementation in case the function needs to be wrapped.
universe@854:      */
universe@854:     __attribute__ ((__nonnull__))
universe@854:     void *(*current_impl)(void const *);
universe@854: 
universe@854:     /**
universe@854:      * Advances the iterator.
universe@854:      *
universe@854:      * When valid returns false, the behavior of this function is undefined.
universe@854:      */
universe@854:     __attribute__ ((__nonnull__))
universe@854:     void (*next)(void *);
universe@854:     /**
universe@854:      * Indicates whether this iterator may remove elements.
universe@854:      */
universe@854:     bool mutating;
universe@854:     /**
universe@854:      * Internal flag for removing the current element when advancing.
universe@854:      */
universe@853:     bool remove;
universe@854: };
universe@854: 
universe@854: /**
universe@854:  * Declares base attributes for an iterator.
universe@858:  * Must be the first member of an iterator structure.
universe@854:  */
universe@854: #define CX_ITERATOR_BASE struct cx_iterator_base_s base
universe@853: 
universe@494: /**
universe@853:  * Internal iterator struct - use CxIterator.
universe@494:  */
universe@853: struct cx_iterator_s {
universe@854:     CX_ITERATOR_BASE;
universe@494: 
universe@494:     /**
universe@853:      * Handle for the current element.
universe@495:      */
universe@495:     void *elem_handle;
universe@495: 
universe@495:     /**
universe@495:      * Handle for the source collection, if any.
universe@495:      */
universe@853:     union {
universe@853:         /**
universe@853:          * Access for mutating iterators.
universe@853:          */
universe@853:         void *m;
universe@853:         /**
universe@853:          * Access for normal iterators.
universe@853:          */
universe@853:         void const *c;
universe@853:     } src_handle;
universe@495: 
universe@495:     /**
universe@551:      * Field for storing a key-value pair.
universe@551:      * May be used by iterators that iterate over k/v-collections.
universe@551:      */
universe@551:     struct {
universe@551:         /**
universe@551:          * A pointer to the key.
universe@551:          */
universe@630:         void const *key;
universe@551:         /**
universe@551:          * A pointer to the value.
universe@551:          */
universe@551:         void *value;
universe@551:     } kv_data;
universe@551: 
universe@551:     /**
universe@551:      * Field for storing a slot number.
universe@551:      * May be used by iterators that iterate over multi-bucket collections.
universe@551:      */
universe@551:     size_t slot;
universe@551: 
universe@551:     /**
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@850: 
universe@850:     /**
universe@850:      * The size of an individual element.
universe@850:      */
universe@850:     size_t elem_size;
universe@850: 
universe@850:     /**
universe@850:      * May contain the total number of elements, if known.
universe@850:      * Shall be set to \c SIZE_MAX when the total number is unknown during iteration.
universe@850:      */
universe@850:     size_t elem_count;
universe@630: };
universe@630: 
universe@630: /**
universe@853:  * Iterator type.
universe@630:  *
olaf@740:  * An iterator points to a certain element in a (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@630:  * @note Objects that are pointed to by an iterator are always mutable through that iterator. However,
universe@853:  * any concurrent mutation of the collection other than by this iterator makes this iterator invalid
universe@853:  * and it must not be used anymore.
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@630:  * @param iter the iterator
universe@494:  * @return true iff the iterator points to valid data
universe@494:  */
universe@854: #define cxIteratorValid(iter) (iter).base.valid(&(iter))
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@630:  * @param iter the iterator
universe@494:  * @return a pointer to the current element
universe@494:  */
universe@854: #define cxIteratorCurrent(iter) (iter).base.current(&iter)
universe@494: 
universe@494: /**
universe@494:  * Advances the iterator to the next element.
universe@494:  *
universe@630:  * @param iter the iterator
universe@494:  */
universe@854: #define cxIteratorNext(iter) (iter).base.next(&iter)
universe@630: 
universe@630: /**
universe@829:  * Flags the current element for removal, if this iterator is mutating.
universe@630:  *
universe@630:  * @param iter the iterator
universe@630:  */
universe@854: #define cxIteratorFlagRemoval(iter) (iter).base.remove |= (iter).base.mutating
universe@494: 
universe@496: /**
universe@858:  * Obtains a reference to an arbitrary iterator.
universe@858:  *
universe@858:  * This is useful for APIs that expect some iterator as an argument.
universe@858:  *
universe@858:  * @param iter the iterator
universe@858:  */
universe@858: #define cxIteratorRef(iter) &((iter).base)
universe@858: 
universe@858: /**
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@630: for (type elem; cxIteratorValid(iter) && (elem = (type)cxIteratorCurrent(iter)) != NULL ; cxIteratorNext(iter))
universe@496: 
universe@850: 
universe@850: /**
universe@852:  * Creates an iterator for the specified plain array.
universe@851:  *
universe@851:  * The \p array can be \c NULL in which case the iterator will be immediately
universe@851:  * initialized such that #cxIteratorValid() returns \c false.
universe@851:  *
universe@851:  *
universe@851:  * @param array a pointer to the array (can be \c NULL)
universe@851:  * @param elem_size the size of one array element
universe@851:  * @param elem_count the number of elements in the array
universe@851:  * @return an iterator for the specified array
universe@851:  */
universe@851: __attribute__((__warn_unused_result__))
universe@851: CxIterator cxIterator(
universe@851:         void const *array,
universe@851:         size_t elem_size,
universe@851:         size_t elem_count
universe@851: );
universe@851: 
universe@851: /**
universe@852:  * Creates a mutating iterator for the specified plain array.
universe@850:  *
universe@850:  * While the iterator is in use, the array may only be altered by removing
universe@850:  * elements through #cxIteratorFlagRemoval(). Every other change to the array
universe@850:  * will bring this iterator to an undefined state.
universe@850:  *
universe@850:  * When \p remove_keeps_order is set to \c false, removing an element will only
universe@850:  * move the last element to the position of the removed element, instead of
universe@850:  * moving all subsequent elements by one. Usually, when the order of elements is
universe@850:  * not important, this parameter should be set to \c false.
universe@850:  *
universe@850:  * The \p array can be \c NULL in which case the iterator will be immediately
universe@850:  * initialized such that #cxIteratorValid() returns \c false.
universe@850:  *
universe@850:  *
universe@850:  * @param array a pointer to the array (can be \c NULL)
universe@850:  * @param elem_size the size of one array element
universe@850:  * @param elem_count the number of elements in the array
universe@850:  * @param remove_keeps_order \c true if the order of elements must be preserved
universe@850:  * when removing an element
universe@850:  * @return an iterator for the specified array
universe@850:  */
universe@850: __attribute__((__warn_unused_result__))
universe@853: CxIterator cxMutIterator(
universe@850:         void *array,
universe@850:         size_t elem_size,
universe@850:         size_t elem_count,
universe@850:         bool remove_keeps_order
universe@850: );
universe@850: 
universe@628: #endif // UCX_ITERATOR_H