toolkit: comparison ucx/cx/iterator.h

-:fe49cff3c571
+:bb7da585debc
+/*
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+*
+* Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
+*
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions are met:
+*
+*   1. Redistributions of source code must retain the above copyright
+*      notice, this list of conditions and the following disclaimer.
+*
+*   2. Redistributions in binary form must reproduce the above copyright
+*      notice, this list of conditions and the following disclaimer in the
+*      documentation and/or other materials provided with the distribution.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+* POSSIBILITY OF SUCH DAMAGE.
+*/
+/**
+* \file iterator.h
+* \brief Interface for iterator implementations.
+* \author Mike Becker
+* \author Olaf Wintermann
+* \copyright 2-Clause BSD License
+*/
+#ifndef UCX_ITERATOR_H
+#define UCX_ITERATOR_H
+#include "common.h"
+struct cx_iterator_base_s {
+/**
+* True iff the iterator points to valid data.
+*/
+__attribute__ ((__nonnull__))
+bool (*valid)(const void *);
+/**
+* Returns a pointer to the current element.
+*
+* When valid returns false, the behavior of this function is undefined.
+*/
+__attribute__ ((__nonnull__))
+void *(*current)(const void *);
+/**
+* Original implementation in case the function needs to be wrapped.
+*/
+__attribute__ ((__nonnull__))
+void *(*current_impl)(const void *);
+/**
+* Advances the iterator.
+*
+* When valid returns false, the behavior of this function is undefined.
+*/
+__attribute__ ((__nonnull__))
+void (*next)(void *);
+/**
+* Indicates whether this iterator may remove elements.
+*/
+bool mutating;
+/**
+* Internal flag for removing the current element when advancing.
+*/
+bool remove;
+};
+/**
+* Declares base attributes for an iterator.
+* Must be the first member of an iterator structure.
+*/
+#define CX_ITERATOR_BASE struct cx_iterator_base_s base
+/**
+* Internal iterator struct - use CxIterator.
+*/
+struct cx_iterator_s {
+CX_ITERATOR_BASE;
+/**
+* Handle for the current element.
+*/
+void *elem_handle;
+/**
+* Handle for the source collection, if any.
+*/
+union {
+/**
+* Access for mutating iterators.
+*/
+void *m;
+/**
+* Access for normal iterators.
+*/
+const void *c;
+} src_handle;
+/**
+* Field for storing a key-value pair.
+* May be used by iterators that iterate over k/v-collections.
+*/
+struct {
+/**
+* A pointer to the key.
+*/
+const void *key;
+/**
+* A pointer to the value.
+*/
+void *value;
+} kv_data;
+/**
+* Field for storing a slot number.
+* May be used by iterators that iterate over multi-bucket collections.
+*/
+size_t slot;
+/**
+* If the iterator is position-aware, contains the index of the element in the underlying collection.
+* Otherwise, this field is usually uninitialized.
+*/
+size_t index;
+/**
+* The size of an individual element.
+*/
+size_t elem_size;
+/**
+* May contain the total number of elements, if known.
+* Shall be set to \c SIZE_MAX when the total number is unknown during iteration.
+*/
+size_t elem_count;
+};
+/**
+* Iterator type.
+*
+* An iterator points to a certain element in a (possibly unbounded) chain of elements.
+* Iterators that are based on collections (which have a defined "first" element), are supposed
+* to be "position-aware", which means that they keep track of the current index within the collection.
+*
+* @note Objects that are pointed to by an iterator are always mutable through that iterator. However,
+* any concurrent mutation of the collection other than by this iterator makes this iterator invalid
+* and it must not be used anymore.
+*/
+typedef struct cx_iterator_s CxIterator;
+/**
+* Checks if the iterator points to valid data.
+*
+* This is especially false for past-the-end iterators.
+*
+* @param iter the iterator
+* @return true iff the iterator points to valid data
+*/
+#define cxIteratorValid(iter) (iter).base.valid(&(iter))
+/**
+* Returns a pointer to the current element.
+*
+* The behavior is undefined if this iterator is invalid.
+*
+* @param iter the iterator
+* @return a pointer to the current element
+*/
+#define cxIteratorCurrent(iter) (iter).base.current(&iter)
+/**
+* Advances the iterator to the next element.
+*
+* @param iter the iterator
+*/
+#define cxIteratorNext(iter) (iter).base.next(&iter)
+/**
+* Flags the current element for removal, if this iterator is mutating.
+*
+* @param iter the iterator
+*/
+#define cxIteratorFlagRemoval(iter) (iter).base.remove |= (iter).base.mutating
+/**
+* Obtains a reference to an arbitrary iterator.
+*
+* This is useful for APIs that expect some iterator as an argument.
+*
+* @param iter the iterator
+*/
+#define cxIteratorRef(iter) &((iter).base)
+/**
+* Loops over an iterator.
+* @param type the type of the elements
+* @param elem the name of the iteration variable
+* @param iter the iterator
+*/
+#define cx_foreach(type, elem, iter) \
+for (type elem; cxIteratorValid(iter) && (elem = (type)cxIteratorCurrent(iter)) != NULL ; cxIteratorNext(iter))
+/**
+* Creates an iterator for the specified plain array.
+*
+* The \p array can be \c NULL in which case the iterator will be immediately
+* initialized such that #cxIteratorValid() returns \c false.
+*
+*
+* @param array a pointer to the array (can be \c NULL)
+* @param elem_size the size of one array element
+* @param elem_count the number of elements in the array
+* @return an iterator for the specified array
+*/
+__attribute__((__warn_unused_result__))
+CxIterator cxIterator(
+const void *array,
+size_t elem_size,
+size_t elem_count
+);
+/**
+* Creates a mutating iterator for the specified plain array.
+*
+* While the iterator is in use, the array may only be altered by removing
+* elements through #cxIteratorFlagRemoval(). Every other change to the array
+* will bring this iterator to an undefined state.
+*
+* When \p remove_keeps_order is set to \c false, removing an element will only
+* move the last element to the position of the removed element, instead of
+* moving all subsequent elements by one. Usually, when the order of elements is
+* not important, this parameter should be set to \c false.
+*
+* The \p array can be \c NULL in which case the iterator will be immediately
+* initialized such that #cxIteratorValid() returns \c false.
+*
+*
+* @param array a pointer to the array (can be \c NULL)
+* @param elem_size the size of one array element
+* @param elem_count the number of elements in the array
+* @param remove_keeps_order \c true if the order of elements must be preserved
+* when removing an element
+* @return an iterator for the specified array
+*/
+__attribute__((__warn_unused_result__))
+CxIterator cxMutIterator(
+void *array,
+size_t elem_size,
+size_t elem_count,
+bool remove_keeps_order
+);
+#endif // UCX_ITERATOR_H

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comparison: ucx/cx/iterator.h

ucx/cx/iterator.h