dav: comparison ucx/cx/iterator.h

-:1f40ca07ae1b
+:839fefbdedc7
 /**
 * \file iterator.h
 * \brief Interface for iterator implementations.
 * \author Mike Becker
 * \author Olaf Wintermann
-* \version 3.0
 * \copyright 2-Clause BSD License
 */
 #ifndef UCX_ITERATOR_H
 #define UCX_ITERATOR_H
 #include "common.h"
-/**
-* The base of mutating and non-mutating iterators.
-*/
 struct cx_iterator_base_s {
 /**
 * True iff the iterator points to valid data.
 */
 __attribute__ ((__nonnull__))
 *
 * When valid returns false, the behavior of this function is undefined.
 */
 __attribute__ ((__nonnull__))
 void (*next)(void *);
-/**
-* Flag current element for removal, if possible.
-*
-* When valid returns false, the behavior of this function is undefined.
-*/
-__attribute__ ((__nonnull__))
-bool (*flag_removal)(void *);
 /**
 * Indicates whether this iterator may remove elements.
 */
 bool mutating;
 /**
 * Internal flag for removing the current element when advancing.
 */
 bool remove;
 };
 /**
-* Internal iterator struct - use CxMutIterator.
+* Declares base attributes for an iterator.
 */
-struct cx_mut_iterator_s {
+#define CX_ITERATOR_BASE struct cx_iterator_base_s base
 /**
-* The base properties of this iterator.
+* Internal iterator struct - use CxIterator.
 */
-struct cx_iterator_base_s base;
+struct cx_iterator_s {
+CX_ITERATOR_BASE;
-/**
-* Handle for the current element, if required.
+/**
+* Handle for the current element.
 */
 void *elem_handle;
 /**
 * Handle for the source collection, if any.
 */
-void *src_handle;
+union {
+/**
+* Access for mutating iterators.
+*/
+void *m;
+/**
+* Access for normal iterators.
+*/
+void const *c;
+} src_handle;
 /**
 * Field for storing a key-value pair.
 * May be used by iterators that iterate over k/v-collections.
 */
 /**
 * 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;
 };
 /**
-* Mutating iterator value type.
+* Iterator type.
 *
-* An iterator points to a certain element in an (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 mutable through that iterator. However, if the
-* iterator is based on a collection and the underlying collection is mutated by other means than this iterator
-* (e.g. elements added or removed), the iterator becomes invalid (regardless of what cxIteratorValid() returns)
-* and MUST be re-obtained from the collection.
-*
-* @see CxIterator
-*/
-typedef struct cx_mut_iterator_s CxMutIterator;
-/**
-* Internal iterator struct - use CxIterator.
-*/
-struct cx_iterator_s {
-/**
-* The base properties of this iterator.
-*/
-struct cx_iterator_base_s base;
-/**
-* Handle for the current element, if required.
-*/
-void *elem_handle;
-/**
-* Handle for the source collection, if any.
-*/
-void const *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.
-*/
-void const *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;
-};
-/**
-* Iterator value 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,
-* this iterator cannot mutate the collection itself (add or remove elements) and any mutation of the
+* any concurrent mutation of the collection other than by this iterator makes this iterator invalid
-* collection by other means makes this iterator invalid (regardless of what cxIteratorValid() returns).
+* and it must not be used anymore.
-*
-* @see CxMutIterator
 */
 typedef struct cx_iterator_s CxIterator;
 /**
 * Checks if the iterator points to valid data.
 * @param iter the iterator
 */
 #define cxIteratorNext(iter) (iter).base.next(&iter)
 /**
-* Flags the current element for removal.
+* Flags the current element for removal, if this iterator is mutating.
 *
 * @param iter the iterator
-* @return false if this iterator cannot remove the element
+*/
-*/
+#define cxIteratorFlagRemoval(iter) (iter).base.remove |= (iter).base.mutating
-#define cxIteratorFlagRemoval(iter) (iter).base.flag_removal(&iter)
 /**
 * 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(
+void const *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

Mercurial > hg > dav / file comparison

comparison: ucx/cx/iterator.h

ucx/cx/iterator.h