webserver: comparison src/ucx/cx/iterator.h

-:eb48f716b31c
+:e10457d74fe1
 * 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
+* @file iterator.h
-* \brief Interface for iterator implementations.
+* @brief Interface for iterator implementations.
-* \author Mike Becker
+* @author Mike Becker
-* \author Olaf Wintermann
+* @author Olaf Wintermann
-* \version 3.0
+* @copyright 2-Clause BSD License
-* \copyright 2-Clause BSD License
 */
 #ifndef UCX_ITERATOR_H
 #define UCX_ITERATOR_H
 #include "common.h"
-/**
+#ifdef __cplusplus
-* The base of mutating and non-mutating iterators.
+extern "C" {
+#endif
+/**
+* Common data for all iterators.
 */
 struct cx_iterator_base_s {
 /**
-* True iff the iterator points to valid data.
+* True if the iterator points to valid data.
 */
-__attribute__ ((__nonnull__))
+bool (*valid)(const void *);
-bool (*valid)(void const *);
 /**
 * Returns a pointer to the current element.
 *
 * When valid returns false, the behavior of this function is undefined.
 */
-__attribute__ ((__nonnull__))
+void *(*current)(const void *);
-void *(*current)(void const *);
 /**
 * Original implementation in case the function needs to be wrapped.
 */
-__attribute__ ((__nonnull__))
+void *(*current_impl)(const void *);
-void *(*current_impl)(void const *);
 /**
 * Advances the iterator.
 *
 * 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.
+* Convenience type definition for the base structure of an iterator.
-*/
+* @see #CX_ITERATOR_BASE
-struct cx_mut_iterator_s {
+*/
+typedef struct cx_iterator_base_s CxIteratorBase;
-/**
-* The base properties of this iterator.
+/**
-*/
+* Declares base attributes for an iterator.
-struct cx_iterator_base_s base;
+* Must be the first member of an iterator structure.
+*/
-/**
+#define CX_ITERATOR_BASE struct cx_iterator_base_s base
-* Handle for the current element, if required.
+/**
+* Internal iterator struct - use CxIterator.
+*/
+struct cx_iterator_s {
+/**
+* Inherited common data for all iterators.
+*/
+CX_ITERATOR_BASE;
+/**
+* Handle for the current element.
 */
 void *elem_handle;
 /**
 * Handle for the source collection, if any.
 */
-void *src_handle;
+union {
-/**
-* Field for storing a key-value pair.
-* May be used by iterators that iterate over k/v-collections.
-*/
-struct {
 /**
-* A pointer to the key.
+* Access for mutating iterators.
 */
-void const *key;
+void *m;
 /**
-* A pointer to the value.
+* Access for normal iterators.
 */
-void *value;
+const void *c;
-} kv_data;
+} src_handle;
-/**
-* 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;
 };
 /**
-* 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.
 *
-* This is especially false for past-the-end iterators.
+* @param iter the iterator
-*
+* @retval true if the iterator points to valid data
-* @param iter the iterator
+* @retval false if the iterator already moved past the end
-* @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
+* @see cxIteratorValid()
 */
 #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.
+* Flags the current element for removal, if this iterator is mutating.
 *
-* @param iter the iterator
+* Does nothing for non-mutating iterators.
-* @return false if this iterator cannot remove the element
+*
-*/
+* @param iter the iterator
-#define cxIteratorFlagRemoval(iter) (iter).base.flag_removal(&iter)
+*/
+#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
+* @return (@c struct @c cx_iterator_base_s*) a pointer to 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.
+*
+* This iterator yields the addresses of the array elements.
+* If you want to iterator over an array of pointers, you can
+* use cxIteratorPtr() to create an iterator which directly
+* yields the stored pointers.
+*
+* @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
+* @see cxIteratorPtr()
+*/
+cx_attr_nodiscard
+cx_attr_export
+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
+*/
+cx_attr_nodiscard
+cx_attr_export
+CxIterator cxMutIterator(
+void *array,
+size_t elem_size,
+size_t elem_count,
+bool remove_keeps_order
+);
+/**
+* Creates an iterator for the specified plain pointer array.
+*
+* This iterator assumes that every element in the array is a pointer
+* and yields exactly those pointers during iteration (while in contrast
+* an iterator created with cxIterator() would return the addresses
+* of those pointers within the array).
+*
+* @param array a pointer to the array (can be @c NULL)
+* @param elem_count the number of elements in the array
+* @return an iterator for the specified array
+* @see cxIterator()
+*/
+cx_attr_nodiscard
+cx_attr_export
+CxIterator cxIteratorPtr(
+const void *array,
+size_t elem_count
+);
+/**
+* Creates a mutating iterator for the specified plain pointer array.
+*
+* This is the mutating variant of cxIteratorPtr(). See also
+* cxMutIterator().
+*
+* @param array a pointer to the array (can be @c NULL)
+* @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
+* @see cxMutIterator()
+* @see cxIteratorPtr()
+*/
+cx_attr_nodiscard
+cx_attr_export
+CxIterator cxMutIteratorPtr(
+void *array,
+size_t elem_count,
+bool remove_keeps_order
+);
+#ifdef __cplusplus
+} // extern "C"
+#endif
 #endif // UCX_ITERATOR_H

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comparison: src/ucx/cx/iterator.h

src/ucx/cx/iterator.h