/*
* 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