ucx: src/cx/iterator.h@ac5e7f789048 (annotated)

src/cx/iterator.h@ac5e7f789048 (annotated)

src/cx/iterator.h

Sat, 26 Nov 2022 16:58:41 +0100

author: Mike Becker <universe@uap-core.de>
date: Sat, 26 Nov 2022 16:58:41 +0100
changeset 630: ac5e7f789048
parent 628: 1e2be40f0cb5
child 641: d402fead3386
permissions: -rw-r--r--

separate iterators and mutating iterators

Trade tons of code duplication for const-correctness.

 /*
  * 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
  * \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__))
     bool (*valid)(void const *);
     /**
      * Returns a pointer to the current element.
      */
     __attribute__ ((__nonnull__))
     void *(*current)(void const *);
     /**
      * Advances the iterator.
      */
     __attribute__ ((__nonnull__))
     void (*next)(void *);
     /**
      * Flag current element for removal, if possible.
      */
     __attribute__ ((__nonnull__))
     bool (*flag_removal)(void *);
     /**
      * Indicates whether this iterator is muting.
      */
     bool mutating;
     /**
      * Internal flag for removing the current element when advancing.
      */
     bool remove;
 };
 /**
  * Internal iterator struct - use CxMutIterator.
  */
 struct cx_mut_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 *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;
 };
 /**
  * Mutating iterator value 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 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 always mutable through that iterator. However,
  * this iterator cannot mutate the collection itself (add or remove elements) and any mutation of the
  * collection by other means make this iterator invalid (regardless of what cxIteratorValid() returns).
  *
  * @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
  * @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.
  *
  * @param iter the iterator
  * @return false if this iterator cannot remove the element
  */
 #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))
 #endif // UCX_ITERATOR_H

Mercurial > hg > ucx / annotate

src/cx/iterator.h@ac5e7f789048 (annotated)

src/cx/iterator.h