1/*
2 * Copyright (c) 2019 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28/*
29 * Copyright (c) 1998-1999 Apple Computer, Inc. All rights reserved.
30 *
31 * HISTORY
32 *
33 */
34
35#ifndef _OS_OSITERATOR_H
36#define _OS_OSITERATOR_H
37
38#include <libkern/c++/OSObject.h>
39
40/*!
41 * @header
42 *
43 * @abstract
44 * This header declares the OSIterator collection class.
45 */
46
47
48/*!
49 * @class OSIterator
50 * @abstract
51 * The abstract superclass for Libkern iterators.
52 *
53 * @discussion
54 * OSIterator is the abstract superclass for all Libkern C++ object iterators.
55 * It defines the basic interface for iterating and resetting.
56 * See @link //apple_ref/cpp/macro/OSCollection OSCollection@/link and
57 * @link //apple_ref/cpp/macro/OSCollectionIterator OSCollectionIterator@/link
58 * for more information.
59 *
60 * With very few exceptions in the I/O Kit, all Libkern-based C++
61 * classes, functions, and macros are <b>unsafe</b>
62 * to use in a primary interrupt context.
63 * Consult the I/O Kit documentation related to primary interrupts
64 * for more information.
65 *
66 * OSIterator provides no concurrency protection.
67 */
68class OSIterator : public OSObject
69{
70 OSDeclareAbstractStructors(OSIterator);
71
72public:
73/*!
74 * @function reset
75 *
76 * @abstract
77 * Resets the iterator to the beginning of the collection,
78 * as if it had just been created.
79 *
80 * @discussion
81 * Subclasses must implement this pure virtual member function.
82 */
83 virtual void reset() = 0;
84
85
86/*!
87 * @function isValid
88 *
89 * @abstract
90 * Check that the collection hasn't been modified during iteration.
91 *
92 * @result
93 * <code>true</code> if the iterator is valid for continued use,
94 * <code>false</code> otherwise
95 * (typically because the collection being iterated has been modified).
96 *
97 * @discussion
98 * Subclasses must implement this pure virtual member function.
99 */
100 virtual bool isValid() = 0;
101
102
103/*!
104 * @function getNextObject
105 *
106 * @abstract
107 * Advances to and returns the next object in the iteration.
108 *
109 * @return
110 * The next object in the iteration context,
111 * <code>NULL</code> if there is no next object
112 * or if the iterator is no longer valid.
113 *
114 * @discussion
115 * The returned object will be released if removed from the collection;
116 * if you plan to store the reference, you should call
117 * <code>@link
118 * //apple_ref/cpp/instm/OSObject/retain/virtualvoid/()
119 * retain@/link</code>
120 * on that object.
121 *
122 * Subclasses must implement this pure virtual function
123 * to check for validity with
124 * <code>@link isValid isValid@/link</code>,
125 * and then to advance the iteration context to the next object (if any)
126 * and return that next object, or <code>NULL</code> if there is none.
127 */
128 virtual OSObject *getNextObject() = 0;
129
130 OSMetaClassDeclareReservedUnused(OSIterator, 0);
131 OSMetaClassDeclareReservedUnused(OSIterator, 1);
132 OSMetaClassDeclareReservedUnused(OSIterator, 2);
133 OSMetaClassDeclareReservedUnused(OSIterator, 3);
134};
135
136#endif /* ! _OS_OSITERATOR_H */
137