1/*
2 * Copyright (C) 2013 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef JSManagedValue_h
27#define JSManagedValue_h
28
29#import <JavaScriptCore/JSBase.h>
30#import <JavaScriptCore/WebKitAvailability.h>
31
32#if JSC_OBJC_API_ENABLED
33
34@class JSValue;
35@class JSContext;
36
37/*!
38@interface
39@discussion JSManagedValue represents a "conditionally retained" JSValue.
40 "Conditionally retained" means that as long as either the JSManagedValue's
41 JavaScript value is reachable through the JavaScript object graph
42 or the JSManagedValue object is reachable through the external Objective-C
43 object graph as reported to the JSVirtualMachine using
44 addManagedReference:withOwner:, the corresponding JavaScript value will
45 be retained. However, if neither of these conditions are true, the
46 corresponding JSValue will be released and set to nil.
47
48 The primary use case for JSManagedValue is for safely referencing JSValues
49 from the Objective-C heap. It is incorrect to store a JSValue into an
50 Objective-C heap object, as this can very easily create a reference cycle,
51 keeping the entire JSContext alive.
52*/
53#ifndef JSC_OBJC_API_AVAILABLE_MAC_OS_X_1080
54NS_CLASS_AVAILABLE(10_9, 7_0)
55#else
56OBJC_VISIBLE
57#endif
58@interface JSManagedValue : NSObject
59
60/*!
61@method
62@abstract Create a JSManagedValue from a JSValue.
63@param value
64@result The new JSManagedValue.
65*/
66+ (JSManagedValue *)managedValueWithValue:(JSValue *)value;
67+ (JSManagedValue *)managedValueWithValue:(JSValue *)value andOwner:(id)owner NS_AVAILABLE(10_10, 8_0);
68
69/*!
70@method
71@abstract Create a JSManagedValue.
72@param value
73@result The new JSManagedValue.
74*/
75- (instancetype)initWithValue:(JSValue *)value;
76
77/*!
78@property
79@abstract Get the JSValue from the JSManagedValue.
80@result The corresponding JSValue for this JSManagedValue or
81 nil if the JSValue has been collected.
82*/
83@property (readonly, strong) JSValue *value;
84
85@end
86
87#endif // JSC_OBJC_API_ENABLED
88
89#endif // JSManagedValue_h
90