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1/*
2 * Copyright (C) 2008, 2009 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 *
8 * 1.  Redistributions of source code must retain the above copyright
9 *     notice, this list of conditions and the following disclaimer.
10 * 2.  Redistributions in binary form must reproduce the above copyright
11 *     notice, this list of conditions and the following disclaimer in the
12 *     documentation and/or other materials provided with the distribution.
13 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
14 *     its contributors may be used to endorse or promote products derived
15 *     from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#import "WebNSObjectExtras.h"
30
31#import <wtf/Assertions.h>
32
33@interface WebMainThreadInvoker : NSProxy
34{
35    id target;
36    id exception;
37}
38@end
39
40static bool returnTypeIsObject(NSInvocation *invocation)
41{
42    // Could use either _C_ID or NSObjCObjectType, but it seems that neither is
43    // both available and non-deprecated on all versions of Mac OS X we support.
44    return strchr([[invocation methodSignature] methodReturnType], '@');
45}
46
47@implementation WebMainThreadInvoker
48
49- (id)initWithTarget:(id)passedTarget
50{
51    target = passedTarget;
52    return self;
53}
54
55- (void)forwardInvocation:(NSInvocation *)invocation
56{
57    [invocation setTarget:target];
58    [invocation performSelectorOnMainThread:@selector(_webkit_invokeAndHandleException:) withObject:self waitUntilDone:YES];
59    if (exception) {
60        id exceptionToThrow = [exception autorelease];
61        exception = nil;
62        @throw exceptionToThrow;
63    } else if (returnTypeIsObject(invocation)) {
64        // _webkit_invokeAndHandleException retained the return value on the main thread.
65        // Now autorelease it on the calling thread.
66        id returnValue;
67        [invocation getReturnValue:&returnValue];
68        [returnValue autorelease];
69    }
70}
71
72- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector
73{
74    return [target methodSignatureForSelector:selector];
75}
76
77- (void)handleException:(id)passedException
78{
79    ASSERT(!exception);
80    exception = [passedException retain];
81}
82
83@end
84
85@implementation NSInvocation (WebMainThreadInvoker)
86
87- (void)_webkit_invokeAndHandleException:(WebMainThreadInvoker *)exceptionHandler
88{
89    @try {
90        [self invoke];
91    } @catch (id exception) {
92        [exceptionHandler handleException:exception];
93        return;
94    }
95    if (returnTypeIsObject(self)) {
96        // Retain the return value on the main thread.
97        // -[WebMainThreadInvoker forwardInvocation:] will autorelease it on the calling thread.
98        id value;
99        [self getReturnValue:&value];
100        [value retain];
101    }
102}
103
104@end
105
106@implementation NSObject (WebNSObjectExtras)
107
108- (id)_webkit_invokeOnMainThread
109{
110    return [[[WebMainThreadInvoker alloc] initWithTarget:self] autorelease];
111}
112
113@end
114