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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 
     40 static 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 - (id)_webkit_invokeOnMainThread
    114 {
    115     return [[[WebMainThreadInvoker alloc] initWithTarget:self] autorelease];
    116 }
    117 
    118 @end
    119