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| 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #import "base/mac/objc_property_releaser.h" | |
| 6 | |
| 7 #import <objc/runtime.h> | |
| 8 #include <stdlib.h> | |
| 9 | |
| 10 #include <string> | |
| 11 | |
| 12 #include "base/logging.h" | |
| 13 | |
| 14 namespace base { | |
| 15 namespace mac { | |
| 16 | |
| 17 namespace { | |
| 18 | |
| 19 // Returns the name of the instance variable backing the property, if known, | |
| 20 // if the property is marked "retain" or "copy". If the instance variable name | |
| 21 // is not known (perhaps because it was not automatically associated with the | |
| 22 // property by @synthesize) or if the property is not "retain" or "copy", | |
| 23 // returns an empty string. | |
| 24 std::string ReleasableInstanceName(objc_property_t property) { | |
| 25 // TODO(mark): Starting in newer system releases, the Objective-C runtime | |
| 26 // provides a function to break the property attribute string into | |
| 27 // individual attributes (property_copyAttributeList), as well as a function | |
| 28 // to look up the value of a specific attribute | |
| 29 // (property_copyAttributeValue). When the SDK defining that interface is | |
| 30 // final, this function should be adapted to walk the attribute list as | |
| 31 // returned by property_copyAttributeList when that function is available in | |
| 32 // preference to scanning through the attribute list manually. | |
| 33 | |
| 34 // The format of the string returned by property_getAttributes is documented | |
| 35 // at | |
| 36 // http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjC
RuntimeGuide/Articles/ocrtPropertyIntrospection.html#//apple_ref/doc/uid/TP40008
048-CH101-SW6 | |
| 37 const char* property_attributes = property_getAttributes(property); | |
| 38 | |
| 39 std::string instance_name; | |
| 40 bool releasable = false; | |
| 41 while (*property_attributes) { | |
| 42 char name = *property_attributes; | |
| 43 | |
| 44 const char* value = ++property_attributes; | |
| 45 while (*property_attributes && *property_attributes != ',') { | |
| 46 ++property_attributes; | |
| 47 } | |
| 48 | |
| 49 switch (name) { | |
| 50 // It might seem intelligent to check the type ('T') attribute to verify | |
| 51 // that it identifies an NSObject-derived type (the attribute value | |
| 52 // begins with '@'.) This is a bad idea beacuse it fails to identify | |
| 53 // CFTypeRef-based properties declared as __attribute__((NSObject)), | |
| 54 // which just show up as pointers to their underlying CFType structs. | |
| 55 // | |
| 56 // Quoting | |
| 57 // http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/
ObjectiveC/Chapters/ocProperties.html#//apple_ref/doc/uid/TP30001163-CH17-SW27 | |
| 58 // | |
| 59 // > In Mac OS X v10.6 and later, you can use the __attribute__ keyword | |
| 60 // > to specify that a Core Foundation property should be treated like | |
| 61 // > an Objective-C object for memory management: | |
| 62 // > @property(retain) __attribute__((NSObject)) CFDictionaryRef | |
| 63 // > myDictionary; | |
| 64 case 'C': // copy | |
| 65 case '&': // retain | |
| 66 releasable = true; | |
| 67 break; | |
| 68 case 'V': // instance variable name | |
| 69 // 'V' is specified as the last attribute to occur in the | |
| 70 // documentation, but empirically, it's not always the last. In | |
| 71 // GC-supported or GC-required code, the 'P' (GC-eligible) attribute | |
| 72 // occurs after 'V'. | |
| 73 instance_name.assign(value, property_attributes - value); | |
| 74 break; | |
| 75 } | |
| 76 | |
| 77 if (*property_attributes) { | |
| 78 ++property_attributes; | |
| 79 } | |
| 80 } | |
| 81 | |
| 82 if (releasable) { | |
| 83 return instance_name; | |
| 84 } | |
| 85 | |
| 86 return std::string(); | |
| 87 } | |
| 88 | |
| 89 } // namespace | |
| 90 | |
| 91 void ObjCPropertyReleaser::Init(id object, Class classy) { | |
| 92 DCHECK(!object_); | |
| 93 DCHECK(!class_); | |
| 94 CHECK([object isKindOfClass:classy]); | |
| 95 | |
| 96 object_ = object; | |
| 97 class_ = classy; | |
| 98 } | |
| 99 | |
| 100 void ObjCPropertyReleaser::ReleaseProperties() { | |
| 101 DCHECK(object_); | |
| 102 DCHECK(class_); | |
| 103 | |
| 104 unsigned int property_count = 0; | |
| 105 objc_property_t* properties = class_copyPropertyList(class_, &property_count); | |
| 106 | |
| 107 for (unsigned int property_index = 0; | |
| 108 property_index < property_count; | |
| 109 ++property_index) { | |
| 110 objc_property_t property = properties[property_index]; | |
| 111 std::string instance_name = ReleasableInstanceName(property); | |
| 112 if (!instance_name.empty()) { | |
| 113 id instance_value = nil; | |
| 114 Ivar instance_variable = | |
| 115 object_getInstanceVariable(object_, instance_name.c_str(), | |
| 116 (void**)&instance_value); | |
| 117 DCHECK(instance_variable); | |
| 118 [instance_value release]; | |
| 119 } | |
| 120 } | |
| 121 | |
| 122 free(properties); | |
| 123 | |
| 124 // Clear object_ and class_ in case this ObjCPropertyReleaser will live on. | |
| 125 // It's only expected to release the properties it supervises once per Init. | |
| 126 object_ = nil; | |
| 127 class_ = nil; | |
| 128 } | |
| 129 | |
| 130 } // namespace mac | |
| 131 } // namespace base | |
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