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- // Copyright 2014 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #import "base/mac/scoped_objc_class_swizzler.h"
- #include <string.h>
- #include "base/check_op.h"
- namespace base::mac {
- ScopedObjCClassSwizzler::ScopedObjCClassSwizzler(Class target,
- Class source,
- SEL selector)
- : old_selector_impl_(NULL), new_selector_impl_(NULL) {
- Init(target, source, selector, selector);
- }
- ScopedObjCClassSwizzler::ScopedObjCClassSwizzler(Class target,
- SEL original,
- SEL alternate)
- : old_selector_impl_(NULL), new_selector_impl_(NULL) {
- Init(target, target, original, alternate);
- }
- ScopedObjCClassSwizzler::~ScopedObjCClassSwizzler() {
- if (old_selector_impl_ && new_selector_impl_)
- method_exchangeImplementations(old_selector_impl_, new_selector_impl_);
- }
- IMP ScopedObjCClassSwizzler::GetOriginalImplementation() const {
- // Note that while the swizzle is in effect the "new" method is actually
- // pointing to the original implementation, since they have been swapped.
- return method_getImplementation(new_selector_impl_);
- }
- void ScopedObjCClassSwizzler::Init(Class target,
- Class source,
- SEL original,
- SEL alternate) {
- old_selector_impl_ = class_getInstanceMethod(target, original);
- new_selector_impl_ = class_getInstanceMethod(source, alternate);
- if (!old_selector_impl_ && !new_selector_impl_) {
- // Try class methods.
- old_selector_impl_ = class_getClassMethod(target, original);
- new_selector_impl_ = class_getClassMethod(source, alternate);
- }
- DCHECK(old_selector_impl_);
- DCHECK(new_selector_impl_);
- if (!old_selector_impl_ || !new_selector_impl_)
- return;
- // The argument and return types must match exactly.
- const char* old_types = method_getTypeEncoding(old_selector_impl_);
- const char* new_types = method_getTypeEncoding(new_selector_impl_);
- DCHECK(old_types);
- DCHECK(new_types);
- DCHECK_EQ(0, strcmp(old_types, new_types));
- if (!old_types || !new_types || strcmp(old_types, new_types)) {
- old_selector_impl_ = new_selector_impl_ = NULL;
- return;
- }
- method_exchangeImplementations(old_selector_impl_, new_selector_impl_);
- }
- } // namespace base::mac
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