text: // Copyright 2013 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.
  //
  #ifndef IOS_TESTING_SCOPED_BLOCK_SWIZZLER_H_
  #define IOS_TESTING_SCOPED_BLOCK_SWIZZLER_H_
  
  #include <objc/runtime.h>
  
  // Helper class that replaces a method implementation with a given block.
  // ScopedBlockSwizzler automatically swizzles when it is constructed and
  // reinstalls the original method implementation when it goes out of scope.
  class ScopedBlockSwizzler {
   public:
    // Constructs a new ScopedBlockSwizzler object and replaces the implementation
    // of |selector| on the |target| class with the given |block|.
    // ScopedBlockSwizzler first tries to swizzle a class method; if one is not
    // found, it tries to swizzle an instance method.  It is an error to pass a
    // |selector| that does not exist on the |target| class.
    ScopedBlockSwizzler(Class target, SEL selector, id block);
  
    // Constructs a new ScopedBlockSwizzler object and replaces the implementation
    // of |selector| on the |target| class with the given |block|.
    // |class_method| specifies if the swizzled method is a class method (YES) or
    // an instance method (NO). This can be use to disambiguate if the class
    // contains both method types with the same selector.
    ScopedBlockSwizzler(Class target, SEL selector, id block, BOOL class_method);
  
    ScopedBlockSwizzler(const ScopedBlockSwizzler&) = delete;
    ScopedBlockSwizzler& operator=(const ScopedBlockSwizzler&) = delete;
  
    // Destroys the ScopedBlockSwizzler object, removing the swizzled method and
    // reinstalling the original method implementation.
    virtual ~ScopedBlockSwizzler();
  
   private:
    // The method that is to be swizzled.  Can be either a class method or an
    // instance method.
    Method method_;
  
    // The original implementation of the swizzled method, saved so that it can be
    // reinstalled when this object goes out of scope.
    IMP original_imp_;
  };
  
  #endif  // IOS_TESTING_SCOPED_BLOCK_SWIZZLER_H_
  