1 // Copyright (c) 2012 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 #ifndef BASE_MAC_BIND_OBJC_BLOCK_H_ 6 #define BASE_MAC_BIND_OBJC_BLOCK_H_ 7 8 #include <Block.h> 9 10 #include "base/bind.h" 11 #include "base/callback_forward.h" 12 #include "base/mac/scoped_block.h" 13 14 // BindBlock builds a callback from an Objective-C block. Example usages: 15 // 16 // Closure closure = BindBlock(^{DoSomething();}); 17 // 18 // Callback<int(void)> callback = BindBlock(^{return 42;}); 19 // 20 // Callback<void(const std::string&, const std::string&)> callback = 21 // BindBlock(^(const std::string& arg0, const std::string& arg1) { 22 // ... 23 // }); 24 // 25 // These variadic templates will accommodate any number of arguments, however 26 // the underlying templates in bind_internal.h and callback.h are limited to 27 // seven total arguments, and the bound block itself is used as one of these 28 // arguments, so functionally the templates are limited to binding blocks with 29 // zero through six arguments. 30 31 namespace base { 32 33 namespace internal { 34 35 // Helper function to run the block contained in the parameter. 36 template<typename R, typename... Args> 37 R RunBlock(base::mac::ScopedBlock<R(^)(Args...)> block, Args... args) { 38 R(^extracted_block)(Args...) = block.get(); 39 return extracted_block(args...); 40 } 41 42 } // namespace internal 43 44 // Construct a callback from an objective-C block with up to six arguments (see 45 // note above). 46 template<typename R, typename... Args> 47 base::Callback<R(Args...)> BindBlock(R(^block)(Args...)) { 48 return base::Bind( 49 &base::internal::RunBlock<R, Args...>, 50 base::mac::ScopedBlock<R (^)(Args...)>( 51 base::mac::internal::ScopedBlockTraits<R (^)(Args...)>::Retain( 52 block))); 53 } 54 55 } // namespace base 56 57 #endif // BASE_MAC_BIND_OBJC_BLOCK_H_ 58
