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55 lines
1.5 KiB
C++
55 lines
1.5 KiB
C++
//===- Defer.h - 'defer' helper macro ---------------------------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This filed defines a 'defer' macro for performing a cleanup on any exit out
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// of a scope.
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//
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//===----------------------------------------------------------------------===//
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#ifndef __SWIFT_DEFER_H
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#define __SWIFT_DEFER_H
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namespace swift {
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template <typename F>
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class DoAtScopeExit {
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F &Fn;
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DoAtScopeExit(DoAtScopeExit&) = delete;
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void operator=(DoAtScopeExit&) = delete;
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public:
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DoAtScopeExit(F &Fn) : Fn(Fn){}
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~DoAtScopeExit() {
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Fn();
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}
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};
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}
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#define DEFER_CONCAT_IMPL(x, y) x##y
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#define DEFER_MACRO_CONCAT(x, y) DEFER_CONCAT_IMPL(x, y)
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/// This macro is used to register a function / lambda to be run on exit from a
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/// scope. Its typical use looks like:
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///
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/// defer([&]{
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/// stuff
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/// })
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///
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#define defer(x) \
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auto DEFER_MACRO_CONCAT(defer_func, __LINE__) = (x); \
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swift::DoAtScopeExit<decltype(DEFER_MACRO_CONCAT(defer_func, __LINE__))> \
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DEFER_MACRO_CONCAT(defer_local, __LINE__)\
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(DEFER_MACRO_CONCAT(defer_func, __LINE__));
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#endif
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