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authorDongHun Kwak <dh0128.kwak@samsung.com>2019-12-05 15:12:59 +0900
committerDongHun Kwak <dh0128.kwak@samsung.com>2019-12-05 15:12:59 +0900
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parent3fdc3e5ee96dca5b11d1694975a65200787eab86 (diff)
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+
+#ifndef BOOST_CONTRACT_CONSTRUCTOR_PRECONDITION_HPP_
+#define BOOST_CONTRACT_CONSTRUCTOR_PRECONDITION_HPP_
+
+// Copyright (C) 2008-2018 Lorenzo Caminiti
+// Distributed under the Boost Software License, Version 1.0 (see accompanying
+// file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
+// See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
+
+/** @file
+Program preconditions for constructors.
+*/
+
+// IMPORTANT: Included by contract_macro.hpp so must #if-guard all its includes.
+#include <boost/contract/core/config.hpp>
+#ifndef BOOST_CONTRACT_NO_PRECONDITIONS
+ #include <boost/contract/core/exception.hpp>
+ #ifndef BOOST_CONTRACT_ALL_DISABLE_NO_ASSERTION
+ #include <boost/contract/detail/checking.hpp>
+ #endif
+#endif
+
+namespace boost { namespace contract {
+
+/**
+Program preconditions for constructors.
+
+This class must be the very first base of the class declaring the
+constructor for which preconditions are programmed (that way constructor
+arguments can be checked by preconditions even before they are used to
+initialize other base classes):
+
+@code
+ class u
+ #define BASES private boost::contract::constructor_precondition<u>, \
+ public b
+ : BASES
+ {
+ ...
+ #undef BASES
+
+ public:
+ explicit u(unsigned x) :
+ boost::contract::constructor_precondition<u>([&] {
+ BOOST_CONTRACT_ASSERT(x != 0);
+ ...
+ }),
+ b(1.0 / float(x))
+ {
+ ...
+ }
+
+ ...
+ };
+@endcode
+
+User-defined classes should inherit privately from this class (to not alter the
+public interface of user-defined classes).
+In addition, this class should never be declared as a virtual base (because
+virtual bases are initialized only once across the entire inheritance hierarchy
+preventing preconditions of other base classes from being checked).
+
+Unions cannot have base classes in C++ so this class can be used to declare a
+local object within the constructor definition just before
+@RefFunc{boost::contract::constructor} is used (see
+@RefSect{extras.unions, Unions}).
+
+@see @RefSect{tutorial.constructors, Constructors}
+
+@tparam Class The class type of the constructor for which preconditions are
+ being programmed.
+*/
+template<class Class>
+class constructor_precondition { // Copyable (has no data).
+public:
+ /**
+ Construct this object without specifying constructor preconditions.
+
+ This is implicitly called for those constructors of the contracted class
+ that do not specify preconditions.
+
+ @note Calling this default constructor should amount to negligible
+ compile-time and run-time overheads (likely to be optimized away
+ completely by most compilers).
+ */
+ constructor_precondition() {}
+
+ /**
+ Construct this object specifying constructor preconditions.
+
+ @param f Nullary functor called by this library to check constructor
+ preconditions @c f().
+ Assertions within this functor call are usually programmed
+ using @RefMacro{BOOST_CONTRACT_ASSERT}, but any exception thrown
+ by a call to this functor indicates a contract failure (and will
+ result in this library calling
+ @RefFunc{boost::contract::precondition_failure}).
+ This functor should capture variables by (constant) value, or
+ better by (constant) reference to avoid extra copies.
+ */
+ template<typename F>
+ explicit constructor_precondition(F const& f) {
+ #ifndef BOOST_CONTRACT_NO_PRECONDITIONS
+ try {
+ #ifndef BOOST_CONTRACT_ALL_DISABLE_NO_ASSERTION
+ if(boost::contract::detail::checking::already()) return;
+ #ifndef BOOST_CONTRACT_PRECONDITIONS_DISABLE_NO_ASSERTION
+ boost::contract::detail::checking k;
+ #endif
+ #endif
+ f();
+ } catch(...) { precondition_failure(from_constructor); }
+ #endif
+ }
+
+ // Default copy operations (so user's derived classes can be copied, etc.).
+};
+
+} } // namespace
+
+#endif // #include guard
+