draft behaviour of a optional/switchable object link
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src/lib/optional-ref.hpp
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87
src/lib/optional-ref.hpp
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/*
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OPTIONAL-REF.hpp - optional and switchable reference
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Copyright (C) Lumiera.org
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2010, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef LIB_OPTIONAL_REF_H
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#define LIB_OPTIONAL_REF_H
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#include "lib/error.hpp"
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#include "lib/bool-checkable.hpp"
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#include "lib/util.hpp"
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//#include <boost/type_traits/remove_const.hpp>
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//#include <boost/noncopyable.hpp>
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//#include <tr1/functional>
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namespace lib {
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using lumiera::error::LUMIERA_ERROR_BOTTOM_VALUE;
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/**
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* Reference wrapper implemented as constant function,
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* returning the (fixed) reference on invocation
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*/
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template<typename T>
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class ReturnRef
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{
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T& ref_;
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public:
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ReturnRef(T& target) : ref_(target) { }
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T& operator() () const { return ref_;}
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};
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template<typename T>
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ReturnRef<T>
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refFunction (T& target)
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{
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return ReturnRef<T> (target);
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}
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/**
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* Optional or switchable link to an existing object.
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* This reference wrapper normally behaves like a reference,
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* but has the ability to be \em disabled. This disabled state
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* is managed automatically by ctor and dtor, can be detected
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* through \c bool check and -- contrary to a \c NULL pointer
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* -- produces a real exception instead of crashing.
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* @note \em not taking ownership of the pointee
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*/
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template<typename T>
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class OptionalRef
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{
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T* ref_;
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public:
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OptionalRef() : ref_(0) { }
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OptionalRef(T& target) : ref_(&target) { }
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~OptionalRef() { ref_ = 0; }
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};
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} // namespace lib
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#endif
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@ -78,6 +78,7 @@ test_lib_SOURCES = \
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$(testlib_srcdir)/null-value-test.cpp \
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$(testlib_srcdir)/opaque-holder-test.cpp \
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$(testlib_srcdir)/opaque-unchecked-buffer-test.cpp \
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$(testlib_srcdir)/optional-ref-test.cpp \
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$(testlib_srcdir)/query/query-utils-test.cpp \
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$(testlib_srcdir)/removefromsettest.cpp \
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$(testlib_srcdir)/sanitised-identifier-test.cpp \
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157
tests/lib/optional-ref-test.cpp
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157
tests/lib/optional-ref-test.cpp
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/*
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OptionalRef(Test) - verify an optional and switchable object link
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Copyright (C) Lumiera.org
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2010, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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* *****************************************************/
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#include "lib/test/run.hpp"
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#include "lib/test/test-helper.hpp"
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//#include "lib/util.hpp"
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#include "lib/optional-ref.hpp"
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//#include <tr1/functional>
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//#include <iostream>
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//#include <cstdlib>
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//#include <string>
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//#include <vector>
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namespace lib {
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namespace test{
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using ::Test;
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using lib::test::randStr;
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using std::string;
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/*******************************************************************************
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* @test verify a reference-like wrapper class, used to provide a switchable link
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* to an already existing object.
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*
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* @see lib::OptionalRef
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* @see lib::AutoRegistered usage example
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*/
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class OptionalRef_test : public Test
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{
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virtual void
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run (Arg)
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{
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string s1 (randStr(50));
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string s2 (randStr(50));
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typedef OptionalRef<string> SRef;
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SRef r1;
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CHECK (!r1);
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VERIFY_ERROR (BOTTOM_VALUE, s1 = r1 );
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VERIFY_ERROR (BOTTOM_VALUE, s1 == r1 );
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VERIFY_ERROR (BOTTOM_VALUE, r1 == s1 );
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CHECK (!r1.points_to (s1));
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r1.link_to (s1);
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CHECK (r1);
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CHECK (r1 == s1);
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CHECK (s1 == r1);
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CHECK (r1.points_to (s1));
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SRef r2(s2);
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CHECK (r2);
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CHECK (r2 == s2);
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CHECK (r2.points_to (s2));
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CHECK (!r2.points_to (s1));
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CHECK (!r1.points_to (s2));
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CHECK (r2 != r1);
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CHECK (r1 != r2);
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r2.link_to (s1);
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CHECK (r2);
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CHECK (r2 == s1);
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CHECK (r2 == r1);
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CHECK (r1 == r2);
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CHECK (r2.points_to (s1));
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CHECK (!r2.points_to (s2));
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r2.clear();
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CHECK (!r2);
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VERIFY_ERROR (BOTTOM_VALUE, s1 = r2 );
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VERIFY_ERROR (BOTTOM_VALUE, s1 == r2 );
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VERIFY_ERROR (BOTTOM_VALUE, r2 == s1 );
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VERIFY_ERROR (BOTTOM_VALUE, r2 == s2 );
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CHECK (r1 != r2); // comparison with bottom ref allowed
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CHECK (r2 != r1);
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//OptionalRef objects are copyable values
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r2 = r1;
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CHECK (r2);
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CHECK (r2 == r1);
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CHECK (r1 == r2);
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CHECK (r2 == s1);
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r1.link_to (s2);
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CHECK (r2 != r1); // but they are indeed independent instances
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CHECK (r1 != r2);
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CHECK (r2 == s1);
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CHECK (r2 != s2);
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CHECK (r1 == s2);
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SRef r3(r2);
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CHECK (r3);
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CHECK (r3 == r2);
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CHECK (r2 == r3);
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CHECK (r3 == s1);
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CHECK (r3 != r1);
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CHECK (r1 != r3);
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CHECK (r3 != s2);
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// access is secured even after destruction
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CHECK (r3);
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r1.~OptionalRef();
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CHECK (!r3);
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VERIFY_ERROR (BOTTOM_VALUE, r3 == s1 );
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CHECK (r3 != r2);
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r2.clear();
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CHECK (!r2);
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CHECK (r3 == r2);
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CHECK (r2 == r3);
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}
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};
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LAUNCHER (OptionalRef_test, "unit common");
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}} // namespace lib::test
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