Ichthyostega
059dbd8c75
there was still a subtle bug in this helper. testing your own test fixture is sometimes a good idea ;-)
141 lines
4.3 KiB
C++
141 lines
4.3 KiB
C++
/*
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TestHelperVariadic(Test) - verify variadic template diagnostics helper
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Copyright (C) Lumiera.org
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2014, 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
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the 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 <iostream>
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#include <utility>
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#include <string>
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#include <cmath>
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using std::string;
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using std::cout;
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namespace lib {
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namespace test{
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namespace test{
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namespace { // test fixture...
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class Interface
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{
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public:
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Interface(){}
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Interface(Interface const& o) { cout << "COPY.CT from "<<&o<<" !!!\n"; }
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Interface(Interface const&& o) { cout << "MOVE.CT from "<<&o<<" !!!\n"; }
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Interface& operator= (Interface const& o) { cout << "COPY= from "<<&o<<" !!!\n"; return *this; }
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Interface& operator= (Interface const&& o) { cout << "MOVE= from "<<&o<<" !!!\n"; return *this; }
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virtual ~Interface() { }
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};
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class Impl
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: public Interface
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{
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string s_;
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public:
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Impl(string ss ="ZOMG") : s_(ss) { }
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};
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inline double
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makeRvalue()
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{
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return atan2(0,-0.0);
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}
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}//(End) test fixture
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/****************************************************************************//**
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* @test document usage of the diagnostics helper for variadic templates.
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* Errors in variadic template instantiations are sometimes hard to spot,
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* due to the intricacies of template argument matching and the
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* reference collapsing rules. Our diagnostics facility is itself a
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* variadic function template, which, when supplied with an argument pack,
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* will build a diagnostic string describing the arguments.
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* @warning care has to be taken to pass the template arguments properly,
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* since template argument matching might mess up the reference kind
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* (rvalue, lvalue) of the passed types. Thus, either use std::forward,
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* or spell out the template argument(s) explicitly on invocation
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*
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* @see showVariadicTypes()
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* @see TestHelper_test
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*/
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class TestHelperVariadic_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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double d = makeRvalue();
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double& dr = d;
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Impl obj;
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Interface const& ref = obj;
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cout << "--no-arg--\n" << showVariadicTypes() <<"\n";
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cout << "--value--\n" << showVariadicTypes<double>(d) <<"\n";
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cout << "--reference--\n" << showVariadicTypes<double&>(d) <<"\n";
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cout << "--move--\n" << showVariadicTypes<double&&>(d) <<"\n";
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forwardFunction("two values", "foo", 42L); // passed as REF, MOV
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forwardFunction("matched", d,dr,std::move(dr)); // passed as REF, REF, MOV
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forwardFunction<Interface const&>("baseclass", ref);
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}
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/** this dummy simulates a typical variadic call
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* which takes all arguments as '&&' for the purpose of "perfect forwarding"
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*/
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template<typename... ARGS>
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void
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forwardFunction (string id, ARGS&&... args)
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{
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// in reality here you'd invoke some factory(<std::forward<ARGS>(args)...)
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//
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cout << "--"<<id<<"--\n"
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<< showVariadicTypes<ARGS&&...>(args...)
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<< "\n"
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;
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}
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};
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/** Register this test class... */
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LAUNCHER (TestHelperVariadic_test, "unit common");
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}}} // namespace lib::test::test
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