lumiera_/tests/library/meta/generator-test.cpp
Ichthyostega acc77654d1 clean-up: can now switch remaining downstream usages
after all the relevant library components do support both kinds of
type sequences transparently, any usages in core code can now be
switched over to the new, variadic type sequences.
2025-06-07 01:07:36 +02:00

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/*
Generator(Test) - build an interface + implementation directed by a typelis
Copyright (C)
2008, Hermann Vosseler <Ichthyostega@web.de>
  **Lumiera** is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version. See the file COPYING for further details.
* *****************************************************************/
/** @file generator-test.cpp
** \par what are we doing here??
**
** the following test composes both an interface and the corresponding implementation
** by instantiating "building block" templates over a collection of types. The resulting
** class ends up inheriting a \e virtual function instantiated for each of the types
** in the list. (remember: normally the number and signature of all virtual functions
** need to be absolutely fixed in the class definition)
**
** @see typelist-test.cpp
** @see generator.hpp
** @see lumiera::query::ConfigRules a real world usage example
**
*/
#include "lib/test/run.hpp"
#include "lib/format-string.hpp"
#include "lib/meta/generator.hpp"
#include <iostream>
#include <string>
using util::_Fmt;
using std::string;
using std::cout;
// GCC > 13 warns at class definition when a new overload shadows an inherited virtual function.
// While theoretically correct, this warning is besides the point when an interface is assembled
// by metaprogramming from a chain of template instantiations, driven by a type list
// See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109740
_Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic ignored \"-Woverloaded-virtual\"")
namespace lib {
namespace meta {
namespace test {
/** template for generating lots of different test types */
template<int I>
struct Block
{
static string name;
string talk() { return "__"+name+"__"; }
};
template<int I>
string Block<I>::name = _Fmt("Block<%2i>") % I;
/** Use this building block for assembling an abstract interface */
template<class X>
class TakeIt
{
public:
virtual void eat (X& x) = 0;
virtual ~TakeIt() { }
};
/** Use this building block for chaining corresponding implementation classes. */
template<class X, class BASE>
class DoIt
: public BASE
{
protected:
DoIt () { cout << "ctor DoIt<"<< X::name << " >\n";}
virtual ~DoIt() { cout << "dtor DoIt<"<< X::name << " >\n";}
public:
void eat (X& x) { cout << "devouring" << x.talk() << "\n";}
using BASE::eat; // prevent shadowing
};
using TheTypes = TySeq< Block<1>
, Block<2>
, Block<3>
, Block<5>
, Block<8>
, Block<13>
>::List;
typedef InstantiateForEach<TheTypes,TakeIt> TheInterface;
struct BaseImpl : public TheInterface
{
void eat() { cout << "gulp!\n"; }
};
typedef InstantiateChained<TheTypes,DoIt, BaseImpl> NumberBabbler;
/*********************************************************************//**
* @test check the helpers for dealing with lists-of-types.
* Build an interface and an implementation class
* by inheriting template instantiations
* for a collection of classes</li>
*/
class TypeListGenerator_test : public Test
{
virtual void
run (Arg)
{
NumberBabbler me_can_has_more_numberz;
CHECK (INSTANCEOF (TheInterface, &me_can_has_more_numberz));
TheTypes::Tail::Head b2; // Block<2>
TheTypes::Tail::Tail::Tail::Head b5; // Block<5>
TheTypes::Tail::Tail::Tail::Tail::Tail::Head b13; // Block<13>
me_can_has_more_numberz.eat (b2);
me_can_has_more_numberz.eat (b5);
TakeIt<Block<13>>& subInterface = me_can_has_more_numberz;
subInterface.eat (b13);
me_can_has_more_numberz.eat();
INFO (test, "SizeOf = %zu", sizeof(me_can_has_more_numberz));
}
};
/** Register this test class... */
LAUNCHER (TypeListGenerator_test, "unit common");
}}} // namespace lib::meta::test