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LUMIERA.clone/tests/library/meta/access-casted-test.cpp
Ichthyostega 6998e04f87 verify all invalid cases are spotted by the compiler 
NOTE: this was a one-time verification. Unfortunately there is no way
to verify a failing compilation automatically from a unit-test.
Thus we need to comment out these invalid cases, leaving them
here just for later referral. Need to check those manually
for new compilers to be sure!
2015-04-26 03:17:41 +02:00

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/*
AccessCasted(Test) - verify helper to cast or convert as appropriate
Copyright (C) Lumiera.org
2008, Hermann Vosseler <Ichthyostega@web.de>
This program 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.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
* *****************************************************/
#include "lib/test/run.hpp"
#include "lib/test/test-helper.hpp"
#include "lib/access-casted.hpp"
#include <iostream>
#include <utility>
#include <string>
using std::move;
using std::string;
using std::ostream;
using std::cout;
using std::endl;
using lumiera::error::LUMIERA_ERROR_BOTTOM_VALUE;
namespace util {
namespace test {
namespace { // Test fixture...
struct B {};
struct D : B {};
struct E : D
{
virtual ~E() {};
};
struct F : E {};
using lib::test::tyAbbr;
ostream& operator<< (ostream& s, const B& b) { return s << "B{} adr="<<&b<<" type: "<<tyAbbr(b); }
ostream& operator<< (ostream& s, const D& d) { return s << "D{} adr="<<&d<<" type: "<<tyAbbr(d); }
ostream& operator<< (ostream& s, const E& e) { return s << "E{} adr="<<&e<<" type: "<<tyAbbr(e); }
ostream& operator<< (ostream& s, const F& f) { return s << "F{} adr="<<&f<<" type: "<<tyAbbr(f); }
}//(End)Test fixture
/*************************************************************************************************//**
* @test verify a helper template for accessing values either through conversion or (dynamic) downcast.
* Typically, this helper is used in value holder containers or variant-like data structures,
* where the actual type is given at instantiation time of the template and possibly erased.
*/
class AccessCasted_test : public Test
{
virtual void
run (Arg)
{
D d;
D* pD =&d;
B* pB =pD;
D& rD = *pD;
B& rB = *pB;
D*& rpD = pD;
B*& rpB = pB;
F f;
E& rE = f;
E* pE = &f;
D* pDE = pE;
cout << "can_downcast<B,D> = " << can_downcast<B,D>::value <<endl;
cout << "can_downcast<B*,D*> = " << can_downcast<B*,D*>::value <<endl;
cout << "can_downcast<B&,D&> = " << can_downcast<B&,D&>::value <<endl;
cout << "can_downcast<B&,D*> = " << can_downcast<B&,D*>::value <<endl;
cout << "can_downcast<B*,D&> = " << can_downcast<B*,D&>::value <<endl;
cout << "can_downcast<B*&,D*&> = " << can_downcast<B*&,D*&>::value <<endl;
cout << "can_downcast<D*&,D*&> = " << can_downcast<D*&,D*&>::value <<endl;
cout << "can_downcast<D*,E*> = " << can_downcast<D*,E*>::value <<endl;
cout << "can_downcast<E*,F*> = " << can_downcast<E*,F*>::value <<endl;
cout << "has_RTTI<D*> = " << has_RTTI<D*>::value <<endl;
cout << "has_RTTI<E*> = " << has_RTTI<E*>::value <<endl;
cout << "has_RTTI<F*> = " << has_RTTI<F*>::value <<endl;
cout << "is_convertible<D,D&> = " << std::is_convertible<D,D&>::value <<endl;
cout << "is_convertible<D&,D> = " << std::is_convertible<D&,D>::value <<endl;
cout << "can_use_dynamic_downcast<D,D&> = " << can_use_dynamic_downcast<D,D&>::value <<endl;
cout << "can_use_conversion<D,D&> = " << can_use_conversion<D,D&>::value <<endl;
cout << "can_use_dynamic_downcast<B*,D*> = " << can_use_dynamic_downcast<B*,D*>::value <<endl;
cout << "can_use_conversion<D*,B*> = " << can_use_conversion<D*,B*>::value <<endl;
cout << "can_use_dynamic_downcast<D*&,D*&> = " << can_use_dynamic_downcast<D*&,D*&>::value <<endl;
cout << "can_use_conversion<D*&,D*&> = " << can_use_conversion<D*&,D*&>::value <<endl;
cout << "can_use_conversion<D*,E*> = " << can_use_conversion<D*,E*>::value <<endl;
cout << "can_use_dynamic_downcast<D*&,E*> = " << can_use_dynamic_downcast<D*&,E*>::value <<endl;
cout << "=== standard case: References ==="<<endl;
cout << "Access(D as D&) --->" << AccessCasted<D&>::access(d) <<endl;
cout << "Access(D& as D&) --->" << AccessCasted<D&>::access(rD) <<endl;
D dd1(d);
// AccessCasted<D&>::access(move(dd1)); // does not compile since it would be dangerous; we can't take a l-value ref
// AccessCasted<D&&>::access(rD); // from a r-value (move) reference and we can't move a l-value ref
// AccessCasted<D&&>::access(d); //
cout << "=== build a value object ==="<<endl;
cout << "Access(D as D) --->" << AccessCasted<D>::access(d) <<endl;
cout << "Access(D& as D) --->" << AccessCasted<D>::access(rD) <<endl;
cout << "Access(D&& as D) --->" << AccessCasted<D>::access(move(dd1)) <<endl;
cout << "=== take a pointer ==="<<endl;
cout << "Access(D as D*) --->" << AccessCasted<D*>::access(d) <<endl;
cout << "Access(D& as D*) --->" << AccessCasted<D*>::access(rD) <<endl;
// AccessCasted<D*>::access(move(dd1)); // should not take value moved by r-value-ref as pointer, otherwise the moved object would be lost
cout << "=== dereference a pointer ==="<<endl;
cout << "Access(D* as D&) --->" << AccessCasted<D&>::access(pD) <<endl;
cout << "Access(D* as D) --->" << AccessCasted<D>::access(pD) <<endl;
D* pdd1(pD);
cout << "Access(D*&& as D) --->" << AccessCasted<D>::access(move(pdd1)) <<endl;
D* pNull(0);
VERIFY_ERROR(BOTTOM_VALUE, AccessCasted<D>::access(pNull)); // run-time NULL check
// AccessCasted<D&&>::access(pD); // should not move away a value accessed through a pointer, there might be other users
cout << "=== const correctness ==="<<endl;
cout << "Access(D as D const&) --->" << AccessCasted<D const&>::access(d) <<endl;
cout << "Access(D& as D const&) --->" << AccessCasted<D const&>::access(rD) <<endl;
cout << "Access(D as const D) --->" << AccessCasted<const D>::access(d) <<endl;
cout << "Access(D& as const D) --->" << AccessCasted<const D>::access(rD) <<endl;
cout << "Access(D as const D*) --->" << AccessCasted<const D*>::access(d) <<endl;
cout << "Access(D& as const D*) --->" << AccessCasted<const D*>::access(rD) <<endl;
cout << "Access(D* as D const&) --->" << AccessCasted<D const&>::access(pD) <<endl;
cout << "Access(D* as const D) --->" << AccessCasted<const D>::access(pD) <<endl;
const D cD(d);
D const& rcD(d);
const D* pcD(&cD);
cout << "Access(const D as D const&) --->" << AccessCasted<D const&>::access(cD) <<endl;
cout << "Access(D const& as D const&) --->" << AccessCasted<D const&>::access(rcD) <<endl;
cout << "Access(const D as const D) --->" << AccessCasted<const D>::access(cD) <<endl;
cout << "Access(D const& as const D) --->" << AccessCasted<const D>::access(rcD) <<endl;
cout << "Access(const D as const D*) --->" << AccessCasted<const D*>::access(cD) <<endl;
cout << "Access(D const& as const D*) --->" << AccessCasted<const D*>::access(rcD) <<endl;
cout << "Access(const D* as D const&) --->" << AccessCasted<D const&>::access(pcD) <<endl;
cout << "Access(const D* as const D) --->" << AccessCasted<const D>::access(pcD) <<endl;
cout << "Access(D const& as D) --->" << AccessCasted<D>::access(rcD) <<endl; // it's OK to construct a new (non-const) object from const ref
const D cD1(cD); // likewise it's OK to construct from move-ref. Actually, we're not
cout << "Access(D const&& as D) --->" << AccessCasted<D>::access(move(cD1)) <<endl; // moving anything, but it's up to the receiving ctor to prevent that
// AccessCasted<D&>::access(rcD); // normal ref from const ref is not const correct
// AccessCasted<D*>::access(rcD); // likewise, regular pointer from const ref prohibited
// AccessCasted<D&>::access(pcD); // likewise, regular ref from pointer-to-const
// AccessCasted<D*>::access(pcD); // and regular pointer from pointer-to-const
// AccessCasted<D&&>::access(rcD); // ruled out already because moving a reference is invalid
// AccessCasted<D&&>::access(pcD); // ruled out already because moving a dereferenced pointer is invalid
// AccessCasted<D&>::access(move(cD)); // ruled out already because taking reference from moved value is invalid
// AccessCasted<D*>::access(move(cD)); // and same for taking pointer from a moved value.
cout << "=== work cases: actual conversions ==="<<endl;
// cout << "Access(B& as D&) --->" << AccessCasted<D&>::access(rB) <<endl;
// cout << "Access(D* as D*) --->" << AccessCasted<D*>::access(pD) <<endl;
// cout << "Access(B* as D*) --->" << AccessCasted<D*>::access(pB) <<endl;
// cout << "Access(D*& as D*&) --->" << AccessCasted<D*&>::access(rpD) <<endl;
// cout << "Access(B*& as D*&) --->" << AccessCasted<D*&>::access(rpB) <<endl;
//
// cout << "Access(D as B&) --->" << AccessCasted<B&>::access(d) <<endl;
// cout << "Access(D& as B&) --->" << AccessCasted<B&>::access(rD) <<endl;
// cout << "Access(B& as B&) --->" << AccessCasted<D&>::access(rB) <<endl;
// cout << "Access(D* as B*) --->" << AccessCasted<B*>::access(pD) <<endl;
// cout << "Access(B* as B*) --->" << AccessCasted<B*>::access(pB) <<endl;
// cout << "Access(D*& as B*&) --->" << AccessCasted<B*&>::access(rpD) <<endl;
// cout << "Access(B*& as B*&) --->" << AccessCasted<B*&>::access(rpB) <<endl;
//
// cout << "Access(D as E&) --->" << AccessCasted<E&>::access(d) <<endl;
// cout << "Access(E& as F&) --->" << AccessCasted<F&>::access(rE) <<endl;
// cout << "Access(D(E)* as E*) --->" << AccessCasted<E*>::access(pDE) <<endl;
// cout << "Access(D(E)* as F*) --->" << AccessCasted<F*>::access(pDE) <<endl;
// cout << "Access(E* as F*) --->" << AccessCasted<F*>::access(pE) <<endl;
}
};
/** Register this test class... */
LAUNCHER (AccessCasted_test, "unit common");
}} // namespace lib::meta::test
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