lumiera_/tests/library/several-builder-test.cpp
Ichthyostega 89dd35e70d Library: cover handling limits for virtual baseclass scenario
building on the preceding analysis, we can now demonstrate that
the container is initially able to grow, but looses this capability
after accepting one element of unknown subclass type...
2024-06-16 04:22:28 +02:00

367 lines
14 KiB
C++

/*
SeveralBuilder(Test) - building a limited fixed collection of elements
Copyright (C) Lumiera.org
2008, Hermann Vosseler <Ichthyostega@web.de>
2024, 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.
* *****************************************************/
/** @file several-builder-test.cpp
** unit test \ref SeveralBuilder_test
*/
#include "lib/test/run.hpp"
#include "lib/test/testdummy.hpp"
#include "lib/test/test-coll.hpp"
#include "lib/test/test-helper.hpp"
#include "lib/test/diagnostic-output.hpp"////////////////TODO
#include "lib/iter-explorer.hpp"
#include "lib/format-util.hpp"
#include "lib/util.hpp"
#include "lib/several-builder.hpp"
#include <vector>
#include <array>
using ::test::Test;
using std::vector;
using std::array;
using std::rand;
using lib::explore;
using util::isLimited;
using util::isnil;
using util::join;
namespace lib {
namespace test{
namespace { // diagnostic test types
/**
* Instance tracking sub-dummy
* - implements the Dummy interface
* - holds additional storage
* - specific implementation of the virtual operation
* - includes content of the additional storage into the
* checksum calculation, allowing to detect memory corruption
*/
template<uint i>
class Num
: public test::Dummy
{
std::array<int,i> ext_;
public:
Num (uint seed=i)
: Dummy(seed)
{
ext_.fill(seed);
setVal ((i+1)*seed);
}
~Num()
{
setVal (getVal() - explore(ext_).resultSum());
}
long
calc (int ii) override
{
return i+ii + explore(ext_).resultSum();
}
/// allow for move construction
Num (Num && oNum) noexcept
: Num(0)
{
swap (*this, oNum);
}
Num&
operator= (Num && oNum)
{
if (&oNum != this)
swap (*this, oNum);
return *this;
}
friend void
swap (Num& num1, Num& num2) ///< checksum neutral
{
std::swap (static_cast<Dummy&> (num1)
,static_cast<Dummy&> (num2));
std::swap (num1.ext_, num2.ext_);
}
};
/**
* A non-copyable struct with 16bit alignment
* - not trivially default constructible
* - but trivially destructible
*/
struct ShortBlocker
: util::NonCopyable
{
int16_t val{short(1 + (rand() % 1'000))};
};
} // (END) test types
/***************************************************************//**
* @test use lib::Several to establish small collections of elements,
* possibly with sub-classing and controlled allocation.
* - the container is populated through a separate builder
* - the number of elements is flexible during population
* - the actual container allows random-access via base interface
* @see several-builder.hpp
*/
class SeveralBuilder_test : public Test
{
virtual void
run (Arg)
{
simpleUsage();
check_Builder();
check_ErrorHandling();
check_ElementStorage();
check_CustomAllocator();
}
/** @test demonstrate basic behaviour
* @todo WIP 6/24 ✔ define ⟶ ✔ implement
*/
void
simpleUsage()
{
auto elms = makeSeveral({1,1,2,3,5,8,13}).build();
CHECK (elms.size() == 7);
CHECK (elms.back() == 13);
CHECK (elms[3] == 3);
CHECK (join (elms,"-") == "1-1-2-3-5-8-13"_expect);
}
/** @test various ways to build an populate the container
* - with a defined interface type \a I, instances of arbitrary subclasses
* can be added, assuming there is sufficient pre-allocated buffer space;
* all these subclass instances are accessed through the common interface.
* - yet the added elements can also be totally unrelated, in which case an
* *unchecked wild cast* will happen on access; while certainly dangerous,
* this behaviour allows for special low-level data layout tricks.
* - the results from an iterator can be used to populate by copy
* @todo WIP 6/24 ✔ define ⟶ ✔ implement
*/
void
check_Builder()
{
{ // Scenario-1 : Baseclass and arbitrary subclass elements
SeveralBuilder<Dummy> builder;
CHECK (isnil (builder));
builder.emplace<Num<3>>()
.emplace<Num<2>>(1);
CHECK (2 == builder.size());
builder.fillElm(2);
CHECK (4 == builder.size());
builder.fillElm(3, 5);
CHECK (7 == builder.size());
Several<Dummy> elms = builder.build();
CHECK ( isnil(builder));
CHECK (not isnil(elms));
CHECK (7 == elms.size());
CHECK (elms[0].getVal() == (3+1)*3); // indeed a Num<3> with default-seed ≡ 3
CHECK (elms[0].calc(1) == 3 + 1 + (3+3+3)); // indeed called the overridden calc() operation
CHECK (elms[1].getVal() == (2+1)*1); // indeed a Num<2> with seed ≡ 1
CHECK (elms[1].calc(1) == 2 + 1 + (1+1)); // indeed the overridden calc() picking from the Array(1,1)
CHECK (isLimited (1, elms[2].getVal(), 100'000'000)); // indeed a Dummy with default random seed
CHECK (isLimited (1, elms[3].getVal(), 100'000'000)); // and this one too, since we filled in two instances
CHECK (elms[4].getVal() == 5); // followed by tree instances Dummy(5)
CHECK (elms[5].getVal() == 5);
CHECK (elms[6].getVal() == 5);
CHECK (elms[6].calc(1) == 5+1); // indeed invoking the base implementation of calc()
}
{ // Scenario-2 : unrelated element types
SeveralBuilder<uint32_t> builder;
auto urgh = array<char,5>{"Urgh"};
auto phi = (1+sqrtf(5))/2;
builder.append (urgh, phi, -1); // can emplace arbitrary data
CHECK (3 == builder.size());
Several<uint32_t> elms = builder.build(); // WARNING: data accessed by wild cast to interface type
CHECK (3 == elms.size());
CHECK (elms[0] == * reinterpret_cast<const uint32_t*> ("Urgh"));
CHECK (elms[1] == * reinterpret_cast<uint32_t*> (&phi));
CHECK (elms[2] == uint32_t(-1));
}
{ // Scenario-3 : copy values from iterator
SeveralBuilder<int> builder;
VecI seq = getTestSeq_int<VecI> (10);
builder.appendAll (seq);
CHECK (10 == builder.size());
auto elms = builder.build();
CHECK (10 == elms.size());
CHECK (join (elms,"-") == "0-1-2-3-4-5-6-7-8-9"_expect);
}
}
/** @test TODO proper handling of exceptions during population
* - when the container is filled with arbitrary subclasses
* of a base interface with virtual destructor, the first element is used
* to accommodate the storage spread; larger elements or elements of a completely
* different type can not be accommodated and the container can not grow beyond
* the initially allocated reserve (defined to be 10 elements by default).
* - when the container is defined to hold elements of a specific fixed subclass,
* it can be filled with default-constructed instances, and the initial allocation
* can be expanded by move-relocation. Yet totally unrelated elements can not be
* accepted (due to unknown destructor); and when accepting another unspecific
* subclass instance, the ability to grow by move-relocation is lost.
* @todo WIP 6/24 🔁 define ⟶ ✔ implement
*/
void
check_ErrorHandling()
{
{ // Scenario-1 : Baseclass and arbitrary subclass elements
SeveralBuilder<Dummy> builder;
// The first element will _prime_ the container for a suitable usage pattern
builder.emplace<Num<1>>();
CHECK (1 == builder.size());
// Notably the first element established the _spread_ between index positions,
// which effectively limits the size of objects to be added. Moreover, since
// the element type was detected to be non-trivial, we can not correct this
// element spacing by shifting existing allocations (`memmove()` not possible)
CHECK (sizeof(Num<1>) < sizeof(Num<5>));
VERIFY_FAIL ("Unable to place element of type Num<5u> (size="
, builder.emplace<Num<5>>() );
CHECK (1 == builder.size());
// Furthermore, the first element was detected to be a subclass,
// and the interface type `Dummy` has a virtual destructor;
// all added elements must comply to this scheme, once established
VERIFY_FAIL ("Unable to handle (trivial-)destructor for element type long, "
"since this container has been primed to use virtual-baseclass-destructors."
, builder.emplace<long>(55) );
CHECK (1 == builder.size());
// the initial allocation added some reserve buffer space (for 10 elements)
// and we can fill that space with arbitrary subclass instances
builder.fillElm (5);
CHECK (6 == builder.size());
// But the initial allocation can not be increased, since that would require
// a re-allocation of a larger buffer, followed by copying the elements;
// but since the established scheme allows for _arbitrary_ subclasses,
// the builder does not know the exact type for safe element relocation.
VERIFY_FAIL ("Several-container is unable to accommodate further element of type Dummy"
, builder.fillElm (20) );
CHECK (10 == builder.size());
}
{ // Scenario-2 : Baseclass and elements of a single fixed subclass
SeveralBuilder<Dummy, Num<5>> builder;
builder.fillElm(5);
CHECK (5 == builder.size());
// trigger re-alloc by moving into larger memory block
builder.fillElm(14);
CHECK (19 == builder.size());
CHECK (builder.size() > INITIAL_ELM_CNT);
// with the elements added thus far, this instance has been primed to
// rely on a fixed well known element type for move-growth and to use
// the virtual base class destructor for clean-up. It is thus not possible
// to add another element that is not related to this baseclass...
VERIFY_FAIL ("Unable to handle (trivial-)destructor for element type ShortBlocker, "
"since this container has been primed to use virtual-baseclass-destructors."
, builder.emplace<ShortBlocker>() );
CHECK (19 == builder.size());
CHECK (sizeof(ShortBlocker) < sizeof(Num<5>)); // it was not rejected due to size...
// However, a subclass /different than the defined element type/ is acceptable,
// but only to the condition to lock any further container growth by move-reallocation.
// The rationale is that we can still destroy through the virtual base destructor,
// but we aren't able to move elements safely any more, since we don't capture the type.
builder.emplace<Num<1>>();
CHECK (20 == builder.size());
// But here comes the catch: since we choose to accept arbitrary sub-types not identified in detail,
// the container has lost its ability of move-reallocation; with 20 elements the current reserve
// is exhausted and we are now unable to add any further elements beyond that point.
VERIFY_FAIL ("unable to move elements of mixed unknown detail type, which are not trivially movable"
, builder.fillElm(5); );
// the container is still sound however
auto elms = builder.build();
CHECK (20 == elms.size());
// verify that member fields were not corrupted
for (uint i=0; i<=18; ++i)
CHECK (elms[i].calc(i) == 5 + i + (5+5+5+5+5));
CHECK (elms.back().calc(0) == 1 + 0 + (1));
}
}
/** @test TODO verify correct placement of instances within storage
* @todo WIP 6/24 🔁 define ⟶ implement
*/
void
check_ElementStorage()
{
}
/** @test TODO demonstrate integration with a custom allocator
* @todo WIP 6/24 🔁 define ⟶ implement
*/
void
check_CustomAllocator()
{
}
};
/** Register this test class... */
LAUNCHER (SeveralBuilder_test, "unit common");
}} // namespace lib::test