finish ScopedCollection (closes #877)

This commit is contained in:
Fischlurch 2012-01-05 23:17:16 +01:00
parent 72e8d22454
commit e5c42e05e6
3 changed files with 294 additions and 89 deletions

View file

@ -29,8 +29,35 @@
** The storage holding all those child objects is allocated in one chunk
** and never adjusted.
**
** - TODO: retro-fit with RefArray interface
** \par usage patterns
** The common ground for all usage of this container is to hold and some
** with exclusive ownership; when the enclosing container goes out of scope,
** all the dtors of the embedded objects will be invoked. Frequently this
** side effect is the reason for using the container: we want to own some
** resource handles to be available exactly as long as the managing object
** needs and accesses them.
**
** There are two different usage patterns for populating a ScopedCollection
** - the "stack style" usage creates an empty container (using the one arg
** ctor just to specify the maximum size). The storage to hold up to this
** number of objects is (heap) allocated right away, but no objects are
** created. Later on, individual objects are "pushed" into the collection
** by invoking #appendNewElement() to create a new element of the default
** type I) or #appendNew<Type>(args) to create some subtype. This way,
** the container is being filled successively.
** - the "RAII style" usage strives to create all of the content objects
** right away, immediately after the memory allocation. This usage pattern
** avoids any kind of "lifecylce state". Either the container comes up sane
** and fully populated, or the ctor call fails and any already created
** objects are discarded.
** @note intentionally there is no operation to discard individual objects,
** all you can do is to #clear() the whole container.
** @note the container can hold instances of a subclass of the type defined
** by the template parameter I. But you need to ensure in this case
** that the defined buffer size for each element (2nt template parameter)
** is sufficient to hold any of these subclass instances. This condition
** is protected by a static assertion (compilation failure).
** @warning when using subclasses, a virtual dtor is mandatory
** @warning deliberately \em not threadsafe
**
** @see ScopedCollection_test
@ -52,6 +79,8 @@
#include <boost/noncopyable.hpp>
#include <boost/scoped_array.hpp>
#include <boost/static_assert.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/type_traits/is_base_of.hpp>
namespace lib {
@ -87,7 +116,7 @@ namespace lib {
class ElementHolder
: boost::noncopyable
{
mutable char buf_[siz];
public:
@ -107,9 +136,13 @@ namespace lib {
/** Abbreviation for placement new */
#define TYPE_SANITY_CHECK \
BOOST_STATIC_ASSERT ((boost::is_base_of<I,TY>::value || boost::is_same<I,TY>::value))
/** Abbreviation for placement new */
#define EMBEDDED_ELEMENT_CTOR(_CTOR_CALL_) \
BOOST_STATIC_ASSERT (siz >= sizeof(TY));\
TYPE_SANITY_CHECK; \
return *new(&buf_) _CTOR_CALL_; \
@ -178,6 +211,7 @@ namespace lib {
EMBEDDED_ELEMENT_CTOR ( TY(a1,a2,a3,a4,a5) )
}
#undef EMBEDDED_ELEMENT_CTOR
#undef TYPE_SANITY_CHECK
};
@ -197,6 +231,13 @@ namespace lib {
, elements_(new ElementHolder[maxElements])
{ }
/** creating a ScopedCollection in RAII-style:
* The embedded elements will be created immediately.
* Ctor fails in case of any error during element creation.
* @param builder functor to be invoked for each "slot".
* It gets an ElementHolder& as parameter, and should
* use this to create an object of some I-subclass
*/
template<class CTOR>
ScopedCollection (size_t maxElements, CTOR builder)
: level_(0)
@ -216,6 +257,22 @@ namespace lib {
throw;
} }
/* == some pre-defined Builders == */
class FillAll; ///< fills the ScopedCollection with default constructed I-instances
template<typename TY>
class FillWith; ///< fills the ScopedCollection with default constructed TY-instances
template<typename IT>
class PullFrom; ///< fills by copy-constructing values pulled from the iterator IT
template<typename IT>
static PullFrom<IT>
pull (IT iter) ///< convenience shortcut to pull from any given Lumiera Forward Iterator
{
return PullFrom<IT> (iter);
}
void
clear()
@ -437,5 +494,71 @@ namespace lib {
/* === Supplement: pre-defined element builders === */
/** \par usage
* Pass an instance of this builder functor as 2nd parameter
* to ScopedCollections's ctor. (an anonymous instance is OK).
* Using this variant of the compiler switches the collection to RAII-style:
* It will immediately try to create all the embedded objects, invoking this
* builder functor for each "slot" to hold such an embedded object. Actually,
* this "slot" is an ElementHolder instance, which provides functions for
* placement-creating objects into this embedded buffer.
*/
template<class I, size_t siz>
class ScopedCollection<I,siz>::FillAll
{
public:
void
operator() (typename ScopedCollection<I,siz>::ElementHolder& storage)
{
storage.template create<I>();
}
};
template<class I, size_t siz>
template<typename TY>
class ScopedCollection<I,siz>::FillWith
{
public:
void
operator() (typename ScopedCollection<I,siz>::ElementHolder& storage)
{
storage.template create<TY>();
}
};
/** \par usage
* This variant allows to "pull" elements from an iterator.
* Actually, the collection will try to create each element right away,
* by invoking the copy ctor and passing the value yielded by the iterator.
* @note anything in accordance to the Lumera Forward Iterator pattern is OK.
* This rules out just passing a plain STL iterator (because these can't
* tell for themselves when they're exhausted). Use an suitable iter-adapter
* instead, e.g. by invoking lib::iter_stl::eachElm(stl_container)
*/
template<class I, size_t siz>
template<typename IT>
class ScopedCollection<I,siz>::PullFrom
{
IT iter_;
typedef typename iter::TypeBinding<IT>::value_type ElementType;
public:
PullFrom (IT source)
: iter_(source)
{ }
void
operator() (typename ScopedCollection<I,siz>::ElementHolder& storage)
{
storage.template create<ElementType> (*iter_);
++iter_;
}
};
} // namespace lib
#endif

View file

@ -617,7 +617,7 @@ out: ^\.throw some exceptions...
END
PLANNED "Managed Collection (I)" ScopedCollection_test <<END
TEST "Managed Collection (I)" ScopedCollection_test <<END
return: 0
END

View file

@ -67,8 +67,20 @@ namespace test{
if (trigger == getVal())
throw new error::Fatal ("Subversive Bomb", LUMIERA_ERROR_SUBVERSIVE);
}
SubDummy()
: Dummy()
, trigger_(-1)
{ }
};
inline uint
sum (uint n)
{
return n*(n+1) / 2;
}
}//(End) subversive test data
@ -97,6 +109,8 @@ namespace test{
building_RAII_Style();
building_StackStyle();
iterating();
verify_defaultPopulator();
verify_iteratorPopulator();
}
@ -178,90 +192,6 @@ namespace test{
}
CHECK (0 == Dummy::checksum());
}
/** Functor to populate the Collection */
class Populator
{
uint i_;
int off_;
int trigg_;
public:
Populator (int baseOffset, int triggerCode)
: i_(0)
, off_(baseOffset)
, trigg_(triggerCode)
{ }
void
operator() (CollD::ElementHolder& storage)
{
switch (i_ % 2)
{
case 0:
storage.create<Dummy> (i_+off_);
break;
case 1:
storage.create<SubDummy> (i_+off_, trigg_);
break;
}
++i_;
}
};
/** @test using the ScopedCollection according to the RAII pattern.
* For this usage style, the collection is filled right away, during
* construction. If anything goes wrong, the whole collection is
* cleared and invalidated. Consequently there is no tangible "lifecycle"
* at the usage site. Either the collection is fully usable, or not at all.
* This requires the client to provide a functor (callback) to define
* the actual objects to be created within the ScopedCollection. These
* may as well be subclasses of the base type I, provided the general
* element storage size #siz was chosen sufficiently large to hold
* those subclass instances.
*
* This test demonstrates the most elaborate usage pattern, where
* the client provides a full blown functor object, which even
* has embedded state. But, generally speaking, anything
* exposing a suitable function call operator is acceptable.
*/
void
building_RAII_Style()
{
CHECK (0 == Dummy::checksum());
{
int rr = rand() % 100;
int trigger = 101;
CollD coll (6, Populator(rr, trigger));
CHECK (!isnil (coll));
CHECK (6 == coll.size());
CHECK (0 != Dummy::checksum());
CHECK (coll[0].acc(0) == 0 + rr);
CHECK (coll[1].acc(0) == 1 + rr + trigger);
CHECK (coll[2].acc(0) == 2 + rr);
CHECK (coll[3].acc(0) == 3 + rr + trigger);
CHECK (coll[4].acc(0) == 4 + rr);
CHECK (coll[5].acc(0) == 5 + rr + trigger);
coll.clear();
CHECK (0 == Dummy::checksum());
// Verify Error handling while in creation:
// SubDummy explodes on equal ctor parameters
// which here happens for i==7
VERIFY_ERROR (SUBVERSIVE, CollD(10, Populator(0, 7)) );
// any already created object was properly destroyed
CHECK (0 == Dummy::checksum());
}
CHECK (0 == Dummy::checksum());
}
/** @test using the ScopedCollection to hold a variable
@ -335,9 +265,161 @@ namespace test{
}
CHECK (0 == Dummy::checksum());
}
/** @test using the ScopedCollection according to the RAII pattern.
* For this usage style, the collection is filled right away, during
* construction. If anything goes wrong, the whole collection is
* cleared and invalidated. Consequently there is no tangible "lifecycle"
* at the usage site. Either the collection is fully usable, or not at all.
* This requires the client to provide a functor (callback) to define
* the actual objects to be created within the ScopedCollection. These
* may as well be subclasses of the base type I, provided the general
* element storage size #siz was chosen sufficiently large to hold
* those subclass instances.
*
* This test demonstrates the most elaborate usage pattern, where
* the client provides a full blown functor object #Populator,
* which even has embedded state. Generally speaking, anything
* exposing a suitable function call operator is acceptable.
*/
void
building_RAII_Style()
{
CHECK (0 == Dummy::checksum());
{
int rr = rand() % 100;
int trigger = 101;
CollD coll (6, Populator(rr, trigger));
CHECK (!isnil (coll));
CHECK (6 == coll.size());
CHECK (0 != Dummy::checksum());
CHECK (coll[0].acc(0) == 0 + rr);
CHECK (coll[1].acc(0) == 1 + rr + trigger);
CHECK (coll[2].acc(0) == 2 + rr);
CHECK (coll[3].acc(0) == 3 + rr + trigger);
CHECK (coll[4].acc(0) == 4 + rr);
CHECK (coll[5].acc(0) == 5 + rr + trigger);
coll.clear();
CHECK (0 == Dummy::checksum());
// Verify Error handling while in creation:
// SubDummy explodes on equal ctor parameters
// which here happens for i==7
VERIFY_ERROR (SUBVERSIVE, CollD(10, Populator(0, 7)) );
// any already created object was properly destroyed
CHECK (0 == Dummy::checksum());
}
CHECK (0 == Dummy::checksum());
}
/** Functor to populate the Collection */
class Populator
{
uint i_;
int off_;
int trigg_;
public:
Populator (int baseOffset, int triggerCode)
: i_(0)
, off_(baseOffset)
, trigg_(triggerCode)
{ }
void
operator() (CollD::ElementHolder& storage)
{
switch (i_ % 2)
{
case 0:
storage.create<Dummy> (i_+off_);
break;
case 1:
storage.create<SubDummy> (i_+off_, trigg_);
break;
}
++i_;
}
};
/** @test for using ScopedCollection in RAII style,
* several pre-defined "populators" are provided.
* The most obvious one being just to fill the
* collection with default constructed objects.
*/
void
verify_defaultPopulator()
{
CHECK (0 == Dummy::checksum());
CollD coll (25, CollD::FillAll() );
CHECK (!isnil (coll));
CHECK (25 == coll.size());
CHECK (0 != Dummy::checksum());
for (CollD::iterator ii = coll.begin(); ii; ++ii)
{
CHECK ( INSTANCEOF (Dummy, & (*ii)));
CHECK (!INSTANCEOF (SubDummy, & (*ii)));
}
}
void
verify_subclassPopulator()
{
CHECK (0 == Dummy::checksum());
CollD coll (25, CollD::FillWith<SubDummy>() );
CHECK (!isnil (coll));
CHECK (25 == coll.size());
CHECK (0 != Dummy::checksum());
for (CollD::iterator ii = coll.begin(); ii; ++ii)
CHECK (INSTANCEOF (SubDummy, & (*ii)));
}
void
verify_iteratorPopulator()
{
typedef ScopedCollection<uint> CollI;
CollI source (25);
for (uint i=0; i < source.capacity(); ++i)
source.appendNew<uint>(i); // holding the numbers 0..24
CollI coll (20, CollI::pull(source.begin()));
// this immediately pulls in the first 20 elements
CHECK (!isnil (coll));
CHECK (20 == coll.size());
CHECK (25 == source.size());
for (uint i=0; i < coll.size(); ++i)
{
CHECK (coll[i] == i );
CHECK (coll[i] == source[i]);
}
// note: the iterator is assumed to deliver a sufficient amount of elements
VERIFY_ERROR (ITER_EXHAUST, CollI (50, CollI::pull (source.begin())));
}
};
LAUNCHER (ScopedCollection_test, "unit common");