#include <CRingSelectionPredicate.h>
class CRingSelectionPredicate {CRingSelectionPredicate();CRingSelectionPredicate(unsigned int nType, uint32_t* types);CRingSelectionPredicate(unsigned int nType, uint32_t* type, bool* sample);CRingSelectionPredicate(const CRingSelectionPredicate& rhs);virtual ~CRingSelectionPredicate();CRingSelectionPredicate& operator=(const CRingSelectionPredicate& rhs);const int operator==(const CRingSelectionPredicate& rhs);const int operator!=(const CRingSelectionPredicate& rhs);virtual bool operator()(CRingBuffer& ring);virtual = 0 bool selectThis(uint32_t type);void selectItem(CRingBuffer& ring);protected void addSelectionItem(uint32_t type, bool sample = false);protected SelectionMapIterator find(uint32_t type);protected SelectionMapIterator end();protected uint32_t longswap(uint32_t input);protected void addSelectionItems(std::vector<ItemType> selections);}
CRingSelectionPredicate is an abstract base
class that can be subclassed to create specific predicates to selectively
grab items from a ring buffer via
CRingItem::getFromRing.
The base class provides a set of item types and flags, and functions
to maintain that set. The meaning of those are up to the specific concrete
predicate. The operator() is provided that
is sufficient for predicates that treat the flag as a request to
sample data of that type by checking if a type is acceptable or not
via the pure virtual function selectThis.
CRingSelectionPredicate();
Default constructor for a the base class, the list of type/flag pairs remains empty.
CRingSelectionPredicate(unsigned int nType, uint32_t* types);
Constructs the base class with
nType type/flag pairs where
types is an array of types and all of
the flags are set to be false.
CRingSelectionPredicate(unsigned int nType, uint32_t* type, bool* sample);
Constructs a base class as above, however the state of the
flag that corresponds to each type
is specfied in the corresponding element of sample.
CRingSelectionPredicate(const CRingSelectionPredicate& rhs);
Provides support for copy construction of an object derived
from CRingSelectionPredicate by copying the
type/flag pairs from rhs.
CRingSelectionPredicate& operator=(const CRingSelectionPredicate& rhs);
Provides support for assignment in selection predicates, by
assigning the type/flag set of rhs to
those of the object.
const int operator==(const CRingSelectionPredicate& rhs);
Provides support for equality comparison of
selection predicates by comparing the type/flag pairs of
rhs to those of the object.
const int operator!=(const CRingSelectionPredicate& rhs);
Provides support for inequality comparisons of selection predicates by comparing for equality and returning the boolean inverse of the result.
virtual bool operator()(CRingBuffer& ring);
Provides a default predicate call for
CRingBuffer::blockWhile.
The default action is to block until an item is in the ring.
when an item is in the ring, its type is retrieved and passed to
selectThis. If that function returns
true the item is skipped. If
false is returned, and either the item type
is not in the item list or is in the item list but with its flag
false, then false is returned, ending the
block and allowing the caller to retrieve the selected item.
If the item is in the list an has a true flag, the item is skipped
if it is not the most recently inserted item in the ring, otherwise
blocking is terminated.
virtual = 0 bool selectThis(uint32_t type);
This is a pure virtual member that must be implemented by
concrete classes. type is the item type
of an item in the ring buffer. The function should return
true to skip the item,and
false if the item is of an acceptable type.
See, however the description of
operator()
to see how that item type's flag can modify the interpretation
of this return value.
void selectItem(CRingBuffer& ring);
This member function interacts with the ring buffer
ring to block the caller, skipping
items inserted in the ring until one that matches the predicate
is available.
Normally, this is intended to be called from
CRingItem::getFromRing.
Protected member functions are utilities that area
available to derived classes. Note that since the
CRingSelectionPredicate class is
an abstract base class, there can never be instances of it.
protected void addSelectionItem(uint32_t type, bool sample = false);
Adds an item type and sample
flag to the set of type/flag pairs maintained by this base class.
As the actual interpretation of this list is partially up to
the selectThis method, this is not exposed
to the public. Concrete class implementations are expected to provide
an appropriately named member function that delegates to this.
protected SelectionMapIterator find(uint32_t type);
Locates type in the list of type/flag pairs.
Returns a pointer like object SelectionMapIterator.
This 'points' to a std::pair<uint32_t, ItemType>.
If the item is not found, the iterator will compare as
== to the value returned from
end.
protected SelectionMapIterator end();
Returns the value that find returns if
the item type searched for is not found.
protected uint32_t longswap(uint32_t input);
Swaps bytes in the longword input and
returns the result.
protected void addSelectionItems(std::vector<ItemType> selections);
Calls addSelectionItem once for each item
in selections.
While the class does not export any public data or data types,
it does provide several protected data types that are important
to know about if you are deriving a class from
CRingSelectionPredicate. All of the type
names are in the scope of CRingSelectionPredicate::.
ItemType
This is the structure that holds type/value pairs.
It contains the fields
s_sampled, which is the flag, and
s_itemType, which is the item
type.
While s_sampled is intended
to convey that tiems of that s_itemType
should be sampled, this is not required if the concrete class
overrides operator()
This struct supports equality and inequality comparision.
This is a typedef for std::map<uint32_t, ItemType>.
This is a typedef for SelectionMap::iterator.