Oracle Coherence for C++ API
Release 3.7.1.0

E22845-01

WrapperCollections::AbstractWrapperEntry Class Reference

#include <coherence/util/WrapperCollections.hpp>

Inherits Object, and Map::Entry.

Inherited by ConverterCollections::ConverterEntry, and TypedCollections::TypedEntry.

List of all members.


Detailed Description

Map::Entry implementation which delegates all calls to another Map::Entry.
 

Public Types

typedef spec::Handle Handle
 AbstractWrapperEntry Handle definition.
typedef spec::View View
 AbstractWrapperEntry View definition.
typedef spec::Holder Holder
 AbstractWrapperEntry Holder definition.

Public Member Functions

virtual Object::View getKey () const
 Return the key corresponding to this entry.

Returns:
the key corresponding to this entry.
virtual Object::Holder getValue () const
 Return the value corresponding to this entry.

Returns:
the value corresponding to this entry.
virtual Object::Holder getValue ()
 Return the value corresponding to this entry.

Returns:
the value corresponding to this entry.
virtual Object::Holder setValue (Object::Holder ohValue)
 Update the value corresponding to this entry.

Parameters:
 ohValue the new value for the entry
Returns:
the prior value
virtual void toStream (std::ostream &out) const
 Output a human-readable description of this Object to the given stream.

coherence::lang::operator<<(std::ostream, Object::View) is defined and will call into the toStream method, to output Objects. If a managed String object is desired, the COH_TO_STRING macro can be used to build up a String from streamable contents.

 Object::View vKey   = ...
 Object::View vValue = ...
 std::cout << vKey << " = " << vValue << std::endl;

 String::Handle hs = COH_TO_STRING(vKey << " = " << vValue);

Parameters:
 out the stream used to output the description
virtual size32_t hashCode () const
 Return a hash code value for the Object.

This method is supported for the benefit of hash-based containers.

The general contract of hashCode is:

  • Whenever it is invoked on the same Object more than once during an execution of an application, the hashCode method must consistently return the same value, provided no information used in equals comparisons on the object is modified. This value need not remain consistent from one execution of an application to another execution of the same application.
  • If two Objects are equal according to the equals method, then calling the hashCode method on each of the two Objects must produce the same value.
  • It is not required that if two Objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct results. However, the programmer should be aware that producing distinct results for unequal objects may improve the performance of hash-based containers.

The default implementation is identity based.

Returns:
a hash code value for this Object
virtual bool equals (Object::View v) const
  
virtual bool isImmutable () const
 Return true iff no further changes can be made to the Object, that would effect the outcome of a call to its equals method.

Except for Objects which are naturally immutable (such as String), being immutable generally implies that the Object is only referenced via const pointers or views. Objects which hold references to child Objects, may need to take the immutability of their children into account when determining their own immutability.

This extended check is not performed by the default implementation, but can be integrated into the immutability checks by overriding this method, as well as making use of MemberHandles to reference child Objects.

A typical derived implementation may look as follows:

 bool isImmutable() const
     {
     if (m_fImmutable) // check recorded state
         {
         return true; // already marked as immutable, avoid calculation
         }
     else if (Object::isImmutable()) // ensure shallow immutability
         {
         // ensure deep immutability
         if (m_child1->isImmutable() && m_child2->isImmutable() ...
                                     && m_childN->isImmutable())
             {
             // record and return immutability
             return m_fImmutable = true;
             }
         // some Objects which comprise this Object are still mutable
         }
     return false;
     }
 

The default implementation return true iff the Object is only referenced via const pointers and or views.

Returns:
true iff the Object is immutable

Protected Member Functions

 AbstractWrapperEntry (Map::Entry::Holder ohEntryDelegate)
 Create an AbstractWrapperEntry which delegates to the specified Map::Entry.
 AbstractWrapperEntry (const AbstractWrapperEntry &that)
 Copy constructor.
virtual
Map::Entry::Handle 
getDelegate ()
 Return a handle to the delegate.
virtual Map::Entry::View getDelegate () const
 Return a view to the delegate.

Constructor & Destructor Documentation

AbstractWrapperEntry ( Map::Entry::Holder  ohEntryDelegate  )  [protected]

Create an AbstractWrapperEntry which delegates to the specified Map::Entry.

Parameters:
 ohEntryDelegate the Entry to delegate to


Member Function Documentation

virtual Map::Entry::Handle getDelegate (  )  [protected, virtual]

Return a handle to the delegate.

Returns:
the delegate handle
Exceptions:
 UnsupportedOperationException if the delegate is a view

virtual Map::Entry::View getDelegate (  )  const [protected, virtual]

Return a view to the delegate.

Returns:
the delegate view


The documentation for this class was generated from the following file:
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