Class AbstractExtractor

Abstract base for IValueExtractor implementations.

Inheritance

object

AbstractExtractor

AbstractCompositeExtractor

ConditionalExtractor

EntryExtractor

IdentityExtractor

KeyExtractor

PofExtractor

ReflectionExtractor

UniversalExtractor

Implements

IValueExtractor

IQueryCacheComparer

IComparer

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Tangosol.Util.Extractor

Assembly: Coherence.dll

Syntax

public abstract class AbstractExtractor : IValueExtractor, IQueryCacheComparer, IComparer

Remarks

It provides common functionality that allows any extending extractor to be used as a value Comparer.

Starting with Coherence 3.5, when used to extract information that is coming from a ICache, subclasses have the additional ability to operate against the ICacheEntry instead of just the value. In other words, like the EntryExtractor class, this allows an extractor implementation to extract a desired value using all available information on the corresponding ICacheEntry object and is intended to be used in advanced custom scenarios, when application code needs to look at both key and value at the same time or can make some very specific assumptions regarding to the implementation details of the underlying Entry object. To maintain full backwards compatibility, the default behavior remains to extract from the Value property of the ICacheEntry.

Note: Subclasses are responsible for initialization and POF and/or Lite serialization of the m_target field.

Fields

KEY

Indicates that the ExtractFromEntry(ICacheEntry) operation should use the Entry's value.

Declaration

public static readonly int KEY

Field Value

Type	Description
int

VALUE

Indicates that the ExtractFromEntry(ICacheEntry) operation should use the Entry's value.

Declaration

public static readonly int VALUE

Field Value

Type	Description
int

m_target

Specifies which part of the entry should be used by the ExtractFromEntry(ICacheEntry) operation. Legal values are VALUE (default) or KEY.

Declaration

protected int m_target

Field Value

Type	Description
int

Remarks

Subclasses are responsible for initialization and POF and/or Lite serialization of this field.

Properties

Target

The target of the extractor.

Declaration

public int Target { get; }

Property Value

Type	Description
int

Methods

Compare(object, object)

Compares its two arguments for order.

Declaration

public virtual int Compare(object o1, object o2)

Parameters

Type	Name	Description
object	o1	The first object to be compared.
object	o2	The second object to be compared.

Returns

Type	Description
int	A negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

Remarks

Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second. null values are evaluated as "less then" any non-null value.

CompareEntries(IQueryCacheEntry, IQueryCacheEntry)

Compare two entries.

Declaration

public virtual int CompareEntries(IQueryCacheEntry entry1, IQueryCacheEntry entry2)

Parameters

Type	Name	Description
IQueryCacheEntry	entry1	The first entry to compare values from; read-only.
IQueryCacheEntry	entry2	The second entry to compare values from; read-only.

Returns

Type	Description
int	A negative integer, zero, or a positive integer as the first entry denotes a value that is is less than, equal to, or greater than the value denoted by the second entry

Exceptions

Type	Condition
InvalidCastException	If the arguments' types prevent them from being compared by this IComparer.
ArgumentException	If the extractor cannot handle the passed objects for any other reason; an implementor should include a descriptive message.

Extract(object)

Extract the value from the passed object.

Declaration

public virtual object Extract(object obj)

Parameters

Type	Name	Description
object	obj	An object to retrieve the value from.

Returns

Type	Description
object	The extracted value as an object; null is an acceptable value.

Remarks

The returned value may be null.

Exceptions

Type	Condition
InvalidCastException	If this IValueExtractor is incompatible with the passed object to extract a value from and the implementation requires the passed object to be of a certain type.
ArgumentException	If this AbstractExtractor cannot handle the passed object for any other reason; an implementor should include a descriptive message.

See Also

Extract(object)

ExtractFromEntry(ICacheEntry)

Extract the value from the passed Entry object. The returned value should follow the conventions outlined in the Extract(object) method.

Declaration

public virtual object ExtractFromEntry(ICacheEntry entry)

Parameters

Type	Name	Description
ICacheEntry	entry	An Entry object to extract a desired value from

Returns

Type	Description
object	The extracted value

Remarks

By overriding this method, an extractor implementation is able to extract a desired value using all available information on the corresponding ICacheEntry object and is intended to be used in advanced custom scenarios, when application code needs to look at both key and value at the same time or can make some very specific assumptions regarding to the implementation details of the underlying Entry object.

ExtractOriginalFromEntry(CacheEntry)

Extract the value from the "original value" of the passed CacheEntry object or the key (if targeted). This method's conventions are exactly the same as the ExtractFromEntry(ICacheEntry) method.

Declaration

public virtual object ExtractOriginalFromEntry(CacheEntry entry)

Parameters

Type	Name	Description
CacheEntry	entry	A CacheEntry object whose original value should be used to extract the desired value from.

Returns

Type	Description
object	The extracted value or null if the original value is not present.

Implements

IValueExtractor

IQueryCacheComparer

IComparer