#include <coherence/util/extractor/KeyExtractor.hpp>
Inherits AbstractExtractor.
The major difference between the KeyExtractor and a standard ReflectionExtractor is that when used in various EntryFilter implementations it forces the evaluation of entry keys rather than entry values.
For example, consider a key object that consists of two properties: "FirstName" and "LastName". To retrieve all keys that have a value of the "LastName" property equal to "Smith", the following query could be used:
ValueExtractor::View extractor = KeyExtractor::create("getLastName"); Set::View setKeys = cache->keySet(EqualsFilter::create(extractor, "Smith"));
As of Coherence 3.5, the same effect can be achieved for subclasses of the AbstractExtractor, for example:
ValueExtractor::View vExtractor = ReflectionExtractor::create("getLastName", NULL, AbstractExtractor::KEY); Set::View setKeys = cache->keySet(EqualsFilter::create(vExtractor, "Smith"));
Public Types | |||||||||||||
typedef spec::Handle | Handle | ||||||||||||
KeyExtractor Handle definition. | |||||||||||||
typedef spec::View | View | ||||||||||||
KeyExtractor View definition. | |||||||||||||
typedef spec::Holder | Holder | ||||||||||||
KeyExtractor Holder definition. | |||||||||||||
Public Member Functions | |||||||||||||
virtual Object::Holder | extract (Object::Holder ohTarget) const | ||||||||||||
Extract the value from the passed object. The returned value may be NULL.
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virtual void | readExternal (PofReader::Handle hIn) | ||||||||||||
virtual void | writeExternal (PofWriter::Handle hOut) const | ||||||||||||
virtual bool | equals (Object::View v) const | ||||||||||||
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
The default implementation is identity based.
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virtual TypedHandle < const String > | toString () const | ||||||||||||
Output a human-readable description of this Object to the given stream. Note that when overriding this method the return type must be TypedHandle<const String> rather then String::View. These two types are assignment compatible but not equivalent and declaring the override with String::View will not be a compatible override. coherence::lang::operator<<(std::ostream, Object::View) is defined and will call into the toString 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 and is generally how toString() will be implemented.
Object::View vKey = ... Object::View vValue = ... std::cout << vKey << " = " << vValue << std::endl; String::View vs = COH_TO_STRING(vKey << " = " << vValue); The COH_TO_STRING macro is also the most common way to implement the toString method. For example:
virtual TypedHandle<const String> Person::toString() const { return COH_TO_STRING("Name: " << f_sName << " SSN: " << f_nSSN); }
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virtual ValueExtractor::View | getExtractor () const | ||||||||||||
Obtain the underlying ValueExtractor. | |||||||||||||
Protected Member Functions | |||||||||||||
KeyExtractor () | |||||||||||||
Create and return a Handle to a new Object instance. | |||||||||||||
KeyExtractor (ValueExtractor::View vExtractor) | |||||||||||||
Construct a KeyExtractor based on a specified ValueExtractor. | |||||||||||||
Protected Attributes | |||||||||||||
MemberView < ValueExtractor > | m_vExtractor | ||||||||||||
The underlying ValueExtractor. |
KeyExtractor | ( | ValueExtractor::View | vExtractor | ) | [protected] |
Construct a KeyExtractor based on a specified ValueExtractor.
vExtractor | the underlying ValueExtractor |
virtual ValueExtractor::View getExtractor | ( | ) | const [virtual] |