Class AttributeSource

An AttributeSource contains a list of different Attributes, and methods to add and get them. There can only be a single instance of an attribute in the same AttributeSource instance. This is ensured by passing in the actual type of the IAttribute to the AddAttribute<T>(), which then checks if an instance of that type is already present. If yes, it returns the instance, otherwise it creates a new instance and returns it.

Inheritance
object
AttributeSource
TokenStream
Inherited Members
Namespace: Lucene.Net.Util
Assembly: Lucene.Net.dll
Syntax
public class AttributeSource

Constructors

AttributeSource()

An AttributeSource using the default attribute factory DEFAULT_ATTRIBUTE_FACTORY.

Declaration
public AttributeSource()

AttributeSource(AttributeSource)

An AttributeSource that uses the same attributes as the supplied one.

Declaration
public AttributeSource(AttributeSource input)
Parameters
Type Name Description
AttributeSource input

AttributeSource(AttributeFactory)

An AttributeSource using the supplied AttributeSource.AttributeFactory for creating new IAttribute instances.

Declaration
public AttributeSource(AttributeSource.AttributeFactory factory)
Parameters
Type Name Description
AttributeSource.AttributeFactory factory

Properties

HasAttributes

Returns true, if this AttributeSource has any attributes

Declaration
public bool HasAttributes { get; }
Property Value
Type Description
bool

Methods

AddAttributeImpl(Attribute)

Expert: Adds a custom Attribute instance with one or more IAttribute interfaces.

Please note: It is not guaranteed, that att is added to the AttributeSource, because the provided attributes may already exist. You should always retrieve the wanted attributes using GetAttribute<T>() after adding with this method and cast to your Type. The recommended way to use custom implementations is using an AttributeSource.AttributeFactory.

Declaration
public void AddAttributeImpl(Attribute att)
Parameters
Type Name Description
Attribute att

AddAttribute<T>()

The caller must pass in an interface type that extends IAttribute. This method first checks if an instance of the corresponding class is already in this AttributeSource and returns it. Otherwise a new instance is created, added to this AttributeSource and returned.

Declaration
public T AddAttribute<T>() where T : IAttribute
Returns
Type Description
T
Type Parameters
Name Description
T

CaptureState()

Captures the state of all Attributes. The return value can be passed to RestoreState(State) to restore the state of this or another AttributeSource.

Declaration
public virtual AttributeSource.State CaptureState()
Returns
Type Description
AttributeSource.State

ClearAttributes()

Resets all Attributes in this AttributeSource by calling Clear() on each IAttribute implementation.

Declaration
public void ClearAttributes()

CloneAttributes()

Performs a clone of all Attribute instances returned in a new AttributeSource instance. This method can be used to e.g. create another TokenStream with exactly the same attributes (using AttributeSource(AttributeSource)). You can also use it as a (non-performant) replacement for CaptureState(), if you need to look into / modify the captured state.

Declaration
public AttributeSource CloneAttributes()
Returns
Type Description
AttributeSource

CopyTo(AttributeSource)

Copies the contents of this AttributeSource to the given target AttributeSource. The given instance has to provide all IAttributes this instance contains. The actual attribute implementations must be identical in both AttributeSource instances; ideally both AttributeSource instances should use the same AttributeSource.AttributeFactory. You can use this method as a replacement for RestoreState(State), if you use CloneAttributes() instead of CaptureState().

Declaration
public void CopyTo(AttributeSource target)
Parameters
Type Name Description
AttributeSource target

Equals(object)

Determines whether the specified object is equal to the current object.

Declaration
public override bool Equals(object obj)
Parameters
Type Name Description
object obj

The object to compare with the current object.
Returns
Type Description
bool

true if the specified object is equal to the current object; otherwise, false.
Overrides

GetAttributeClassesEnumerator()

Returns a new iterator that iterates the attribute classes in the same order they were added in.

Declaration
public IEnumerator<Type> GetAttributeClassesEnumerator()
Returns
Type Description
IEnumerator<Type>

GetAttributeFactory()

Returns the used AttributeSource.AttributeFactory.

Declaration
public AttributeSource.AttributeFactory GetAttributeFactory()
Returns
Type Description
AttributeSource.AttributeFactory

GetAttributeImplsEnumerator()

Returns a new iterator that iterates all unique IAttribute implementations. This iterator may contain less entries than GetAttributeClassesEnumerator(), if one instance implements more than one IAttribute interface.

Declaration
public IEnumerator<Attribute> GetAttributeImplsEnumerator()
Returns
Type Description
IEnumerator<Attribute>

GetAttribute<T>()

The caller must pass in an interface type that extends IAttribute. Returns the instance of the corresponding Attribute contained in this AttributeSource

Declaration
public virtual T GetAttribute<T>() where T : IAttribute
Returns
Type Description
T
Type Parameters
Name Description
T
Exceptions
Type Condition
ArgumentException

if this AttributeSource does not contain the Attribute. It is recommended to always use AddAttribute<T>() even in consumers of TokenStreams, because you cannot know if a specific TokenStream really uses a specific Attribute. AddAttribute<T>() will automatically make the attribute available. If you want to only use the attribute, if it is available (to optimize consuming), use HasAttribute<T>().

GetHashCode()

Serves as the default hash function.

Declaration
public override int GetHashCode()
Returns
Type Description
int

A hash code for the current object.
Overrides

HasAttribute<T>()

The caller must pass in an interface type that extends IAttribute. Returns true, if this AttributeSource contains the corrsponding Attribute.

Declaration
public bool HasAttribute<T>() where T : IAttribute
Returns
Type Description
bool
Type Parameters
Name Description
T

ReflectAsString(bool)

This method returns the current attribute values as a string in the following format by calling the ReflectWith(IAttributeReflector) method:

  • if prependAttClass=true:"AttributeClass.Key=value,AttributeClass.Key=value"
  • if prependAttClass=false:"key=value,key=value"
Declaration
public string ReflectAsString(bool prependAttClass)
Parameters
Type Name Description
bool prependAttClass
Returns
Type Description
string
See Also

ReflectWith(IAttributeReflector)

This method is for introspection of attributes, it should simply add the key/values this AttributeSource holds to the given IAttributeReflector.

This method iterates over all IAttribute implementations and calls the corresponding ReflectWith(IAttributeReflector) method.

Declaration
public void ReflectWith(IAttributeReflector reflector)
Parameters
Type Name Description
IAttributeReflector reflector
See Also

RestoreState(State)

Restores this state by copying the values of all attribute implementations that this state contains into the attributes implementations of the targetStream. The targetStream must contain a corresponding instance for each argument contained in this state (e.g. it is not possible to restore the state of an AttributeSource containing a ICharTermAttribute into a AttributeSource using a Token instance as implementation).

Note that this method does not affect attributes of the targetStream that are not contained in this state. In other words, if for example the targetStream contains an IOffsetAttribute, but this state doesn't, then the value of the IOffsetAttribute remains unchanged. It might be desirable to reset its value to the default, in which case the caller should first call ClearAttributes() (TokenStream.ClearAttributes() on the targetStream.
Declaration
public void RestoreState(AttributeSource.State state)
Parameters
Type Name Description
AttributeSource.State state

ToString()

Returns a string consisting of the class's simple name, the hex representation of the identity hash code, and the current reflection of all attributes.

Declaration
public override string ToString()
Returns
Type Description
string
Overrides
See Also