org.apache.lucene.queryParser.ext
Class Extensions

java.lang.Object
  org.apache.lucene.queryParser.ext.Extensions

public class Extensions
extends Object

The Extensions class represents an extension mapping to associate ParserExtension instances with extension keys. An extension key is a string encoded into a Lucene standard query parser field symbol recognized by ExtendableQueryParser. The query parser passes each extension field token to splitExtensionField(String, String) to separate the extension key from the field identifier.

In addition to the key to extension mapping this class also defines the field name overloading scheme. ExtendableQueryParser uses the given extension to split the actual field name and extension key by calling splitExtensionField(String, String). To change the order or the key / field name encoding scheme users can subclass Extensions to implement their own.

See Also:

ExtendableQueryParser, ParserExtension

Nested Class Summary

static class

Extensions.Pair<Cur,Cud> This class represents a generic pair.

Field Summary

static char

DEFAULT_EXTENSION_FIELD_DELIMITER The default extension field delimiter character.

Constructor Summary

Extensions()
Creates a new Extensions instance with the DEFAULT_EXTENSION_FIELD_DELIMITER as a delimiter character.

Extensions(char extensionFieldDelimiter)
Creates a new Extensions instance

Method Summary

void	add(String key, ParserExtension extension) Adds a new ParserExtension instance associated with the given key.
String	buildExtensionField(String extensionKey) Builds an extension field string from a given extension key and the default query field.
String	buildExtensionField(String extensionKey, String field) Builds an extension field string from a given extension key and the extensions field.
String	escapeExtensionField(String extfield) Escapes an extension field.
ParserExtension	getExtension(String key) Returns the ParserExtension instance for the given key or null if no extension can be found for the key.
char	getExtensionFieldDelimiter() Returns the extension field delimiter
Extensions.Pair<String,String>	splitExtensionField(String defaultField, String field) Splits a extension field and returns the field / extension part as a Extensions.Pair.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_EXTENSION_FIELD_DELIMITER

public static final char DEFAULT_EXTENSION_FIELD_DELIMITER

The default extension field delimiter character. This constant is set to ':'

See Also:

Constant Field Values

Constructor Detail

Extensions

public Extensions()

Creates a new Extensions instance with the DEFAULT_EXTENSION_FIELD_DELIMITER as a delimiter character.

Extensions

public Extensions(char extensionFieldDelimiter)

Creates a new Extensions instance

Parameters:

extensionFieldDelimiter - the extensions field delimiter character

Method Detail

add

public void add(String key,
                ParserExtension extension)

Adds a new ParserExtension instance associated with the given key.

Parameters:

key - the parser extension key

extension - the parser extension

getExtension

public final ParserExtension getExtension(String key)

Returns the ParserExtension instance for the given key or null if no extension can be found for the key.

Parameters:

key - the extension key

Returns:

the ParserExtension instance for the given key or null if no extension can be found for the key.

getExtensionFieldDelimiter

public char getExtensionFieldDelimiter()

Returns the extension field delimiter

Returns:

the extension field delimiter

splitExtensionField

public Extensions.Pair<String,String> splitExtensionField(String defaultField,
                                                          String field)

Splits a extension field and returns the field / extension part as a Extensions.Pair. This method tries to split on the first occurrence of the extension field delimiter, if the delimiter is not present in the string the result will contain a null value for the extension key and the given field string as the field value. If the given extension field string contains no field identifier the result pair will carry the given default field as the field value.

Parameters:

defaultField - the default query field

field - the extension field string

Returns:

a Extensions.Pair with the field name as the Extensions.Pair.cur and the extension key as the Extensions.Pair.cud

escapeExtensionField

public String escapeExtensionField(String extfield)

Escapes an extension field. The default implementation is equivalent to QueryParser.escape(String).

Parameters:

extfield - the extension field identifier

Returns:

the extension field identifier with all special chars escaped with a backslash character.

buildExtensionField

public String buildExtensionField(String extensionKey)

Builds an extension field string from a given extension key and the default query field. The default field and the key are delimited with the extension field delimiter character. This method makes no assumption about the order of the extension key and the field. By default the extension key is appended to the end of the returned string while the field is added to the beginning. Special Query characters are escaped in the result.

Note: Extensions subclasses must maintain the contract between buildExtensionField(String) and splitExtensionField(String, String) where the latter inverts the former.

buildExtensionField

public String buildExtensionField(String extensionKey,
                                  String field)

Builds an extension field string from a given extension key and the extensions field. The field and the key are delimited with the extension field delimiter character. This method makes no assumption about the order of the extension key and the field. By default the extension key is appended to the end of the returned string while the field is added to the beginning. Special Query characters are escaped in the result.

Note: Extensions subclasses must maintain the contract between buildExtensionField(String, String) and splitExtensionField(String, String) where the latter inverts the former.

Parameters:

extensionKey - the extension key

field - the field to apply the extension on.

Returns:

escaped extension field identifier

See Also:

to use the default query field