io.druid.query.extraction

Class NamespacedExtractor

java.lang.Object

io.druid.query.extraction.LookupExtractor

io.druid.query.extraction.NamespacedExtractor

public class NamespacedExtractor
extends LookupExtractor

Namespaced extraction is a special case of DimExtractionFn where the actual extractor is pulled from a map of known implementations. In the event that an unknown namespace is passed, a simple reflective function is returned instead.

Constructor Summary

Constructors

Constructor and Description
NamespacedExtractor(com.google.common.base.Function<String,com.google.common.base.Function<String,String>> namespaces, com.google.common.base.Function<String,com.google.common.base.Function<String,List<String>>> reverseNamespaces, String namespace)

Method Summary

Modifier and Type	Method and Description
String	apply(String value) Apply a particular lookup methodology to the input string
byte[]	getCacheKey() Create a cache key for use in results caching
String	getNamespace()
List<String>	unapply(String value) Provide the reverse mapping from a given value to a list of keys

Methods inherited from class io.druid.query.extraction.LookupExtractor

applyAll, unapplyAll

Methods inherited from class java.lang.Object

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

Constructor Detail

NamespacedExtractor

public NamespacedExtractor(@NotNull
                           com.google.common.base.Function<String,com.google.common.base.Function<String,String>> namespaces,
                           @NotNull
                           com.google.common.base.Function<String,com.google.common.base.Function<String,List<String>>> reverseNamespaces,
                           @NotNull
                           String namespace)

Method Detail

getNamespace

public String getNamespace()

getCacheKey

public byte[] getCacheKey()

Description copied from class: LookupExtractor

Create a cache key for use in results caching

Specified by:

getCacheKey in class LookupExtractor

Returns:

A byte array that can be used to uniquely identify if results of a prior lookup can use the cached values

apply

public String apply(String value)

Description copied from class: LookupExtractor

Apply a particular lookup methodology to the input string

Specified by:

apply in class LookupExtractor

Parameters:

value - The value to apply the lookup to. May not be null

Returns:

The lookup, or null key cannot have the lookup applied to it and should be treated as missing.

unapply

public List<String> unapply(@NotNull
                            String value)

Description copied from class: LookupExtractor

Provide the reverse mapping from a given value to a list of keys

Specified by:

unapply in class LookupExtractor

Parameters:

value - the value to apply the reverse lookup Null and empty are considered to be the same value = nullToEmpty(value)

Returns:

the list of keys that maps to value or empty list. Note that for the case of a none existing value in the lookup we have to cases either return an empty list OR list with null element. returning an empty list implies that user want to ignore such a lookup value. In the other hand returning a list with the null element implies user want to map the none existing value to the key null.