com.neurosys.etl.common.transformers

Class JoinTransformer<T>

java.lang.Object

com.neurosys.etl.common.transformers.JoinTransformer<T>

All Implemented Interfaces:

FunctionTransformer, Function, org.apache.commons.collections.Transformer

Direct Known Subclasses:

ListConcatTransformer, MapConcatTransformer, StringConcatTransformer

public abstract class JoinTransformer<T>
extends Object
implements FunctionTransformer

Joins multiple Transformers result as input in a Serial fashion (order of the List of Transformers provided)
If no processor is provided (null value); then the output is the same as input.
The Join results are expected to be of type hence the type can directly also be provided in the List

Author:

Arjun Dhar

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.commons.collections.Predicate	filter Filter tokens out if the result is false
protected List	processors List of processor Transformers or type T (direct result), objects

Constructor Summary

Constructors

Constructor and Description
JoinTransformer()
JoinTransformer(List processors)

Method Summary

Modifier and Type	Method and Description
protected T	cleanDangligngDelimets(T result) If a filter is given then there maybe dangling delimiters in the end.
org.apache.commons.collections.Predicate	getFilter() Filter tokens out if the result is false
List	getProcessors()
protected abstract T	join(T result, Object transformedInput) Join results of type T
protected T	joinDelimet(T result, Object processor, boolean hasNext) In Join operations it maybe desired a delimeter is needed between joins of two processors in sequence.
void	setFilter(org.apache.commons.collections.Predicate filter) Filter tokens out if the result is false
void	setProcessors(List processors)
Object	transform(Object input)

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.neurosys.etl.common.transformers.FunctionTransformer

apply

Methods inherited from interface java.util.function.Function

andThen, compose, identity

Field Detail

processors

protected List processors

List of processor Transformers or type T (direct result), objects

filter

protected org.apache.commons.collections.Predicate filter

Filter tokens out if the result is false

Can be null:

true

Default value:

null

Constructor Detail

JoinTransformer

public JoinTransformer()

JoinTransformer

public JoinTransformer(List processors)

Method Detail

getProcessors

public List getProcessors()

setProcessors

public void setProcessors(List processors)

join

protected abstract T join(T result,
                          Object transformedInput)
                   throws ContinueProcessingException

Join results of type T

Parameters:

result - as ; intermediate result as a result of the Chain processing on the list of processors as a result of a previous join(Object, Object) or input.

transformedInput - as Object of type T that maybe a literal from the processors or as a result of transformation from a processor that acts on the main input
Example: Define processors as {"A", Transformer1}; with input : {"hello"}
Then transformedInput for 1st iteration = "A"
Then transformedInput for 2nd iteration = Transformer1.transform("hello")

Returns:

result as T

Throws:

ContinueProcessingException - if we want to ignore the call with the param and continue with the mail processing loop in transform(Object)

joinDelimet

protected T joinDelimet(T result,
                        Object processor,
                        boolean hasNext)

In Join operations it maybe desired a delimeter is needed between joins of two processors in sequence.

Parameters:

result - as T so far of all joins

processor - as type T or Transformer

hasNext - as boolean (if there are any more processors in the chain). If false the current processor is the last. Note: If a filter is defined; hasNext cannot factor the next in the chain will be part of result or not. However, if there are any dangling delims left cleanDangligngDelimets(Object) can be defined.

Returns:

Object as result after delimition

cleanDangligngDelimets

protected T cleanDangligngDelimets(T result)

If a filter is given then there maybe dangling delimiters in the end. This method, defines how they can be cleared.

Parameters:

result -

Returns:

transform

public Object transform(Object input)

Specified by:

transform in interface org.apache.commons.collections.Transformer

getFilter

public org.apache.commons.collections.Predicate getFilter()

Filter tokens out if the result is false

Can be null:

true

Default value:

null

setFilter

public void setFilter(org.apache.commons.collections.Predicate filter)

Filter tokens out if the result is false

Can be null:

true

Default value:

null