org.apache.pig.piggybank.evaluation.util
Class SearchQuery

java.lang.Object
  org.apache.pig.EvalFunc<String>
      org.apache.pig.piggybank.evaluation.util.SearchQuery

public class SearchQuery
extends EvalFunc<String>

This small UDF takes a search engine URL (Google/Yahoo/AOL/Live) containing the search query and extracts it. The URL is assumed to be encoded. The query is normalized, converting it to lower-case, removing punctuations, removing extra spaces.

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

SearchQuery()

Method Summary

String	exec(Tuple tuple) This callback method must be implemented by all subclasses.
List<FuncSpec>	getArgToFuncMapping() Allow a UDF to specify type specific implementations of itself.
Schema	outputSchema(Schema input) Report the schema of the output of this UDF.

Methods inherited from class org.apache.pig.EvalFunc

finish, getCacheFiles, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, isAsynchronous, progress, setPigLogger, setReporter, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

SearchQuery

public SearchQuery()

Method Detail

exec

public String exec(Tuple tuple)
            throws IOException

Description copied from class: EvalFunc

This callback method must be implemented by all subclasses. This is the method that will be invoked on every Tuple of a given dataset. Since the dataset may be divided up in a variety of ways the programmer should not make assumptions about state that is maintained between invocations of this method.

Specified by:

exec in class EvalFunc<String>

Parameters:

tuple - the Tuple to be processed.

Returns:

result, of type T.

Throws:

IOException

getArgToFuncMapping

public List<FuncSpec> getArgToFuncMapping()
                                   throws FrontendException

Description copied from class: EvalFunc

Allow a UDF to specify type specific implementations of itself. For example, an implementation of arithmetic sum might have int and float implementations, since integer arithmetic performs much better than floating point arithmetic. Pig's typechecker will call this method and using the returned list plus the schema of the function's input data, decide which implementation of the UDF to use.

Overrides:

getArgToFuncMapping in class EvalFunc<String>

Returns:

A List containing FuncSpec objects representing the EvalFunc class which can handle the inputs corresponding to the schema in the objects. Each FuncSpec should be constructed with a schema that describes the input for that implementation. For example, the sum function above would return two elements in its list:

1. FuncSpec(this.getClass().getName(), new Schema(new Schema.FieldSchema(null, DataType.DOUBLE)))
2. FuncSpec(IntSum.getClass().getName(), new Schema(new Schema.FieldSchema(null, DataType.INTEGER)))

This would indicate that the main implementation is used for doubles, and the special implementation IntSum is used for ints.

Throws:

FrontendException

outputSchema

public Schema outputSchema(Schema input)

Description copied from class: EvalFunc

Report the schema of the output of this UDF. Pig will make use of this in error checking, optimization, and planning. The schema of input data to this UDF is provided.

Overrides:

outputSchema in class EvalFunc<String>

Parameters:

input - Schema of the input

Returns:

Schema of the output