com.orientechnologies.orient.core.sql.functions

Class OSQLFunctionAbstract

java.lang.Object

com.orientechnologies.orient.core.sql.functions.OSQLFunctionAbstract

All Implemented Interfaces:

OSQLFunction

Direct Known Subclasses:

OLuceneSearchFunctionTemplate, OLuceneSearchMoreLikeThisFunction, OSpatialFunctionAbstract, OSQLFunctionCoalesce, OSQLFunctionConfigurableAbstract, OSQLFunctionDate, OSQLFunctionDecode, OSQLFunctionDistance, OSQLFunctionDistinct, OSQLFunctionEncode, OSQLFunctionFormat, OSQLFunctionFormat, OSQLFunctionGremlin, OSQLFunctionIf, OSQLFunctionIfNull, OSQLFunctionIndexKeySize, OSQLFunctionMode, OSQLFunctionPercentile, OSQLFunctionSysdate, OSQLFunctionThrowCME, OSQLFunctionUUID, OSQLFunctionVariance, OSQLStaticReflectiveFunction, OSTAsBinaryFunction, OSTAsGeoJSONFunction, OSTAsTextFunction, OSTBufferFunction, OSTDisjointFunction, OSTEnvelopFunction, OSTEqualsFunction, OSTGeomFromGeoJSONFunction, OSTGeomFromTextFunction, OSTSrid

public abstract class OSQLFunctionAbstract
extends Object
implements OSQLFunction

Abstract class to extend to build Custom SQL Functions. Extend it and register it with: OSQLParser.getInstance().registerStatelessFunction() or OSQLParser.getInstance().registerStatefullFunction() to being used by the SQL engine.

Author:

Luca Garulli (l.garulli--(at)--orientdb.com)

Field Summary

Fields

Modifier and Type	Field and Description
protected int	maxParams
protected int	minParams
protected String	name

Constructor Summary

Constructors

Constructor and Description
OSQLFunctionAbstract(String iName, int iMinParams, int iMaxParams)

Method Summary

Modifier and Type	Method and Description
boolean	aggregateResults() A function can make calculation on several records before returning a result.
void	config(Object[] iConfiguredParameters) Configure the function.
boolean	filterResult() A function can act both as transformation or filtering records.
protected String	getDistributedStorageId()
int	getMaxParams() Maximum number of parameter this function can handle.
int	getMinParams() Minimum number of parameter this function must have.
String	getName() Function name, the name is used by the sql parser to identify a call this function.
Object	getResult() Only called when function aggregates results after all records have been passed to the function.
protected Object	getSingleItem(Object source) Attempt to extract a single item from object if it's a multi value OMultiValue If source is a multi value
protected Object	getSingleProperty(Object source, boolean requireSingleProperty) Attempts to identify the source as a map-like object with single property and return it.
Object	mergeDistributedResult(List<Object> resultsToMerge) This method correspond to distributed query execution
protected boolean	returnDistributedResult()
void	setResult(Object iResult) Called by OCommandExecutor, given parameter is the number of results.
boolean	shouldMergeDistributedResult() This method correspond to distributed query execution
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.orientechnologies.orient.core.sql.functions.OSQLFunction

execute, getSyntax

Field Detail

name

protected String name

minParams

protected int minParams

maxParams

protected int maxParams

Constructor Detail

OSQLFunctionAbstract

public OSQLFunctionAbstract(String iName,
                            int iMinParams,
                            int iMaxParams)

Method Detail

getName

public String getName()

Description copied from interface: OSQLFunction

Function name, the name is used by the sql parser to identify a call this function.

Specified by:

getName in interface OSQLFunction

Returns:

String , function name, never null or empty.

getMinParams

public int getMinParams()

Description copied from interface: OSQLFunction

Minimum number of parameter this function must have.

Specified by:

getMinParams in interface OSQLFunction

Returns:

minimum number of parameters

getMaxParams

public int getMaxParams()

Description copied from interface: OSQLFunction

Maximum number of parameter this function can handle.

Specified by:

getMaxParams in interface OSQLFunction

Returns:

maximum number of parameters ??? -1 , negative or Integer.MAX_VALUE for unlimited ???

toString

public String toString()

Overrides:

toString in class Object

config

public void config(Object[] iConfiguredParameters)

Description copied from interface: OSQLFunction

Configure the function.

Specified by:

config in interface OSQLFunction

aggregateResults

public boolean aggregateResults()

Description copied from interface: OSQLFunction

A function can make calculation on several records before returning a result.

Example of such function : sum, count, max, min ...

The final result of the aggregation is obtain by calling OSQLFunction.getResult()

Specified by:

aggregateResults in interface OSQLFunction

Returns:

true if function aggregate results

filterResult

public boolean filterResult()

Description copied from interface: OSQLFunction

A function can act both as transformation or filtering records. If the function may reduce the number final records than it must return true.

Function should return null for the execute method if the record must be excluded.

Specified by:

filterResult in interface OSQLFunction

Returns:

true if the function acts as a record filter.

getResult

public Object getResult()

Description copied from interface: OSQLFunction

Only called when function aggregates results after all records have been passed to the function.

Specified by:

getResult in interface OSQLFunction

Returns:

Aggregation result

setResult

public void setResult(Object iResult)

Description copied from interface: OSQLFunction

Called by OCommandExecutor, given parameter is the number of results. ??? strange ???

Specified by:

setResult in interface OSQLFunction

shouldMergeDistributedResult

public boolean shouldMergeDistributedResult()

Description copied from interface: OSQLFunction

This method correspond to distributed query execution

Specified by:

shouldMergeDistributedResult in interface OSQLFunction

Returns:

true if results that comes from different nodes need to be merged to obtain valid one, false otherwise

mergeDistributedResult

public Object mergeDistributedResult(List<Object> resultsToMerge)

Description copied from interface: OSQLFunction

This method correspond to distributed query execution

Specified by:

mergeDistributedResult in interface OSQLFunction

Parameters:

resultsToMerge - is the results that comes from different nodes

Returns:

is the valid merged result

returnDistributedResult

protected boolean returnDistributedResult()

getDistributedStorageId

protected String getDistributedStorageId()

getSingleItem

protected Object getSingleItem(Object source)

Attempt to extract a single item from object if it's a multi value OMultiValue If source is a multi value

Parameters:

source - a value to attempt extract single value from it

Returns:

If source is not a multi value, it will return source as is. If it is, it will return the single element in it. If source is a multi value with more than 1 element null is returned, indicating an error

getSingleProperty

protected Object getSingleProperty(Object source,
                                   boolean requireSingleProperty)

Attempts to identify the source as a map-like object with single property and return it.

Parameters:

source - The object to check

requireSingleProperty - True if the method should return null when source doesn't have a single property. Otherwise, the object will be returned.

Returns:

If source is a map-like object with single property, that property will be returned If source is a map-like object with multiple properties and requireSingleProperty is true, null is returned indicating an error If source is not a map-like object, it is returned