Package com.arcadedb.query.sql.executor

Interface SQLFunction

All Known Implementing Classes:

SQLFunctionAbsoluteValue, SQLFunctionAbstract, SQLFunctionAstar, SQLFunctionAverage, SQLFunctionBoth, SQLFunctionBothE, SQLFunctionBothV, SQLFunctionCoalesce, SQLFunctionConcat, SQLFunctionConfigurableAbstract, SQLFunctionCount, SQLFunctionDate, SQLFunctionDecode, SQLFunctionDifference, SQLFunctionDijkstra, SQLFunctionDistance, SQLFunctionEncode, SQLFunctionFirst, SQLFunctionFormat, SQLFunctionHeuristicPathFinderAbstract, SQLFunctionIf, SQLFunctionIfNull, SQLFunctionIn, SQLFunctionInE, SQLFunctionIntersect, SQLFunctionInV, SQLFunctionLast, SQLFunctionList, SQLFunctionMap, SQLFunctionMathAbstract, SQLFunctionMax, SQLFunctionMedian, SQLFunctionMin, SQLFunctionMode, SQLFunctionMove, SQLFunctionMoveFiltered, SQLFunctionMultiValueAbstract, SQLFunctionOut, SQLFunctionOutE, SQLFunctionOutV, SQLFunctionPathFinder, SQLFunctionPercentile, SQLFunctionSet, SQLFunctionShortestPath, SQLFunctionStandardDeviation, SQLFunctionStrcmpci, SQLFunctionSum, SQLFunctionSymmetricDifference, SQLFunctionSysdate, SQLFunctionUnionAll, SQLFunctionUUID, SQLFunctionVariance, SQLStaticReflectiveFunction

public interface SQLFunction

Interface that defines a SQL Function. Functions can be state-less if registered as instance, or state-full when registered as class. State-less function are reused across queries, so don't keep any run-time information inside of it. State-full function, instead, stores Implement it and register it with: OSQLParser.getInstance().registerFunction() to being used by the SQL engine.

??? could it be possible to have a small piece of code here showing where to register a function using services ???

Author:

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

Method Summary

Modifier and Type	Method	Description
boolean	aggregateResults()	A function can make calculation on several records before returning a result.
void	config(Object[] configuredParameters)	Configure the function.
Object	execute(Object iThis, Identifiable iCurrentRecord, Object iCurrentResult, Object[] iParams, CommandContext iContext)	Process a record.
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.
String	getSyntax()	Returns a convenient SQL String representation of the function.

Method Detail

execute

Object execute(Object iThis,
               Identifiable iCurrentRecord,
               Object iCurrentResult,
               Object[] iParams,
               CommandContext iContext)

Process a record.

Parameters:

iThis -

iCurrentRecord - : current record

iCurrentResult - TODO

iParams - : function parameters, number is ensured to be within minParams and maxParams.

iContext - : object calling this function

Returns:

function result, can be null. Special cases : can be null if function aggregate results, can be null if function filter results : this mean result is excluded

config

void config(Object[] configuredParameters)

Configure the function.

Parameters:

configuredParameters -

aggregateResults

boolean aggregateResults()

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 obtained by calling getResult()

Returns:

true if function aggregate results

getName

String getName()

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

Returns:

String , function name, never null or empty.

getSyntax

String getSyntax()

Returns a convenient SQL String representation of the function.

Example :

  myFunction( param1, param2, [optionalParam3])
 

This text will be used in exception messages.

Returns:

String , never null.

getResult

Object getResult()

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

Returns:

Aggregation result