Package org.apache.cassandra.cql3.functions

Class FunctionFactory

java.lang.Object

org.apache.cassandra.cql3.functions.FunctionFactory

Direct Known Subclasses:

MaskingFunction.Factory

public abstract class FunctionFactory
extends Object

Class for dynamically building different overloads of a CQL Function according to specific function calls.

For example, the factory for the max function will return a (text) -> text function if it's called with an text argument, like in max('abc'). It however will return a (list<int>) -> list<int> function if it's called with max([1,2,3]), etc.

This is meant to be used to create functions that require too many overloads to have them pre-created in memory. Note that in the case of functions accepting collections, tuples or UDTs the number of overloads is potentially infinite.

Field Summary

Fields

Modifier and Type	Field	Description
protected final FunctionName	name	The name of the built functions.
protected final List<FunctionParameter>	parameters	The accepted parameters.

Constructor Summary

Constructors

Constructor	Description
FunctionFactory(String name, FunctionParameter... parameters)

Method Summary

Modifier and Type	Method	Description
protected abstract NativeFunction	doGetOrCreateFunction(List<AbstractType<?>> argTypes, AbstractType<?> receiverType)	Returns a function compatible with the specified signature.
NativeFunction	getOrCreateFunction(List<? extends AssignmentTestable> args, AbstractType<?> receiverType, String receiverKeyspace, String receiverTable)	Returns a function with a signature compatible with the specified function call.
InvalidRequestException	invalidNumberOfArgumentsException()
FunctionName	name()
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

name

protected final FunctionName name

The name of the built functions.

parameters

protected final List<FunctionParameter> parameters

The accepted parameters.

Constructor Details

FunctionFactory

public FunctionFactory(String name,
 FunctionParameter... parameters)

Parameters:

name - the name of the built functions

parameters - the accepted parameters

Method Details

name

public FunctionName name()

getOrCreateFunction

@Nullable
public NativeFunction getOrCreateFunction(List<? extends AssignmentTestable> args,
 AbstractType<?> receiverType,
 String receiverKeyspace,
 String receiverTable)

Returns a function with a signature compatible with the specified function call.

Parameters:

args - the arguments in the function call for which the function is going to be built

receiverType - the expected return type of the function call for which the function is going to be built

receiverKeyspace - the name of the recevier keyspace

receiverTable - the name of the recevier table

Returns:

a function with a signature compatible with the specified function call, or null if the factory cannot create a function for the supplied arguments but there might be another factory with the same name() able to do it.

invalidNumberOfArgumentsException

public InvalidRequestException invalidNumberOfArgumentsException()

doGetOrCreateFunction

@Nullable
protected abstract NativeFunction doGetOrCreateFunction(List<AbstractType<?>> argTypes,
 AbstractType<?> receiverType)

Returns a function compatible with the specified signature.

Parameters:

argTypes - the types of the function arguments

receiverType - the expected return type of the function

Returns:

a function compatible with the specified signature, or null if this cannot create a function for the supplied arguments but there might be another factory with the same name() able to do it.

toString

public String toString()

Overrides:

toString in class Object