Package org.apache.cassandra.cql3.functions

Interface ScalarFunction

All Superinterfaces:

AssignmentTestable, Function

All Known Subinterfaces:

PartialScalarFunction

All Known Implementing Classes:

BytesConversionFcts.FromBlobFunction, BytesConversionFcts.ToBlobFunction, DefaultMaskingFunction, FromJsonFct, HashMaskingFunction, JavaBasedUDFunction, MaskingFunction, NativeScalarFunction, NullMaskingFunction, PartialMaskingFunction, ReplaceMaskingFunction, TimeFcts.FloorDateFunction, TimeFcts.FloorTimestampFunction, TimeFcts.FloorTimeUuidFunction, TimeFcts.TemporalConversionFunction, ToJsonFct, TokenFct, UDFunction

public interface ScalarFunction
extends Function

Determines a single output value based on any number of input values.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.cassandra.cql3.AssignmentTestable

AssignmentTestable.TestResult

Field Summary

Fields inherited from interface org.apache.cassandra.cql3.functions.Function

UNRESOLVED

Method Summary

Modifier and Type	Method	Description
java.nio.ByteBuffer	execute(Arguments arguments)	Applies this function to the specified arguments.
boolean	isCalledOnNullInput()
default boolean	isMonotonic()	Checks if the function is monotonic.
default ScalarFunction	partialApplication(ProtocolVersion protocolVersion, java.util.List<java.nio.ByteBuffer> partialArguments)	Does a partial application of the function.

Methods inherited from interface org.apache.cassandra.cql3.AssignmentTestable

getCompatibleTypeIfKnown, testAssignment

Methods inherited from interface org.apache.cassandra.cql3.functions.Function

addFunctionsTo, argTypes, columnName, compare, isAggregate, isNative, isPure, name, newArguments, referencesUserType, returnType

Method Detail

isCalledOnNullInput

boolean isCalledOnNullInput()

isMonotonic

default boolean isMonotonic()

Checks if the function is monotonic.

A function is monotonic if it is either entirely nonincreasing or nondecreasing given an ordered set of inputs.

Returns:

true if the function is monotonic false otherwise.

execute

java.nio.ByteBuffer execute(Arguments arguments)
                     throws InvalidRequestException

Applies this function to the specified arguments.

Parameters:

arguments - the input arguments for the function

Returns:

the result of applying this function to the arguments

Throws:

InvalidRequestException - if this function cannot not be applied to the arguments

partialApplication

default ScalarFunction partialApplication(ProtocolVersion protocolVersion,
                                          java.util.List<java.nio.ByteBuffer> partialArguments)

Does a partial application of the function. That is, given only some of the arguments of the function provided, return a new function that only expect the arguments not provided.

To take an example, if you consider the function

     text foo(int a, text b, text c, int d)
 

then foo.partialApplication([3, <ommitted>, 'bar', <omitted>]) will return a function bar of signature:

     text bar(text b, int d)
 

and such that for any value of b and d, bar(b, d) == foo(3, b, 'bar', d).

Parameters:

protocolVersion - protocol version used for arguments

partialArguments - a list of input arguments for the function where some arguments can be Function.UNRESOLVED. The input must be of size this.argsType().size(). For convenience, it is allowed both to pass a list with all arguments being Function.UNRESOLVED (the function is then returned directly) and with none of them unresolved (in which case, if the function is pure, it is computed and a dummy no-arg function returning the result is returned).

Returns:

a function corresponding to the partial application of this function to the arguments of partialArguments that are not Function.UNRESOLVED.