Package weka.core.expressionlanguage.common

Class IfElseMacro

java.lang.Object

weka.core.expressionlanguage.common.IfElseMacro

All Implemented Interfaces:

Macro, MacroDeclarations

public class IfElseMacro
extends Object
implements MacroDeclarations, Macro

A macro declaration exposing the ifelse function.

The ifelse macro can be used as follows:
ifelse(condition, ifpart, elsepart)

Whith the following constraints:

• condition must be of boolean type
• ifpart and elsepart must be of the same type
• ifpart must be either of boolean, double or string type

Examples:

• ifelse(A < B, true, A = B)
• ifelse(A = B, 4.0^2, 1/5)
• ifelse(A > B, 'bigger', 'smaller')

Version:

$Revision: 1000 $

Author:

Benjamin Weber ( benweber at student dot ethz dot ch )

Constructor Summary

Constructors

Constructor	Description
IfElseMacro()

Method Summary

Modifier and Type	Method	Description
Node	evaluate(Node... params)	Evaluates the ifelse macro
Macro	getMacro(String name)	Tries to fetch the macro
boolean	hasMacro(String name)	Whether the macro is declared

Methods inherited from class java.lang.Object

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

Constructor Detail

IfElseMacro

public IfElseMacro()

Method Detail

hasMacro

public boolean hasMacro(String name)

Whether the macro is declared

Specified by:

hasMacro in interface MacroDeclarations

Parameters:

name - name of the macro

Returns:

whether the macro is declared

getMacro

public Macro getMacro(String name)

Tries to fetch the macro

The same invariant of MacroDeclarations applies here too.

Specified by:

getMacro in interface MacroDeclarations

Parameters:

name - name of the macro

Returns:

a macro

evaluate

public Node evaluate(Node... params)
              throws SemanticException

Evaluates the ifelse macro

Specified by:

evaluate in interface Macro

Parameters:

params - the parameters

Returns:

an AST (abstract syntax tree) node evaluating the ifelse function

Throws:

SemanticException