weka.core.expressionlanguage.common

Class Operators

java.lang.Object

weka.core.expressionlanguage.common.Operators

public class Operators
extends java.lang.Object

A class to specify the semantics of operators in the expressionlanguage

To move the operator semantics outside the parser they are specified here.
The parser can then call these methods so that operators can be resolved to AST (abstract syntax tree) nodes.

Version:

$Revision: 1000 $

Author:

Benjamin Weber ( benweber at student dot ethz dot ch )

Constructor Summary

Constructors

Constructor and Description
Operators()

Method Summary

Modifier and Type	Method and Description
static Primitives.BooleanExpression	and(Node left, Node right) '&' or 'and' logical and operator
static Node	division(Node left, Node right) '/' division operator
static Primitives.BooleanExpression	equal(Node left, Node right) '=' equal operator
static Primitives.BooleanExpression	greaterEqual(Node left, Node right) '>=' greater equal operator
static Primitives.BooleanExpression	greaterThan(Node left, Node right) '>' greater than operator
static Primitives.BooleanExpression	is(Node left, Node right) 'is' is operator (to check for string equality)
static Primitives.BooleanExpression	lessEqual(Node left, Node right) '<=' less equal operator
static Primitives.BooleanExpression	lessThan(Node left, Node right) '<' less than operator
static Node	minus(Node left, Node right) '-' minus operator
static Primitives.BooleanExpression	not(Node expr) '!' or 'not' logical not operator
static Primitives.BooleanExpression	or(Node left, Node right) '|' or 'or' logical or operator
static Node	plus(Node left, Node right) '+' plus operator
static Node	pow(Node left, Node right) '^' power operator
static Primitives.BooleanExpression	regexp(Node left, Node right) 'regexp' regexp operator (to check for string matching a given regular expression)
static Node	times(Node left, Node right) '*' times operator
static Node	uminus(Node expr) '-' unary minus operator
static Node	uplus(Node expr) '+' unary plus operator

Methods inherited from class java.lang.Object

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

Constructor Detail

Operators

public Operators()

Method Detail

plus

public static Node plus(Node left,
                        Node right)
                 throws SemanticException

'+' plus operator

Throws:

SemanticException

minus

public static Node minus(Node left,
                         Node right)
                  throws SemanticException

'-' minus operator

Throws:

SemanticException

times

public static Node times(Node left,
                         Node right)
                  throws SemanticException

'*' times operator

Throws:

SemanticException

division

public static Node division(Node left,
                            Node right)
                     throws SemanticException

'/' division operator

Throws:

SemanticException

uplus

public static Node uplus(Node expr)
                  throws SemanticException

'+' unary plus operator

Throws:

SemanticException

uminus

public static Node uminus(Node expr)
                   throws SemanticException

'-' unary minus operator

Throws:

SemanticException

pow

public static Node pow(Node left,
                       Node right)
                throws SemanticException

'^' power operator

Throws:

SemanticException

lessThan

public static Primitives.BooleanExpression lessThan(Node left,
                                                    Node right)
                                             throws SemanticException

'<' less than operator

Throws:

SemanticException

lessEqual

public static Primitives.BooleanExpression lessEqual(Node left,
                                                     Node right)
                                              throws SemanticException

'<=' less equal operator

Throws:

SemanticException

greaterThan

public static Primitives.BooleanExpression greaterThan(Node left,
                                                       Node right)
                                                throws SemanticException

'>' greater than operator

Throws:

SemanticException

greaterEqual

public static Primitives.BooleanExpression greaterEqual(Node left,
                                                        Node right)
                                                 throws SemanticException

'>=' greater equal operator

Throws:

SemanticException

equal

public static Primitives.BooleanExpression equal(Node left,
                                                 Node right)
                                          throws SemanticException

'=' equal operator

Throws:

SemanticException

not

public static Primitives.BooleanExpression not(Node expr)
                                        throws SemanticException

'!' or 'not' logical not operator

Throws:

SemanticException

and

public static Primitives.BooleanExpression and(Node left,
                                               Node right)
                                        throws SemanticException

'&' or 'and' logical and operator

Throws:

SemanticException

or

public static Primitives.BooleanExpression or(Node left,
                                              Node right)
                                       throws SemanticException

'|' or 'or' logical or operator

Throws:

SemanticException

is

public static Primitives.BooleanExpression is(Node left,
                                              Node right)
                                       throws SemanticException

'is' is operator (to check for string equality)

Throws:

SemanticException

regexp

public static Primitives.BooleanExpression regexp(Node left,
                                                  Node right)
                                           throws SemanticException

'regexp' regexp operator (to check for string matching a given regular expression)

Throws:

SemanticException