org.vanilladb.core.sql.predicate

Class BinaryArithmeticExpression

java.lang.Object

org.vanilladb.core.sql.predicate.BinaryArithmeticExpression

All Implemented Interfaces:

Expression

public class BinaryArithmeticExpression
extends Object
implements Expression

An expression consisting of a binary arithmetic operator and two sub-expressions as operands.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BinaryArithmeticExpression.Operator

Field Summary

Fields

Modifier and Type	Field and Description
static BinaryArithmeticExpression.Operator	OP_ADD
static BinaryArithmeticExpression.Operator	OP_DIV
static BinaryArithmeticExpression.Operator	OP_MUL
static BinaryArithmeticExpression.Operator	OP_SUB

Constructor Summary

Constructors

Constructor and Description
BinaryArithmeticExpression(Expression lhs, BinaryArithmeticExpression.Operator op, Expression rhs) Creates a binary arithmetic expression by wrapping two expressions and one operator.

Method Summary

Modifier and Type	Method and Description
Constant	asConstant() Return the evaluated constant value if both expressions are constant.
String	asFieldName() This method should never be called.
Constant	evaluate(Record rec) Evaluates the arithmetic expression by computing on the values from the record.
boolean	isApplicableTo(Schema sch) Returns true if both expressions are in the specified schema.
boolean	isConstant() Returns true if both expressions are constant.
boolean	isFieldName() Returns false.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

OP_ADD

public static final BinaryArithmeticExpression.Operator OP_ADD

OP_SUB

public static final BinaryArithmeticExpression.Operator OP_SUB

OP_MUL

public static final BinaryArithmeticExpression.Operator OP_MUL

OP_DIV

public static final BinaryArithmeticExpression.Operator OP_DIV

Constructor Detail

BinaryArithmeticExpression

public BinaryArithmeticExpression(Expression lhs,
                                  BinaryArithmeticExpression.Operator op,
                                  Expression rhs)

Creates a binary arithmetic expression by wrapping two expressions and one operator.

Parameters:

lhs - the left hand side expression

op - the operator

rhs - the right hand side expression

Method Detail

isConstant

public boolean isConstant()

Returns true if both expressions are constant.

Specified by:

isConstant in interface Expression

Returns:

true if the expression is a constant

See Also:

Expression.isConstant()

isFieldName

public boolean isFieldName()

Returns false.

Specified by:

isFieldName in interface Expression

Returns:

true if the expression denotes a field

See Also:

Expression.isFieldName()

asConstant

public Constant asConstant()

Return the evaluated constant value if both expressions are constant.

Specified by:

asConstant in interface Expression

Returns:

the expression as a constant

See Also:

Expression.asConstant()

asFieldName

public String asFieldName()

This method should never be called. Throws a ClassCastException.

Specified by:

asFieldName in interface Expression

Returns:

the expression as a field name

See Also:

Expression.asFieldName()

evaluate

public Constant evaluate(Record rec)

Evaluates the arithmetic expression by computing on the values from the record.

Specified by:

evaluate in interface Expression

Parameters:

rec - the record

Returns:

the value of the expression, as a constant

See Also:

Expression.evaluate(Record)

isApplicableTo

public boolean isApplicableTo(Schema sch)

Returns true if both expressions are in the specified schema.

Specified by:

isApplicableTo in interface Expression

Parameters:

sch - the schema

Returns:

true if all fields in the expression are in the schema

See Also:

Expression.isApplicableTo(Schema)

toString

public String toString()

Overrides:

toString in class Object