uk.org.ogsadai.expression.arithmetic
Class BinaryExpression

java.lang.Object
  uk.org.ogsadai.expression.arithmetic.BinaryExpression

All Implemented Interfaces:

ArithmeticExpression

Direct Known Subclasses:

Div, Minus, Mult, Plus

public abstract class BinaryExpression
extends java.lang.Object
implements ArithmeticExpression

A binary numeric operator in an arithmetic expression.

Author:

The OGSA-DAI Project Team.

Field Summary

protected int	mContextType Context dependent type.
protected Evaluator	mEval Evaluator for this operator.
protected ArithmeticExpression	mLeftChild left child expression.
protected ColumnMetadata	mOriginalType Type of this table column.
protected ArithmeticExpression	mRightChild right child expression.
protected ColumnMetadata	mType Return type.

Constructor Summary

BinaryExpression(ArithmeticExpression child1, ArithmeticExpression child2)
Constructs a new binary numeric operator with the given children.

Method Summary

void	configure(TupleMetadata metadata) Configures the expression with the metadata.
void	configure(TupleMetadata metadata, java.util.Set<Attribute> correlatedAttributes) Configures the expression with the metadata.
void	evaluate(Tuple tuple) Evaluates the arithmetic expression on the given input tuple.
ArithmeticExpression[]	getChildren() Returns the children of this arithmetic expression.
ArithmeticExpression	getLeftExpression() Gets left operand expression.
ColumnMetadata	getMetadata() Get the result type that is returned when evaluating this expression with tuples of the given type.
java.lang.Object	getResult() Returns the result of the evaluation.
ArithmeticExpression	getRightExpression() Gets right operand expression.
abstract java.lang.Number	localEvaluate(java.lang.Number lhs, java.lang.Number rhs) Performs operation specific evaluation.
protected abstract void	printOperator(java.lang.StringBuffer buf) Append the operator name (e.g.
void	resetType() Reset type to original.
void	setContextType(int type) Set context type for an expression.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface uk.org.ogsadai.expression.arithmetic.ArithmeticExpression

accept

Field Detail

mEval

protected Evaluator mEval

Evaluator for this operator.

mLeftChild

protected ArithmeticExpression mLeftChild

left child expression.

mRightChild

protected ArithmeticExpression mRightChild

right child expression.

mType

protected ColumnMetadata mType

Return type.

mOriginalType

protected ColumnMetadata mOriginalType

Type of this table column.

mContextType

protected int mContextType

Context dependent type.

Constructor Detail

BinaryExpression

public BinaryExpression(ArithmeticExpression child1,
                        ArithmeticExpression child2)

Constructs a new binary numeric operator with the given children.

Parameters:

child1 - left hand child expression

child2 - right hand child expression

Method Detail

setContextType

public void setContextType(int type)

Set context type for an expression.

Specified by:

setContextType in interface ArithmeticExpression

Parameters:

type - context tuple type

resetType

public void resetType()

Reset type to original.

Specified by:

resetType in interface ArithmeticExpression

localEvaluate

public abstract java.lang.Number localEvaluate(java.lang.Number lhs,
                                               java.lang.Number rhs)

Performs operation specific evaluation.

Parameters:

lhs - left hand side value

rhs - right hand side value

Returns:

result of the evaluation

evaluate

public final void evaluate(Tuple tuple)
                    throws ExpressionEvaluationException

Evaluates the arithmetic expression on the given input tuple.

Specified by:

evaluate in interface ArithmeticExpression

Parameters:

tuple - input tuple

Throws:

ExpressionEvaluationException - if expression can not be evaluated

getResult

public final java.lang.Object getResult()

Returns the result of the evaluation. In the expression is an aggregation function the result is aggregated from all input tuples up to this point.

Specified by:

getResult in interface ArithmeticExpression

Returns:

result of the evaluation

getChildren

public ArithmeticExpression[] getChildren()

Returns the children of this arithmetic expression.

Specified by:

getChildren in interface ArithmeticExpression

Returns:

child expressions

configure

public void configure(TupleMetadata metadata)
               throws TypeMismatchException

Configures the expression with the metadata. This method must be called before evaluating the expression or calling getMetadata(). This method is also used for type validation.

Specified by:

configure in interface ArithmeticExpression

Parameters:

metadata - tuple metadata

Throws:

TypeMismatchException - when the operand types are incompatible

configure

public void configure(TupleMetadata metadata,
                      java.util.Set<Attribute> correlatedAttributes)
               throws TypeMismatchException

Configures the expression with the metadata. This method must be called before evaluating the expression or calling getMetadata(). This method is also used for type validation. A set of correlated attributes can be passed in to support type validation of correlated attributes.

Specified by:

configure in interface ArithmeticExpression

Parameters:

metadata - tuple metadata

correlatedAttributes - set of correlated attributes, containing their types.

Throws:

TypeMismatchException - when the operand types are incompatible

getMetadata

public ColumnMetadata getMetadata()

Get the result type that is returned when evaluating this expression with tuples of the given type.

Specified by:

getMetadata in interface ArithmeticExpression

Returns:

result type

printOperator

protected abstract void printOperator(java.lang.StringBuffer buf)

Append the operator name (e.g. "+") to the given string buffer.

Parameters:

buf - buffer

getLeftExpression

public ArithmeticExpression getLeftExpression()

Gets left operand expression.

Returns:

left operand expression

getRightExpression

public ArithmeticExpression getRightExpression()

Gets right operand expression.

Returns:

right operand expression.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object