org.josql.expressions
Class BinaryExpression

java.lang.Object
  org.josql.expressions.Expression
      org.josql.expressions.BinaryExpression

Direct Known Subclasses:

AndOrExpression, BetweenExpression, EqualsExpression, GTLTExpression, InExpression, IsNullExpression, LikeExpression

public abstract class BinaryExpression
extends Expression

Super-class of Expressions that return a binary result.

A binary expression must always have a LHS. The RHS is optional.

Field Summary

protected Expression	left
protected Expression	right

Constructor Summary

BinaryExpression()

Method Summary

Class	getExpectedReturnType(Query q) Return the expected return type from this expression.
Expression	getLeft() Get the LHS.
Expression	getRight() Get the RHS.
Object	getValue(Object o, Query q) Get the value of this expression.
boolean	hasFixedResult(Query q) Return whether this expression, and more specifically the left and right parts of the expression return a fixed result.
void	init(Query q) Init the expression.
void	setLeft(Expression exp)
void	setRight(Expression exp)

Methods inherited from class org.josql.expressions.Expression

isBracketed, isTrue, setBracketed, toString

Methods inherited from class java.lang.Object

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

Field Detail

left

protected Expression left

right

protected Expression right

Constructor Detail

BinaryExpression

public BinaryExpression()

Method Detail

hasFixedResult

public boolean hasFixedResult(Query q)

Return whether this expression, and more specifically the left and right parts of the expression return a fixed result. Sub-classes may override this method for more tailored results, especially if the binary expression does not demand a RHS.

Specified by:

hasFixedResult in class Expression

Parameters:

q - The Query object.

Returns:

true if the expression has a fixed result.

getExpectedReturnType

public Class getExpectedReturnType(Query q)

Return the expected return type from this expression.

Specified by:

getExpectedReturnType in class Expression

Parameters:

q - The Query object.

Returns:

The class of the return type, this method ALWAYS returns Boolean.class.

init

public void init(Query q)
          throws QueryParseException

Init the expression. Sub-classes will often override this method. This method just calls: Expression.init(Query) on the LHS and RHS (if present) of the expression.

Specified by:

init in class Expression

Parameters:

q - The Query object.

Throws:

QueryParseException - If the LHS and/or RHS cannot be inited.

getValue

public Object getValue(Object o,
                       Query q)
                throws QueryExecutionException

Get the value of this expression. This will always return an instance of: java.lang.Boolean created as the result of a call to: Expression.getValue(Object,Query).

Specified by:

getValue in class Expression

Parameters:

o - The object to evaluate the expression on.

q - The Query object.

Returns:

An instance of Boolean.

Throws:

QueryExecutionException - If the expression cannot be evaluated.

getRight

public Expression getRight()

Get the RHS.

Returns:

The RHS of the expression.

getLeft

public Expression getLeft()

Get the LHS.

Returns:

The LHS of the expression.

setLeft

public void setLeft(Expression exp)

setRight

public void setRight(Expression exp)