org.josql.expressions

Class AliasedExpression

java.lang.Object

org.josql.expressions.Expression

org.josql.expressions.AliasedExpression

Direct Known Subclasses:

AliasedFunction

public class AliasedExpression
extends Expression

Represents an expression that also has an alias. SELECT columns may have aliases as may the functions in the "EXECUTE ON" clause.

Field Summary

Fields

Modifier and Type	Field and Description
protected Expression	exp

Constructor Summary

Constructors

Constructor and Description
AliasedExpression()

Method Summary

Modifier and Type	Method and Description
String	getAlias() Get the alias for the expression.
Class	getExpectedReturnType(Query q) Get the expected return type for the expression.
Expression	getExpression() Get the expression being aliased.
Object	getValue(Object o, Query q) Get the value for this expression.
boolean	hasFixedResult(Query q) Return whether this expression has a fixed result.
void	init(Query q) Init this expression.
boolean	isTrue(Object o, Query q) Indicate whether the expression evaluates to true.
void	setAlias(String a)
void	setExpression(Expression exp)
String	toString() Return a string representation of the aliased expression.

Methods inherited from class org.josql.expressions.Expression

isBracketed, setBracketed

Methods inherited from class java.lang.Object

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

Field Detail

exp

protected Expression exp

Constructor Detail

AliasedExpression

public AliasedExpression()

Method Detail

hasFixedResult

public boolean hasFixedResult(Query q)

Return whether this expression has a fixed result. See: Expression.hasFixedResult(Query) for more details.

Specified by:

hasFixedResult in class Expression

Parameters:

q - The Query object.

Returns:

true if the expression returns a fixed result, false otherwise.

getExpectedReturnType

public Class getExpectedReturnType(Query q)
                            throws QueryParseException

Get the expected return type for the expression.

Specified by:

getExpectedReturnType in class Expression

Parameters:

q - The Query object.

Returns:

The class of the return type.

Throws:

QueryParseException - If an error occurs whilst trying to determine the return type.

init

public void init(Query q)
          throws QueryParseException

Init this expression. All that occurs here is that the aliased expression is inited via: Expression.init(Query).

Specified by:

init in class Expression

Parameters:

q - The Query object.

Throws:

QueryParseException - If an error occurs during the initialisation of the expression.

getAlias

public String getAlias()

Get the alias for the expression.

Returns:

The alias.

setAlias

public void setAlias(String a)

getExpression

public Expression getExpression()

Get the expression being aliased.

Returns:

The expression.

setExpression

public void setExpression(Expression exp)

isTrue

public boolean isTrue(Object o,
                      Query q)
               throws QueryExecutionException

Indicate whether the expression evaluates to true.

Specified by:

isTrue in class Expression

Parameters:

o - The object to perform the expression on.

q - The Query object.

Returns:

true if the expression evaulates to true, false otherwise.

Throws:

QueryExecutionException - If something goes wrong during execution of the: Expression.isTrue(Object,Query) method.

See Also:

Expression.isTrue(Object,Query)

getValue

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

Get the value for this expression.

Specified by:

getValue in class Expression

Parameters:

o - The object to perform the expression on.

q - The Query object.

Returns:

The result of calling: Expression.getValue(Object,Query).

Throws:

QueryExecutionException - If something goes wrong with the execution of the expression.

toString

public String toString()

Return a string representation of the aliased expression. Returns in the form: Expression AS Alias.

Specified by:

toString in class Expression

Returns:

The result of calling: Expression.toString() + AS + getAlias().