Package net.ssehub.easy.instantiation.core.model.expressions

Class ExpressionEvaluator

java.lang.Object

net.ssehub.easy.instantiation.core.model.expressions.Expression

net.ssehub.easy.instantiation.core.model.expressions.ExpressionEvaluator

All Implemented Interfaces:

IStringValueProvider, IVilType

public class ExpressionEvaluator
extends Expression
implements IVilType, IStringValueProvider

A wrapper type to pass and evaluate expressions in VIL languages. This is helpful to realize expression-based collection selection and projection operators. In case of aggregating expressions, consider multiple declarators, in particular getResultType() and for evaluation initializeDeclarators() and getResultValue().

Author:

Holger Eichelberger

Nested Class Summary

Nested classes/interfaces inherited from interface net.ssehub.easy.instantiation.core.model.vilTypes.IStringValueProvider

IStringValueProvider.StringComparator

Field Summary

Fields

Modifier and Type	Field	Description
private java.util.List<VariableDeclaration>	declarators
private EvaluationVisitor	evaluationVisitor
private Expression	expression
private VariableDeclaration	iterator

Constructor Summary

Constructors

Constructor	Description
ExpressionEvaluator(Expression expression, VariableDeclaration iterator, java.util.List<? extends VariableDeclaration> declarators)	Creates an expression evaluator.

Method Summary

Modifier and Type	Method	Description
java.lang.Object	accept(IExpressionVisitor visitor)	Visits the expression.
void	bind(EvaluationVisitor evaluationVisitor)	Binds the evaluation visitor.
java.lang.Object	evaluate(java.lang.Object iteratorValue)	Evaluates the wrapped expression.
VariableDeclaration	getDeclarator(int index)	Returns the specified declarator.
int	getDeclaratorsCount()	Returns the number of declarators.
Expression	getExpression()	Returns the expression.
VariableDeclaration	getIteratorVariable()	Returns the iterator variable.
private VariableDeclaration	getResultDeclarator()	Returns the explicit result declarator of an aggregating iterator.
TypeDescriptor<?>	getResultType()	Returns the explicit result type of an aggregating iterator.
java.lang.Object	getResultValue()	Returns the explicit result value of an aggregating iterator.
java.lang.String	getStringValue(IStringValueProvider.StringComparator comparator)	Returns the string value of this object.
TypeDescriptor<?>	inferType()	Infers the type of this expression including the type of the contained sub-expressions.
void	initializeDeclarators()	Initializes the declarators in case of default values given and changes the runtime environment accordingly.
void	unbind()	Unbinds the evaluation visitor (see evaluate(Object)).

Methods inherited from class net.ssehub.easy.instantiation.core.model.expressions.Expression

getFormattingHint, replaceEmptyLine

Methods inherited from class java.lang.Object

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

Field Detail

evaluationVisitor

private EvaluationVisitor evaluationVisitor

expression

private Expression expression

iterator

private VariableDeclaration iterator

declarators

private java.util.List<VariableDeclaration> declarators

Constructor Detail

ExpressionEvaluator

public ExpressionEvaluator(Expression expression,
                           VariableDeclaration iterator,
                           java.util.List<? extends VariableDeclaration> declarators)

Creates an expression evaluator.

Parameters:

expression - the expression to evaluate on

iterator - the iterator variable, one of declarators

declarators - all declarators of this expression in source sequence, if null a list consisting of iterator will be created

Method Detail

getDeclaratorsCount

public int getDeclaratorsCount()

Returns the number of declarators.

Returns:

the number of declarators

getDeclarator

public VariableDeclaration getDeclarator(int index)

Returns the specified declarator.

Parameters:

index - the 0-based index

Returns:

the declarator

Throws:

java.lang.IndexOutOfBoundsException - if index < 0 || index >= getDeclaratorsCount()

getResultType

public TypeDescriptor<?> getResultType()

Returns the explicit result type of an aggregating iterator.

Returns:

the explicit result type (if there are multiple declarators than it's the first one if it has a default value), null else

getResultDeclarator

private VariableDeclaration getResultDeclarator()

Returns the explicit result declarator of an aggregating iterator.

Returns:

the explicit declarator (if there are multiple declarators than it's the first one if it has a default value), null else

getResultValue

public java.lang.Object getResultValue()
                                throws VilException

Returns the explicit result value of an aggregating iterator.

Returns:

the explicit value, null else

Throws:

VilException - in case that obtaining the result value fails

bind

public void bind(EvaluationVisitor evaluationVisitor)

Binds the evaluation visitor. Must be called before evaluate(Object).

Parameters:

evaluationVisitor - the evaluation visitor used for evaluating the contained expression

unbind

public void unbind()

Unbinds the evaluation visitor (see evaluate(Object)).

evaluate

public java.lang.Object evaluate(java.lang.Object iteratorValue)
                          throws VilException

Evaluates the wrapped expression. This method is intended to be called from the type being evaluated (which does not have access to the evaluationVisitor). Thus, bind(EvaluationVisitor) must be called before and unbind() shall be called by the type being evaluated.

Parameters:

iteratorValue - the current value when iterating with the expression

Returns:

the result of evaluating expression in the current context of evaluationVisitor

Throws:

VilException - in case that the evaluation fails

getExpression

public Expression getExpression()

Returns the expression. Before evaluating this expression, the iterator variable must be bound with an actual value.

Returns:

the expression to be evaluated

getIteratorVariable

public VariableDeclaration getIteratorVariable()

Returns the iterator variable.

Returns:

the iterator variable

inferType

public TypeDescriptor<?> inferType()
                            throws VilException

Description copied from class: Expression

Infers the type of this expression including the type of the contained sub-expressions.

Specified by:

inferType in class Expression

Returns:

the type of this expression

Throws:

VilException - in case that inferring the type fails

accept

public java.lang.Object accept(IExpressionVisitor visitor)
                        throws VilException

Description copied from class: Expression

Visits the expression.

Specified by:

accept in class Expression

Parameters:

visitor - the visitor

Returns:

the result of visiting this expression (may be null)

Throws:

VilException - in case that visiting fails (e.g., execution)

getStringValue

public java.lang.String getStringValue(IStringValueProvider.StringComparator comparator)

Description copied from interface: IStringValueProvider

Returns the string value of this object.

Specified by:

getStringValue in interface IStringValueProvider

Parameters:

comparator - if the sequence of elements, e.g., in case of collections, shall be ordered according to the comparator, null if the original sequence shall be returned

Returns:

the string value

initializeDeclarators

public void initializeDeclarators()
                           throws VilException

Initializes the declarators in case of default values given and changes the runtime environment accordingly.

Throws:

VilException - if evaluating or setting the evaluated value fails