com.singularsys.jep.walkers

Class DoNothingVisitor

java.lang.Object

com.singularsys.jep.walkers.DoNothingVisitor

All Implemented Interfaces:

JepComponent, ParserVisitor, java.io.Serializable

Direct Known Subclasses:

CommandVisitor, DeepCopyVisitor, ExpressionCleaner, RewriteVisitor, SubstitutionVisitor

public class DoNothingVisitor
extends java.lang.Object
implements ParserVisitor, JepComponent

A Visitor which visits each node of a expression tree and does nothing. This visitor is intended as a base class for other visitors which manipulate expressions.

This class will always leave the original expression intact, but may reuse unchanged parts of the expression.

Since:

3.3 number of children no longer needs to be the same

Author:

Rich Morris Created on 16-Nov-2003

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected FunctionTable	ft Convenience reference to the FunctionTable
protected Jep	jep Jep instance
protected NodeFactory	nf Convenience reference to the NodeFactory
protected OperatorTableI	ot Convenience reference to the OperatorTableI
protected VariableTable	vt Convenience reference to the VariableTable

Constructor Summary

Constructors

Constructor and Description
DoNothingVisitor() Constructor to use with JepComponent mechanism, init method must be called.
DoNothingVisitor(Jep j)

Method Summary

Modifier and Type	Method and Description
protected boolean	childrenHaveChanged(Node node, Node[] children) Tests if the children of a node have changed
protected Node	copyChildrenIfNeeded(Node node, Node[] children) Sets the children of a node if they have changed for it current children.
FunctionTable	getFunctionTable()
JepComponent	getLightWeightInstance() Gets a light-weight instance suitable for using in multiple threads.
NodeFactory	getNodeFactory()
OperatorTableI	getOperatorTable()
VariableTable	getVariableTable()
void	init(Jep j) Initialize the component.
java.lang.Object	visit(ASTConstant node, java.lang.Object data) Visit a constant node.
java.lang.Object	visit(ASTFunNode node, java.lang.Object data) Visit a function node.
java.lang.Object	visit(ASTOpNode node, java.lang.Object data) Visit a operator node.
java.lang.Object	visit(ASTVarNode node, java.lang.Object data) Visit a variable node.
Node	visit(Node node)
protected Node[]	visitChildren(Node node, java.lang.Object data) Gets the result of visiting children of a array of nodes.
Node	visitNode(Node node, java.lang.Object data) Used to recursively visit the children of a node.

Methods inherited from class java.lang.Object

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

Field Detail

jep

protected Jep jep

Jep instance

nf

protected NodeFactory nf

Convenience reference to the NodeFactory

vt

protected VariableTable vt

Convenience reference to the VariableTable

ft

protected FunctionTable ft

Convenience reference to the FunctionTable

ot

protected OperatorTableI ot

Convenience reference to the OperatorTableI

Constructor Detail

DoNothingVisitor

public DoNothingVisitor()

Constructor to use with JepComponent mechanism, init method must be called.

DoNothingVisitor

public DoNothingVisitor(Jep j)

Method Detail

getLightWeightInstance

public JepComponent getLightWeightInstance()

Description copied from interface: JepComponent

Gets a light-weight instance suitable for using in multiple threads.

Specified by:

getLightWeightInstance in interface JepComponent

Returns:

this

init

public void init(Jep j)

Description copied from interface: JepComponent

Initialize the component. This methods is called whenever a component is added to Jep. Hence it allows components to keep track of the other components they may rely on.

Specified by:

init in interface JepComponent

Parameters:

j - the current Jep instance

visit

public Node visit(Node node)
           throws JepException

Throws:

JepException

visitNode

public Node visitNode(Node node,
                      java.lang.Object data)
               throws JepException

Used to recursively visit the children of a node.

Parameters:

node - Node to visit

data - user specified data

Returns:

a Node with the modified tree

Throws:

JepException

visitChildren

protected Node[] visitChildren(Node node,
                               java.lang.Object data)
                        throws JepException

Gets the result of visiting children of a array of nodes.

Parameters:

node - current node being visited

data - user specified data

Returns:

an array of results from visiting each child of the node.

Throws:

JepException

visit

public java.lang.Object visit(ASTConstant node,
                              java.lang.Object data)
                       throws JepException

Visit a constant node. Can be overridden by sub-classes.

Specified by:

visit in interface ParserVisitor

Throws:

JepException

visit

public java.lang.Object visit(ASTVarNode node,
                              java.lang.Object data)
                       throws JepException

Visit a variable node. Can be overridden by sub-classes.

Specified by:

visit in interface ParserVisitor

Throws:

JepException

visit

public java.lang.Object visit(ASTFunNode node,
                              java.lang.Object data)
                       throws JepException

Visit a function node. Can be overridden by sub-classes.

Specified by:

visit in interface ParserVisitor

Throws:

JepException

visit

public java.lang.Object visit(ASTOpNode node,
                              java.lang.Object data)
                       throws JepException

Visit a operator node. Can be overridden by sub-classes.

Specified by:

visit in interface ParserVisitor

Throws:

JepException

copyChildrenIfNeeded

protected Node copyChildrenIfNeeded(Node node,
                                    Node[] children)
                             throws JepException

Sets the children of a node if they have changed for it current children.

Throws:

JepException

childrenHaveChanged

protected boolean childrenHaveChanged(Node node,
                                      Node[] children)

Tests if the children of a node have changed

Parameters:

node - the original node

children - the new set of children.

Returns:

true if the children have changed, false otherwise

getNodeFactory

public NodeFactory getNodeFactory()

getOperatorTable

public OperatorTableI getOperatorTable()

getVariableTable

public VariableTable getVariableTable()

getFunctionTable

public FunctionTable getFunctionTable()