mwalk.visitor
Class AbstractVisitor

java.lang.Object
  |
  +--mwalk.visitor.AbstractVisitor

Direct Known Subclasses:

CollapseVisitor, DataVisitor, GlobalVisitor, JoinVisitor, MergeVisitor, PathlessVisitor, PrimaryPathVisitor, PrintVisitor, RandomPathVisitor, TraceVisitor

public abstract class AbstractVisitor

extends java.lang.Object

implements Visitor

Abstract class which defines a set of default methods for most visitors. This class defines methods for Visitor, UpVisitor, and DownVisitor although it only implements Visitor. This allows sub-classes to regulate which calls actually get made.

Version:

1.0

Author:

Robert Chalmers

Field Summary

private static java.lang.String	CFG_BASE Base of keys in configuration file
protected ActivityEvaluator	eval Evaluator used to determine activity when walking
protected java.util.Hashtable	seen Hash table used to track who we have seen and processed
protected boolean	verbose Whether the visitor prints verbose messages in verbose mode

Constructor Summary

AbstractVisitor()
Default constructor.

Method Summary

boolean	again(Tree tree) Check whether the visitor wants another pass over the tree.
protected boolean	cfgBoolean(java.lang.String key) Get a configuration value as a boolean.
protected int	cfgInt(java.lang.String key) Get a configuration value as an integer.
protected java.lang.String	cfgString(java.lang.String key) Get a configuration value as a string.
protected Visitor	cfgVisitor(java.lang.String key) Get a configuration value as a visitor object.
ActivityEvaluator	evaluator() Return the current activity evaluator.
void	evaluator(ActivityEvaluator eval) Set the current activity evaluator.
TreeNode[]	getChildren(Tree tree, TreeNode node) Retrieve the list of children of this node.
TreeNode[]	getParents(Tree tree, TreeNode node) Retrieve the list of parents of this node.
java.util.Enumeration	getReceivers(Tree tree) Get a list of active receivers.
boolean	haveSeen(TreeNode node)
boolean	haveVisited(TreeNode node)
boolean	init(Tree tree) Initialize the visitor state.
boolean	markSeen(TreeNode node)
boolean	markVisited(TreeNode node)
boolean	nextReceiver(Tree tree, Receiver recv) Check whether the next receiver should start a visiting path.
boolean	postfix() Whether to visit after visiting parent/children.
boolean	prefix() Whether to visit prior to visiting parent/children.
void	reset(Tree tree) Reset the visitor for a new pass over the tree.
boolean	verbose() Check whether the visitor is verbose.
java.lang.Object	visitDown(Tree tree, TreeNode node) Visit the current node prior to visiting children.
java.lang.Object	visitDown(Tree tree, TreeNode node, java.util.Vector list) Visit the current node after visiting children.
java.lang.Object	visitUp(Tree tree, TreeNode node) Visit the current node prior to visiting parent.
java.lang.Object	visitUp(Tree tree, TreeNode node, java.util.Vector list) Visit the current node after visiting parent.
boolean	walkDown() Whether to walk down the tree.
boolean	walkUp() Whether to walk up the tree.

Methods inherited from class java.lang.Object

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

Field Detail

CFG_BASE

private static final java.lang.String CFG_BASE

Base of keys in configuration file

eval

protected ActivityEvaluator eval

Evaluator used to determine activity when walking

seen

protected java.util.Hashtable seen

Hash table used to track who we have seen and processed

verbose

protected boolean verbose

Whether the visitor prints verbose messages in verbose mode

Constructor Detail

AbstractVisitor

public AbstractVisitor()

Default constructor.

Method Detail

evaluator

public ActivityEvaluator evaluator()

Return the current activity evaluator.

Specified by:

evaluator in interface Visitor

Returns:

ActivityEvaluator current evaluator

evaluator

public void evaluator(ActivityEvaluator eval)

Set the current activity evaluator.

Specified by:

evaluator in interface Visitor

Parameters:

ActivityEvaluator - new evaluator

verbose

public boolean verbose()

Check whether the visitor is verbose.

Specified by:

verbose in interface Visitor

Returns:

boolean whether visitor is verbose

prefix

public boolean prefix()

Whether to visit prior to visiting parent/children.

Specified by:

prefix in interface Visitor

Returns:

boolean whether to visit prior

postfix

public boolean postfix()

Whether to visit after visiting parent/children.

Specified by:

postfix in interface Visitor

Returns:

boolean whether to visit after

init

public boolean init(Tree tree)

Initialize the visitor state.

Specified by:

init in interface Visitor

Parameters:

Tree - current tree instance

Returns:

boolean whether to walk again

reset

public void reset(Tree tree)

Reset the visitor for a new pass over the tree.

Specified by:

reset in interface Visitor

Parameters:

Tree - vistited tree

again

public boolean again(Tree tree)

Check whether the visitor wants another pass over the tree.

Specified by:

again in interface Visitor

Parameters:

Tree - vistited tree

Returns:

boolean whether to walk again

walkUp

public boolean walkUp()

Whether to walk up the tree.

Returns:

boolean whether to walk up the tree

getReceivers

public java.util.Enumeration getReceivers(Tree tree)

Get a list of active receivers.

Parameters:

Tree - current tree instance

Returns:

Enumeration list of receivers to visit

nextReceiver

public boolean nextReceiver(Tree tree,
                            Receiver recv)

Check whether the next receiver should start a visiting path.

Parameters:

Tree - current tree instance

Receiver - next receiver

Returns:

boolean whether to visit next receiver

visitUp

public java.lang.Object visitUp(Tree tree,
                                TreeNode node)
                         throws VisitException

Visit the current node prior to visiting parent.

Parameters:

Tree - current tree instance

TreeNode - current node

Returns:

Object optional return value to pass back along the path

Throws:

VisitException - if a problem ocurred during visit

visitUp

public java.lang.Object visitUp(Tree tree,
                                TreeNode node,
                                java.util.Vector list)
                         throws VisitException

Visit the current node after visiting parent.

Parameters:

Tree - current tree instance

TreeNode - current node

Object - list of return values passed back along the path

Returns:

Object optional return value to pass back along the path

Throws:

VisitException - if a problem ocurred during visit

getParents

public TreeNode[] getParents(Tree tree,
                             TreeNode node)

Retrieve the list of parents of this node.

Parameters:

Tree - vistited tree

TreeNode - currently visited node

Returns:

TreeNode[] array of parent nodes of currently visited node

walkDown

public boolean walkDown()

Whether to walk down the tree.

Returns:

boolean whether to walk down the tree

visitDown

public java.lang.Object visitDown(Tree tree,
                                  TreeNode node)
                           throws VisitException

Visit the current node prior to visiting children. This method is called if prefix() returns true.

Parameters:

Tree - current tree instance

TreeNode - current node

Returns:

Object optional return value to pass back along the path

Throws:

VisitException - if a problem ocurred during visit

visitDown

public java.lang.Object visitDown(Tree tree,
                                  TreeNode node,
                                  java.util.Vector list)
                           throws VisitException

Visit the current node after visiting children. This method is called if postfix() returns true.

Parameters:

Tree - current tree instance

TreeNode - current node

Object - list of return values passed back along the path

Returns:

Object optional return value to pass back along the path

Throws:

VisitException - if a problem ocurred during visit

getChildren

public TreeNode[] getChildren(Tree tree,
                              TreeNode node)

Retrieve the list of children of this node.

Parameters:

Tree - vistited tree

TreeNode - currently visited node

Returns:

TreeNode[] array of child nodes of currently visited node

haveSeen

public boolean haveSeen(TreeNode node)

haveVisited

public boolean haveVisited(TreeNode node)

markSeen

public boolean markSeen(TreeNode node)

markVisited

public boolean markVisited(TreeNode node)

cfgString

protected java.lang.String cfgString(java.lang.String key)

Get a configuration value as a string. Returns null if value not found.

Parameters:

String - key string

Returns:

String config value

cfgInt

protected int cfgInt(java.lang.String key)

Get a configuration value as an integer. Returns -1 if value not found.

Parameters:

String - key string

Returns:

int config value

cfgBoolean

protected boolean cfgBoolean(java.lang.String key)

Get a configuration value as a boolean. Returns false if value not found.

Parameters:

String - key string

Returns:

boolean config value

cfgVisitor

protected Visitor cfgVisitor(java.lang.String key)

Get a configuration value as a visitor object. Returns null if value not found.

Parameters:

String - key string

Returns:

Visitor instantiated visitor