polyglot.visit

Class HaltingVisitor

java.lang.Object

polyglot.visit.NodeVisitor

polyglot.visit.HaltingVisitor

All Implemented Interfaces:

java.lang.Cloneable, Copy<NodeVisitor>

Direct Known Subclasses:

DeadCodeEliminator.DefUseFinder, DeepCopy, ErrorHandlingVisitor, SimplifyExpressionsForBoxing

public abstract class HaltingVisitor
extends NodeVisitor

A HaltingVisitor is used to prune the traversal of the AST at a particular node. Clients can call bypass(Node n) to have the visitor skip n and its children when recursing through the AST.

Nested Class Summary

Nested classes/interfaces inherited from interface polyglot.util.Copy

Copy.Util

Field Summary

Fields

Modifier and Type	Field and Description
protected java.util.Collection<Node>	bypass
protected Node	bypassParent

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	HaltingVisitor(Lang lang)

Method Summary

Methods

Modifier and Type	Method and Description
HaltingVisitor	bypass(java.util.Collection<? extends Node> c) Return a new visitor that will bypass all nodes in collection c.
HaltingVisitor	bypass(Node n) Return a new visitor that bypasses node n during visit children.
HaltingVisitor	bypassChildren(Node n) Return a new visitor that will bypass all children of node n.
Node	override(Node parent, Node n) Given a tree rooted at n, the visitor has the option of overriding all traversal of the children of n.
HaltingVisitor	visitChildren() Return a new visitor that will visit all children.

Methods inherited from class polyglot.visit.NodeVisitor

begin, copy, enter, enter, finish, finish, lang, leave, leave, override, toString, visitEdge, visitEdgeNoOverride

Methods inherited from class java.lang.Object

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

Field Detail

bypassParent

protected Node bypassParent

bypass

protected java.util.Collection<Node> bypass

Constructor Detail

HaltingVisitor

protected HaltingVisitor(Lang lang)

Method Detail

bypassChildren

public HaltingVisitor bypassChildren(Node n)

Return a new visitor that will bypass all children of node n.

visitChildren

public HaltingVisitor visitChildren()

Return a new visitor that will visit all children.

bypass

public HaltingVisitor bypass(Node n)

Return a new visitor that bypasses node n during visit children.

bypass

public HaltingVisitor bypass(java.util.Collection<? extends Node> c)

Return a new visitor that will bypass all nodes in collection c.

override

public Node override(Node parent,
            Node n)

Description copied from class: NodeVisitor

Given a tree rooted at n, the visitor has the option of overriding all traversal of the children of n. If no changes were made to n and the visitor wishes to prevent further traversal of the tree, then it should return n. If changes were made to the subtree, then the visitor should return a copy of n with appropriate changes. Finally, if the visitor does not wish to override traversal of the subtree rooted at n, then it should return null.

The default implementation of this method is to call override(n), as most subclasses do not need to know the parent of the node n.

Overrides:

override in class NodeVisitor

Parameters:

parent - The parent of n, null if n has no parent.

n - The root of the subtree to be traversed.

Returns:

A node if normal traversal is to stop, null if it is to continue.