jltools.visit
Class SemanticVisitor

java.lang.Object
  |
  +--jltools.ast.NodeVisitor
        |
        +--jltools.visit.BaseVisitor
              |
              +--jltools.visit.SemanticVisitor

Direct Known Subclasses:

AmbiguityRemover, FieldLabelResolver, JifLabelSubst, LabelChecker, TypeAmbiguityRemover, TypeChecker

public abstract class SemanticVisitor

extends BaseVisitor

A visitor which maintains a context. This is the base class of the disambiguation and type checking visitors.

Inner Class Summary

protected static class	SemanticVisitor.Abort Exception used to abort a visitor pass.
protected static class	SemanticVisitor.Catcher Class used to implement error propagation.

Field Summary

protected SemanticVisitor.Catcher	catcher
protected Context	context

Fields inherited from class jltools.visit.BaseVisitor

job

Constructor Summary

SemanticVisitor(Job job)

Method Summary

protected boolean	catchErrors(Node n) Return true if we should catch errors thrown when visiting the node.
Context	context()
NodeVisitor	enter(Node n) Begin normal traversal of a subtree rooted at n.
protected void	enterScope(Node n)
Node	leave(Node old, Node n, NodeVisitor v) This method is called after all of the children of n have been visited.
protected Node	leaveCall(Node n)
protected Node	leaveCall(Node old, Node n, NodeVisitor v)
protected void	leaveScope(Node n)
protected boolean	newCatcher(Node n) Create a new exception catcher for the node.
Node	override(Node n) Given a tree rooted at n, the visitor has the option of overriding all traversal of the children of n.
protected Node	overrideCall(Node n)

Methods inherited from class jltools.visit.BaseVisitor

errorQueue, importTable, job, nodeFactory, parsedResolver, typeSystem

Methods inherited from class jltools.ast.NodeVisitor

finish, toString

Methods inherited from class java.lang.Object

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

Field Detail

context

protected Context context

catcher

protected SemanticVisitor.Catcher catcher

Constructor Detail

SemanticVisitor

public SemanticVisitor(Job job)

Method Detail

context

public Context context()

overrideCall

protected Node overrideCall(Node n)
                     throws SemanticException

leaveCall

protected Node leaveCall(Node old,
                         Node n,
                         NodeVisitor v)
                  throws SemanticException

leaveCall

protected Node leaveCall(Node n)
                  throws SemanticException

enterScope

protected void enterScope(Node n)

leaveScope

protected void leaveScope(Node n)

catchErrors

protected boolean catchErrors(Node n)

Return true if we should catch errors thrown when visiting the node.

newCatcher

protected boolean newCatcher(Node n)

Create a new exception catcher for the node. If a catcher is already created for this node or we should not catch exceptions at this node, return false, otherwise return true. Returning true will indicate to the override() method that exceptions should be caught when visiting the node.

override

public Node override(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.

Overrides:

override in class NodeVisitor

Following copied from class: jltools.ast.NodeVisitor

Parameters:

n - The root of the subtree to be traversed.

Returns:

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

enter

public NodeVisitor enter(Node n)

Description copied from class: NodeVisitor

Begin normal traversal of a subtree rooted at n. This gives the visitor the option of changing internal state or returning a new visitor which will be used to visit the children of n.

Overrides:

enter in class NodeVisitor

Following copied from class: jltools.ast.NodeVisitor

Parameters:

n - The root of the subtree to be traversed.

Returns:

The NodeVisitor which should be used to visit the children of n.

leave

public Node leave(Node old,
                  Node n,
                  NodeVisitor v)

Description copied from class: NodeVisitor

This method is called after all of the children of n have been visited. In this case, these children were visited by the visitor v. This is the last chance for the visitor to modify the tree rooted at n. This method will be called exactly the same number of times as entry is called. That is, for each node that is not overriden, enter and leave are each called exactly once.

Note that if old == n then the vistior should make a copy of n before modifying it. It should then return the modified copy.

Overrides:

leave in class NodeVisitor

Following copied from class: jltools.ast.NodeVisitor

Parameters:

old - The original state of root of the current subtree.

n - The current state of the root of the current subtree.

v - The NodeVisitor object used to visit the children.

Returns:

The final result of the traversal of the tree rooted at n.