jltools.visit
Class ExceptionChecker

java.lang.Object
  |
  +--jltools.ast.NodeVisitor
        |
        +--jltools.visit.ExceptionChecker

public class ExceptionChecker

extends NodeVisitor

Visitor which checks if exceptions are caught or declared properly.

Field Summary

protected ErrorQueue	eq
protected java.util.LinkedList	freelist
protected SubtypeSet	thrown
protected TypeSystem	ts

Constructor Summary

	ExceptionChecker(TypeSystem ts, ErrorQueue eq)
protected	ExceptionChecker(TypeSystem ts, ErrorQueue eq, java.util.LinkedList freelist)

Method Summary

ExceptionChecker	alloc()
NodeVisitor	enter(Node n) This method is called when we are to perform a "normal" traversal of a subtree rooted at n.
Node	leave(Node old, Node n, NodeVisitor v) Here, we pop the stack frame that we pushed in enter and agregate the exceptions.
Node	override(Node n) Given a tree rooted at n, the visitor has the option of overriding all traversal of the children of n.
void	release(ExceptionChecker ec)
void	throwsException(Type t) The ast nodes will use this callback to notify us that they throw an exception of type t.
SubtypeSet	throwsSet() Method to allow the throws clause and method body to inspect and modify the throwsSet.
TypeSystem	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

thrown

protected SubtypeSet thrown

ts

protected TypeSystem ts

eq

protected ErrorQueue eq

freelist

protected java.util.LinkedList freelist

Constructor Detail

ExceptionChecker

public ExceptionChecker(TypeSystem ts,
                        ErrorQueue eq)

ExceptionChecker

protected ExceptionChecker(TypeSystem ts,
                           ErrorQueue eq,
                           java.util.LinkedList freelist)

Method Detail

typeSystem

public TypeSystem typeSystem()

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)

This method is called when we are to perform a "normal" traversal of a subtree rooted at n. At every node, we will push a stack frame. Each child node will add the exceptions that it throws to this stack frame. For most nodes ( excdeption for the try / catch) will just aggregate the stack frames.

Overrides:

enter in class 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)

Here, we pop the stack frame that we pushed in enter and agregate the exceptions.

Overrides:

leave in class 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.

throwsException

public void throwsException(Type t)

The ast nodes will use this callback to notify us that they throw an exception of type t. This should only be called by MethodExpr node, and throw node, since they are the only node which can generate exceptions.

Parameters:

t - The type of exception that the node throws.

throwsSet

public SubtypeSet throwsSet()

Method to allow the throws clause and method body to inspect and modify the throwsSet.

alloc

public ExceptionChecker alloc()

release

public void release(ExceptionChecker ec)