Package com.singularsys.jep.walkers

Class PrefixTreeWalker

java.lang.Object

com.singularsys.jep.walkers.PrefixTreeWalker

Direct Known Subclasses:

PrefixTreeDumper

public abstract class PrefixTreeWalker
extends Object

Base class for routines which use a non-recursive tree walker strategy. The typical recursive strategy can use a lot of stack frames for very large expressions these can cause a stack overflow exception. Subclasses should implement the visit methods of ParserVisitor to traverse the various nodes. In general these methods should not recursively walk the child nodes. This class uses a prefix traversal scheme hence the nodes of '1+2' will be visited in the order +,1,2.

Author:

Richard Morris

See Also:

• PostfixTreeWalker

Constructor Summary

Constructors

Constructor	Description
PrefixTreeWalker()

Method Summary

Modifier and Type	Method	Description
protected abstract void	visit(ASTConstant node, int nchildren, int depth1)
protected abstract void	visit(ASTFunNode node, int nchildren, int depth1)
protected abstract void	visit(ASTOpNode node, int nchildren, int depth1)
protected abstract void	visit(ASTVarNode node, int nchildren, int depth1)
void	walk(Node top)	Uses a non-recursive method to traverse the tree under the node 'top'.

Methods inherited from class java.lang.Object

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

Constructor Details

PrefixTreeWalker

public PrefixTreeWalker()

Method Details

walk

public void walk(Node top)
          throws JepException

Uses a non-recursive method to traverse the tree under the node 'top'.

Parameters:

top - the top node of the parse tree.

Throws:

JepException

visit

protected abstract void visit(ASTFunNode node,
 int nchildren,
 int depth1)
                       throws JepException

Throws:

JepException

visit

protected abstract void visit(ASTOpNode node,
 int nchildren,
 int depth1)
                       throws JepException

Throws:

JepException

visit

protected abstract void visit(ASTVarNode node,
 int nchildren,
 int depth1)
                       throws JepException

Throws:

JepException

visit

protected abstract void visit(ASTConstant node,
 int nchildren,
 int depth1)
                       throws JepException

Throws:

JepException