com.agentfactory.common.parser
Class Handler

java.lang.Object
  com.agentfactory.common.parser.Handler

public abstract class Handler
extends java.lang.Object

This is an abstract base class that should be extended to implement support for individual statement types within the source programming language. Subclasses must implement two types of method:

• the generateParseTree(...) method is responsible for converting a list of tokens into a node structure.
• the accept(Node, XXXVisitor) methods implement support for the various types of visitor that are required by the compiler.

The first method is invoked directly by the parser, while the other methods are invoked through method level reflection that is implemented in the accept(Node, Visitor) method of this class.

Constructor Summary

Handler()

Method Summary

void	accept(Node node, Visitor visitor) Implements part of the Visitor pattern for tree traversal.
abstract Node	generateParseTree(java.util.List<Token> statement) Subclasses should implement this method, which is responsible for converting a statement (in the form of a list of Tokens) into a Node structure.
java.lang.String	toString(Node node)

Methods inherited from class java.lang.Object

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

Constructor Detail

Handler

public Handler()

Method Detail

generateParseTree

public abstract Node generateParseTree(java.util.List<Token> statement)
                                throws SyntaxError

Subclasses should implement this method, which is responsible for converting a statement (in the form of a list of Tokens) into a Node structure. As part of its implementation, this method should check whether or not the statement is of the corresponding type. That is, this method may be passed statements that are not the responsibility of this class. In such cases, this method should return null. In the event that this method detects a syntax error in the statement, the method should throw a SyntaxError exception.

Parameters:

statement - a list of tokens that correspond to a single statement in the source language.

Returns:

null if the statment is not the responsibility of this class, and a node structure if it is the classes responsibility and the statement is correctly formed.

Throws:

a - syntax error exception if the statement is incorrectly formed.

SyntaxError

accept

public void accept(Node node,
                   Visitor visitor)
            throws SemanticError

Implements part of the Visitor pattern for tree traversal. This method is invoked by all classes that implement the Visitor interface, and uses reflection to invoke a corresponding accept(Node, XXXVisitor) method in the concrete subclasses.

Parameters:

node - the node that is currently being visited

visitor - a visitor object that is currently traversing the parse tree

Throws:

SemanticError

toString

public java.lang.String toString(Node node)