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Add-ons for the ANTLR parser generator
There is a newer version: 0.1.3
package it.twenfir.antlr.ast;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

/**
 * The base class of AST nodes.
 * Provides access to children nodes and to source code location information.
 * Position is expressed as source code line and character as well as start and end tokens.
 */
public abstract class AstNode {
	
    private Location location;
    private AstNode parent;
    private List children = new ArrayList<>();

    /**
     * Constructor.
     * 
     * @param location the node's position within the source file
     */
    public AstNode(Location location) {
        this.location = location;
    }

    /**
     * Return the node's parent.
     * 
     * @return the node's parent
     */
    public AstNode getParent() {
		return parent;
	}

    /**
     * Set the node's parent.
     * 
     * @param parent the node's parent
     */
	void setParent(AstNode parent) {
		this.parent = parent;
	}

	/** 
     * Return the line where the node's text is located in the source code.
     * 
     * @return the line number
     */
    public int getLine() {
        return location.getLine();
    }

    /** 
     * Return the position in the line where the node's text is located in the source code.
     * 
     * @return the position in the line
     */
    public int getPos() {
        return location.getPos();
    }

    /** 
     * Return the start token in the ANTLR token stream.
     * 
     * @return the start token
     */
    public int getStart() {
        return location.getStart();
    }

    /** 
     * Return the end token in the ANTLR token stream.
     * 
     * @return the end token
     */
    public int getEnd() {
        return location.getEnd();
    }

    /** 
     * Add a child node.
     * 
     * @param child the child node
     */
    public void addChild(AstNode child) {
    	if ( child != null ) {
        	children.add(child);
        	child.setParent(this);
    	}
    }
    
    /** 
     * Add a collection of children nodes.
     * 
     * @param       the children's type
     * @param children the children nodes
     */
    public  void addChildren(Collection children) {
    	if ( children != null ) {
    		for ( N n : children ) {
    			children.add(n);
    			n.setParent(this);
    		}
    	}
    }
    
    /** 
     * Return all the node's children.
     * 
     * @return an iterator over the node's children
     */
    public Iterator getChildren() {
    	return children.iterator();
    }
    
    /** 
     * Return a single child node of the specified type, assumed to be the only such node.
     * 
     * @param  the type of the requested child
     * @param clazz    the class object of the requested child node
     * @return         the child node, or null if none exists
     */
    public  ChildT getChild(Class clazz) {
    	ChildrenIterator iter = new ChildrenIterator(getChildren(), clazz);
    	return iter.hasNext() ? iter.next() : null;
    }
    
    /** 
     * Return all the children nodes of the specified type.
     * 
     * @param  the type of the requested children
     * @param clazz    the class object of the requested children
     * @return         an iterator over children of the specified type
     */
    public  Iterator getChildren(Class clazz) {
    	return new ChildrenIterator(getChildren(), clazz);
    }
    
    /** 
     * Return a single descendant node of the specified type, assumed to be the only such node.
     * 
     * @param  the type of the requested child
     * @param clazz    the class object of the requested child node
     * @return         the descendant node, or null if none exists
     */
    public  ChildT getDescendant(Class clazz) {
    	ChildrenIterator iter = new ChildrenIterator(new WalkerIterator(this), clazz);
    	return iter.hasNext() ? iter.next() : null;
    }
    
    /** 
     * Return all the descendant nodes of the specified type.
     * 
     * @param  the type of the requested children
     * @param clazz    the class object of the requested children
     * @return         an iterator over descendants of the specified type
     */
    public  Iterator getDescendants(Class clazz) {
    	return new ChildrenIterator(new WalkerIterator(this), clazz);
    }
	
    /** 
     * Default implementation of accept for AstVisitor's.
     * 
     * @param  the type returned by the visitor
     * @param visitor  the visitor
     * @return         the result of the visit
     */
    public  ValueT accept(AstVisitor visitor) {
    	return visitor.visit(this);
    }
    
    /** 
     * Return the class name of the node.
     * 
     * @return the class name
     */
    public String getType() {
        return this.getClass().getSimpleName();
    }
}