ASTIterator.java

/*
 * ASTIterator.java
 * 
 * Copyright (c) 2006 David Holroyd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package uk.co.badgersinfoil.metaas.impl;

import java.util.NoSuchElementException;
import uk.co.badgersinfoil.metaas.impl.antlr.LinkedListTree;


/**
 * Iterates over the children of the given AST node.
 */
public class ASTIterator {
	private LinkedListTree parent;
	private int index = -1;

	public ASTIterator(LinkedListTree parent) {
		if (parent == null) {
			throw new IllegalArgumentException("null not allowed");
		}
		this.parent = parent;
	}
	public boolean hasNext() {
		return index < parent.getChildCount()-1;
	}
	public LinkedListTree next(int tokenType) {
		if (!hasNext()) {
			throw new IllegalStateException("expected " + ASTUtils.tokenName(tokenType) + " but reached last child");
		}
		if (parent.getChild(index+1).getType() != tokenType) {
			throw new IllegalStateException("expected " + ASTUtils.tokenName(tokenType) + " but got " + parent.getChild(index+1));
		}
		return next();
	}
	public LinkedListTree next() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		index++;
		return (LinkedListTree)parent.getChild(index);
	}
	/**
	 * After a call to remove, another call to next() is required to access
	 * the element following the one just deleted.
	 */
	public void remove() {
		parent.deleteChild(index);
		index--;
	}
	public void replace(LinkedListTree replacement) {
		parent.setChildWithTokens(index, replacement);
	}
	public LinkedListTree search(int tokenType) {
		while (hasNext()) {
			LinkedListTree ast = next();
			if (ast.getType() == tokenType) {
				return ast;
			}
		}
		return null;
	}

	public LinkedListTree find(int tokenType) {
		LinkedListTree result = search(tokenType);
		if (result != null) {
			return result;
		}
		throw new IllegalStateException("expected " + ASTUtils.tokenName(tokenType) + " but not found");
	}
	

	public void insertBeforeCurrent(LinkedListTree insert) {
		parent.addChildWithTokens(index, insert);
	}
	
	public int getCurrentIndex() {
		return index;
	}
}