astpair.java

来自「SRI international 发布的OAA框架软件」· Java 代码 · 共 44 行

package antlr_oaa;

/* ANTLR Translator Generator
 * Project led by Terence Parr at http://www.jGuru.com
 * Software rights: http://www.antlr.org/RIGHTS.html
 *
 * $Id: ASTPair.java,v 1.1 2002/11/08 17:38:24 agno Exp $
 */

import antlr_oaa.collections.AST;

/** ASTPair:  utility class used for manipulating a pair of ASTs
  * representing the current AST root and current AST sibling.
  * This exists to compensate for the lack of pointers or 'var'
  * arguments in Java.
  */
public class ASTPair {
	public AST root;		// current root of tree
	public AST child;		// current child to which siblings are added

    /** Make sure that child is the last sibling */
    public final void advanceChildToEnd() {
	if (child != null) {
	    while (child.getNextSibling() != null) {
		child = child.getNextSibling();
	    }
	}
    }

    /** Copy an ASTPair.  Don't call it clone() because we want type-safety */
    public ASTPair copy() {
	ASTPair tmp = new ASTPair();
	tmp.root = root;
	tmp.child = child;
	return tmp;
    }

    public String toString() {
	String r = root==null ? "null" : root.getText();
	String c = child==null ? "null" : child.getText();
	return "["+r+","+c+"]";
    }
}