/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later.
* See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
*/
package org.hibernate.hql.internal.ast.util;
import antlr.ASTFactory;
import antlr.collections.AST;
/**
* Appends child nodes to a parent efficiently.
*
* @author Joshua Davis
*/
public class ASTAppender {
private AST parent;
private AST last;
private ASTFactory factory;
/**
* Builds an appender using the given factory and parent
*
* @param factory The AST factory
* @param parent The AST parent
*/
public ASTAppender(ASTFactory factory, AST parent) {
this.factory = factory;
this.parent = parent;
this.last = ASTUtil.getLastChild( parent );
}
/**
* Append a new child to parent using the given node type and text, but only if the
* text is non-empty
*
* @param type The node type
* @param text The node text
* @param appendIfEmpty Should we do the append if the text is empty?
*
* @return The generated AST node; may return {@code null}
*/
public AST append(int type, String text, boolean appendIfEmpty) {
if ( text != null && ( appendIfEmpty || text.length() > 0 ) ) {
return append( factory.create( type, text ) );
}
else {
return null;
}
}
/**
* Append the given AST node as a child of parent.
*
* @param child The child to append
*
* @return Returns what was passed in.
*/
public AST append(AST child) {
if ( last == null ) {
parent.setFirstChild( child );
}
else {
last.setNextSibling( child );
}
last = child;
return last;
}
}