Helpers.java

/*
Copyright (c) 2008 Arno Haase, Andr� Arnold.
All rights reserved. This program and the accompanying materials
are made available under the terms of the Eclipse Public License v1.0
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/epl-v10.html

Contributors:
    Arno Haase - initial API and implementation
    Andr� Arnold
 */
package org.eclipse.xtend.backend.common;

import java.util.Arrays;
import java.util.Collections;


/**
 * This class contains commonly used helper operations.
 * 
 * @author Arno Haase (http://www.haase-consulting.com)
 * @author Andr� Arnold
 */
public class Helpers {
    public static QualifiedName TO_STRING_METHOD_NAME = new QualifiedName ("toString");
    public static QualifiedName EQUALS_NAME = new QualifiedName ("operatorEquals");
    
    /**
     * This method is public static so as to be available as a helper method for all code that needs to call "toString".
     *  It calls "toString" on an object, taking into account all potential overriding extensions.<br>
     */
    public static CharSequence overridableToString (ExecutionContext ctx, Object o) {
        if (o == null)
            return "";
        
        if (o instanceof EfficientLazyString)
            return (CharSequence) o;
        
        final Object resultRaw = ctx.getFunctionDefContext().invoke (ctx, TO_STRING_METHOD_NAME, Collections.singletonList (o));
        if (resultRaw instanceof CharSequence)
            return (CharSequence) resultRaw;
        
        return String.valueOf (resultRaw);
    }

    public static boolean nullSafeEquals (ExecutionContext ctx, Object o1, Object o2) {
        if (o1 == o2)
            return true;
        
        if (o1 == null || o2 == null)
            return false;
        
        return (Boolean) ctx.getFunctionDefContext().invoke (ctx, EQUALS_NAME, Arrays.asList (o1, o2));
    }
}