OverrideTest.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.syslib;

import static org.eclipse.xtend.backend.testhelpers.BackendTestHelper.SOURCE_POS;
import static org.eclipse.xtend.backend.testhelpers.BackendTestHelper.createEmptyExecutionContext;
import static org.eclipse.xtend.backend.testhelpers.BackendTestHelper.createEmptyFdc;
import static org.eclipse.xtend.backend.testhelpers.BackendTestHelper.createLiteral;
import static org.junit.Assert.assertEquals;

import java.util.Arrays;

import org.eclipse.xtend.backend.common.ExecutionContext;
import org.eclipse.xtend.backend.common.ExpressionBase;
import org.eclipse.xtend.backend.common.NamedFunction;
import org.eclipse.xtend.backend.expr.ConcatExpression;
import org.eclipse.xtend.backend.functions.FunctionDefContextInternal;
import org.eclipse.xtend.backend.testhelpers.NamedFunctionFactory;
import org.eclipse.xtend.backend.types.CompositeTypesystem;
import org.eclipse.xtend.backend.types.builtin.LongType;
import org.eclipse.xtend.backend.types.builtin.ObjectType;
import org.junit.Test;


/**
 * 
 * @author Arno Haase (http://www.haase-consulting.com)
 * @author Andr� Arnold
 */
public class OverrideTest {
    /**
     * This method tests that it is possible to override a function from the syslib by
     *  contributing another function of the same signature to the fdc.
     */
    @Test public void testOverride () {
        final NamedFunction myLongToString = new NamedFunctionFactory ("toString", LongType.INSTANCE) {
            public Object invoke (ExecutionContext ctx, Object[] params) {
                return "Long<" + params[0] + ">";
            }
        }.create();
        final NamedFunction myObjectToString = new NamedFunctionFactory ("toString", ObjectType.INSTANCE) {
            public Object invoke (ExecutionContext ctx, Object[] params) {
                return "Object<" + params[0] + ">";
            }
        }.create();
        
        final ExpressionBase expr = new ConcatExpression (Arrays.asList (createLiteral (25L), createLiteral ("Abc")), SOURCE_POS);
        
        final FunctionDefContextInternal fdc = createEmptyFdc (new CompositeTypesystem ());
        fdc.register (myLongToString, true);
        fdc.register (myObjectToString, true);
        
        final ExecutionContext ctx = createEmptyExecutionContext();
        assertEquals ("25Abc", expr.evaluate (ctx).toString());
        
        ctx.setFunctionDefContext(fdc);
        assertEquals ("Long<25>Object<Abc>", expr.evaluate (ctx).toString());
        
    }
}