freemarker-core/src/main/java/org/apache/freemarker/core/BuiltInForHashEx.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.freemarker.core;

import org.apache.freemarker.core.model.TemplateHashModelEx;
import org.apache.freemarker.core.model.TemplateModel;

abstract class BuiltInForHashEx extends ASTExpBuiltIn {

    @Override
    TemplateModel _eval(Environment env) throws TemplateException {
        TemplateModel model = target.eval(env);
        if (model instanceof TemplateHashModelEx) {
            return calculateResult((TemplateHashModelEx) model, env);
        }
        throw MessageUtils.newUnexpectedOperandTypeException(target, model, TemplateHashModelEx.class, env);
    }
    
    abstract TemplateModel calculateResult(TemplateHashModelEx hashExModel, Environment env)
            throws TemplateException, InvalidReferenceException;
    
    protected TemplateException newWrongTemplateModelMethodReturnValueException(
            String methodName, TemplateModel tm, Environment env) {
        return new TemplateException(
                new _ErrorDescriptionBuilder(
                    "The exteneded hash (of class ", tm.getClass().getName(), ") " +
                        methodName +  " method has returned null, which is illegal. The extended hash was " +
                        "returned by this expression:")
                .blame(target),
                env, this);
    }
    
}