freemarker-core/src/main/java/org/apache/freemarker/core/BuiltInForSequence.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.TemplateModel;
import org.apache.freemarker.core.model.TemplateSequenceModel;

/**
 * Built-in that meant to acts on {@link TemplateSequenceModel}-s only.
 */
abstract class BuiltInForSequence extends ASTExpBuiltIn {

    @Override
    TemplateModel _eval(Environment env)
            throws TemplateException {
        TemplateModel model = target.eval(env);
        if (!(model instanceof TemplateSequenceModel)) {
            throw MessageUtils.newUnexpectedOperandTypeException(target, model, TemplateSequenceModel.class, env);
        }
        return calculateResult((TemplateSequenceModel) model);
    }

    abstract TemplateModel calculateResult(TemplateSequenceModel tsm) throws TemplateException;

}