/*
 * 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 freemarker.core;

import freemarker.template.TemplateException;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;

abstract class BuiltInForMarkupOutput extends BuiltIn {
    
    @Override
    TemplateModel _eval(Environment env)
            throws TemplateException {
        TemplateModel model = target.eval(env);
        if (!(model instanceof TemplateMarkupOutputModel)) {
            throw new NonMarkupOutputException(target, model, env);
        }
        return calculateResult((TemplateMarkupOutputModel) model);
    }
    
    protected abstract TemplateModel calculateResult(TemplateMarkupOutputModel model) throws TemplateModelException;
    
}