src/main/java/freemarker/core/RangeModel.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 freemarker.core;

import freemarker.template.SimpleNumber;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
import freemarker.template.TemplateSequenceModel;

abstract class RangeModel implements TemplateSequenceModel, java.io.Serializable {
    
    private final int begin;

    public RangeModel(int begin) {
        this.begin = begin;
    }

    final int getBegining() {
        return begin;
    }
    
    final public TemplateModel get(int index) throws TemplateModelException {
        if (index < 0 || index >= size()) {
            throw new _TemplateModelException("Range item index ", Integer.valueOf(index), " is out of bounds.");
        }
        long value = begin + getStep() * (long) index;
        return value <= Integer.MAX_VALUE ? new SimpleNumber((int) value) : new SimpleNumber(value);
    }
    
    /**
     * @return {@code 1} or {@code -1}; other return values need not be properly handled until FTL supports other steps.
     */
    abstract int getStep();
    
    abstract boolean isRightUnbounded();
    
    abstract boolean isRightAdaptive();
    
    abstract boolean isAffactedByStringSlicingBug();

}