EnumTransform.java

/**
 * Copyright 2014 Sunny Gleason and original author or authors
 *
 * Licensed 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 io.kazuki.v0.internal.v2schema.types;

import io.kazuki.v0.store.schema.model.Transform;
import io.kazuki.v0.store.schema.model.TransformException;

import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;



/**
 * Validates / transforms values using the schema-defined ENUM.
 */
public class EnumTransform implements Transform<Object, Integer> {
  private final Map<String, Integer> toMapping;
  private final List<String> values;

  public EnumTransform(List<String> values) {
    int id = 0;

    Map<String, Integer> toMapping = new LinkedHashMap<String, Integer>();
    List<String> theValues = new ArrayList<String>();

    for (String value : values) {
      toMapping.put(value, id);
      theValues.add(value);
      id += 1;
    }

    this.toMapping = Collections.unmodifiableMap(toMapping);
    this.values = Collections.unmodifiableList(theValues);
  }

  @Override
  public Integer pack(Object instance) throws TransformException {
    if (instance == null) {
      throw new TransformException("must not be null");
    }

    String instanceString = instance.toString();

    if (!toMapping.containsKey(instanceString)) {
      throw new TransformException("is not a valid enum value : " + instanceString);
    }

    return toMapping.get(instanceString);
  }

  @Override
  public Object unpack(Integer instance) throws TransformException {
    if (instance == null) {
      throw new TransformException("must not be null");
    }

    if (instance < 0) {
      throw new TransformException("must be greater than or equal to zero");
    }

    if (instance >= values.size()) {
      throw new TransformException("value not found : " + instance);
    }

    return values.get(instance);
  }
}