CollectionConverterSupport.java

/*
 * Copyright (c) 2009-present the 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 com.planet57.gshell.util.converter.collections;

import java.beans.PropertyEditor;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import com.planet57.gshell.util.converter.ConverterSupport;
import com.planet57.gshell.util.converter.basic.StringConverter;

import javax.annotation.Nullable;

import static com.google.common.base.Preconditions.checkNotNull;

/**
 * Support for collection converters.
 *
 * @since 2.0
 */
public abstract class CollectionConverterSupport
    extends ConverterSupport
{
  private final PropertyEditor editor;

  public CollectionConverterSupport(final Class type) {
    this(type, new StringConverter());
  }

  public CollectionConverterSupport(final Class type, final PropertyEditor editor) {
    super(type);
    this.editor = checkNotNull(editor);
  }

  @Override
  protected final Object convertToObject(final String text) throws Exception {
    List list = CollectionUtil.toList(text, editor);
    if (list == null) {
      return null;
    }

    return createCollection(list);
  }

  protected abstract Object createCollection(final List list) throws Exception;

  @Override
  @SuppressWarnings({"unchecked"})
  protected final String convertToString(final Object value) {
    Collection values;
    if (value.getClass().isArray()) {
      values = new ArrayList(Array.getLength(value));
      for (int i = 0; i < Array.getLength(value); i++) {
        values.add(Array.get(value, i));
      }
    }
    else {
      values = (Collection) value;
    }

    return CollectionUtil.toString(values, editor);
  }
}