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Java Simplified. Extensions and Useful Constructs for the Java Platform. Codeprimate Elements (a.k.a. cp-elements) is a Java library and micro-framework used to simplify the development of software applications written in Java. Elements packages several APIs into one library in order to address various application concerns and aspects of software design and development collectively and conveniently. Elements is a highly simple, yet robust and proven library built on solid OO principles, software design patterns and best practices to effectively solve common and reoccurring problems in software development.

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/*
 * Copyright 2016 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 org.cp.elements.data.struct.tabular;

import static org.cp.elements.lang.RuntimeExceptionsFactory.newIllegalStateException;
import static org.cp.elements.util.CollectionUtils.nullSafeIterable;

import java.util.Collections;
import java.util.Iterator;

import org.cp.elements.lang.Assert;

/**
 * {@link AbstractView} is an abstract base class implementing the {@link View} interface to provide functionality
 * common to all {@link View} implementations.
 *
 * @author John J. Blum
 * @see org.cp.elements.data.struct.tabular.Column
 * @see org.cp.elements.data.struct.tabular.Row
 * @see org.cp.elements.data.struct.tabular.Table
 * @see org.cp.elements.data.struct.tabular.View
 * @since 1.0.0
 */
@SuppressWarnings("unused")
public abstract class AbstractView implements View {

  /**
   * Factory method constructing a new {@link View} initialized with the given {@link Column Columns}
   * and {@link Row Rows}.
   *
   * @param columns {@link Column Columns} defining the projection of the {@link View}.
   * @param rows {@link Row Rows} defining the contents of thew {@link View}.
   * @return a new {@link View} initialized with the given {@link Column Columns} and {@link Row Rows}.
   * @throws IllegalArgumentException if {@link Column Columns} are {@literal null} or empty.
   * @see org.cp.elements.data.struct.tabular.Column
   * @see org.cp.elements.data.struct.tabular.Row
   * @see java.lang.Iterable
   */
  public static View of(Iterable columns, Iterable rows) {

    Assert.notNull(columns, "Columns [null] are required");
    Assert.isTrue(columns.iterator().hasNext(), "Columns [empty] are required");

    return new AbstractView() {

      @Override
      public Iterable columns() {
        return columns;
      }

      @Override
      public Iterator iterator() {
        return nullSafeIterable(rows).iterator();
      }
    };
  }

  private String name;

  /**
   * Sets the {@link String name} of this {@link View}.
   *
   * @param name {@link String} containing the name of this {@link View}.
   */
  public void setName(String name) {
    this.name = name;
  }

  /**
   * Returns the {@link String name} of this {@link View}.
   *
   * @return a {@link String} containing the name of this {@link View}.
   */
  @Override
  public String getName() {
    return this.name;
  }

  /**
   * Returns an {@link Iterable} to iterate over the {@link Column Columns} in this {@link View}.
   *
   * @return an {@link Iterable} to iterate over the {@link Column Columns} in this {@link View}.
   * @see org.cp.elements.data.struct.tabular.Column
   * @see java.lang.Iterable
   */
  @Override
  public Iterable columns() {
    throw newIllegalStateException("Columns for this View have not been defined");
  }

  /**
   * Returns an {@link Iterator} to iterate over the rows in this {@link View}.
   *
   * @return an {@link Iterator} to iterate over the rows in this {@link View}.
   * @see java.util.Iterator
   */
  @Override
  public Iterator iterator() {
    return Collections.emptyIterator();
  }

  /**
   * Builder method used to set the {@link String name} of this {@link View}.
   *
   * @param  {@link Class sub-type} of this {@link View}.
   * @param name {@link String} containing the name of this {@link View}.
   * @return this {@link View}.
   * @see #setName(String)
   */
  @SuppressWarnings("unchecked")
  public  T named(String name) {
    setName(name);
    return (T) this;
  }

  /**
   * Returns a {@link String} representation of this {@link View}.
   *
   * By default, this method returns the {@link String name} of this {@link View}
   * by calling {@link #getName()}.
   *
   * @return a {@link String} describing this {@link View}.
   * @see java.lang.Object#toString()
   * @see #getName()
   */
  @Override
  public String toString() {
    return getName();
  }
}