org.scalautils.ComposedNormalizingEquality.scala Maven / Gradle / Ivy

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/*
 * Copyright 2001-2013 Artima, Inc.
 *
 * 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.scalautils

/**
 * An Equality implementation that determines the equality of two objects by normalizing 
 * both objects, if possible, and then comparing the results using an equality (as defined by
 * the areEqual method of DefaultEquality).
 * 
 *  * import org.scalautils._
 *
 * class StringEquality extends NormalizedEquality[String] {
 *   def isInstanceOfA(b: Any) = b.isInstanceOf[String]
 *   def normalized(s: String): String = s.trim.toLowerCase
 * }
 * 
 *
 */
private[scalautils] final class ComposedNormalizingEquality[A](
  override val afterNormalizationEquality: Equality[A],
  uniformity: Uniformity[A]
) extends NormalizingEquality[A] {

  /**
   * Normalizes the passed object.
   *
   * @param o the object to normalize
   * @return the normalized form of the passed object
   */
  def normalized(a: A): A = uniformity.normalized(a)

  def normalizedCanHandle(b: Any): Boolean = uniformity.normalizedCanHandle(b)

  /* TODO: Fix scaladoc
   * Indicates whether the passed object is an instance of type A.
   *
   * 
   * This method is invoked by sibling method areEqual to determine whether or not
   * b can be cast to A so that it can be safely passed to normalized.
   * To implement this method, simply call b.isInstanceOf[A] for the actual A type.
   * For example, if you are defining a NormalizedEquality[String], your isInstanceOf
   * method should look like:
   * 
   *
   *    * def isInstanceOfA(b: Any) = b.isInstanceOf[String]
   * 
   *
   * 
   * If you are defining a NormalizedEquality[xml.Node] your isInstanceOf method
   * should look like:
   * 
   *
   *    * def isInstanceOfA(b: Any) = b.isInstanceOf[xml.Node]
   * 
   *
   * @param b the object to inspect to determine whether it is an instance of A
   * @return true if the passed object is an instance of A
   */
  def normalizedOrSame(b: Any): Any = uniformity.normalizedOrSame(b)
}