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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

/**
 * Defines a custom way to normalize instances of a type.
 *
 * 
 * This trait exists to enforce that Normalization instances can be
 * passed to whenBothAre and whenAllAre, but not decidedBy.
 * 
 * 
 * @tparam A the type whose normalization is being defined
 */
trait Normalization[A] { thisNormalization =>

  /**
   * Returns a normalized form of the passed object.
   *
   * 
   * If the passed object is already in normal form, this method may return the same instance passed.
   * 
   *
   * @param a the object to normalize
   * @return the normalized form of the passed object
   */
  def normalized(a: A): A

  /**
   * Returns a new Normalization that composes this and the passed Normalization.
   *
   * 
   * The normalized method of the Normalization's returned by this method returns a normalized form of the passed
   * object obtained by passing it first to this Normalization's normalized method,
   * then passing that result to the other (i.e., passed to and as other) Normalization's normalized method.
   * Essentially, the body of the composed normalized method is:
   * 
   *
   *    * normalizationPassedToAnd.normalized(normalizationOnWhichAndWasInvoked.normalized(a))
   * 
   *
   * @param other a Normalization to 'and' with this one
   * @return a Normalization representing the composition of this and the passed Normalization
   */
  final def and(other: Normalization[A]): Normalization[A] =
    new Normalization[A] {
      def normalized(a: A): A = other.normalized(thisNormalization.normalized(a))
    }
}