Lift Framework example source code file (NamedPartialFunction.scala)

This example Lift Framework source code file (NamedPartialFunction.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lift Framework tags/keywords

a, a, b, b, boolean, box, full, namedpartialfunction, namedpf, partialfunction, seq, seq, string, string

The Lift Framework NamedPartialFunction.scala source code

/*
 * Copyright 2008-2011 WorldWide Conferencing, LLC
 *
 * 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 net.liftweb 
package util 

import common._

/**
 * This trait is used to represent a PartialFunction with additional
 * associated metadata, a name that allows the NamedPartialFunction
 * to be looked up dynamically.
 */
trait NamedPartialFunction[-A, +B] extends PartialFunction[A, B] {
  def functionName: String
}

/**
 * This class is the base implementation of the NamedPartialFunction trait.
 */
class NamedPF[-A, +B](name: String, f: PartialFunction[A, B]) extends NamedPartialFunction[A, B] {
  override def isDefinedAt(x: A): Boolean = f.isDefinedAt(x)
  override def apply(x: A): B = f(x)
  def functionName = name
}

object NamedPF {
  /**
   * Curried constructor for NamedPF
   */
  def apply[A, B](name: String)(f: PartialFunction[A,B]):
  NamedPartialFunction[A,B] = new NamedPF(name, f)

  /**
   * Find the first partial function in the specified sequence that
   * is defined at the given value.
   *
   * @param value the value to use to test each PartialFunction
   * @param lst the sequence to search for a PartialFunction defined at <code>value
   * @return a Full Box containing the PartialFunction if found,
   * or Empty othewise.
   */
  def find[A, B](value: A, lst: Seq[PartialFunction[A, B]]):
  Box[PartialFunction[A, B]] = lst.find(_.isDefinedAt(value))

  /**
   * Determine whether any PartialFunction in the specified sequence
   * is defined at the specified value.
   *
   * @param value the value to use to test each PartialFunction
   * @param lst the sequence to search for a PartialFunction defined at <code>value
   * @return whether such a PartialFunction is found
   */
  def isDefinedAt[A, B](value: A, lst: Seq[PartialFunction[A, B]]): Boolean =
  find(value, lst).isDefined

  /**
   * Find the first PartialFunction in the specified sequence that is defined
   * at the specified value, apply it to that value and return the result
   * or throw a MatchError on failure to find such a function.
   *
   * @param value the value to use to test each PartialFunction
   * @param lst the sequence to search for a PartialFunction defined at <code>value
   * @return the result of applying any such PartialFunction to the specified value.
   * @throws MatchError on failure to find such a PartialFunction
   */
  def apply[A, B](value: A, lst: Seq[PartialFunction[A, B]]): B =
  find(value, lst) match {
    case Full(pf) => pf.apply(value)
    case _ => throw new MatchError(value)
  }

  /**
   * Find the first PartialFunction in the specified sequence that is defined
   * at the specified value, apply it to that value and return the result
   * in a Full Box if found; return Empty otherwise
   *
   * @param value the value to use to test each PartialFunction
   * @param lst the sequence to search for a PartialFunction defined at <code>value
   * @return a Full Box containing the result of applying the first PartialFunction which is
   * defined at the specified value to that value, or Empty if no such PartialFunction is found
   */
  def applyBox[A, B](value: A, lst: Seq[PartialFunction[A, B]]): Box[B] =
  find(value, lst).map(_.apply(value))
}