Lift Framework example source code file (FieldFinder.scala)

This example Lift Framework source code file (FieldFinder.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

anyref, anyref, boolean, class, class, classmanifest, fieldfinder, list, list, method, nil, nil, not, string

The Lift Framework FieldFinder.scala source code

/*
 * Copyright 2006-2011 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 mapper


class FieldFinder[T: ClassManifest](metaMapper: AnyRef, logger: net.liftweb.common.Logger) {
  import java.lang.reflect._

  logger.debug("Created FieldFinder for " + classManifest[T].erasure)

  def isMagicObject(m: Method) = m.getReturnType.getName.endsWith("$"+m.getName+"$") && m.getParameterTypes.length == 0

  def typeFilter: Class[_]=>Boolean = classManifest[T].erasure.isAssignableFrom

  /**
    * Find the magic mapper fields on the superclass
    */
  def findMagicFields(onMagic: AnyRef, startingClass: Class[_]): List[Method] = {
    // If a class name ends in $module, it's a subclass created for scala object instances
    def deMod(in: String): String =
      if (in.endsWith("$module")) in.substring(0, in.length - 7)
      else in

    // find the magic fields for the given superclass
    def findForClass(clz: Class[_]): List[Method] = clz match {
      case null => Nil
      case c =>
        // get the names of fields that represent the type we want

        val fields = Map(c.getDeclaredFields.
                          filter{f =>
                            val ret = typeFilter(f.getType)
                            logger.trace("typeFilter(" + f.getType + "); T=" + classManifest[T].erasure)
                            ret
                          }.
                          map(f => (deMod(f.getName), f)) :_*)

        logger.trace("fields: " + fields)

        // this method will find all the super classes and super-interfaces
        def getAllSupers(clz: Class[_]): List[Class[_]] = clz match {
          case null => Nil
          case c =>
            c :: c.getInterfaces.toList.flatMap(getAllSupers) :::
            getAllSupers(c.getSuperclass)
        }

        // does the method return an actual instance of an actual class that's
        // associated with this Mapper class
        def validActualType(meth: Method): Boolean = {
          try {
            // invoke the method
            meth.invoke(onMagic) match {
              case null =>
                logger.debug("Not a valid mapped field: %s".format(meth.getName))
                false
              case inst =>
                // do we get a T of some sort back?
                if (!typeFilter(inst.getClass)) false
                else {
                  // find out if the class name of the actual thing starts
                  // with the name of this class or some superclass...
                  // basically, is an inner class of this class
                  getAllSupers(clz).find{
                    c =>
                    inst.getClass.getName.startsWith(c.getName)}.isDefined
                }
            }

          } catch {
            case e =>
              logger.debug("Not a valid mapped field: %s, got exception: %s".format(meth.getName, e))
              false
          }
        }

        // find all the declared methods
        val meths = c.getDeclaredMethods.toList.
        filter(_.getParameterTypes.length == 0). // that take no parameters
        filter(m => Modifier.isPublic(m.getModifiers)). // that are public
        filter(m => fields.contains(m.getName) && // that are associated with private fields
                fields(m.getName).getType == m.getReturnType).
        filter(validActualType) // and have a validated type

        meths ::: findForClass(clz.getSuperclass)
    }

    findForClass(startingClass).distinct
  }

  lazy val accessorMethods = findMagicFields(metaMapper, metaMapper.getClass.getSuperclass)
}