/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2002-2006, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala
import scala.collection.mutable.{Map, HashMap}
/** <p>Defines a finite set of values specific to the enumeration. Typically
* these values enumerate all possible forms something can take and provide a
* lightweight alternative to case classes.</p>
* <p>Each call to a <code>Value</code> method adds a new unique value to the
* enumeration. To be accessible, these values are usually defined as
* <code>val</code> members of the evaluation</p>
* <p>All values in an enumeration share a common, unique type defined as the
* <code>Value</code> type member of the enumeration (<code>Value</code>
* selected on the stable identifier path of the enumeration instance).</p>
* <p><b>Example use</b></p>
* <pre>
* <b>object</b> Main <b>extends</b> Application {
*
* <b>object</b> WeekDays <b>extends</b> Enumeration {
* <b>val</b> Mon, Tue, Wed, Thu, Fri, Sat, Sun = Value
* }
*
* <b>def</b> isWorkingDay(d: WeekDays.Value) =
* ! (d == WeekDays.Sat || d == WeekDays.Sun)
*
* WeekDays filter (isWorkingDay) foreach { d => Console.println(d) }
* }</pre>
*
* @param initial The initial value from which to count the integers that
* identifies values at run-time.
* @param names The sequence of names to give to this enumeration's values.
*
* @author Matthias Zenger
* @version 1.0, 10/02/04 */
abstract class Enumeration(initial: Int, names: String*) {
def this() = this(0, null)
def this(names: String*) = this(0, names: _*)
/** The name of this enumeration. */
def name = {
val cname = this.getClass().getName()
if (cname.endsWith("$"))
cname.substring(0, cname.length() - 1)
else if (cname.endsWith("$class"))
cname.substring(0, cname.length() - 6)
else
cname
}
/** The mapping from the integer used to identifying values to the actual
* values. */
private val values: Map[Int, Value] = new HashMap
/** The cache listing all values of this enumeration. */
private var vcache: List[Value] = null
private def updateCache: List[Value] =
if (vcache eq null) {
vcache = values.values.toList.sort((p1, p2) => p1.id < p2.id);
vcache
} else
vcache;
/** The integer to use to identify the next created value. */
protected var nextId = initial
/** The string to use to name the next created value. */
protected var nextName = names.elements
/** The highest integer amongst those used to identify values in this
* enumeration. */
private var topId = initial
/** The highest integer amongst those used to identify values in this
* enumeration. */
final def maxId = topId
/** The value in this enumeration identified by integer <code>x</code>. */
final def apply(x: Int): Value = values(x)
/** A new iterator over all values of this enumeration. */
final def elements: Iterator[Value] = updateCache.elements
/** Apply a function f to all values of this enumeration. */
def foreach(f: Value => Unit): Unit = elements foreach f
/** Apply a predicate p to all values of this enumeration and return
* true, iff the predicate yields true for all values. */
def forall(p: Value => Boolean): Boolean = elements forall p
/** Apply a predicate p to all values of this enumeration and return
* true, iff there is at least one value for which p yields true. */
def exists(p: Value => Boolean): Boolean = elements exists p
/** Returns an iterator resulting from applying the given function f to each
* value of this enumeration. */
def map[b](f: Value => b): Iterator[b] = elements map f
/** Applies the given function f to each value of this enumeration, then
* concatenates the results. */
def flatMap[b](f: Value => Iterator[b]): Iterator[b] = elements flatMap f
/** Returns all values of this enumeration that satisfy the predicate p.
* The order of values is preserved. */
def filter(p: Value => Boolean): Iterator[Value] = elements filter p
override def toString(): String = updateCache.mkString("{", ", ", "}")
/** Creates a fresh value, part of this enumeration. */
protected final def Value: Value =
new Val(nextId, if (nextName.hasNext) nextName.next else null)
/** Creates a fresh value, part of this enumeration, identified by the integer
* <code>i</code>.
* @param i An integer that identifies this value at run-time. It must be
* unique amongst all values of the enumeration. */
protected final def Value(i: Int): Value =
new Val(i, if (nextName.hasNext) nextName.next else null)
/** Creates a fresh value, part of this enumeration, called <code>name</code>.
* @param name A human-readable name for that value. */
protected final def Value(name: String): Value = new Val(nextId, name)
/** Creates a fresh value, part of this enumeration, called <code>name</code>
* and identified by the integer <code>i</code>.
* @param i An integer that identifies this value at run-time. It must be
* unique amongst all values of the enumeration.
* @param name A human-readable name for that value. */
protected final def Value(i: Int, name: String): Value = new Val(i, name)
/** The type of the enumerated values. */
abstract class Value extends Ordered[Value] {
def id: Int
override def compare(that: Value): Int = this.id - that.id
}
/** A class implementing the Value type. This class can be overriden to
* change the enumeration's naming and integer identification behaviour. */
protected class Val(i: Int, name: String) extends Value {
def this(i: Int) =
this(i, if (nextName.hasNext) nextName.next else i.toString())
def this(name: String) = this(nextId, name)
def this() =
this(nextId, if (nextName.hasNext) nextName.next else nextId.toString())
assert(!values.isDefinedAt(i))
values(i) = this
nextId = i + 1
if (nextId > topId)
topId = nextId
def id = i
override def toString() =
if (name eq null) Enumeration.this.name + "(" + i + ")"
else name
}
}
