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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2006-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://www.scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection
/**
* A collection of implicit conversions supporting interoperability between Scala and Java
* collections.
* <p>
* The following conversions are supported,
* <p>
* <ul>
* <li><code>scala.collection.Iterable</code> <=> <code>java.lang.Iterable</code></li>
* <li><code>scala.collection.Iterable</code> <=> <code>java.util.Collection</code></li>
* <li><code>scala.collection.Iterator</code> <=> <code>java.util.{ Iterator, Enumeration }</code></li>
* <li><code>scala.collection.mutable.Buffer</code> <=> <code>java.util.List</code></li>
* <li><code>scala.collection.mutable.Set</code> <=> <code>java.util.Set</code></li>
* <li><code>scala.collection.mutable.Map</code> <=> <code>java.util.Map</code></li>
* <ul>
* <p>
* In all cases, converting from a source type to a target type and back again will return
* the original source object, eg.
* <p>
* <pre>
* import scala.collections.jcl.Conversions._
*
* val sl = new scala.collection.mutable.ListBuffer[Int]
* val jl : java.util.List[Int] = sl
* val sl2 : scala.collection.mutable.Buffer[Int] = jl
* assert(sl eq sl2)g
* </pre>
*
* <p>
* Note that no conversion is provided from scala.collection.immutable.List to java.util.List.
* Instead it is convertible to an immutable java.util.Collection which provides size and
* interation capabilities, but not access by index as would be provided by java.util.List.
* This is intentional: in combination the implementation of scala.collection.immutable.List
* and the typical usage patterns of java.util.List would perform extremely poorly.
*
* @author Miles Sabin
*/
object JavaConversions {
import java.{ lang => jl, util => ju }
import scala.collection.{ generic, immutable, mutable, Traversable }
import scala.reflect.Manifest
// Scala => Java
/**
* Implicitly converts a Scala <code>Iterator</code> to a Java <code>Iterator</code>.
* The returned Java <code>Iterator</code> is backed by the provided Scala
* <code>Iterator</code> and any side-effects of using it via the Java interface will
* be visible via the Scala interface and vice versa.
* <p>
* If the Scala <code>Iterator</code> was previously obtained from an implicit or
* explicit call of <code>asIterator(java.util.Iterator)</code> then the original
* Java <code>Iterator</code> will be returned.
*
* @param i The <code>Iterator</code> to be converted.
* @return A Java <code>Iterator</code> view of the argument.
*/
implicit def asIterator[A](i : Iterator[A]) = i match {
case JIteratorWrapper(wrapped) => wrapped
case _ => IteratorWrapper(i)
}
/**
* Implicitly converts a Scala <code>Iterator</code> to a Java <code>Enumeration</code>.
* The returned Java <code>Enumeration</code> is backed by the provided Scala
* <code>Iterator</code> and any side-effects of using it via the Java interface will
* be visible via the Scala interface and vice versa.
* <p>
* If the Scala <code>Iterator</code> was previously obtained from an implicit or
* explicit call of <code>asIterator(java.util.Enumeration)</code> then the
* original Java <code>Enumeration</code> will be returned.
*
* @param i The <code>Iterator</code> to be converted.
* @return A Java <code>Enumeration</code> view of the argument.
*/
implicit def asEnumeration[A](i : Iterator[A]) = i match {
case JEnumerationWrapper(wrapped) => wrapped
case _ => IteratorWrapper(i)
}
/**
* Implicitly converts a Scala <code>Iterable</code> to a Java <code>Iterable</code>.
* The returned Java <code>Iterable</code> is backed by the provided Scala
* <code>Iterable</code> and any side-effects of using it via the Java interface will
* be visible via the Scala interface and vice versa.
* <p>
* If the Scala <code>Iterable</code> was previously obtained from an implicit or
* explicit call of <code>asIterable(java.lang.Iterable)</code> then the original
* Java <code>Iterable</code> will be returned.
*
* @param i The <code>Iterable</code> to be converted.
* @return A Java <code>Iterable</code> view of the argument.
*/
implicit def asIterable[A](i : Iterable[A]) = i match {
case JIterableWrapper(wrapped) => wrapped
case _ => IterableWrapper(i)
}
/**
* Implicitly converts a Scala <code>Iterable</code> to an immutable Java
* <code>Collection</code>.
* <p>
* If the Scala <code>Iterable</code> was previously obtained from an implicit or
* explicit call of <code>asSizedIterable(java.util.Collection)</code> then the original
* Java <code>Collection</code> will be returned.
*
* @param i The <code>SizedIterable</code> to be converted.
* @return A Java <code>Collection</code> view of the argument.
*/
implicit def asCollection[A](i : Iterable[A]) = i match {
case JCollectionWrapper(wrapped) => wrapped
case _ => new IterableWrapper(i)
}
/**
* Implicitly converts a Scala mutable <code>Buffer</code> to a Java <code>List</code>.
* The returned Java <code>List</code> is backed by the provided Scala
* <code>Buffer</code> and any side-effects of using it via the Java interface will
* be visible via the Scala interface and vice versa.
* <p>
* If the Scala <code>Buffer</code> was previously obtained from an implicit or
* explicit call of <code>asBuffer(java.util.List)</code> then the original
* Java <code>List</code> will be returned.
*
* @param b The <code>Buffer</code> to be converted.
* @return A Java <code>List</code> view of the argument.
*/
implicit def asList[A](b : mutable.Buffer[A]) : ju.List[A] = b match {
case JListWrapper(wrapped) => wrapped
case _ => new MutableBufferWrapper(b)
}
/**
* Implicitly converts a Scala mutable <code>Set</code> to a Java <code>Set</code>.
* The returned Java <code>Set</code> is backed by the provided Scala
* <code>Set</code> and any side-effects of using it via the Java interface will
* be visible via the Scala interface and vice versa.
* <p>
* If the Scala <code>Set</code> was previously obtained from an implicit or
* explicit call of <code>asSet(java.util.Set)</code> then the original
* Java <code>Set</code> will be returned.
*
* @param s The <code>Set</code> to be converted.
* @return A Java <code>Set</code> view of the argument.
*/
implicit def asSet[A](s : mutable.Set[A])(implicit m : Manifest[A]) : ju.Set[A] = s match {
case JSetWrapper(wrapped) => wrapped
case _ => new MutableSetWrapper(s)(m)
}
/**
* Implicitly converts a Scala mutable <code>Map</code> to a Java <code>Map</code>.
* The returned Java <code>Map</code> is backed by the provided Scala
* <code>Map</code> and any side-effects of using it via the Java interface will
* be visible via the Scala interface and vice versa.
* <p>
* If the Scala <code>Map</code> was previously obtained from an implicit or
* explicit call of <code>asMap(java.util.Map)</code> then the original
* Java <code>Map</code> will be returned.
*
* @param m The <code>Map</code> to be converted.
* @return A Java <code>Map</code> view of the argument.
*/
implicit def asMap[A, B](m : mutable.Map[A, B])(implicit ma : Manifest[A]) : ju.Map[A, B] = m match {
case JMapWrapper(wrapped) => wrapped
case _ => new MutableMapWrapper(m)(ma)
}
// Java => Scala
/**
* Implicitly converts a Java <code>Iterator</code> to a Scala <code>Iterator</code>.
* The returned Scala <code>Iterator</code> is backed by the provided Java
* <code>Iterator</code> and any side-effects of using it via the Scala interface will
* be visible via the Java interface and vice versa.
* <p>
* If the Java <code>Iterator</code> was previously obtained from an implicit or
* explicit call of <code>asIterator(scala.collection.Iterator)</code> then the original
* Scala <code>Iterator</code> will be returned.
*
* @param i The <code>Iterator</code> to be converted.
* @return A Scala <code>Iterator</code> view of the argument.
*/
implicit def asIterator[A](i : ju.Iterator[A]) = i match {
case IteratorWrapper(wrapped) => wrapped
case _ => JIteratorWrapper(i)
}
/**
* Implicitly converts a Java <code>Enumeration</code> to a Scala <code>Iterator</code>.
* The returned Scala <code>Iterator</code> is backed by the provided Java
* <code>Enumeration</code> and any side-effects of using it via the Scala interface will
* be visible via the Java interface and vice versa.
* <p>
* If the Java <code>Enumeration</code> was previously obtained from an implicit or
* explicit call of <code>asEnumeration(scala.collection.Iterator)</code> then the
* original Scala <code>Iterator</code> will be returned.
*
* @param i The <code>Enumeration</code> to be converted.
* @return A Scala <code>Iterator</code> view of the argument.
*/
implicit def asIterator[A](i : ju.Enumeration[A]) = i match {
case IteratorWrapper(wrapped) => wrapped
case _ => JEnumerationWrapper(i)
}
/**
* Implicitly converts a Java <code>Iterable</code> to a Scala <code>Iterable</code>.
* The returned Scala <code>Iterable</code> is backed by the provided Java
* <code>Iterable</code> and any side-effects of using it via the Scala interface will
* be visible via the Java interface and vice versa.
* <p>
* If the Java <code>Iterable</code> was previously obtained from an implicit or
* explicit call of <code>asIterable(scala.collection.Iterable)</code> then the original
* Scala <code>Iterable</code> will be returned.
*
* @param i The <code>Iterable</code> to be converted.
* @return A Scala <code>Iterable</code> view of the argument.
*/
implicit def asIterable[A](i : jl.Iterable[A]) = i match {
case IterableWrapper(wrapped) => wrapped
case _ => JIterableWrapper(i)
}
/**
* Implicitly converts a Java <code>Collection</code> to an Scala <code>Iterable</code>.
* <p>
* If the Java <code>Collection</code> was previously obtained from an implicit or
* explicit call of <code>asCollection(scala.collection.SizedIterable)</code> then
* the original Scala <code>SizedIterable</code> will be returned.
*
* @param i The <code>Collection</code> to be converted.
* @return A Scala <code>SizedIterable</code> view of the argument.
*/
implicit def asIterable[A](i : ju.Collection[A]) = i match {
case IterableWrapper(wrapped) => wrapped
case _ => JCollectionWrapper(i)
}
/**
* Implicitly converts a Java <code>List</code> to a Scala mutable <code>Buffer</code>.
* The returned Scala <code>Buffer</code> is backed by the provided Java
* <code>List</code> and any side-effects of using it via the Scala interface will
* be visible via the Java interface and vice versa.
* <p>
* If the Java <code>List</code> was previously obtained from an implicit or
* explicit call of <code>asList(scala.collection.mutable.Buffer)</code> then the original
* Scala <code>Buffer</code> will be returned.
*
* @param l The <code>List</code> to be converted.
* @return A Scala mutable <code>Buffer</code> view of the argument.
*/
implicit def asBuffer[A](l : ju.List[A]) = l match {
case MutableBufferWrapper(wrapped) => wrapped
case _ =>new JListWrapper(l)
}
/**
* Implicitly converts a Java <code>Set</code> to a Scala mutable <code>Set</code>.
* The returned Scala <code>Set</code> is backed by the provided Java
* <code>Set</code> and any side-effects of using it via the Scala interface will
* be visible via the Java interface and vice versa.
* <p>
* If the Java <code>Set</code> was previously obtained from an implicit or
* explicit call of <code>asSet(scala.collection.mutable.Set)</code> then the original
* Scala <code>Set</code> will be returned.
*
* @param s The <code>Set</code> to be converted.
* @return A Scala mutable <code>Set</code> view of the argument.
*/
implicit def asSet[A](s : ju.Set[A]) = s match {
case MutableSetWrapper(wrapped) => wrapped
case _ =>new JSetWrapper(s)
}
/**
* Implicitly converts a Java <code>Map</code> to a Scala mutable <code>Map</code>.
* The returned Scala <code>Map</code> is backed by the provided Java
* <code>Map</code> and any side-effects of using it via the Scala interface will
* be visible via the Java interface and vice versa.
* <p>
* If the Java <code>Map</code> was previously obtained from an implicit or
* explicit call of <code>asMap(scala.collection.mutable.Map)</code> then the original
* Scala <code>Map</code> will be returned.
*
* @param m The <code>Map</code> to be converted.
* @return A Scala mutable <code>Map</code> view of the argument.
*/
implicit def asMap[A, B](m : ju.Map[A, B]) = m match {
case MutableMapWrapper(wrapped) => wrapped
case _ =>new JMapWrapper(m)
}
// Private implementations ...
case class IteratorWrapper[A](underlying : Iterator[A]) extends ju.Iterator[A] with ju.Enumeration[A] {
def hasNext = underlying.hasNext
def next = underlying.next
def hasMoreElements = underlying.hasNext
def nextElement = underlying.next
def remove = throw new UnsupportedOperationException
}
case class JIteratorWrapper[A](underlying : ju.Iterator[A]) extends Iterator[A] {
def hasNext = underlying.hasNext
def next = underlying.next
}
case class JEnumerationWrapper[A](underlying : ju.Enumeration[A]) extends Iterator[A] {
def hasNext = underlying.hasMoreElements
def next = underlying.nextElement
}
case class IterableWrapper[A](underlying : Iterable[A]) extends ju.AbstractCollection[A] {
def iterator = underlying.elements
def size = underlying.size
override def isEmpty = underlying.isEmpty
}
case class JIterableWrapper[A](underlying : jl.Iterable[A]) extends Iterable[A] {
def elements = underlying.iterator
def newBuilder[B] = new mutable.ArrayBuffer[B]
}
case class JCollectionWrapper[A](underlying : ju.Collection[A]) extends Iterable[A] {
def elements = underlying.iterator
override def size = underlying.size
override def isEmpty = underlying.isEmpty
def newBuilder[B] = new mutable.ArrayBuffer[B]
}
case class MutableBufferWrapper[A](underlying : mutable.Buffer[A]) extends ju.AbstractList[A] {
def size = underlying.length
def get(i : Int) = underlying(i)
override def set(i : Int, elem: A) = { val p = underlying(i) ; underlying(i) = elem ; p }
override def add(elem : A) = { underlying.append(elem) ; true }
override def remove(i : Int) = underlying.remove(i)
}
case class JListWrapper[A](val underlying : ju.List[A]) extends mutable.Buffer[A] {
def length = underlying.size
override def isEmpty = underlying.isEmpty
override def elements : Iterator[A] = underlying.iterator
def apply(i : Int) = underlying.get(i)
def update(i : Int, elem : A) = underlying.set(i, elem)
def +:(elem : A) = { underlying.subList(0, 0).add(elem) ; this }
def +=(elem : A) = underlying.add(elem)
def insertAll(i : Int, elems : Traversable[A]) = { val ins = underlying.subList(0, i) ; elems.foreach(ins.add(_)) }
def remove(i : Int) = underlying.remove(i)
def clear = underlying.clear
def result = this
}
case class MutableSetWrapper[A](underlying : mutable.Set[A])(m : Manifest[A]) extends ju.AbstractSet[A] {
self =>
def size = underlying.size
override def add(elem: A) = { val sz = underlying.size ; underlying += elem ; sz < underlying.size }
override def remove(elem : AnyRef) = {
m.erasure.isInstance(elem) && {
val sz = underlying.size
underlying -= elem.asInstanceOf[A]
sz > underlying.size
}
}
def iterator = new ju.Iterator[A] {
val ui = underlying.elements
var prev : Option[A] = None
def hasNext = ui.hasNext
def next = { val e = ui.next ; prev = Some(e) ; e }
def remove = prev match {
case Some(e) => self.remove(e.asInstanceOf[AnyRef]) ; prev = None
case _ => throw new IllegalStateException("next must be called at least once before remove")
}
}
}
case class JSetWrapper[A](underlying : ju.Set[A]) extends mutable.Set[A] with generic.SetTemplate[A, JSetWrapper[A]] {
override def size = underlying.size
def elements = underlying.iterator
def contains(elem: A): Boolean = underlying.contains(elem)
def +=(elem: A) { underlying.add(elem) }
def -=(elem: A) { underlying.remove(elem) }
override def clear = underlying.clear
override def empty = JSetWrapper(new ju.HashSet[A])
}
case class MutableMapWrapper[A, B](underlying : mutable.Map[A, B])(m : Manifest[A]) extends ju.AbstractMap[A, B] {
self =>
override def size = underlying.size
override def put(k : A, v : B) = underlying.put(k, v) match {
case Some(v1) => v1
case None => null.asInstanceOf[B]
}
override def remove(k : AnyRef) = {
if (!m.erasure.isInstance(k))
null.asInstanceOf[B]
else {
val k1 = k.asInstanceOf[A]
underlying.get(k1) match {
case Some(v) => underlying -= k1 ; v
case None => null.asInstanceOf[B]
}
}
}
override def entrySet : ju.Set[ju.Map.Entry[A, B]] = new ju.AbstractSet[ju.Map.Entry[A, B]] {
def size = self.size
def iterator = new ju.Iterator[ju.Map.Entry[A, B]] {
val ui = underlying.elements
var prev : Option[A] = None
def hasNext = ui.hasNext
def next = {
val (k, v) = ui.next
prev = Some(k)
new ju.Map.Entry[A, B] {
def getKey = k
def getValue = v
def setValue(v1 : B) = self.put(k, v1)
override def equals(other : Any) = other match {
case e : ju.Map.Entry[_, _] => k == e.getKey && v == e.getValue
case _ => false
}
}
}
def remove = prev match {
case Some(k) => val v = self.remove(k.asInstanceOf[AnyRef]) ; prev = None ; v
case _ => throw new IllegalStateException("next must be called at least once before remove")
}
}
}
}
case class JMapWrapper[A, B](underlying : ju.Map[A, B]) extends mutable.Map[A, B] with generic.MutableMapTemplate[A, B, JMapWrapper[A, B]] {
override def size = underlying.size
def get(k : A) = {
val v = underlying.get(k)
if (v != null)
Some(v)
else if(underlying.containsKey(k))
Some(null.asInstanceOf[B])
else
None
}
def update(k : A, v : B) { underlying.put(k, v) }
def -=(k : A) = { underlying.remove(k) ; this }
def elements = new Iterator[(A, B)] {
val ui = underlying.entrySet.iterator
def hasNext = ui.hasNext
def next = { val e = ui.next ; (e.getKey, e.getValue) }
}
override def clear = underlying.clear
override def empty = JMapWrapper(new ju.HashMap[A, B])
}
}
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