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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection
package immutable
import generic._
/** <p>
* A generic template for immutable maps from keys of type <code>A</code>
* to values of type <code>B</code>.<br/>
* To implement a concrete map, you need to provide implementations of the
* following methods (where <code>This</code> is the type of the map in
* question):
* </p>
* <pre>
* <b>def</b> get(key: A): Option[B]
* <b>def</b> iterator: Iterator[(A, B)]
* <b>def</b> + [B1 >: B](kv: (A, B)): Map[A, B1]
* <b>def</b> - (key: A): This</pre>
* <p>
* If you wish that methods <code>like</code>, <code>take</code>, <code>drop</code>,
* <code>filter</code> return the same kind of map, you should also override:
* </p>
* <pre>
* <b>def</b> empty: This</pre>
* <p>
* It is also good idea to override methods <code>foreach</code> and
* <code>size</code> for efficiency.
* </p>
*
* @author Martin Odersky
* @version 2.8
* @since 2.8
*/
trait MapLike[A, +B, +This <: MapLike[A, B, This] with Map[A, B]] extends scala.collection.MapLike[A, B, This] {
self =>
import scala.collection.Traversable
/** A new immutable map containing updating this map with a given key/value mapping.
* @param key the key
* @param value the value
* @return A new map with the new key/value mapping
*/
override def updated [B1 >: B](key: A, value: B1): immutable.Map[A, B1] = this + ((key, value))
/** Add a key/value pair to this map, returning a new map.
* @param kv the key/value pair
* @return A new map with the new binding added to this map
*/
def + [B1 >: B] (kv: (A, B1)): immutable.Map[A, B1]
/** Adds two or more elements to this collection and returns
* a new collection.
*
* @param elem1 the first element to add.
* @param elem2 the second element to add.
* @param elems the remaining elements to add.
*/
override def + [B1 >: B] (elem1: (A, B1), elem2: (A, B1), elems: (A, B1) *): immutable.Map[A, B1] =
this + elem1 + elem2 ++ elems
/** Adds a number of elements provided by a traversable object
* and returns a new collection with the added elements.
*
* @param elems the traversable object.
*/
override def ++[B1 >: B](elems: Traversable[(A, B1)]): immutable.Map[A, B1] =
((repr: immutable.Map[A, B1]) /: elems) (_ + _)
/** Adds a number of elements provided by an iterator
* and returns a new collection with the added elements.
*
* @param iter the iterator
*/
override def ++[B1 >: B] (iter: Iterator[(A, B1)]): immutable.Map[A, B1] =
((repr: immutable.Map[A, B1]) /: iter) (_ + _)
/** This function transforms all the values of mappings contained
* in this map with function <code>f</code>.
*
* @param f A function over keys and values
* @return the updated map
*/
def transform[C, That](f: (A, B) => C)(implicit bf: BuilderFactory[(A, C), That, This]): That = {
val b = bf(repr)
for ((key, value) <- this) b += ((key, f(key, value)))
b.result
}
/** Returns a new map with all key/value pairs for which the predicate
* <code>p</code> returns <code>true</code>.
*
* @param p A predicate over key-value pairs
* @note This method works by successively removing elements fro which the
* predicate is false from this set.
* If removal is slow, or you expect that most elements of the set$
* will be removed, you might consider using <code>filter</code>
* with a negated predicate instead.
*/
override def filterNot(p: ((A, B)) => Boolean): This = {
var res: This = repr
for (kv <- this)
if (p(kv)) res = (res - kv._1).asInstanceOf[This] // !!! concrete overrides abstract problem
res
}
@deprecated("use `updated' instead")
def update[B1 >: B](key: A, value: B1): immutable.Map[A, B1] = updated(key, value).asInstanceOf[immutable.Map[A, B1]]
}
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