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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2007, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection.immutable
import Predef._
/** <p>An object for creating immutable maps. These are implemented using
* <a href="HashMap.html">immutable hash maps</a>.
* </p>*/
object Map {
def empty[A, B]: Map[A, B] = new EmptyMap[A, B]
def apply[A, B](elems: (A, B)*) = empty[A, B] ++ elems
}
/** <p>
* This class defines the interface for immutable maps. Operations
* on an immutable map leave the original map unchanged, and return
* a new map if needed.
* </p>
* <p>
* Concrete map implementations have to provide functionality for
* the abstract methods in <a href="../Map.html" target="contentFrame">
* <code>scala.collection.Map</code></a> as well as for
* <code>factory</code>, <code>update</code>, and <code>-</code>.
* </p>
*
* @author Matthias Zenger
* @author Erik Stenman
* @author Martin Odersky
* @version 1.2, 31/06/2006
*/
trait Map[A, +B] extends collection.Map[A, B] {
/** This method returns a new map instance of the same class
* mapping keys of the same type to values of type <code>C</code>.
*/
def empty[C]: Map[A, C]
/** This method allows one to create a new map with an
* additional mapping from <code>key</code>
* to <code>value</code>. If the map contains already a
* mapping for <code>key</code>, it will be overridden by this
* function.
*
* @param key ...
* @param value ...
* @return the created map
* @deprecated use <code>+({A, B})</code> instead
*/
def update [B1 >: B] (key: A, value: B1): Map[A, B1]
/** Add a key/value pair to this 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)): Map[A, B1] = update(kv._1, kv._2)
/** Add two or more key/value pairs to this map.
* @param kv1 the first key/value pair.
* @param kv2 the second key/value pair.
* @param kvs the remaining key/value pairs.
* @return A new map with the new bindings added
*/
def + [B1 >: B] (kv1: (A, B1), kv2: (A, B1), kvs: (A, B1)*): Map[A, B1] =
this + kv1 + kv2 ++ kvs
/** Add a sequence of key/value pairs to this map.
* @param kvs the iterable object containing all key/value pairs.
* @return A new map with the new bindings added
*/
def ++ [B1 >: B] (kvs: Iterable[(A, B1)]): Map[A, B1] =
((this: Map[A, B1]) /: kvs) ((m, kv) => m + kv)
/** Add a sequence of key/value pairs to this map.
* @param kvs the iterator containing all key/value pairs.
* @return A new map with the new bindings added
*/
def ++ [B1 >: B] (kvs: Iterator[(A, B1)]): Map[A, B1] =
((this: Map[A, B1]) /: kvs) ((m, kv) => m + kv)
/** Remove a key from this map
* @param key the key to be removed
* @return If the map does not contain a binding for <code>key</code>
* it is returned unchanged. Otherwise, return a new map
* without a binding for <code>key</code>
*/
def - (key: A): Map[A, B]
/** Remove two or more keys from this map
* @param key1 the first key to be removed
* @param key2 the second key to be removed
* @param keys the remaining keys to be removed
* @return A map without bindings for <code>keys</code>
* If the map is mutable, the bindings are removed in place
* and the map itself is returned.
* If the map is immutable, a new map with the bindings removed is returned.
*/
def - (key1: A, key2: A, keys: A*): Map[A, B] =
this - key1 - key2 -- keys
/** Remove a sequence of keys from this map
* @param keys the keys to be removed
* @return A map without bindings for the given keys.
* If the map is mutable, the bindings are removed in place
* and the map itself is returned.
* If the map is immutable, a new map with the bindings removed is returned.
*/
def -- (keys: Iterable[A]): Map[A, B] = this -- keys.elements
/** Remove a sequence of keys from this map
* @param keys the keys to be removed
* @return A map without bindings for the given keys.
* If the map is mutable, the bindings are removed in place
* and the map itself is returned.
* If the map is immutable, a new map with the bindings removed is returned.
*/
def -- (keys: Iterator[A]): Map[A, B] =
(this /: keys) ((m, key) => m - key)
/** The same map with a given default function */
def withDefault[B1 >: B](d: A => B1): Map[A, B1] = new Map[A, B1] {
def size = Map.this.size
def get(key: A) = Map.this.get(key)
def elements = Map.this.elements
def empty[C] = Map.this.empty
def update [B2 >: B1](key: A, value: B2): Map[A, B2] =
Map.this.update(key, value) withDefault d
def -(key: A): Map[A, B1] = Map.this - key withDefault d
override def default(key: A): B1 = d(key)
}
/** The same map with a given default value */
def withDefaultValue[B1 >: B](d: B1): Map[A, B1] = withDefault(x => d)
/** 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](f: (A, B) => C): Map[A, C] = {
var res = empty[C]
foreach { case (key, value) => res = res.update(key, f(key, value)) }
res
}
/** This method removes all the mappings for which the predicate
* <code>p</code> returns <code>false</code>.
*
* @param p A prediacte over key-value pairs
* @return the updated map
*/
override def filter(p: ((A, B)) => Boolean): Map[A, B] = {
var res = this
foreach {
case kv @ (key, _) => if (!p(kv)) { res = res - key }
}
res
}
/** <p>
* This method defines syntactic sugar for adding a
* mapping. It is typically used in the following way:
* </p>
* <pre>
* map + key -> value
* </pre>
* @deprecated use <code>+({A, B})</code> instead
*/
@deprecated def +(key: A): MapTo = new MapTo(key)
/** <code>incl</code> can be used to add many mappings at the same time
* to the map. The method assumes that a mapping is represented
* by a <code>Pair</code> object who's first component denotes the
* key, and who's second component refers to the value.
*
* @param mappings ...
* @return ...
* @deprecated use <code>+</code> instead
*/
@deprecated def incl[B1 >: B](mappings: (A, B1)*): Map[A, B1] = incl(mappings)
/** <code>incl</code> can be used to add many mappings at the same time
* to the map. The method assumes that each mapping is represented
* by an Iterator over <code>Pair</code> objects who's first component
* denotes the key, and who's second component refers to the value.
*
* @deprecated use <code>++</code> instead
*/
@deprecated def incl[B1 >: B](map: Iterable[(A, B1)]): Map[A, B1] = {
val iter = map.elements
var res: Map[A, B1] = this
while (iter.hasNext) {
val (key, value) = iter.next
res = res.update(key, value)
}
res
}
/** This method will return a map where all the mappings
* for the given sequence of keys are removed from the map.
*
* @param keys ...
* @return the updated map
* @deprecated use <code>-</code> instead
*/
@deprecated def excl(keys: A*): Map[A, B] = excl(keys)
/** This method removes all the mappings for keys provided by an
* iterator over the elements of the <code>keys</code> object.
*
* @param keys ...
* @return the updated map
* @deprecated use <code>--</code> instead
*/
@deprecated def excl(keys: Iterable[A]): Map[A, B] = {
val iter = keys.elements
var res = this
while (iter.hasNext) {
res = res - iter.next
}
res
}
/** This method controls how a mapping is represented in the string
* representation provided by method <code>toString</code>.
*
* @param p ...
* @return the string representation of a map entry
*/
@deprecated def mappingToString[B1 >: B](p: (A, B1)) =
p._1.toString() + " -> " + p._2
/** @deprecated use <code>+({A, B})</code> instead
*/
@deprecated class MapTo(key: A) {
def -> [B1 >: B](value: B1) = update(key, value)
}
}
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