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package examples
object maps {
import scala.collection.immutable._
trait MapStruct[kt, vt] {
trait Map extends Function1[kt, vt] {
def extend(key: kt, value: vt): Map
def remove(key: kt): Map
def domain: Stream[kt]
def range: Stream[vt]
}
type map <: Map
val empty: map
}
class AlgBinTree[kt >: Null <: Ordered[kt], vt >: Null <: AnyRef]() extends MapStruct[kt, vt] {
type map = AlgMap
val empty: AlgMap = Empty()
private case class Empty() extends AlgMap {}
private case class Node(key: kt, value: vt, l: map, r: map) extends AlgMap {}
trait AlgMap extends Map {
def apply(key: kt): vt = this match {
case Empty() => null
case Node(k, v, l, r) =>
if (key < k) l.apply(key)
else if (key > k) r.apply(key)
else v
}
def extend(key: kt, value: vt): map = this match {
case Empty()=> Node(key, value, empty, empty)
case Node(k, v, l, r) =>
if (key < k) Node(k, v, l.extend(key, value), r)
else if (key > k) Node(k, v, l, r.extend(key, value))
else Node(k, value, l, r)
}
def remove(key: kt): map = this match {
case Empty()=> empty
case Node(k, v, l, r) =>
if (key < k) Node(k, v, l.remove(key), r)
else if (key > k) Node(k, v, l, r.remove(key))
else if (l == empty) r
else if (r == empty) l
else {
val midKey = r.domain.head
Node(midKey, r.apply(midKey), l, r.remove(midKey))
}
}
def domain: Stream[kt] = this match {
case Empty()=> Stream.empty
case Node(k, v, l, r) => l.domain append Stream.cons(k, r.domain)
}
def range: Stream[vt] = this match {
case Empty()=> Stream.empty
case Node(k, v, l, r) => l.range append Stream.cons(v, r.range)
}
}
}
class OOBinTree[kt >: Null <: Ordered[kt], vt >: Null <: AnyRef]() extends MapStruct[kt, vt] {
type map = OOMap
trait OOMap extends Map {
def apply(key: kt): vt
def extend(key: kt, value: vt): map
def remove(key: kt): map
def domain: Stream[kt]
def range: Stream[vt]
}
val empty: OOMap = new OOMap {
def apply(key: kt): vt = null
def extend(key: kt, value: vt) = new Node(key, value, empty, empty)
def remove(key: kt) = empty
def domain: Stream[kt] = Stream.empty
def range: Stream[vt] = Stream.empty
}
private class Node(k: kt, v: vt, l: map, r: map) extends OOMap {
def apply(key: kt): vt =
if (key < k) l.apply(key)
else if (key > k) r.apply(key)
else v;
def extend(key: kt, value: vt): map =
if (key < k) new Node(k, v, l.extend(key, value), r)
else if (key > k) new Node(k, v, l, r.extend(key, value))
else new Node(k, value, l, r)
def remove(key: kt): map =
if (key < k) new Node(k, v, l.remove(key), r)
else if (key > k) new Node(k, v, l, r.remove(key))
else if (l == empty) r
else if (r == empty) l
else {
val midKey = r.domain.head
new Node(midKey, r(midKey), l, r.remove(midKey))
}
def domain: Stream[kt] = l.domain append Stream.cons(k, r.domain)
def range: Stream[vt] = l.range append Stream.cons(v, r.range)
}
}
class MutBinTree[kt >: Null <: Ordered[kt], vt >: Null <: AnyRef]() extends MapStruct[kt, vt] {
type map = MutMap
class MutMap(key: kt, value: vt) extends Map {
val k = key
var v = value
var l, r = empty
def apply(key: kt): vt =
if (this == empty) null
else if (key < k) l.apply(key)
else if (key > k) r.apply(key)
else v
def extend(key: kt, value: vt): map =
if (this == empty) new MutMap(key, value)
else {
if (key < k) l = l.extend(key, value)
else if (key > k) r = r.extend(key, value)
else v = value
this
}
def remove(key: kt): map =
if (this == empty) this
else if (key < k) { l = l.remove(key); this }
else if (key > k) { r = r.remove(key); this }
else if (l == empty) r
else if (r == empty) l
else {
var mid = r
while (!(mid.l == empty)) { mid = mid.l }
mid.r = r.remove(mid.k)
mid.l = l
mid
}
def domain: Stream[kt] =
if (this == empty) Stream.empty
else l.domain append Stream.cons(k, r.domain)
def range: Stream[vt] =
if (this == empty) Stream.empty
else l.range append Stream.cons(v, r.range)
}
val empty = new MutMap(null, null)
}
class Date(y: Int, m: Int, d: Int) extends Ordered[Date] {
def year = y
def month = m
def day = d
def compare(other: Date): Int =
if (year == other.year &&
month == other.month &&
day == other.day)
0
else if (year < other.year ||
year == other.year && month < other.month ||
month == other.month && day < other.day)
-1
else
1
override def equals(that: Any): Boolean =
that.isInstanceOf[Date] && {
val o = that.asInstanceOf[Date];
day == o.day && month == o.month && year == o.year
}
}
def main(args: Array[String]) {
val t = new OOBinTree[Date, String]()
()
}
}
|
