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author | Gilles Dubochet <gilles.dubochet@epfl.ch> | 2005-12-16 18:44:33 +0000 |
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committer | Gilles Dubochet <gilles.dubochet@epfl.ch> | 2005-12-16 18:44:33 +0000 |
commit | 53a3cc7b17f4cf97075b7e71720777fd84109696 (patch) | |
tree | 0cc784e0b47ea49cc151a136d19f20bfa8ee2197 /docs/examples/maps.scala | |
parent | df50e05006b43b007c2587549030d24b5c154398 (diff) | |
download | scala-53a3cc7b17f4cf97075b7e71720777fd84109696.tar.gz scala-53a3cc7b17f4cf97075b7e71720777fd84109696.tar.bz2 scala-53a3cc7b17f4cf97075b7e71720777fd84109696.zip |
Created proper 'docs' folder for new layout.
Diffstat (limited to 'docs/examples/maps.scala')
-rw-r--r-- | docs/examples/maps.scala | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/docs/examples/maps.scala b/docs/examples/maps.scala new file mode 100644 index 0000000000..87489d496d --- /dev/null +++ b/docs/examples/maps.scala @@ -0,0 +1,192 @@ +package examples; + +object maps { + + import scala.collection.immutable._; + + trait MapStruct[kt, vt] { + trait Map with 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 <: Ordered[kt], vt <: AnyRef]() extends MapStruct[kt, vt] { + type map = AlgMap; + + val empty: AlgMap = Empty(); + + private case class + Empty(), + 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 <: Ordered[kt], vt <: 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 <: Ordered[kt], vt <: 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) with Ordered[Date] { + def year = y; + def month = m; + def day = d; + + def compareTo[b >: Date <% Ordered[b]](that: b): int = that match { + case other: Date => + 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 + case _ => + -(that compareTo this) + } + + 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](); + () + } + +} + + + |