diff options
author | Martin Odersky <odersky@gmail.com> | 2003-03-03 14:33:53 +0000 |
---|---|---|
committer | Martin Odersky <odersky@gmail.com> | 2003-03-03 14:33:53 +0000 |
commit | 6749e5dd658522cb63600021a9ee5a86f911cfeb (patch) | |
tree | a22d4bf7f2bf71b5775418dfddaa31a1640313d1 /sources/examples/maps.scala | |
parent | e1fb3fb655a067039870016b3a47e2305d692d98 (diff) | |
download | scala-6749e5dd658522cb63600021a9ee5a86f911cfeb.tar.gz scala-6749e5dd658522cb63600021a9ee5a86f911cfeb.tar.bz2 scala-6749e5dd658522cb63600021a9ee5a86f911cfeb.zip |
*** empty log message ***
Diffstat (limited to 'sources/examples/maps.scala')
-rw-r--r-- | sources/examples/maps.scala | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/sources/examples/maps.scala b/sources/examples/maps.scala new file mode 100644 index 0000000000..3e75049765 --- /dev/null +++ b/sources/examples/maps.scala @@ -0,0 +1,152 @@ +module maps { + + trait MapStruct[kt, vt] { + trait Map extends Function1[kt, vt] with { + 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 <: Ord[kt], vt <: AnyRef]() extends MapStruct[kt, vt] { + type map = AlgMap; + + val empty: AlgMap = Empty(); + + private case class + Empty() extends AlgMap {}, + 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 <: Ord[kt], vt <: AnyRef]() extends MapStruct[kt, vt] { + type map = OOMap; + + trait OOMap extends Map with { + 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]; + } + module empty extends OOMap with { + 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 with { + 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 <: Ord[kt], vt <: AnyRef]() extends MapStruct[kt, vt] { + type map = MutMap; + class MutMap(key: kt, value: vt) extends Map with { + val k = key; + var v = value; + var l = empty, 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); + } +} + + + |