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/**
* Copyright (c) Rich Hickey. All rights reserved.
* The use and distribution terms for this software are covered by the
* Common Public License 1.0 (http://opensource.org/licenses/cpl.php)
* which can be found in the file CPL.TXT at the root of this distribution.
* By using this software in any fashion, you are agreeing to be bound by
* the terms of this license.
* You must not remove this notice, or any other, from this software.
**/
using System;
using System.Collections;
namespace clojure.lang
{
/**
* conses onto rear, peeks/pops from front
* See Okasaki's Batched Queues
* This differs in that it uses a PersistentArrayList as the rear, which is in-order,
* so no reversing or suspensions required for persistent use
*/
public class PersistentQueue : Obj, IPersistentList {
readonly public static PersistentQueue EMPTY = new PersistentQueue(null,null,null);
readonly ISeq f;
readonly PersistentArrayList r;
static readonly int INITIAL_REAR_SIZE = 4;
int _hash = -1;
PersistentQueue(ISeq f, PersistentArrayList r, IPersistentMap meta) {
this.f = f;
this.r = r;
this._meta = meta;
}
override public bool Equals(Object obj)
{
if (!(obj is Sequential))
return false;
ISeq ms = ((IPersistentCollection)obj).seq();
for (ISeq s = seq(); s != null; s = s.rest(), ms = ms.rest())
{
if (ms == null || !RT.equal(s.first(), ms.first()))
return false;
}
return ms.rest() == null;
}
override public int GetHashCode()
{
if (_hash == -1)
{
int hash = 0;
for (ISeq s = seq(); s != null; s = s.rest())
{
hash = RT.hashCombine(hash, RT.hash(s.first()));
}
this._hash = hash;
}
return _hash;
}
public Object peek() {
return RT.first(f);
}
public IPersistentList pop() {
if(f == null) //hmmm... pop of empty queue -> empty queue?
return this;
//throw new IllegalStateException("popping empty queue");
ISeq f1 = f.rest();
PersistentArrayList r1 = r;
if(f1 == null)
{
f1 = RT.seq(r);
r1 = null;
}
return new PersistentQueue(f1, r1,_meta);
}
public int count() {
return RT.count(f) + RT.count(r);
}
public ISeq seq() {
if(f == null)
return null;
return new Seq(f, RT.seq(r));
}
public IPersistentCollection cons(Object o) {
if(f == null) //empty
return new PersistentQueue(RT.list(o), null,_meta);
else
return new PersistentQueue(f,
(PersistentArrayList) (r != null ? r : new PersistentArrayList(INITIAL_REAR_SIZE)).cons(o),
_meta);
}
public override Obj withMeta(IPersistentMap meta)
{
if(_meta == meta)
return this;
Obj ret = (Obj)MemberwiseClone();
ret._meta = meta;
return ret;
}
class Seq : ASeq {
readonly ISeq f;
readonly ISeq rseq;
internal Seq(ISeq f, ISeq rseq) {
this.f = f;
this.rseq = rseq;
}
public override Object first() {
return f.first();
}
public override ISeq rest() {
ISeq f1 = f.rest();
ISeq r1 = rseq;
if (f1 == null)
{
if (rseq == null)
return null;
f1 = rseq;
r1 = null;
}
return new Seq(f1, r1);
}
public override int count() {
return RT.count(f) + RT.count(rseq);
}
}
//*
public static void Main(String[] args) {
if (args.Length != 1)
{
Console.Error.WriteLine("Usage: PersistentQueue n");
return;
}
int n = Int32.Parse(args[0]);
Random rand;
rand = new Random(42);
DateTime startTime;
TimeSpan estimatedTime;
//Queue list = new LinkedList();
Queue list = Queue.Synchronized(new Queue());
Console.WriteLine("Queue");
startTime = DateTime.Now;
for (int i = 0; i < n; i++)
{
list.Enqueue(i);
list.Enqueue(i);
list.Dequeue();
}
for (int i = 0; i < n - 10; i++)
{
list.Dequeue();
}
estimatedTime = DateTime.Now - startTime;
Console.WriteLine("time: " + estimatedTime.Ticks / 10000);
Console.WriteLine("peek: " + list.Peek());
PersistentQueue q = PersistentQueue.EMPTY;
Console.WriteLine("PersistentQueue");
startTime = DateTime.Now;
for (int i = 0; i < n; i++)
{
q = (PersistentQueue) q.cons(i);
q = (PersistentQueue) q.cons(i);
q = (PersistentQueue) q.pop();
}
IPersistentList lastq = null;
IPersistentList lastq2;
for (int i = 0; i < n - 10; i++)
{
//lastq2 = lastq;
//lastq = q;
q = (PersistentQueue) q.pop();
}
estimatedTime = DateTime.Now - startTime;
Console.WriteLine("time: " + estimatedTime.Ticks / 10000);
Console.WriteLine("peek: " + q.peek());
IPersistentList q2 = q;
for (int i = 0; i < 10; i++)
{
q2 = (IPersistentList) q2.cons(i);
}
// for(ISeq s = q.seq();s != null;s = s.rest())
// Console.WriteLine("q: " + s.first());
// for(ISeq s = q2.seq();s != null;s = s.rest())
// Console.WriteLine("q2: " + s.first());
}
//*/
}
}
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