xronos /System.Xronos/Language/PersistentVector.cs

Language C# Lines 217
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/* ****************************************************************************
 * 
 * Copyright (c) 2008 Stefan Rusek and Benjamin Pollack
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * 
 * ***************************************************************************/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;

namespace System.Xronos.Language
{
    public class PersistentVector : PersistentVectorBase
    {
        const int ChunkingFactor = 32;

        readonly int cnt;
        readonly object[][] chunks;
        readonly object[] tail;

        public static readonly PersistentVector Empty = new PersistentVector(0, null, RT.EmptyArray);

        public static PersistentVector Create(ISequence seq)
        {
            IPersistentVector ret = Empty;
            for (; seq != null; seq = seq.rest())
                ret = ret.cons(seq.first());
            return (PersistentVector)ret;
        }

        public static PersistentVector Create(object[] list)
        {
            if (list.Length == 0)
                return Empty;

            List<object[]> newChunks = new List<object[]>();

            for (int i = 0; i < list.Length; i += ChunkingFactor)
            {
                var arr = new object[Math.Min(ChunkingFactor, list.Length - i)];
                Array.Copy(list, i, arr, 0, arr.Length);
                newChunks.Add(arr);
            }

            var tail = newChunks[newChunks.Count - 1];
            newChunks.RemoveAt(newChunks.Count - 1);

            return new PersistentVector(list.Length,
                newChunks.Count != 0 ? newChunks.ToArray() : null,
                tail);
        }

        public static PersistentVector Create(IList list)
        {
            if (list.Count == 0)
                return Empty;

            List<object[]> newChunks = new List<object[]>();

            for (int i = 0; i < list.Count; i += ChunkingFactor)
            {
                var arr = new object[Math.Min(ChunkingFactor, list.Count - i)];
                for (int j = 0; j < arr.Length; j++)
                    arr[j] = list[i + j];
                newChunks.Add(arr);
            }

            var tail = newChunks[newChunks.Count - 1];
            newChunks.RemoveAt(newChunks.Count - 1);

            return new PersistentVector(list.Count,
                newChunks.Count != 0 ? newChunks.ToArray() : null,
                tail);
        }

        public static PersistentVector Create(IEnumerable list)
        {
            var ilist = list as IList;
            if (ilist != null)
                return Create(ilist);
            
            IPersistentVector ret = Empty;
            foreach (var item in list)
                ret = ret.cons(item);
            return (PersistentVector)ret;
        }

        private PersistentVector(int cnt, object[][] chunks, object[] tail)
            : base(null)
        {
            this.cnt = cnt;
            this.chunks = chunks;
            this.tail = tail;
        }

        private PersistentVector(IPersistentMap meta, int cnt, object[][] chunks, object[] tail)
            : base(meta)
        {
            this.cnt = cnt;
            this.chunks = chunks;
            this.tail = tail;
        }

        private int TailOffset { get { return cnt - tail.Length; } }

        public override int Count
        {
            get { return cnt; }
        }

        public override object this[int index]
        {
            get
            {
                if (index >= 0 && index < cnt)
                {
                    if (index >= TailOffset)
                        return tail[index - TailOffset];
                    return chunks[index / ChunkingFactor][index % ChunkingFactor];
                }
                throw new IndexOutOfRangeException();
            }
            set
            {
                throw new NotSupportedException();
            }
        }

        private T[] Append<T>(T[] arr, T t)
        {
            T[] newArr = new T[arr.Length + 1];
            Array.Copy(arr, newArr, arr.Length);
            newArr[arr.Length] = t;
            return newArr;
        }

        private T[] Replace<T>(T[] arr, int i, T val)
        {
            T[] newArr = new T[arr.Length];
            Array.Copy(arr, newArr, arr.Length);
            newArr[i] = val;
            return newArr;
        }

        private T[] RemoveOne<T>(T[] arr, out T last)
        {
            T[] newArr = new T[arr.Length - 1];
            Array.Copy(arr, 1, newArr, 0, newArr.Length);
            last = arr[newArr.Length];
            return newArr;
        }

        public override IPersistentVector assocN(int i, object val)
        {
            var newChunks = chunks;
            var newTail = tail;

            if (i >= TailOffset)
            {
                newTail = Replace(newTail, i - TailOffset, val);
            }
            else
            {
                var ixChunk = i / ChunkingFactor;
                newChunks = Replace(newChunks, ixChunk, Replace(newChunks[ixChunk], i % ChunkingFactor, val));
            }

            return new PersistentVector(cnt, newChunks, newTail);
        }

        public override IPersistentVector cons(object o)
        {
            var newChunks = chunks;
            var newTail = tail;

            if (newTail.Length == ChunkingFactor)
            {
                newChunks = Append(newChunks, newTail);
                newTail = new[] { o };
            }
            else
                newTail = Append(newTail, o);

            return new PersistentVector(cnt + 1, newChunks, newTail);
        }

        public override XronosObject withMeta(IPersistentMap meta)
        {
            return new PersistentVector(meta, cnt, chunks, tail);
        }

        public override IPersistentCollection empty()
        {
            return (IPersistentCollection)Empty.withMeta(meta());
        }
    }
}
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