/* ****************************************************************************

 *

 * Copyright (c) Microsoft Corporation. 

 *

 * This source code is subject to terms and conditions of the Microsoft Public License. A 

 * copy of the license can be found in the License.html file at the root of this distribution. If 

 * you cannot locate the  Microsoft Public License, please send an email to 

 * dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 

 * by the terms of the Microsoft Public License.

 *

 * You must not remove this notice, or any other, from this software.

 *

 *

 * ***************************************************************************/



using System;

using System.Collections;

using System.Collections.Generic;

using System.Diagnostics;

using System.Text;



using Microsoft.Scripting.Runtime;

using Microsoft.Scripting.Utils;



namespace IronPython.Runtime.Operations {

    internal static class IListOfByteOps {

        internal static int Compare(this IList<byte>/*!*/ self, IList<byte>/*!*/ other) {

            for (int i = 0; i < self.Count && i < other.Count; i++) {

                if (self[i] != other[i]) {

                    if (self[i] > other[i]) {

                        return 1;

                    } else {

                        return -1;

                    }

                }

            }



            if (self.Count == other.Count) {

                return 0;

            }



            return self.Count > other.Count ? +1 : -1;

        }



        internal static int Compare(this IList<byte>/*!*/ self, string other) {

            for (int i = 0; i < self.Count && i < other.Length; i++) {

                if ((char)self[i] != other[i]) {

                    if ((char)self[i] > other[i]) {

                        return 1;

                    } else {

                        return -1;

                    }

                }

            }



            if (self.Count == other.Length) {

                return 0;

            }



            return self.Count > other.Length ? +1 : -1;

        }



        internal static bool EndsWith(this IList<byte>/*!*/ self, IList<byte>/*!*/ suffix) {

            if (self.Count < suffix.Count) {

                return false;

            }



            int offset = self.Count - suffix.Count;

            for (int i = 0; i < suffix.Count; i++) {

                if (suffix[i] != self[i + offset]) {

                    return false;

                }

            }



            return true;

        }



        internal static bool EndsWith(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ suffix, int start) {

            int len = bytes.Count;

            if (start > len) return false;

            // map the negative indice to its positive counterpart

            if (start < 0) {

                start += len;

                if (start < 0) start = 0;

            }

            return bytes.Substring(start).EndsWith(suffix);

        }



        //  With optional start, test beginning at that position (the char at that index is

        //  included in the test). With optional end, stop comparing at that position (the 

        //  char at that index is not included in the test)

        internal static bool EndsWith(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ suffix, int start, int end) {

            int len = bytes.Count;

            if (start > len) return false;

            // map the negative indices to their positive counterparts

            else if (start < 0) {

                start += len;

                if (start < 0) start = 0;

            }

            if (end >= len) {

                return bytes.Substring(start).EndsWith(suffix);

            } else if (end < 0) {

                end += len;

                if (end < 0) {

                    return false;

                }

            }

            if (end < start) {

                return false;

            }

            return bytes.Substring(start, end - start).EndsWith(suffix);

        }



        internal static bool EndsWith(this IList<byte>/*!*/ bytes, PythonTuple/*!*/ suffix) {

            foreach (object obj in suffix) {

                if (bytes.EndsWith(ByteOps.CoerceBytes(obj))) {

                    return true;

                }

            }

            return false;

        }



        internal static bool EndsWith(this IList<byte>/*!*/ bytes, PythonTuple/*!*/ suffix, int start) {

            int len = bytes.Count;

            if (start > len) return false;

            // map the negative indice to its positive counterpart

            if (start < 0) {

                start += len;

                if (start < 0) {

                    start = 0;

                }

            }

            foreach (object obj in suffix) {

                if (bytes.Substring(start).EndsWith(ByteOps.CoerceBytes(obj))) {

                    return true;

                }

            }

            return false;

        }



        internal static bool EndsWith(this IList<byte>/*!*/ bytes, PythonTuple/*!*/ suffix, int start, int end) {

            int len = bytes.Count;

            if (start > len) return false;

            // map the negative indices to their positive counterparts

            else if (start < 0) {

                start += len;

                if (start < 0) {

                    start = 0;

                }

            }

            if (end >= len) {

                end = len;

            } else if (end < 0) {

                end += len;

                if (end < 0) {

                    return false;

                }

            }

            if (end < start) {

                return false;

            }



            foreach (object obj in suffix) {

                if (bytes.Substring(start, end - start).EndsWith(ByteOps.CoerceBytes(obj))) {

                    return true;

                }

            }

            return false;

        }



        internal static bool StartsWith(this IList<byte>/*!*/ self, IList<byte>/*!*/ prefix) {

            if (self.Count < prefix.Count) {

                return false;

            }



            for (int i = 0; i < prefix.Count; i++) {

                if (prefix[i] != self[i]) {

                    return false;

                }

            }



            return true;

        }



        internal static int IndexOfAny(this IList<byte>/*!*/ str, IList<byte>/*!*/ separators, int i) {

            for (; i < str.Count; i++) {

                for (int j = 0; j < separators.Count; j++) {

                    if (str[i] == separators[j]) {

                        return i;

                    }

                }

            }

            return -1;

        }



        internal static int IndexOf(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ sub, int start) {

            return IndexOf(bytes, sub, start, bytes.Count - start);

        }



        internal static int IndexOf(this IList<byte>/*!*/ self, IList<byte>/*!*/ ssub, int start, int length) {

            if (ssub == null) {

                throw PythonOps.TypeError("cannot do None in bytes or bytearray");

            } else if (ssub.Count == 0) {

                return 0;

            }



            byte firstByte = ssub[0];

            for (int i = start; i < start + length; i++) {

                if (self[i] == firstByte) {

                    bool differ = false;



                    for (int j = 1; j < ssub.Count; j++) {

                        if (j + i == start + length || ssub[j] != self[i + j]) {

                            differ = true;

                            break;

                        }

                    }



                    if (!differ) {

                        return i;

                    }

                }

            }



            return -1;

        }



        internal static bool IsTitle(this IList<byte>/*!*/ bytes) {

            if (bytes.Count == 0) {

                return false;

            }



            bool prevCharCased = false, currCharCased = false, containsUpper = false;

            for (int i = 0; i < bytes.Count; i++) {

                if (bytes[i].IsUpper()) {

                    containsUpper = true;

                    if (prevCharCased)

                        return false;

                    else

                        currCharCased = true;

                } else if (bytes[i].IsLower())

                    if (!prevCharCased)

                        return false;

                    else

                        currCharCased = true;

                else

                    currCharCased = false;

                prevCharCased = currCharCased;

            }



            //  if we've gone through the whole string and haven't encountered any rule 

            //  violations but also haven't seen an Uppercased char, then this is not a 

            //  title e.g. '\n', all whitespace etc.

            return containsUpper;

        }



        internal static bool IsUpper(this IList<byte>/*!*/ bytes) {

            bool foundUpper = false;

            foreach (byte b in bytes) {

                foundUpper = foundUpper || b.IsUpper();

                if (b.IsLower()) {

                    return false;

                }

            }

            return foundUpper;

        }



        internal static List<byte> Title(this IList<byte>/*!*/ self) {

            if (self.Count == 0) {

                return null;

            }



            List<byte> retchars = new List<byte>(self);

            bool prevCharCased = false;

            bool currCharCased = false;

            int i = 0;

            do {

                if (retchars[i].IsUpper() || retchars[i].IsLower()) {

                    if (!prevCharCased)

                        retchars[i] = retchars[i].ToUpper();

                    else

                        retchars[i] = retchars[i].ToLower();

                    currCharCased = true;

                } else {

                    currCharCased = false;

                }

                i++;

                prevCharCased = currCharCased;

            } while (i < retchars.Count);

            return retchars;

        }



        internal static int LastIndexOf(this IList<byte>/*!*/ self, IList<byte>/*!*/ sub, int start, int length) {

            byte firstByte = sub[sub.Count - 1];            

            for (int i = start - 1; i >= start - length; i--) {

                if (self[i] == firstByte) {

                    bool differ = false;



                    if (sub.Count != 1) {

                        for (int j = sub.Count - 2, selfIndex = 1; j >= 0; j--, selfIndex++) {

                            if (sub[j] != self[i - selfIndex]) {

                                differ = true;

                                break;

                            }

                        }

                    }



                    if (!differ) {

                        return i - sub.Count + 1;

                    }

                }

            }



            return -1;

        }



        internal static List<byte>/*!*/[]/*!*/ Split(this IList<byte>/*!*/ str, IList<byte>/*!*/ separators, int maxComponents, StringSplitOptions options) {

            ContractUtils.RequiresNotNull(str, "str");

            bool keep_empty = (options & StringSplitOptions.RemoveEmptyEntries) != StringSplitOptions.RemoveEmptyEntries;

            

            if (separators == null) {

                Debug.Assert(!keep_empty);

                return SplitOnWhiteSpace(str, maxComponents);

            }



            List<List<byte>> result = new List<List<byte>>(maxComponents == Int32.MaxValue ? 1 : maxComponents + 1);



            int i = 0;

            int next;

            while (maxComponents > 1 && i < str.Count && (next = IndexOfAny(str, separators, i)) != -1) {

                if (next > i || keep_empty) {

                    result.Add(Substring(str, i, next - i));

                    maxComponents--;

                }



                i = next + separators.Count;

            }



            if (i < str.Count || keep_empty) {

                /*while (i < str.Count) {

                    if (!separators.Contains(str[i])) {

                        break;

                    }



                    i++;

                }*/

                result.Add(Substring(str, i));

            }



            return result.ToArray();

        }



        internal static List<byte>/*!*/[]/*!*/ SplitOnWhiteSpace(this IList<byte>/*!*/ str, int maxComponents) {

            ContractUtils.RequiresNotNull(str, "str");

            



            List<List<byte>> result = new List<List<byte>>(maxComponents == Int32.MaxValue ? 1 : maxComponents + 1);



            int i = 0;

            int next;

            while (maxComponents > 1 && i < str.Count && (next = IndexOfWhiteSpace(str, i)) != -1) {

                if (next > i) {

                    result.Add(Substring(str, i, next - i));

                    maxComponents--;

                }



                i = next + 1;

            }



            if (i < str.Count) {

                // check if we only have white space remaining

                while (i < str.Count) {

                    if (!str[i].IsWhiteSpace()) {

                        break;

                    }



                    i++;

                }



                if (i < str.Count) {

                    result.Add(Substring(str, i));

                }

            }



            return result.ToArray();

        }



        internal static bool StartsWith(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ prefix, int start, int end) {

            int len = bytes.Count;

            if (start > len) {

                return false;

            } else if (start < 0) {

                // map the negative indices to their positive counterparts

                start += len;

                if (start < 0) {

                    start = 0;

                }

            }

            if (end >= len) {

                return bytes.Substring(start).StartsWith(prefix);

            } else if (end < 0) {

                end += len;

                if (end < 0) {

                    return false;

                }

            }

            if (end < start) {

                return false;

            }



            return bytes.Substring(start, end - start).StartsWith(prefix);

        }



        internal static List<byte>/*!*/ Replace(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ old, IList<byte>/*!*/ new_, int maxsplit) {

            if (new_ == null) {

                throw PythonOps.TypeError("expected bytes or bytearray, got NoneType");

            }



            if (maxsplit == -1) {

                maxsplit = old.Count + 1;

            } 

            

            if (old.Count == 0) {

                return ReplaceEmpty(bytes, new_, maxsplit);

            }



            List<byte> ret = new List<byte>(bytes.Count);



            int index;

            int start = 0;



            while (maxsplit > 0 && (index = bytes.IndexOf(old, start)) != -1) {

                ret.AddRange(bytes.Substring(start, index - start));

                ret.AddRange(new_);

                start = index + old.Count;

                maxsplit--;

            }

            ret.AddRange(bytes.Substring(start));



            return ret;

        }



        private static List<byte>/*!*/ ReplaceEmpty(this IList<byte>/*!*/ self, IList<byte>/*!*/ new_, int maxsplit) {

            int max = maxsplit > self.Count ? self.Count : maxsplit;

            List<byte> ret = new List<byte>(self.Count * (new_.Count + 1));

            for (int i = 0; i < max; i++) {

                ret.AddRange(new_);

                ret.Add(self[i]);

            }

            for (int i = max; i < self.Count; i++) {

                ret.Add(self[i]);

            }

            if (maxsplit > max) {

                ret.AddRange(new_);

            }



            return ret;

        }



        internal static int ReverseFind(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ sub, int? start, int? end) {

            if (sub == null) {

                throw PythonOps.TypeError("expected string, got NoneType");

            } else if (start > bytes.Count) {

                return -1;

            }



            int iStart, iEnd;

            iStart = FixStart(bytes, start);

            iEnd = FixEnd(bytes, end);



            if (iStart > iEnd) {

                // can't possibly match anything, not even an empty string

                return -1;

            } else if (sub.Count == 0) {

                // match at the end

                return iEnd;

            } else if (end == 0) {

                // can't possibly find anything

                return -1;

            }



            return bytes.LastIndexOf(sub, iEnd, iEnd - iStart);

        }



        internal static List/*!*/ RightSplit(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ sep, int maxsplit, Func<IList<byte>/*!*/, IList<byte>>/*!*/ ctor) {

            //  rsplit works like split but needs to split from the right;

            //  reverse the original string (and the sep), split, reverse 

            //  the split list and finally reverse each element of the list

            IList<byte> reversed = bytes.ReverseBytes();

            if (sep != null) {

                sep = sep.ReverseBytes();

            }



            List temp = null, ret = null;

            temp = ctor(reversed).Split(sep, maxsplit, x => ctor(x));

            temp.reverse();

            int resultlen = temp.__len__();

            if (resultlen != 0) {

                ret = new List(resultlen);

                foreach (IList<byte> s in temp)

                    ret.AddNoLock(ctor(s.ReverseBytes()));

            } else {

                ret = temp;

            }

            return ret;

        }



        internal static int IndexOfWhiteSpace(this IList<byte>/*!*/ str, int start) {

            while (start < str.Count && !str[start].IsWhiteSpace()) start++;



            return (start == str.Count) ? -1 : start;

        }





        internal static byte[]/*!*/ ReverseBytes(this IList<byte>/*!*/ s) {

            byte[] rchars = new byte[s.Count];

            for (int i = s.Count - 1, j = 0; i >= 0; i--, j++) {

                rchars[j] = s[i];

            }

            return rchars;

        }



        internal static List<byte>/*!*/ Substring(this IList<byte>/*!*/ bytes, int start) {

            return Substring(bytes, start, bytes.Count - start);

        }



        internal static List<byte>/*!*/ Substring(this IList<byte>/*!*/ bytes, int start, int len) {

            List<byte> substr = new List<byte>();

            for (int i = start; i < start + len; i++) {

                substr.Add(bytes[i]);

            }

            return substr;

        }



        internal static List<byte>/*!*/ Multiply(this IList<byte>/*!*/ self, int count) {

            if (count <= 0) {

                return new List<byte>();

            }

            List<byte> res = new List<byte>(checked(self.Count * count));

            for (int i = 0; i < count; i++) {

                res.AddRange(self);

            }

            return res;

        }



        internal static List<byte>/*!*/ Capitalize(this IList<byte>/*!*/ bytes) {

            List<byte> res = new List<byte>(bytes);

            if (res.Count > 0) {

                res[0] = res[0].ToUpper();



                for (int i = 1; i < res.Count; i++) {

                    res[i] = res[i].ToLower();

                }

            }

            return res;

        }



        internal static List<byte> TryCenter(this IList<byte>/*!*/ bytes, int width, int fillchar) {

            int spaces = width - bytes.Count;

            if (spaces <= 0) {

                return null;

            }



            byte fill = fillchar.ToByteChecked();



            List<byte> newBytes = new List<byte>();

            for (int i = 0; i < spaces / 2; i++) {

                newBytes.Add(fill);

            }



            newBytes.AddRange(bytes);

            for (int i = 0; i < (spaces + 1) / 2; i++) {

                newBytes.Add(fill);

            }

            return newBytes;

        }



        internal static int CountOf(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ ssub, int start, int end) {

            if (ssub == null) {

                throw PythonOps.TypeError("expected bytes or byte array, got NoneType");

            }



            if (start > bytes.Count) {

                return 0;

            }

            start = PythonOps.FixSliceIndex(start, bytes.Count);

            end = PythonOps.FixSliceIndex(end, bytes.Count);



            if (ssub.Count == 0) {

                return Math.Max((end - start) + 1, 0);

            }



            int count = 0;

            while (true) {

                if (end <= start) break;



                int index = bytes.IndexOf(ssub, start, end - start);

                if (index == -1) break;

                count++;

                start = index + ssub.Count;

            }

            return count;

        }



        internal static List<byte>/*!*/ ExpandTabs(this IList<byte>/*!*/ bytes, int tabsize) {            

            List<byte> ret = new List<byte>(bytes.Count * 2);



            int col = 0;

            for (int i = 0; i < bytes.Count; i++) {

                byte ch = bytes[i];

                switch (ch) {

                    case (byte)'\n':

                    case (byte)'\r': col = 0; ret.Add(ch); break;

                    case (byte)'\t':

                        if (tabsize > 0) {

                            int tabs = tabsize - (col % tabsize);

                            int existingSize = ret.Capacity;

                            ret.Capacity = checked(existingSize + tabs);

                            for (int j = 0; j < tabs; j++) {

                                ret.Add((byte)' ');

                            }

                            col = 0;

                        }

                        break;

                    default:

                        col++;

                        ret.Add(ch);

                        break;

                }

            }

            return ret;

        }



        internal static int IndexOfByte(this IList<byte>/*!*/ bytes, int item, int start, int stop) {

            start = PythonOps.FixSliceIndex(start, bytes.Count);

            stop = PythonOps.FixSliceIndex(stop, bytes.Count);



            for (int i = start; i < Math.Min(stop, bytes.Count); i++) {

                if (bytes[i] == item) {

                    return i;

                }

            }



            throw PythonOps.ValueError("bytearray.index(item): item not in bytearray");

        }



        internal static string/*!*/ BytesRepr(this IList<byte>/*!*/ bytes) {

            StringBuilder res = new StringBuilder();

            res.Append("b'");

            for (int i = 0; i < bytes.Count; i++) {

                byte ch = bytes[i];



                switch (ch) {

                    case (byte)'\\': res.Append("\\\\"); break;

                    case (byte)'\t': res.Append("\\t"); break;

                    case (byte)'\n': res.Append("\\n"); break;

                    case (byte)'\r': res.Append("\\r"); break;

                    case (byte)'\'':

                        res.Append('\\');

                        res.Append('\'');

                        break;

                    default:

                        if (ch < ' ' || (ch >= 0x7f && ch <= 0xff)) {

                            res.AppendFormat("\\x{0:x2}", ch);

                        } else {

                            res.Append((char)ch);

                        }

                        break;

                }

            }

            res.Append("'");

            return res.ToString();

        }



        internal static List<byte>/*!*/ ZeroFill(this IList<byte>/*!*/ bytes, int width, int spaces) {

            List<byte> ret = new List<byte>(width);

            if (bytes.Count > 0 && bytes[0].IsSign()) {

                ret.Add(bytes[0]);

                for (int i = 0; i < spaces; i++) {

                    ret.Add((byte)'0');

                }

                for (int i = 1; i < bytes.Count; i++) {

                    ret.Add(bytes[i]);

                }

            } else {

                for (int i = 0; i < spaces; i++) {

                    ret.Add((byte)'0');

                }

                ret.AddRange(bytes);

            }

            return ret;

        }



        internal static List<byte>/*!*/ ToLower(this IList<byte>/*!*/ bytes) {

            List<byte> res = new List<byte>();

            for (int i = 0; i < bytes.Count; i++) {

                res.Add(bytes[i].ToLower());

            }

            return res;

        }



        internal static List<byte>/*!*/ ToUpper(this IList<byte>/*!*/ bytes) {

            List<byte> res = new List<byte>();

            for (int i = 0; i < bytes.Count; i++) {

                res.Add(bytes[i].ToUpper());

            }

            return res;

        }



        internal static List<byte>/*!*/ Translate(this IList<byte>/*!*/ bytes, IList<byte> table, IList<byte> deletechars) {

            List<byte> res = new List<byte>();

            for (int i = 0; i < bytes.Count; i++) {

                if (deletechars == null || !deletechars.Contains(bytes[i])) {

                    if (table == null) {

                        res.Add(bytes[i]);

                    } else {

                        res.Add(table[bytes[i]]);

                    }

                }

            }

            return res;

        }



        internal static List<byte> RightStrip(this IList<byte>/*!*/ bytes) {

            int i;

            for (i = bytes.Count - 1; i >= 0; i--) {

                if (!bytes[i].IsWhiteSpace()) {

                    break;

                }

            }



            if (i == bytes.Count - 1) {

                return null;

            }



            List<byte> res = new List<byte>();

            for (int j = 0; j <= i; j++) {

                res.Add(bytes[j]);

            }



            return res;

        }



        internal static List<byte> RightStrip(this IList<byte>/*!*/ bytes, IList<byte> chars) {

            int i;

            for (i = bytes.Count - 1; i >= 0; i--) {

                if (!chars.Contains(bytes[i])) {

                    break;

                }

            }



            if (i == bytes.Count - 1) {

                return null;

            }



            List<byte> res = new List<byte>();

            for (int j = 0; j <= i; j++) {

                res.Add(bytes[j]);

            }



            return res;

        }



        internal static List/*!*/ SplitLines(this IList<byte>/*!*/ bytes, bool keepends, Func<List<byte>/*!*/, object>/*!*/ ctor) {

            List ret = new List();

            int i, linestart;

            for (i = 0, linestart = 0; i < bytes.Count; i++) {

                if (bytes[i] == '\n' || bytes[i] == '\r') {

                    //  special case of "\r\n" as end of line marker

                    if (i < bytes.Count - 1 && bytes[i] == '\r' && bytes[i + 1] == '\n') {

                        if (keepends)

                            ret.AddNoLock(ctor(bytes.Substring(linestart, i - linestart + 2)));

                        else

                            ret.AddNoLock(ctor(bytes.Substring(linestart, i - linestart)));

                        linestart = i + 2;

                        i++;

                    } else { //'\r', '\n', or unicode new line as end of line marker

                        if (keepends)

                            ret.AddNoLock(ctor(bytes.Substring(linestart, i - linestart + 1)));

                        else

                            ret.AddNoLock(ctor(bytes.Substring(linestart, i - linestart)));

                        linestart = i + 1;

                    }

                }

            }

            //  the last line needs to be accounted for if it is not empty

            if (i - linestart != 0) {

                ret.AddNoLock(ctor(bytes.Substring(linestart, i - linestart)));

            }

            return ret;

        }



        internal static List<byte> LeftStrip(this IList<byte>/*!*/ bytes) {

            int i;

            for (i = 0; i < bytes.Count; i++) {

                if (!bytes[i].IsWhiteSpace()) {

                    break;

                }

            }



            if (i == 0) {

                return null;

            }



            List<byte> res = new List<byte>();

            for (; i < bytes.Count; i++) {

                res.Add(bytes[i]);

            }

            return res;

        }



        internal static List<byte> LeftStrip(this IList<byte>/*!*/ bytes, IList<byte> chars) {

            int i;

            for (i = 0; i < bytes.Count; i++) {

                if (!chars.Contains(bytes[i])) {

                    break;

                }

            }



            if (i == 0) {

                return null;

            }



            List<byte> res = new List<byte>();

            for (; i < bytes.Count; i++) {

                res.Add(bytes[i]);

            }

            return res;

        }

        

        internal static List/*!*/ Split(this IList<byte>/*!*/ bytes, IList<byte> sep, int maxsplit, Func<List<byte>/*!*/, object>/*!*/ ctor) {

            Debug.Assert(ctor != null);



            if (sep == null) {

                if (maxsplit == 0) {

                    // Corner case for CPython compatibility

                    List result = PythonOps.MakeEmptyList(1);

                    result.AddNoLock(ctor(bytes.LeftStrip() ?? bytes as List<byte> ?? new List<byte>(bytes)));

                    return result;

                }



                return SplitInternal(bytes, (byte[])null, maxsplit, ctor);

            }



            if (sep.Count == 0) {

                throw PythonOps.ValueError("empty separator");

            } else if (sep.Count == 1) {

                return SplitInternal(bytes, new byte[] { sep[0] }, maxsplit, ctor);

            } else {

                return SplitInternal(bytes, sep, maxsplit, ctor);

            }

        }



        internal static List/*!*/ SplitInternal(IList<byte>/*!*/ bytes, byte[] seps, int maxsplit, Func<List<byte>/*!*/, object>/*!*/ ctor) {

            Debug.Assert(ctor != null);



            if (bytes.Count == 0) {

                return SplitEmptyString(seps != null, ctor);

            } else {

                List<byte>[] r = null;

                //  If the optional second argument sep is absent or None, the words are separated 

                //  by arbitrary strings of whitespace characters (space, tab, newline, return, formfeed);



                r = bytes.Split(seps, (maxsplit < 0) ? Int32.MaxValue : maxsplit + 1,

                    GetStringSplitOptions(seps));



                List ret = PythonOps.MakeEmptyList(r.Length);

                foreach (List<byte> s in r) {

                    ret.AddNoLock(ctor(s));

                }

                return ret;

            }

        }



        private static StringSplitOptions GetStringSplitOptions(IList<byte> seps) {

            return (seps == null) ? StringSplitOptions.RemoveEmptyEntries : StringSplitOptions.None;

        }



        internal static List/*!*/ SplitInternal(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ separator, int maxsplit, Func<List<byte>/*!*/, object>/*!*/ ctor) {

            Debug.Assert(ctor != null);



            if (bytes.Count == 0) {

                return SplitEmptyString(separator != null, ctor);

            }



            List<byte>[] r = bytes.Split(separator, (maxsplit < 0) ? Int32.MaxValue : maxsplit + 1, GetStringSplitOptions(separator));



            List ret = PythonOps.MakeEmptyList(r.Length);

            foreach (List<byte> s in r) {

                ret.AddNoLock(ctor(s));

            }

            return ret;

        }



        private static List/*!*/ SplitEmptyString(bool separators, Func<List<byte>/*!*/, object>/*!*/ ctor) {

            Debug.Assert(ctor != null);



            List ret = PythonOps.MakeEmptyList(1);

            if (separators) {

                ret.AddNoLock(ctor(new List<byte>(0)));

            }

            return ret;

        }



        internal static List<byte> Strip(this IList<byte>/*!*/ bytes) {

            int start;



            for (start = 0; start < bytes.Count; start++) {

                if (!bytes[start].IsWhiteSpace()) {

                    break;

                }

            }



            int end;

            for (end = bytes.Count - 1; end >= 0; end--) {

                if (!bytes[end].IsWhiteSpace()) {

                    break;

                }

            }



            if (start == 0 && end == bytes.Count - 1) {

                return null;

            }



            List<byte> res = new List<byte>();

            for (int j = start; j <= end; j++) {

                res.Add(bytes[j]);

            }



            return res;

        }



        internal static List<byte> Strip(this IList<byte>/*!*/ bytes, IList<byte> chars) {

            int start;



            for (start = 0; start < bytes.Count; start++) {

                if (!chars.Contains(bytes[start])) {

                    break;

                }

            }



            int end;

            for (end = bytes.Count - 1; end >= 0; end--) {

                if (!chars.Contains(bytes[end])) {

                    break;

                }

            }



            if (start == 0 && end == bytes.Count - 1) {

                return null;

            }



            List<byte> res = new List<byte>();

            for (int j = start; j <= end; j++) {

                res.Add(bytes[j]);

            }



            return res;

        }



        internal static List<byte> Slice(this IList<byte>/*!*/ bytes, Slice/*!*/ slice) {

            if (slice == null) {

                throw PythonOps.TypeError("indices must be slices or integers");

            }



            int start, stop, step;

            slice.indices(bytes.Count, out start, out stop, out step);

            if (step == 1) {

                return stop > start ? bytes.Substring(start, stop - start) : null;

            }



            List<byte> newData;

            if (step > 0) {

                if (start > stop) {

                    return null;

                }



                int icnt = (stop - start + step - 1) / step;

                newData = new List<byte>(icnt);

                for (int i = start; i < stop; i += step) {

                    newData.Add(bytes[i]);

                }

            } else {

                if (start < stop) {

                    return null;

                }



                int icnt = (stop - start + step + 1) / step;

                newData = new List<byte>(icnt);

                for (int i = start; i > stop; i += step) {

                    newData.Add(bytes[i]);

                }

            }



            return newData;

        }



        internal static List<byte>/*!*/ SwapCase(this IList<byte>/*!*/ bytes) {

            List<byte> ret = new List<byte>(bytes);

            for (int i = 0; i < bytes.Count; i++) {

                byte ch = ret[i];

                if (ch.IsUpper()) {

                    ret[i] = ch.ToLower();

                } else if (ch.IsLower()) {

                    ret[i] = ch.ToUpper();

                }

            }

            return ret;

        }



        internal static bool StartsWith(this IList<byte>/*!*/ bytes, PythonTuple/*!*/ prefix, int start, int end) {

            int len = bytes.Count;

            if (start > len) return false;

            // map the negative indices to their positive counterparts

            else if (start < 0) {

                start += len;

                if (start < 0) start = 0;

            }

            if (end >= len) end = len;

            else if (end < 0) {

                end += len;

                if (end < 0) return false;

            }

            if (end < start) return false;



            foreach (object obj in prefix) {

                if (bytes.Substring(start, end - start).StartsWith(ByteOps.CoerceBytes(obj))) {

                    return true;

                }

            }

            return false;

        }



        internal static bool StartsWith(this IList<byte>/*!*/ bytes, PythonTuple/*!*/ prefix, int start) {

            int len = bytes.Count;

            if (start > len) return false;

            if (start < 0) {

                start += len;

                if (start < 0) {

                    start = 0;

                }

            }

            foreach (object obj in prefix) {

                if (bytes.Substring(start).StartsWith(ByteOps.CoerceBytes(obj))) {

                    return true;

                }

            }

            return false;

        }



        internal static bool StartsWith(this IList<byte>/*!*/ bytes, PythonTuple/*!*/ prefix) {

            foreach (object obj in prefix) {

                if (bytes.StartsWith(ByteOps.CoerceBytes(obj))) {

                    return true;

                }

            }

            return false;

        }



        internal static bool IsWhiteSpace(this IList<byte>/*!*/ bytes) {

            if (bytes.Count == 0) {

                return false;

            }



            foreach (byte b in bytes) {

                if (!b.IsWhiteSpace()) {

                    return false;

                }

            }

            return true;

        }



        internal static bool IsLower(this IList<byte>/*!*/ bytes) {

            bool foundLower = false;

            foreach (byte b in bytes) {

                foundLower = foundLower || b.IsLower();

                if (b.IsUpper()) {

                    return false;

                }

            }

            return foundLower;

        }



        internal static bool IsDigit(this IList<byte>/*!*/ bytes) {

            if (bytes.Count == 0) {

                return false;

            }



            foreach (byte b in bytes) {

                if (!b.IsDigit()) {

                    return false;

                }

            }

            return true;

        }



        internal static bool IsLetter(this IList<byte>/*!*/ bytes) {

            if (bytes.Count == 0) {

                return false;

            }



            foreach (byte b in bytes) {

                if (!b.IsLetter()) {

                    return false;

                }

            }

            return true;

        }



        internal static bool IsAlphaNumeric(this IList<byte>/*!*/ bytes) {

            if (bytes.Count == 0) {

                return false;

            }



            foreach (byte b in bytes) {

                if (!b.IsDigit() && !b.IsLetter()) {

                    return false;

                }

            }

            return true;

        }



        internal static int Find(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ sub) {

            if (sub == null) {

                throw PythonOps.TypeError("expected byte or byte array, got NoneType");

            }



            return bytes.IndexOf(sub, 0);

        }





        internal static int Find(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ sub, int? start) {

            if (sub == null) {

                throw PythonOps.TypeError("expected byte or byte array, got NoneType");

            } else if (start > bytes.Count) {

                return -1;

            }



            

            int iStart;

            if (start != null) {

                iStart = PythonOps.FixSliceIndex(start.Value, bytes.Count);

            } else {

                iStart = 0;

            }



            return bytes.IndexOf(sub, iStart);

        }





        internal static int Find(this IList<byte>/*!*/ bytes, IList<byte>/*!*/ sub, int? start, int? end) {

            if (sub == null) {

                throw PythonOps.TypeError("expected byte or byte array, got NoneType");

            } else if (start > bytes.Count) {

                return -1;

            }



            int iStart, iEnd;

            iStart = FixStart(bytes, start);

            iEnd = FixEnd(bytes, end);



            if (iEnd < iStart) {

                return -1;

            }



            return bytes.IndexOf(sub, iStart, iEnd - iStart);

        }



        private static int FixEnd(IList<byte> bytes, int? end) {

            int iEnd;

            if (end != null) {

                iEnd = PythonOps.FixSliceIndex(end.Value, bytes.Count);

            } else {

                iEnd = bytes.Count;

            }

            return iEnd;

        }



        private static int FixStart(IList<byte> bytes, int? start) {

            int iStart;

            if (start != null) {

                iStart = PythonOps.FixSliceIndex(start.Value, bytes.Count);

            } else {

                iStart = 0;

            }

            return iStart;

        }



        internal static byte ToByte(this string/*!*/ self, string name, int pos) {

            Debug.Assert(self != null);



            if (self.Length != 1 || self[0] >= 256) {

                throw PythonOps.TypeError(name + "() argument " + pos + " must be char < 256, not string");

            }



            return (byte)self[0];

        }



        internal static byte ToByte(this IList<byte>/*!*/ self, string/*!*/ name, int pos) {

            Debug.Assert(name != null);



            if (self == null) {

                throw PythonOps.TypeError(name + "() argument " + pos + " must be char < 256, not None");

            } else if (self.Count != 1) {

                throw PythonOps.TypeError(name + "() argument " + pos + " must be char < 256, not bytearray or bytes");

            }



            return self[0];

        }



        internal static List<byte>/*!*/ FromHex(string/*!*/ @string) {

            if(@string == null) {

                throw PythonOps.TypeError("expected str, got NoneType");

            }



            List<byte> res = new List<byte>();



            for (int i = 0; i < @string.Length; i++) {

                char c = @string[i];



                int iVal = 0;



                if (Char.IsDigit(c)) {

                    iVal = (c - '0') * 16;

                } else if (c >= 'A' && c <= 'F') {

                    iVal = (c - 'A' + 10) * 16;

                } else if (c >= 'a' && c <= 'f') {

                    iVal = (c - 'a' + 10) * 16;

                } else if (c == ' ') {

                    continue;

                } else {

                    throw PythonOps.ValueError("non-hexadecimal number found in fromhex() arg at position {0}", i);

                }



                i++;

                if (i == @string.Length) {

                    throw PythonOps.ValueError("non-hexadecimal number found in fromhex() arg at position {0}", i - 1);

                }



                c = @string[i];

                if (Char.IsDigit(c)) {

                    iVal += c - '0';

                } else if (c >= 'A' && c <= 'F') {

                    iVal += c - 'A' + 10;

                } else if (c >= 'a' && c <= 'f') {

                    iVal += c - 'a' + 10;

                } else {

                    throw PythonOps.ValueError("non-hexadecimal number found in fromhex() arg at position {0}", i);

                }

                res.Add((byte)iVal);

            }

            return res;

        }



        #region Conversion and Enumeration



        [PythonType("bytes_iterator")]

        private class PythonBytesEnumerator<T> : IEnumerable, IEnumerator<T> {

            private readonly IList<byte>/*!*/ _bytes;

            private readonly Func<byte, T>/*!*/ _conversion;

            private int _index;



            public PythonBytesEnumerator(IList<byte> bytes, Func<byte, T> conversion) {

                Assert.NotNull(bytes);

                Assert.NotNull(conversion);



                _bytes = bytes;

                _conversion = conversion;

                _index = -1;

            }



            #region IEnumerator<T> Members



            public T Current {

                get {

                    if (_index < 0) {

                        throw PythonOps.SystemError("Enumeration has not started. Call MoveNext.");

                    } else if (_index >= _bytes.Count) {

                        throw PythonOps.SystemError("Enumeration already finished.");

                    }

                    return _conversion(_bytes[_index]);

                }

            }



            #endregion



            #region IDisposable Members



            public void Dispose() { }



            #endregion



            #region IEnumerator Members



            object IEnumerator.Current {

                get {

                    return ((IEnumerator<T>)this).Current;

                }

            }



            public bool MoveNext() {

                if (_index >= _bytes.Count) {

                    return false;

                }

                _index++;

                return _index != _bytes.Count;

            }



            public void Reset() {

                _index = -1;

            }



            #endregion



            #region IEnumerable Members



            public IEnumerator GetEnumerator() {

                return this;

            }



            #endregion

        }



        internal static IEnumerable BytesEnumerable(IList<byte> bytes) {

            return new PythonBytesEnumerator<Bytes>(bytes, b => Bytes.Make(new byte[] { b }));

        }



        internal static IEnumerable BytesIntEnumerable(IList<byte> bytes) {

            return new PythonBytesEnumerator<int>(bytes, b => (int)b);

        }



        internal static IEnumerator<Bytes> BytesEnumerator(IList<byte> bytes) {

            return new PythonBytesEnumerator<Bytes>(bytes, b => Bytes.Make(new byte[] { b }));

        }



        internal static IEnumerator<int> BytesIntEnumerator(IList<byte> bytes) {

            return new PythonBytesEnumerator<int>(bytes, b => (int)b);

        }



        #endregion

    }

}