--- a/dwtx/dwtxhelper/mangoicu/UString.d	Mon Jul 07 15:53:07 2008 +0200
+++ b/dwtx/dwtxhelper/mangoicu/UString.d	Mon Jul 07 15:54:03 2008 +0200
@@ -1,1508 +1,1508 @@
-/*******************************************************************************
-
-        @file UString.d
-
-        Copyright (c) 2004 Kris Bell
-
-        This software is provided 'as-is', without any express or implied
-        warranty. In no event will the authors be held liable for damages
-        of any kind arising from the use of this software.
-
-        Permission is hereby granted to anyone to use this software for any
-        purpose, including commercial applications, and to alter it and/or
-        redistribute it freely, subject to the following restrictions:
-
-        1. The origin of this software must not be misrepresented; you must
-           not claim that you wrote the original software. If you use this
-           software in a product, an acknowledgment within documentation of
-           said product would be appreciated but is not required.
-
-        2. Altered source versions must be plainly marked as such, and must
-           not be misrepresented as being the original software.
-
-        3. This notice may not be removed or altered from any distribution
-           of the source.
-
-        4. Derivative works are permitted, but they must carry this notice
-           in full and credit the original source.
-
-
-                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-
-        @version        Initial version, October 2004
-        @author         Kris
-
-        Note that this package and documentation is built around the ICU
-        project (http://oss.software.ibm.com/icu/). Below is the license
-        statement as specified by that software:
-
-
-                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-
-        ICU License - ICU 1.8.1 and later
-
-        COPYRIGHT AND PERMISSION NOTICE
-
-        Copyright (c) 1995-2003 International Business Machines Corporation and
-        others.
-
-        All rights reserved.
-
-        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, and/or sell copies of the Software, and to permit persons
-        to whom the Software is furnished to do so, provided that the above
-        copyright notice(s) and this permission notice appear in all copies of
-        the Software and that both the above copyright notice(s) and this
-        permission notice appear in supporting documentation.
-
-        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
-        OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
-        HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
-        INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
-        FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
-        NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
-        WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-
-        Except as contained in this notice, the name of a copyright holder
-        shall not be used in advertising or otherwise to promote the sale, use
-        or other dealings in this Software without prior written authorization
-        of the copyright holder.
-
-        ----------------------------------------------------------------------
-
-        All trademarks and registered trademarks mentioned herein are the
-        property of their respective owners.
-
-*******************************************************************************/
-
-module dwtx.dwtxhelper.mangoicu.UString;
-
-private import  dwtx.dwtxhelper.mangoicu.ICU,
-                dwtx.dwtxhelper.mangoicu.UChar,
-                dwtx.dwtxhelper.mangoicu.ULocale;
-
-/*******************************************************************************
-
-*******************************************************************************/
-
-private extern (C) void memmove (void* dst, void* src, uint bytes);
-
-/*******************************************************************************
-
-        Bind to the IReadable and IWritable interfaces if we're building
-        along with the mango.io package
-
-*******************************************************************************/
-
-version=Isolated;
-version (Isolated)
-        {
-        private interface ITextOther   {}
-        private interface IStringOther {}
-        }
-     else
-        {
-        private import  dwtx.dwtxhelper.mangoicu.UMango;
-
-        private import  mango.io.model.IReader,
-                        mango.io.model.IWriter;
-
-        private interface ITextOther   : IWritable {}
-        private interface IStringOther : IReadable {}
-        }
-
-
-/*******************************************************************************
-
-        UString is a string class that stores Unicode characters directly
-        and provides similar functionality as the Java String class.
-
-        In ICU, a Unicode string consists of 16-bit Unicode code units.
-        A Unicode character may be stored with either one code unit —
-        which is the most common case — or with a matched pair of
-        special code units ("surrogates"). The data type for code units
-        is UChar.
-
-        For single-character handling, a Unicode character code point is
-        a value in the range 0..0x10ffff. ICU uses the UChar32 type for
-        code points.
-
-        Indexes and offsets into and lengths of strings always count code
-        units, not code points. This is the same as with multi-byte char*
-        strings in traditional string handling. Operations on partial
-        strings typically do not test for code point boundaries. If necessary,
-        the user needs to take care of such boundaries by testing for the code
-        unit values or by using functions like getChar32Start()
-        and getChar32Limit()
-
-        UString methods are more lenient with regard to input parameter values
-        than other ICU APIs. In particular:
-
-        - If indexes are out of bounds for a UString object (< 0 or > length)
-          then they are "pinned" to the nearest boundary.
-
-        - If primitive string pointer values (e.g., const wchar* or char*) for
-          input strings are null, then those input string parameters are treated
-          as if they pointed to an empty string. However, this is not the case
-          for char* parameters for charset names or other IDs.
-
-*******************************************************************************/
-
-class UString : UStringView, IStringOther
-{
-        alias opCat             append;
-        alias opIndexAssign     setCharAt;
-
-        /***********************************************************************
-
-                Create an empty UString with the specified available space
-
-        ***********************************************************************/
-
-        this (uint space = 0)
-        {
-                content.length = space;
-                mutable = true;
-        }
-
-        /***********************************************************************
-
-                Create a UString upon the provided content. If said content
-                is immutable (read-only) then you might consider setting the
-                'mutable' parameter to false. Doing so will avoid allocating
-                heap-space for the content until it is modified.
-
-        ***********************************************************************/
-
-        this (wchar[] content, bool mutable = true)
-        {
-                setTo (content, mutable);
-        }
-
-        /***********************************************************************
-
-                Create a UString via the content of a UStringView. Note that the
-                default is to assume the content is immutable (read-only).
-
-        ***********************************************************************/
-
-        this (UStringView other, bool mutable = false)
-        {
-                this (other.get, mutable);
-        }
-
-        /***********************************************************************
-
-                Create a UString via the content of a UString. If said content
-                is immutable (read-only) then you might consider setting the
-                'mutable' parameter to false. Doing so will avoid allocating
-                heap-space for the content until it is modified via UString
-                methods.
-
-        ***********************************************************************/
-
-        this (UString other, bool mutable = true)
-        {
-                this (other.get, mutable);
-        }
-
-        /***********************************************************************
-
-                Support for reading content via the IO system
-
-        ***********************************************************************/
-
-        version (Isolated){}
-        else
-        {
-                /***************************************************************
-
-                        Internal adapter to handle loading and conversion
-                        of UString content. Once constructed, this may be
-                        used as the target for an IReader. Alternatively,
-                        invoke the load() method with an IBuffer of choice.
-
-                ***************************************************************/
-
-                class UStringDecoder : StringDecoder16
-                {
-                        private UString s;
-
-                        // construct a decoder on the given UString
-                        this (UConverter c, uint bytes, UString s)
-                        {
-                                super (c, bytes);
-                                this.s = s;
-                        }
-
-                        // IReadable adapter to perform the conversion
-                        protected void read (IReader r)
-                        {
-                                load (r.buffer);
-                        }
-
-                        // read from the provided buffer until we
-                        // either have all the content, or an eof
-                        // condition throws an exception.
-                        package void load (IBuffer b)
-                        {
-                                uint produced = super.read (b, s.content);
-                                while (toGo)
-                                      {
-                                      s.expand (toGo);
-                                      produced += super.read (b, s.content[produced..$]);
-                                      }
-                                s.len = produced;
-                        }
-                }
-
-                /***************************************************************
-
-                        Another constructor for loading known content length
-                        into a UString.
-
-                ***************************************************************/
-
-                this (IBuffer buffer, uint contentLength, UConverter cvt)
-                {
-                        this (contentLength);
-                        UStringDecoder sd = new UStringDecoder (cvt, contentLength, this);
-                        sd.load (buffer);
-                }
-
-                /***************************************************************
-
-                        Read as many bytes from the input as is necessary
-                        to produce the expected number of wchar elements.
-                        This uses the default wchar handler, which can be
-                        altered by binding a StringDecoder to the IReader
-                        in use (see UMango for details).
-
-                        We're mutable, so ensure we don't mess with the
-                        IO buffers. Interestingly, changing the length
-                        of a D array will account for slice assignments
-                        (it checks the pointer to see if it's a starting
-                         point in the pool). Unfortunately, that doesn't
-                        catch the case where a slice starts at offset 0,
-                        which is where IBuffer slices may come from.
-
-                        To be safe, we ask the allocator in use whether
-                        the content it provided can be mutated or not.
-                        Note that this is not necessary for UStringView, since
-                        that is a read-only construct.
-
-                ***************************************************************/
-
-                void read (IReader r)
-                {
-                        r.get (content);
-                        len = content.length;
-                        mutable = r.getAllocator.isMutable (content);
-                }
-
-                /***************************************************************
-
-                        Return a streaming decoder that can be used to
-                        populate this UString with a specified number of
-                        input bytes.
-
-                        This differs from the above read() method in the
-                        way content is read: in the above case, exactly
-                        the specified number of wchar elements will be
-                        converter from the input, whereas in this case
-                        a variable number of wchar elements are converted
-                        until 'bytes' have been read from the input. This
-                        is useful in those cases where the original number
-                        of elements has been lost, and only the resultant
-                        converted byte-count remains (a la HTTP).
-
-                        The returned StringDecoder is one-shot only. You may
-                        reuse it (both the converter and the byte count) via
-                        its reset() method.
-
-                        One applies the resultant converter directly with an
-                        IReader like so:
-
-                        @code
-                        UString s = ...;
-                        IReader r = ...;
-
-                        // r >> s.createDecoder(cvt, bytes);
-                        r.get (s.createDecoder(cvt, bytes));
-                        @endcode
-
-                        which will read the specified number of bytes from
-                        the input and convert them to an appropriate number
-                        of wchars within the UString.
-
-                ***************************************************************/
-
-                StringDecoder createDecoder (UConverter c, uint bytes)
-                {
-                        return new UStringDecoder (c, bytes, this);
-                }
-        }
-
-        /***********************************************************************
-
-                Append text to this UString
-
-        ***********************************************************************/
-
-        UString opCat (UStringView other)
-        {
-                return opCat (other.get);
-        }
-
-        /***********************************************************************
-
-                Append partial text to this UString
-
-        ***********************************************************************/
-
-        UString opCat (UStringView other, uint start, uint len=uint.max)
-        {
-                other.pinIndices (start, len);
-                return opCat (other.content [start..start+len]);
-        }
-
-        /***********************************************************************
-
-                Append a single character to this UString
-
-        ***********************************************************************/
-
-        UString opCat (wchar chr)
-        {
-                return opCat (&chr, 1);
-        }
-
-        /***********************************************************************
-
-                Append text to this UString
-
-        ***********************************************************************/
-
-        UString opCat (wchar[] chars)
-        {
-                return opCat (chars.ptr, chars.length);
-        }
-
-        /***********************************************************************
-
-                Converts a sequence of UTF-8 bytes to UChars (UTF-16)
-
-        ***********************************************************************/
-
-        UString opCat (char[] chars)
-        {
-                uint fmt (wchar* dst, uint len, inout UErrorCode e)
-                {
-                        uint x;
-
-                        u_strFromUTF8 (dst, len, &x, chars.ptr, chars.length, e);
-                        return x;
-                }
-
-                expand (chars.length);
-                return format (&fmt, "failed to append UTF char[]");
-        }
-
-        /***********************************************************************
-
-                Set a section of this UString to the specified character
-
-        ***********************************************************************/
-
-        UString setTo (wchar chr, uint start=0, uint len=uint.max)
-        {
-                pinIndices (start, len);
-                if (! mutable)
-                      realloc ();
-                content [start..start+len] = chr;
-                return this;
-        }
-
-        /***********************************************************************
-
-                Set the content to the provided array. Parameter 'mutable'
-                specifies whether the given array is likely to change. If
-                not, the array is aliased until such time this UString is
-                altered.
-
-        ***********************************************************************/
-
-        UString setTo (wchar[] chars, bool mutable = true)
-        {
-                len = chars.length;
-                if ((this.mutable = mutable) == true)
-                     content = chars.dup;
-                else
-                   content = chars;
-                return this;
-        }
-
-        /***********************************************************************
-
-                Replace the content of this UString. If the new content
-                is immutable (read-only) then you might consider setting the
-                'mutable' parameter to false. Doing so will avoid allocating
-                heap-space for the content until it is modified via one of
-                these methods.
-
-        ***********************************************************************/
-
-        UString setTo (UStringView other, bool mutable = true)
-        {
-                return setTo (other.get, mutable);
-        }
-
-        /***********************************************************************
-
-                Replace the content of this UString. If the new content
-                is immutable (read-only) then you might consider setting the
-                'mutable' parameter to false. Doing so will avoid allocating
-                heap-space for the content until it is modified via one of
-                these methods.
-
-        ***********************************************************************/
-
-        UString setTo (UStringView other, uint start, uint len, bool mutable = true)
-        {
-                other.pinIndices (start, len);
-                return setTo (other.content [start..start+len], mutable);
-        }
-
-        /***********************************************************************
-
-                Replace the character at the specified location.
-
-        ***********************************************************************/
-
-        final UString opIndexAssign (wchar chr, uint index)
-        in {
-                if (index >= len)
-                    exception ("index of out bounds");
-           }
-        body
-        {
-                if (! mutable)
-                      realloc ();
-                content [index] = chr;
-                return this;
-        }
-
-        /***********************************************************************
-
-                Remove a piece of this UString.
-
-        ***********************************************************************/
-
-        UString remove (uint start, uint length=uint.max)
-        {
-                pinIndices (start, length);
-                if (length)
-                    if (start >= len)
-                        truncate (start);
-                    else
-                       {
-                       if (! mutable)
-                             realloc ();
-
-                       uint i = start + length;
-                       memmove (&content[start], &content[i], (len-i) * wchar.sizeof);
-                       len -= length;
-                       }
-                return this;
-        }
-
-        /***********************************************************************
-
-                Truncate the length of this UString.
-
-        ***********************************************************************/
-
-        UString truncate (uint length=0)
-        {
-                if (length <= len)
-                    len = length;
-                return this;
-        }
-
-        /***********************************************************************
-
-                Insert leading spaces in this UString
-
-        ***********************************************************************/
-
-        UString padLeading (uint count, wchar padChar = 0x0020)
-        {
-                expand  (count);
-                memmove (&content[count], content.ptr, len * wchar.sizeof);
-                len += count;
-                return setTo (padChar, 0, count);
-        }
-
-        /***********************************************************************
-
-                Append some trailing spaces to this UString.
-
-        ***********************************************************************/
-
-        UString padTrailing (uint length, wchar padChar = 0x0020)
-        {
-                expand (length);
-                len += length;
-                return setTo  (padChar, len-length, length);
-        }
-
-        /***********************************************************************
-
-                Check for available space within the buffer, and expand
-                as necessary.
-
-        ***********************************************************************/
-
-        package final void expand (uint count)
-        {
-                if ((len + count) > content.length)
-                     realloc (count);
-        }
-
-        /***********************************************************************
-
-                Allocate memory due to a change in the content. We handle
-                the distinction between mutable and immutable here.
-
-        ***********************************************************************/
-
-        private final void realloc (uint count = 0)
-        {
-                uint size = (content.length + count + 63) & ~63;
-
-                if (mutable)
-                    content.length = size;
-                else
-                   {
-                   mutable = true;
-                   wchar[] x = content;
-                   content = new wchar [size];
-                   if (len)
-                       content[0..len] = x;
-                   }
-        }
-
-        /***********************************************************************
-
-                Internal method to support UString appending
-
-        ***********************************************************************/
-
-        private final UString opCat (wchar* chars, uint count)
-        {
-                expand (count);
-                content[len..len+count] = chars[0..count];
-                len += count;
-                return this;
-        }
-
-        /***********************************************************************
-
-                Internal method to support formatting into this UString.
-                This is used by many of the ICU wrappers to append content
-                into a UString.
-
-        ***********************************************************************/
-
-        typedef uint delegate (wchar* dst, uint len, inout UErrorCode e) Formatter;
-
-        package final UString format (Formatter format, char[] msg)
-        {
-                UErrorCode   e;
-                uint    length;
-
-                while (true)
-                      {
-                      e = e.OK;
-                      length = format (&content[len], content.length - len, e);
-                      if (e == e.BufferOverflow)
-                          expand (length);
-                      else
-                         break;
-                      }
-
-                if (isError (e))
-                    exception (msg);
-
-                len += length;
-                return this;
-        }
-}
-
-
-/*******************************************************************************
-
-        Immutable (read-only) text -- use UString for mutable strings.
-
-*******************************************************************************/
-
-class UStringView : ICU, ITextOther
-{
-        alias opIndex   charAt;
-
-        // the core of the UStringView and UString attributes. The name 'len'
-        // is used rather than the more obvious 'length' since there is
-        // a collision with the silly array[length] syntactic sugar ...
-        package uint    len;
-        package wchar[] content;
-
-        // this should probably be in UString only, but there seems to
-        // be a compiler bug where it doesn't get initialised correctly,
-        // and it's perhaps useful to have here for when a UString is
-        // passed as a UStringView argument.
-        private bool    mutable;
-
-        // toFolded() argument
-        public enum     CaseOption
-                        {
-                        Default  = 0,
-                        SpecialI = 1
-                        }
-
-        /***********************************************************************
-
-                Hidden constructor
-
-        ***********************************************************************/
-
-        private this ()
-        {
-        }
-
-        /***********************************************************************
-
-                Construct read-only wrapper around the given content
-
-        ***********************************************************************/
-
-        this (wchar[] content)
-        {
-                this.content = content;
-                this.len = content.length;
-        }
-
-        /***********************************************************************
-
-                Support for writing via the Mango IO subsystem
-
-        ***********************************************************************/
-
-        version (Isolated){}
-        else
-        {
-                void write (IWriter w)
-                {
-                        w.put (get);
-                }
-        }
-
-        /***********************************************************************
-
-                Return the valid content from this UStringView
-
-        ***********************************************************************/
-
-        final package wchar[] get ()
-        {
-                return content [0..len];
-        }
-
-        /***********************************************************************
-
-                Is this UStringView equal to another?
-
-        ***********************************************************************/
-
-        final override int opEquals (Object o)
-        {
-                UStringView other = cast(UStringView) o;
-
-                if (other)
-                    return (other is this || compare (other) == 0);
-                return 0;
-        }
-
-        /***********************************************************************
-
-                Compare this UStringView to another.
-
-        ***********************************************************************/
-
-        final override int opCmp (Object o)
-        {
-                UStringView other = cast(UStringView) o;
-
-                if (other is this)
-                    return 0;
-                else
-                   if (other)
-                       return compare (other);
-                return 1;
-        }
-
-        /***********************************************************************
-
-                Hash this UStringView
-
-        ***********************************************************************/
-
-        final override uint toHash ()
-        {
-                return typeid(wchar[]).getHash (&content[0..len]);
-        }
-
-        /***********************************************************************
-
-                Clone this UStringView into a UString
-
-        ***********************************************************************/
-
-        final UString copy ()
-        {
-                return new UString (content);
-        }
-
-        /***********************************************************************
-
-                Clone a section of this UStringView into a UString
-
-        ***********************************************************************/
-
-        final UString extract (uint start, uint len=uint.max)
-        {
-                pinIndices (start, len);
-                return new UString (content[start..start+len]);
-        }
-
-        /***********************************************************************
-
-                Count unicode code points in the length UChar code units of
-                the string. A code point may occupy either one or two UChar
-                code units. Counting code points involves reading all code
-                units.
-
-        ***********************************************************************/
-
-        final uint codePoints (uint start=0, uint length=uint.max)
-        {
-                pinIndices (start, length);
-                return u_countChar32 (&content[start], length);
-        }
-
-        /***********************************************************************
-
-                Return an indication whether or not there are surrogate pairs
-                within the string.
-
-        ***********************************************************************/
-
-        final bool hasSurrogates (uint start=0, uint length=uint.max)
-        {
-                pinIndices (start, length);
-                return codePoints (start, length) != length;
-        }
-
-        /***********************************************************************
-
-                Return the character at the specified position.
-
-        ***********************************************************************/
-
-        final wchar opIndex (uint index)
-        in {
-                if (index >= len)
-                    exception ("index of out bounds");
-           }
-        body
-        {
-                return content [index];
-        }
-
-        /***********************************************************************
-
-                Return the length of the valid content
-
-        ***********************************************************************/
-
-        final uint length ()
-        {
-                return len;
-        }
-
-        /***********************************************************************
-
-                The comparison can be done in code unit order or in code
-                point order. They differ only in UTF-16 when comparing
-                supplementary code points (U+10000..U+10ffff) to BMP code
-                points near the end of the BMP (i.e., U+e000..U+ffff).
-
-                In code unit order, high BMP code points sort after
-                supplementary code points because they are stored as
-                pairs of surrogates which are at U+d800..U+dfff.
-
-        ***********************************************************************/
-
-        final int compare (UStringView other, bool codePointOrder=false)
-        {
-                return compare (other.get, codePointOrder);
-        }
-
-        /***********************************************************************
-
-                The comparison can be done in code unit order or in code
-                point order. They differ only in UTF-16 when comparing
-                supplementary code points (U+10000..U+10ffff) to BMP code
-                points near the end of the BMP (i.e., U+e000..U+ffff).
-
-                In code unit order, high BMP code points sort after
-                supplementary code points because they are stored as
-                pairs of surrogates which are at U+d800..U+dfff.
-
-        ***********************************************************************/
-
-        final int compare (wchar[] other, bool codePointOrder=false)
-        {
-                return u_strCompare (content.ptr, len, other.ptr, other.length, codePointOrder);
-        }
-
-        /***********************************************************************
-
-                The comparison can be done in UTF-16 code unit order or
-                in code point order. They differ only when comparing
-                supplementary code points (U+10000..U+10ffff) to BMP code
-                points near the end of the BMP (i.e., U+e000..U+ffff).
-
-                In code unit order, high BMP code points sort after
-                supplementary code points because they are stored as
-                pairs of surrogates which are at U+d800..U+dfff.
-
-        ***********************************************************************/
-
-        final int compareFolded (UStringView other, CaseOption option = CaseOption.Default)
-        {
-                return compareFolded (other.content, option);
-        }
-
-        /***********************************************************************
-
-                The comparison can be done in UTF-16 code unit order or
-                in code point order. They differ only when comparing
-                supplementary code points (U+10000..U+10ffff) to BMP code
-                points near the end of the BMP (i.e., U+e000..U+ffff).
-
-                In code unit order, high BMP code points sort after
-                supplementary code points because they are stored as
-                pairs of surrogates which are at U+d800..U+dfff.
-
-        ***********************************************************************/
-
-        final int compareFolded (wchar[] other, CaseOption option = CaseOption.Default)
-        {
-                return compareFolded (get, other, option);
-        }
-
-        /***********************************************************************
-
-                Does this UStringView start with specified string?
-
-        ***********************************************************************/
-
-        final bool startsWith (UStringView other)
-        {
-                return startsWith (other.get);
-        }
-
-        /***********************************************************************
-
-                Does this UStringView start with specified string?
-
-        ***********************************************************************/
-
-        final bool startsWith (wchar[] chars)
-        {
-                if (len >= chars.length)
-                    return compareFolded (content[0..chars.length], chars) == 0;
-                return false;
-        }
-
-        /***********************************************************************
-
-                Does this UStringView end with specified string?
-
-        ***********************************************************************/
-
-        final bool endsWith (UStringView other)
-        {
-                return endsWith (other.get);
-        }
-
-        /***********************************************************************
-
-                Does this UStringView end with specified string?
-
-        ***********************************************************************/
-
-        final bool endsWith (wchar[] chars)
-        {
-                if (len >= chars.length)
-                    return compareFolded (content[len-chars.length..len], chars) == 0;
-                return false;
-        }
-
-        /***********************************************************************
-
-                Find the first occurrence of a BMP code point in a string.
-                A surrogate code point is found only if its match in the
-                text is not part of a surrogate pair.
-
-        ***********************************************************************/
-
-        final uint indexOf (wchar c, uint start=0)
-        {
-                pinIndex (start);
-                wchar* s = u_memchr (&content[start], c, len-start);
-                if (s)
-                    return s - content.ptr;
-                return uint.max;
-        }
-
-        /***********************************************************************
-
-                Find the first occurrence of a substring in a string.
-
-                The substring is found at code point boundaries. That means
-                that if the substring begins with a trail surrogate or ends
-                with a lead surrogate, then it is found only if these
-                surrogates stand alone in the text. Otherwise, the substring
-                edge units would be matched against halves of surrogate pairs.
-
-        ***********************************************************************/
-
-        final uint indexOf (UStringView other, uint start=0)
-        {
-                return indexOf (other.get, start);
-        }
-
-        /***********************************************************************
-
-                Find the first occurrence of a substring in a string.
-
-                The substring is found at code point boundaries. That means
-                that if the substring begins with a trail surrogate or ends
-                with a lead surrogate, then it is found only if these
-                surrogates stand alone in the text. Otherwise, the substring
-                edge units would be matched against halves of surrogate pairs.
-
-        ***********************************************************************/
-
-        final uint indexOf (wchar[] chars, uint start=0)
-        {
-                pinIndex (start);
-                wchar* s = u_strFindFirst (&content[start], len-start, chars.ptr, chars.length);
-                if (s)
-                    return s - content.ptr;
-                return uint.max;
-        }
-
-        /***********************************************************************
-
-                Find the last occurrence of a BMP code point in a string.
-                A surrogate code point is found only if its match in the
-                text is not part of a surrogate pair.
-
-        ***********************************************************************/
-
-        final uint lastIndexOf (wchar c, uint start=uint.max)
-        {
-                pinIndex (start);
-                wchar* s = u_memrchr (content.ptr, c, start);
-                if (s)
-                    return s - content.ptr;
-                return uint.max;
-        }
-
-        /***********************************************************************
-
-                Find the last occurrence of a BMP code point in a string.
-                A surrogate code point is found only if its match in the
-                text is not part of a surrogate pair.
-
-        ***********************************************************************/
-
-        final uint lastIndexOf (UStringView other, uint start=uint.max)
-        {
-                return lastIndexOf (other.get, start);
-        }
-
-        /***********************************************************************
-
-                Find the last occurrence of a substring in a string.
-
-                The substring is found at code point boundaries. That means
-                that if the substring begins with a trail surrogate or ends
-                with a lead surrogate, then it is found only if these
-                surrogates stand alone in the text. Otherwise, the substring
-                edge units would be matched against halves of surrogate pairs.
-
-        ***********************************************************************/
-
-        final uint lastIndexOf (wchar[] chars, uint start=uint.max)
-        {
-                pinIndex (start);
-                wchar* s = u_strFindLast (content.ptr, start, chars.ptr, chars.length);
-                if (s)
-                    return s - content.ptr;
-                return uint.max;
-        }
-
-        /***********************************************************************
-
-                Lowercase the characters into a seperate UString.
-
-                Casing is locale-dependent and context-sensitive. The
-                result may be longer or shorter than the original.
-
-                Note that the return value refers to the provided destination
-                UString.
-
-        ***********************************************************************/
-
-        final UString toLower (UString dst)
-        {
-               return toLower (dst, ULocale.Default);
-        }
-
-        /***********************************************************************
-
-                Lowercase the characters into a seperate UString.
-
-                Casing is locale-dependent and context-sensitive. The
-                result may be longer or shorter than the original.
-
-                Note that the return value refers to the provided destination
-                UString.
-
-        ***********************************************************************/
-
-        final UString toLower (UString dst, inout ULocale locale)
-        {
-                uint lower (wchar* dst, uint length, inout UErrorCode e)
-                {
-                        return u_strToLower (dst, length, content.ptr, len, ICU.toString(locale.name), e);
-                }
-
-                dst.expand (len + 32);
-                return dst.format (&lower, "toLower() failed");
-        }
-
-        /***********************************************************************
-
-                Uppercase the characters into a seperate UString.
-
-                Casing is locale-dependent and context-sensitive. The
-                result may be longer or shorter than the original.
-
-                Note that the return value refers to the provided destination
-                UString.
-
-        ***********************************************************************/
-
-        final UString toUpper (UString dst)
-        {
-               return toUpper (dst, ULocale.Default);
-        }
-
-        /***********************************************************************
-
-                Uppercase the characters into a seperate UString.
-
-                Casing is locale-dependent and context-sensitive. The
-                result may be longer or shorter than the original.
-
-                Note that the return value refers to the provided destination
-                UString.
-
-        ***********************************************************************/
-
-        final UString toUpper (UString dst, inout ULocale locale)
-        {
-                uint upper (wchar* dst, uint length, inout UErrorCode e)
-                {
-                        return u_strToUpper (dst, length, content.ptr, len, ICU.toString(locale.name), e);
-                }
-
-                dst.expand (len + 32);
-                return dst.format (&upper, "toUpper() failed");
-        }
-
-        /***********************************************************************
-
-                Case-fold the characters into a seperate UString.
-
-                Case-folding is locale-independent and not context-sensitive,
-                but there is an option for whether to include or exclude
-                mappings for dotted I and dotless i that are marked with 'I'
-                in CaseFolding.txt. The result may be longer or shorter than
-                the original.
-
-                Note that the return value refers to the provided destination
-                UString.
-
-        ***********************************************************************/
-
-        final UString toFolded (UString dst, CaseOption option = CaseOption.Default)
-        {
-                uint fold (wchar* dst, uint length, inout UErrorCode e)
-                {
-                        return u_strFoldCase (dst, length, content.ptr, len, option, e);
-                }
-
-                dst.expand (len + 32);
-                return dst.format (&fold, "toFolded() failed");
-        }
-
-        /***********************************************************************
-
-                Converts a sequence of wchar (UTF-16) to UTF-8 bytes. If
-                the output array is not provided, an array of appropriate
-                size will be allocated and returned. Where the output is
-                provided, it must be large enough to hold potentially four
-                bytes per character for surrogate-pairs or three bytes per
-                character for BMP only. Consider using UConverter where
-                streaming conversions are required.
-
-                Returns an array slice representing the valid UTF8 content.
-
-        ***********************************************************************/
-
-        final char[] toUtf8 (char[] dst = null)
-        {
-                uint    x;
-                UErrorCode   e;
-
-                if (! cast(char*) dst)
-                      dst = new char[len * 4];
-
-                u_strToUTF8 (dst.ptr, dst.length, &x, content.ptr, len, e);
-                testError (e, "failed to convert to UTF8");
-                return dst [0..x];
-        }
-
-        /***********************************************************************
-
-                Remove leading and trailing whitespace from this UStringView.
-                Note that we slice the content to remove leading space.
-
-        ***********************************************************************/
-
-        UStringView trim ()
-        {
-                wchar   c;
-                uint    i = len;
-
-                // cut off trailing white space
-                while (i && ((c = charAt(i-1)) == 0x20 || UChar.isWhiteSpace (c)))
-                       --i;
-                len = i;
-
-                // now remove leading whitespace
-                for (i=0; i < len && ((c = charAt(i)) == 0x20 || UChar.isWhiteSpace (c)); ++i) {}
-                if (i)
-                   {
-                   len -= i;
-                   content = content[i..$-i];
-                   }
-
-                return this;
-        }
-
-        /***********************************************************************
-
-                Unescape a string of characters and write the resulting
-                Unicode characters to the destination buffer.  The following
-                escape sequences are recognized:
-
-                  uhhhh       4 hex digits; h in [0-9A-Fa-f]
-                  Uhhhhhhhh   8 hex digits
-                  xhh         1-2 hex digits
-                  x{h...}     1-8 hex digits
-                  ooo         1-3 octal digits; o in [0-7]
-                  cX          control-X; X is masked with 0x1F
-
-                as well as the standard ANSI C escapes:
-
-                  a => U+0007, \\b => U+0008, \\t => U+0009, \\n => U+000A,
-                  v => U+000B, \\f => U+000C, \\r => U+000D, \\e => U+001B,
-                  \\" =U+0022, \\' => U+0027, \\? => U+003F, \\\\ => U+005C
-
-                Anything else following a backslash is generically escaped.
-                For example, "[a\\-z]" returns "[a-z]".
-
-                If an escape sequence is ill-formed, this method returns an
-                empty string.  An example of an ill-formed sequence is "\\u"
-                followed by fewer than 4 hex digits.
-
-         ***********************************************************************/
-
-        final UString unEscape ()
-        {
-                UString result = new UString (len);
-                for (uint i=0; i < len;)
-                    {
-                    dchar c = charAt(i++);
-                    if (c == 0x005C)
-                       {
-                       // bump index ...
-                       c = u_unescapeAt (&_charAt, &i, len, cast(void*) this);
-
-                       // error?
-                       if (c == 0xFFFFFFFF)
-                          {
-                          result.truncate ();   // return empty string
-                          break;                // invalid escape sequence
-                          }
-                       }
-                    result.append (c);
-                    }
-                return result;
-        }
-
-        /***********************************************************************
-
-                Is this code point a surrogate (U+d800..U+dfff)?
-
-        ***********************************************************************/
-
-        final static bool isSurrogate (wchar c)
-        {
-                return (c & 0xfffff800) == 0xd800;
-        }
-
-        /***********************************************************************
-
-                Is this code unit a lead surrogate (U+d800..U+dbff)?
-
-        ***********************************************************************/
-
-        final static bool isLeading (wchar c)
-        {
-                return (c & 0xfffffc00) == 0xd800;
-        }
-
-        /***********************************************************************
-
-                Is this code unit a trail surrogate (U+dc00..U+dfff)?
-
-        ***********************************************************************/
-
-        final static bool isTrailing (wchar c)
-        {
-                return (c & 0xfffffc00) == 0xdc00;
-        }
-
-        /***********************************************************************
-
-                Adjust a random-access offset to a code point boundary
-                at the start of a code point. If the offset points to
-                the trail surrogate of a surrogate pair, then the offset
-                is decremented. Otherwise, it is not modified.
-
-        ***********************************************************************/
-
-        final uint getCharStart (uint i)
-        in {
-                if (i >= len)
-                    exception ("index of out bounds");
-           }
-        body
-        {
-                if (isTrailing (content[i]) && i && isLeading (content[i-1]))
-                    --i;
-                return i;
-        }
-
-        /***********************************************************************
-
-                Adjust a random-access offset to a code point boundary
-                after a code point. If the offset is behind the lead
-                surrogate of a surrogate pair, then the offset is
-                incremented. Otherwise, it is not modified.
-
-        ***********************************************************************/
-
-        final uint getCharLimit (uint i)
-        in {
-                if (i >= len)
-                    exception ("index of out bounds");
-           }
-        body
-        {
-                if (i && isLeading(content[i-1]) && isTrailing (content[i]))
-                    ++i;
-                return i;
-        }
-
-        /***********************************************************************
-
-                Callback for C unescapeAt() function
-
-        ***********************************************************************/
-
-        extern (C)
-        {
-                typedef wchar function (uint offset, void* context) CharAt;
-
-                private static wchar _charAt (uint offset, void* context)
-                {
-                        return (cast(UString) context).charAt (offset);
-                }
-        }
-
-        /***********************************************************************
-
-                Pin the given index to a valid position.
-
-        ***********************************************************************/
-
-        final private void pinIndex (inout uint x)
-        {
-                if (x > len)
-                    x = len;
-        }
-
-        /***********************************************************************
-
-                Pin the given index and length to a valid position.
-
-        ***********************************************************************/
-
-        final private void pinIndices (inout uint start, inout uint length)
-        {
-                if (start > len)
-                    start = len;
-
-                if (length > (len - start))
-                    length = len - start;
-        }
-
-        /***********************************************************************
-
-                Helper for comparison methods
-
-        ***********************************************************************/
-
-        final private int compareFolded (wchar[] s1, wchar[] s2, CaseOption option = CaseOption.Default)
-        {
-                UErrorCode e;
-
-                int x = u_strCaseCompare (s1.ptr, s1.length, s2.ptr, s2.length, option, e);
-                testError (e, "compareFolded failed");
-                return x;
-        }
-
-
-        /***********************************************************************
-
-                Bind the ICU functions from a shared library. This is
-                complicated by the issues regarding D and DLLs on the
-                Windows platform
-
-        ***********************************************************************/
-
-        private static void* library;
-
-        /***********************************************************************
-
-        ***********************************************************************/
-
-        private static extern (C)
-        {
-                wchar* function (wchar*, uint, wchar*, uint) u_strFindFirst;
-                wchar* function (wchar*, uint, wchar*, uint) u_strFindLast;
-                wchar* function (wchar*, wchar, uint) u_memchr;
-                wchar* function (wchar*, wchar, uint) u_memrchr;
-                int    function (wchar*, uint, wchar*, uint, bool) u_strCompare;
-                int    function (wchar*, uint, wchar*, uint, uint, inout UErrorCode) u_strCaseCompare;
-                dchar  function (CharAt, uint*, uint, void*) u_unescapeAt;
-                uint   function (wchar*, uint) u_countChar32;
-                uint   function (wchar*, uint, wchar*, uint, char*, inout UErrorCode) u_strToUpper;
-                uint   function (wchar*, uint, wchar*, uint, char*, inout UErrorCode) u_strToLower;
-                uint   function (wchar*, uint, wchar*, uint, uint, inout UErrorCode) u_strFoldCase;
-                wchar* function (wchar*, uint, uint*, char*, uint, inout UErrorCode) u_strFromUTF8;
-                char*  function (char*, uint, uint*, wchar*, uint, inout UErrorCode) u_strToUTF8;
-        }
-
-        /***********************************************************************
-
-        ***********************************************************************/
-
-        static  FunctionLoader.Bind[] targets =
-                [
-                {cast(void**) &u_strFindFirst,      "u_strFindFirst"},
-                {cast(void**) &u_strFindLast,       "u_strFindLast"},
-                {cast(void**) &u_memchr,            "u_memchr"},
-                {cast(void**) &u_memrchr,           "u_memrchr"},
-                {cast(void**) &u_strCompare,        "u_strCompare"},
-                {cast(void**) &u_strCaseCompare,    "u_strCaseCompare"},
-                {cast(void**) &u_unescapeAt,        "u_unescapeAt"},
-                {cast(void**) &u_countChar32,       "u_countChar32"},
-                {cast(void**) &u_strToUpper,        "u_strToUpper"},
-                {cast(void**) &u_strToLower,        "u_strToLower"},
-                {cast(void**) &u_strFoldCase,       "u_strFoldCase"},
-                {cast(void**) &u_strFromUTF8,       "u_strFromUTF8"},
-                {cast(void**) &u_strToUTF8,         "u_strToUTF8"},
-                ];
-
-        /***********************************************************************
-
-        ***********************************************************************/
-
-        static this ()
-        {
-                library = FunctionLoader.bind (icuuc, targets);
-                //test ();
-        }
-
-        /***********************************************************************
-
-        ***********************************************************************/
-
-        static ~this ()
-        {
-                FunctionLoader.unbind (library);
-        }
-
-        /***********************************************************************
-
-        ***********************************************************************/
-
-        private static void test()
-        {
-                UString s = new UString (r"aaaqw \uabcd eaaa");
-                char[] x = "dssfsdff";
-                s ~ x ~ x;
-                wchar c = s[3];
-                s[3] = 'Q';
-                int y = s.indexOf ("qwe");
-                s.unEscape ();
-                s.toUpper (new UString);
-                s.padLeading(2).padTrailing(2).trim();
-        }
-}
+/*******************************************************************************
+
+        @file UString.d
+
+        Copyright (c) 2004 Kris Bell
+
+        This software is provided 'as-is', without any express or implied
+        warranty. In no event will the authors be held liable for damages
+        of any kind arising from the use of this software.
+
+        Permission is hereby granted to anyone to use this software for any
+        purpose, including commercial applications, and to alter it and/or
+        redistribute it freely, subject to the following restrictions:
+
+        1. The origin of this software must not be misrepresented; you must
+           not claim that you wrote the original software. If you use this
+           software in a product, an acknowledgment within documentation of
+           said product would be appreciated but is not required.
+
+        2. Altered source versions must be plainly marked as such, and must
+           not be misrepresented as being the original software.
+
+        3. This notice may not be removed or altered from any distribution
+           of the source.
+
+        4. Derivative works are permitted, but they must carry this notice
+           in full and credit the original source.
+
+
+                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+        @version        Initial version, October 2004
+        @author         Kris
+
+        Note that this package and documentation is built around the ICU
+        project (http://oss.software.ibm.com/icu/). Below is the license
+        statement as specified by that software:
+
+
+                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+        ICU License - ICU 1.8.1 and later
+
+        COPYRIGHT AND PERMISSION NOTICE
+
+        Copyright (c) 1995-2003 International Business Machines Corporation and
+        others.
+
+        All rights reserved.
+
+        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, and/or sell copies of the Software, and to permit persons
+        to whom the Software is furnished to do so, provided that the above
+        copyright notice(s) and this permission notice appear in all copies of
+        the Software and that both the above copyright notice(s) and this
+        permission notice appear in supporting documentation.
+
+        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
+        OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+        HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
+        INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
+        FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+        NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
+        WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+        Except as contained in this notice, the name of a copyright holder
+        shall not be used in advertising or otherwise to promote the sale, use
+        or other dealings in this Software without prior written authorization
+        of the copyright holder.
+
+        ----------------------------------------------------------------------
+
+        All trademarks and registered trademarks mentioned herein are the
+        property of their respective owners.
+
+*******************************************************************************/
+
+module dwtx.dwtxhelper.mangoicu.UString;
+
+private import  dwtx.dwtxhelper.mangoicu.ICU,
+                dwtx.dwtxhelper.mangoicu.UChar,
+                dwtx.dwtxhelper.mangoicu.ULocale;
+
+/*******************************************************************************
+
+*******************************************************************************/
+
+private extern (C) void memmove (void* dst, void* src, uint bytes);
+
+/*******************************************************************************
+
+        Bind to the IReadable and IWritable interfaces if we're building
+        along with the mango.io package
+
+*******************************************************************************/
+
+version=Isolated;
+version (Isolated)
+        {
+        private interface ITextOther   {}
+        private interface IStringOther {}
+        }
+     else
+        {
+        private import  dwtx.dwtxhelper.mangoicu.UMango;
+
+        private import  mango.io.model.IReader,
+                        mango.io.model.IWriter;
+
+        private interface ITextOther   : IWritable {}
+        private interface IStringOther : IReadable {}
+        }
+
+
+/*******************************************************************************
+
+        UString is a string class that stores Unicode characters directly
+        and provides similar functionality as the Java String class.
+
+        In ICU, a Unicode string consists of 16-bit Unicode code units.
+        A Unicode character may be stored with either one code unit &#8212;
+        which is the most common case &#8212; or with a matched pair of
+        special code units ("surrogates"). The data type for code units
+        is UChar.
+
+        For single-character handling, a Unicode character code point is
+        a value in the range 0..0x10ffff. ICU uses the UChar32 type for
+        code points.
+
+        Indexes and offsets into and lengths of strings always count code
+        units, not code points. This is the same as with multi-byte char*
+        strings in traditional string handling. Operations on partial
+        strings typically do not test for code point boundaries. If necessary,
+        the user needs to take care of such boundaries by testing for the code
+        unit values or by using functions like getChar32Start()
+        and getChar32Limit()
+
+        UString methods are more lenient with regard to input parameter values
+        than other ICU APIs. In particular:
+
+        - If indexes are out of bounds for a UString object (< 0 or > length)
+          then they are "pinned" to the nearest boundary.
+
+        - If primitive string pointer values (e.g., const wchar* or char*) for
+          input strings are null, then those input string parameters are treated
+          as if they pointed to an empty string. However, this is not the case
+          for char* parameters for charset names or other IDs.
+
+*******************************************************************************/
+
+class UString : UStringView, IStringOther
+{
+        alias opCat             append;
+        alias opIndexAssign     setCharAt;
+
+        /***********************************************************************
+
+                Create an empty UString with the specified available space
+
+        ***********************************************************************/
+
+        this (uint space = 0)
+        {
+                content.length = space;
+                mutable = true;
+        }
+
+        /***********************************************************************
+
+                Create a UString upon the provided content. If said content
+                is immutable (read-only) then you might consider setting the
+                'mutable' parameter to false. Doing so will avoid allocating
+                heap-space for the content until it is modified.
+
+        ***********************************************************************/
+
+        this (wchar[] content, bool mutable = true)
+        {
+                setTo (content, mutable);
+        }
+
+        /***********************************************************************
+
+                Create a UString via the content of a UStringView. Note that the
+                default is to assume the content is immutable (read-only).
+
+        ***********************************************************************/
+
+        this (UStringView other, bool mutable = false)
+        {
+                this (other.get, mutable);
+        }
+
+        /***********************************************************************
+
+                Create a UString via the content of a UString. If said content
+                is immutable (read-only) then you might consider setting the
+                'mutable' parameter to false. Doing so will avoid allocating
+                heap-space for the content until it is modified via UString
+                methods.
+
+        ***********************************************************************/
+
+        this (UString other, bool mutable = true)
+        {
+                this (other.get, mutable);
+        }
+
+        /***********************************************************************
+
+                Support for reading content via the IO system
+
+        ***********************************************************************/
+
+        version (Isolated){}
+        else
+        {
+                /***************************************************************
+
+                        Internal adapter to handle loading and conversion
+                        of UString content. Once constructed, this may be
+                        used as the target for an IReader. Alternatively,
+                        invoke the load() method with an IBuffer of choice.
+
+                ***************************************************************/
+
+                class UStringDecoder : StringDecoder16
+                {
+                        private UString s;
+
+                        // construct a decoder on the given UString
+                        this (UConverter c, uint bytes, UString s)
+                        {
+                                super (c, bytes);
+                                this.s = s;
+                        }
+
+                        // IReadable adapter to perform the conversion
+                        protected void read (IReader r)
+                        {
+                                load (r.buffer);
+                        }
+
+                        // read from the provided buffer until we
+                        // either have all the content, or an eof
+                        // condition throws an exception.
+                        package void load (IBuffer b)
+                        {
+                                uint produced = super.read (b, s.content);
+                                while (toGo)
+                                      {
+                                      s.expand (toGo);
+                                      produced += super.read (b, s.content[produced..$]);
+                                      }
+                                s.len = produced;
+                        }
+                }
+
+                /***************************************************************
+
+                        Another constructor for loading known content length
+                        into a UString.
+
+                ***************************************************************/
+
+                this (IBuffer buffer, uint contentLength, UConverter cvt)
+                {
+                        this (contentLength);
+                        UStringDecoder sd = new UStringDecoder (cvt, contentLength, this);
+                        sd.load (buffer);
+                }
+
+                /***************************************************************
+
+                        Read as many bytes from the input as is necessary
+                        to produce the expected number of wchar elements.
+                        This uses the default wchar handler, which can be
+                        altered by binding a StringDecoder to the IReader
+                        in use (see UMango for details).
+
+                        We're mutable, so ensure we don't mess with the
+                        IO buffers. Interestingly, changing the length
+                        of a D array will account for slice assignments
+                        (it checks the pointer to see if it's a starting
+                         point in the pool). Unfortunately, that doesn't
+                        catch the case where a slice starts at offset 0,
+                        which is where IBuffer slices may come from.
+
+                        To be safe, we ask the allocator in use whether
+                        the content it provided can be mutated or not.
+                        Note that this is not necessary for UStringView, since
+                        that is a read-only construct.
+
+                ***************************************************************/
+
+                void read (IReader r)
+                {
+                        r.get (content);
+                        len = content.length;
+                        mutable = r.getAllocator.isMutable (content);
+                }
+
+                /***************************************************************
+
+                        Return a streaming decoder that can be used to
+                        populate this UString with a specified number of
+                        input bytes.
+
+                        This differs from the above read() method in the
+                        way content is read: in the above case, exactly
+                        the specified number of wchar elements will be
+                        converter from the input, whereas in this case
+                        a variable number of wchar elements are converted
+                        until 'bytes' have been read from the input. This
+                        is useful in those cases where the original number
+                        of elements has been lost, and only the resultant
+                        converted byte-count remains (a la HTTP).
+
+                        The returned StringDecoder is one-shot only. You may
+                        reuse it (both the converter and the byte count) via
+                        its reset() method.
+
+                        One applies the resultant converter directly with an
+                        IReader like so:
+
+                        @code
+                        UString s = ...;
+                        IReader r = ...;
+
+                        // r >> s.createDecoder(cvt, bytes);
+                        r.get (s.createDecoder(cvt, bytes));
+                        @endcode
+
+                        which will read the specified number of bytes from
+                        the input and convert them to an appropriate number
+                        of wchars within the UString.
+
+                ***************************************************************/
+
+                StringDecoder createDecoder (UConverter c, uint bytes)
+                {
+                        return new UStringDecoder (c, bytes, this);
+                }
+        }
+
+        /***********************************************************************
+
+                Append text to this UString
+
+        ***********************************************************************/
+
+        UString opCat (UStringView other)
+        {
+                return opCat (other.get);
+        }
+
+        /***********************************************************************
+
+                Append partial text to this UString
+
+        ***********************************************************************/
+
+        UString opCat (UStringView other, uint start, uint len=uint.max)
+        {
+                other.pinIndices (start, len);
+                return opCat (other.content [start..start+len]);
+        }
+
+        /***********************************************************************
+
+                Append a single character to this UString
+
+        ***********************************************************************/
+
+        UString opCat (wchar chr)
+        {
+                return opCat (&chr, 1);
+        }
+
+        /***********************************************************************
+
+                Append text to this UString
+
+        ***********************************************************************/
+
+        UString opCat (wchar[] chars)
+        {
+                return opCat (chars.ptr, chars.length);
+        }
+
+        /***********************************************************************
+
+                Converts a sequence of UTF-8 bytes to UChars (UTF-16)
+
+        ***********************************************************************/
+
+        UString opCat (char[] chars)
+        {
+                uint fmt (wchar* dst, uint len, inout UErrorCode e)
+                {
+                        uint x;
+
+                        u_strFromUTF8 (dst, len, &x, chars.ptr, chars.length, e);
+                        return x;
+                }
+
+                expand (chars.length);
+                return format (&fmt, "failed to append UTF char[]");
+        }
+
+        /***********************************************************************
+
+                Set a section of this UString to the specified character
+
+        ***********************************************************************/
+
+        UString setTo (wchar chr, uint start=0, uint len=uint.max)
+        {
+                pinIndices (start, len);
+                if (! mutable)
+                      realloc ();
+                content [start..start+len] = chr;
+                return this;
+        }
+
+        /***********************************************************************
+
+                Set the content to the provided array. Parameter 'mutable'
+                specifies whether the given array is likely to change. If
+                not, the array is aliased until such time this UString is
+                altered.
+
+        ***********************************************************************/
+
+        UString setTo (wchar[] chars, bool mutable = true)
+        {
+                len = chars.length;
+                if ((this.mutable = mutable) == true)
+                     content = chars.dup;
+                else
+                   content = chars;
+                return this;
+        }
+
+        /***********************************************************************
+
+                Replace the content of this UString. If the new content
+                is immutable (read-only) then you might consider setting the
+                'mutable' parameter to false. Doing so will avoid allocating
+                heap-space for the content until it is modified via one of
+                these methods.
+
+        ***********************************************************************/
+
+        UString setTo (UStringView other, bool mutable = true)
+        {
+                return setTo (other.get, mutable);
+        }
+
+        /***********************************************************************
+
+                Replace the content of this UString. If the new content
+                is immutable (read-only) then you might consider setting the
+                'mutable' parameter to false. Doing so will avoid allocating
+                heap-space for the content until it is modified via one of
+                these methods.
+
+        ***********************************************************************/
+
+        UString setTo (UStringView other, uint start, uint len, bool mutable = true)
+        {
+                other.pinIndices (start, len);
+                return setTo (other.content [start..start+len], mutable);
+        }
+
+        /***********************************************************************
+
+                Replace the character at the specified location.
+
+        ***********************************************************************/
+
+        final UString opIndexAssign (wchar chr, uint index)
+        in {
+                if (index >= len)
+                    exception ("index of out bounds");
+           }
+        body
+        {
+                if (! mutable)
+                      realloc ();
+                content [index] = chr;
+                return this;
+        }
+
+        /***********************************************************************
+
+                Remove a piece of this UString.
+
+        ***********************************************************************/
+
+        UString remove (uint start, uint length=uint.max)
+        {
+                pinIndices (start, length);
+                if (length)
+                    if (start >= len)
+                        truncate (start);
+                    else
+                       {
+                       if (! mutable)
+                             realloc ();
+
+                       uint i = start + length;
+                       memmove (&content[start], &content[i], (len-i) * wchar.sizeof);
+                       len -= length;
+                       }
+                return this;
+        }
+
+        /***********************************************************************
+
+                Truncate the length of this UString.
+
+        ***********************************************************************/
+
+        UString truncate (uint length=0)
+        {
+                if (length <= len)
+                    len = length;
+                return this;
+        }
+
+        /***********************************************************************
+
+                Insert leading spaces in this UString
+
+        ***********************************************************************/
+
+        UString padLeading (uint count, wchar padChar = 0x0020)
+        {
+                expand  (count);
+                memmove (&content[count], content.ptr, len * wchar.sizeof);
+                len += count;
+                return setTo (padChar, 0, count);
+        }
+
+        /***********************************************************************
+
+                Append some trailing spaces to this UString.
+
+        ***********************************************************************/
+
+        UString padTrailing (uint length, wchar padChar = 0x0020)
+        {
+                expand (length);
+                len += length;
+                return setTo  (padChar, len-length, length);
+        }
+
+        /***********************************************************************
+
+                Check for available space within the buffer, and expand
+                as necessary.
+
+        ***********************************************************************/
+
+        package final void expand (uint count)
+        {
+                if ((len + count) > content.length)
+                     realloc (count);
+        }
+
+        /***********************************************************************
+
+                Allocate memory due to a change in the content. We handle
+                the distinction between mutable and immutable here.
+
+        ***********************************************************************/
+
+        private final void realloc (uint count = 0)
+        {
+                uint size = (content.length + count + 63) & ~63;
+
+                if (mutable)
+                    content.length = size;
+                else
+                   {
+                   mutable = true;
+                   wchar[] x = content;
+                   content = new wchar [size];
+                   if (len)
+                       content[0..len] = x;
+                   }
+        }
+
+        /***********************************************************************
+
+                Internal method to support UString appending
+
+        ***********************************************************************/
+
+        private final UString opCat (wchar* chars, uint count)
+        {
+                expand (count);
+                content[len..len+count] = chars[0..count];
+                len += count;
+                return this;
+        }
+
+        /***********************************************************************
+
+                Internal method to support formatting into this UString.
+                This is used by many of the ICU wrappers to append content
+                into a UString.
+
+        ***********************************************************************/
+
+        typedef uint delegate (wchar* dst, uint len, inout UErrorCode e) Formatter;
+
+        package final UString format (Formatter format, char[] msg)
+        {
+                UErrorCode   e;
+                uint    length;
+
+                while (true)
+                      {
+                      e = e.OK;
+                      length = format (&content[len], content.length - len, e);
+                      if (e == e.BufferOverflow)
+                          expand (length);
+                      else
+                         break;
+                      }
+
+                if (isError (e))
+                    exception (msg);
+
+                len += length;
+                return this;
+        }
+}
+
+
+/*******************************************************************************
+
+        Immutable (read-only) text -- use UString for mutable strings.
+
+*******************************************************************************/
+
+class UStringView : ICU, ITextOther
+{
+        alias opIndex   charAt;
+
+        // the core of the UStringView and UString attributes. The name 'len'
+        // is used rather than the more obvious 'length' since there is
+        // a collision with the silly array[length] syntactic sugar ...
+        package uint    len;
+        package wchar[] content;
+
+        // this should probably be in UString only, but there seems to
+        // be a compiler bug where it doesn't get initialised correctly,
+        // and it's perhaps useful to have here for when a UString is
+        // passed as a UStringView argument.
+        private bool    mutable;
+
+        // toFolded() argument
+        public enum     CaseOption
+                        {
+                        Default  = 0,
+                        SpecialI = 1
+                        }
+
+        /***********************************************************************
+
+                Hidden constructor
+
+        ***********************************************************************/
+
+        private this ()
+        {
+        }
+
+        /***********************************************************************
+
+                Construct read-only wrapper around the given content
+
+        ***********************************************************************/
+
+        this (wchar[] content)
+        {
+                this.content = content;
+                this.len = content.length;
+        }
+
+        /***********************************************************************
+
+                Support for writing via the Mango IO subsystem
+
+        ***********************************************************************/
+
+        version (Isolated){}
+        else
+        {
+                void write (IWriter w)
+                {
+                        w.put (get);
+                }
+        }
+
+        /***********************************************************************
+
+                Return the valid content from this UStringView
+
+        ***********************************************************************/
+
+        final package wchar[] get ()
+        {
+                return content [0..len];
+        }
+
+        /***********************************************************************
+
+                Is this UStringView equal to another?
+
+        ***********************************************************************/
+
+        final override int opEquals (Object o)
+        {
+                UStringView other = cast(UStringView) o;
+
+                if (other)
+                    return (other is this || compare (other) == 0);
+                return 0;
+        }
+
+        /***********************************************************************
+
+                Compare this UStringView to another.
+
+        ***********************************************************************/
+
+        final override int opCmp (Object o)
+        {
+                UStringView other = cast(UStringView) o;
+
+                if (other is this)
+                    return 0;
+                else
+                   if (other)
+                       return compare (other);
+                return 1;
+        }
+
+        /***********************************************************************
+
+                Hash this UStringView
+
+        ***********************************************************************/
+
+        final override uint toHash ()
+        {
+                return typeid(wchar[]).getHash (&content[0..len]);
+        }
+
+        /***********************************************************************
+
+                Clone this UStringView into a UString
+
+        ***********************************************************************/
+
+        final UString copy ()
+        {
+                return new UString (content);
+        }
+
+        /***********************************************************************
+
+                Clone a section of this UStringView into a UString
+
+        ***********************************************************************/
+
+        final UString extract (uint start, uint len=uint.max)
+        {
+                pinIndices (start, len);
+                return new UString (content[start..start+len]);
+        }
+
+        /***********************************************************************
+
+                Count unicode code points in the length UChar code units of
+                the string. A code point may occupy either one or two UChar
+                code units. Counting code points involves reading all code
+                units.
+
+        ***********************************************************************/
+
+        final uint codePoints (uint start=0, uint length=uint.max)
+        {
+                pinIndices (start, length);
+                return u_countChar32 (&content[start], length);
+        }
+
+        /***********************************************************************
+
+                Return an indication whether or not there are surrogate pairs
+                within the string.
+
+        ***********************************************************************/
+
+        final bool hasSurrogates (uint start=0, uint length=uint.max)
+        {
+                pinIndices (start, length);
+                return codePoints (start, length) != length;
+        }
+
+        /***********************************************************************
+
+                Return the character at the specified position.
+
+        ***********************************************************************/
+
+        final wchar opIndex (uint index)
+        in {
+                if (index >= len)
+                    exception ("index of out bounds");
+           }
+        body
+        {
+                return content [index];
+        }
+
+        /***********************************************************************
+
+                Return the length of the valid content
+
+        ***********************************************************************/
+
+        final uint length ()
+        {
+                return len;
+        }
+
+        /***********************************************************************
+
+                The comparison can be done in code unit order or in code
+                point order. They differ only in UTF-16 when comparing
+                supplementary code points (U+10000..U+10ffff) to BMP code
+                points near the end of the BMP (i.e., U+e000..U+ffff).
+
+                In code unit order, high BMP code points sort after
+                supplementary code points because they are stored as
+                pairs of surrogates which are at U+d800..U+dfff.
+
+        ***********************************************************************/
+
+        final int compare (UStringView other, bool codePointOrder=false)
+        {
+                return compare (other.get, codePointOrder);
+        }
+
+        /***********************************************************************
+
+                The comparison can be done in code unit order or in code
+                point order. They differ only in UTF-16 when comparing
+                supplementary code points (U+10000..U+10ffff) to BMP code
+                points near the end of the BMP (i.e., U+e000..U+ffff).
+
+                In code unit order, high BMP code points sort after
+                supplementary code points because they are stored as
+                pairs of surrogates which are at U+d800..U+dfff.
+
+        ***********************************************************************/
+
+        final int compare (wchar[] other, bool codePointOrder=false)
+        {
+                return u_strCompare (content.ptr, len, other.ptr, other.length, codePointOrder);
+        }
+
+        /***********************************************************************
+
+                The comparison can be done in UTF-16 code unit order or
+                in code point order. They differ only when comparing
+                supplementary code points (U+10000..U+10ffff) to BMP code
+                points near the end of the BMP (i.e., U+e000..U+ffff).
+
+                In code unit order, high BMP code points sort after
+                supplementary code points because they are stored as
+                pairs of surrogates which are at U+d800..U+dfff.
+
+        ***********************************************************************/
+
+        final int compareFolded (UStringView other, CaseOption option = CaseOption.Default)
+        {
+                return compareFolded (other.content, option);
+        }
+
+        /***********************************************************************
+
+                The comparison can be done in UTF-16 code unit order or
+                in code point order. They differ only when comparing
+                supplementary code points (U+10000..U+10ffff) to BMP code
+                points near the end of the BMP (i.e., U+e000..U+ffff).
+
+                In code unit order, high BMP code points sort after
+                supplementary code points because they are stored as
+                pairs of surrogates which are at U+d800..U+dfff.
+
+        ***********************************************************************/
+
+        final int compareFolded (wchar[] other, CaseOption option = CaseOption.Default)
+        {
+                return compareFolded (get, other, option);
+        }
+
+        /***********************************************************************
+
+                Does this UStringView start with specified string?
+
+        ***********************************************************************/
+
+        final bool startsWith (UStringView other)
+        {
+                return startsWith (other.get);
+        }
+
+        /***********************************************************************
+
+                Does this UStringView start with specified string?
+
+        ***********************************************************************/
+
+        final bool startsWith (wchar[] chars)
+        {
+                if (len >= chars.length)
+                    return compareFolded (content[0..chars.length], chars) == 0;
+                return false;
+        }
+
+        /***********************************************************************
+
+                Does this UStringView end with specified string?
+
+        ***********************************************************************/
+
+        final bool endsWith (UStringView other)
+        {
+                return endsWith (other.get);
+        }
+
+        /***********************************************************************
+
+                Does this UStringView end with specified string?
+
+        ***********************************************************************/
+
+        final bool endsWith (wchar[] chars)
+        {
+                if (len >= chars.length)
+                    return compareFolded (content[len-chars.length..len], chars) == 0;
+                return false;
+        }
+
+        /***********************************************************************
+
+                Find the first occurrence of a BMP code point in a string.
+                A surrogate code point is found only if its match in the
+                text is not part of a surrogate pair.
+
+        ***********************************************************************/
+
+        final uint indexOf (wchar c, uint start=0)
+        {
+                pinIndex (start);
+                wchar* s = u_memchr (&content[start], c, len-start);
+                if (s)
+                    return s - content.ptr;
+                return uint.max;
+        }
+
+        /***********************************************************************
+
+                Find the first occurrence of a substring in a string.
+
+                The substring is found at code point boundaries. That means
+                that if the substring begins with a trail surrogate or ends
+                with a lead surrogate, then it is found only if these
+                surrogates stand alone in the text. Otherwise, the substring
+                edge units would be matched against halves of surrogate pairs.
+
+        ***********************************************************************/
+
+        final uint indexOf (UStringView other, uint start=0)
+        {
+                return indexOf (other.get, start);
+        }
+
+        /***********************************************************************
+
+                Find the first occurrence of a substring in a string.
+
+                The substring is found at code point boundaries. That means
+                that if the substring begins with a trail surrogate or ends
+                with a lead surrogate, then it is found only if these
+                surrogates stand alone in the text. Otherwise, the substring
+                edge units would be matched against halves of surrogate pairs.
+
+        ***********************************************************************/
+
+        final uint indexOf (wchar[] chars, uint start=0)
+        {
+                pinIndex (start);
+                wchar* s = u_strFindFirst (&content[start], len-start, chars.ptr, chars.length);
+                if (s)
+                    return s - content.ptr;
+                return uint.max;
+        }
+
+        /***********************************************************************
+
+                Find the last occurrence of a BMP code point in a string.
+                A surrogate code point is found only if its match in the
+                text is not part of a surrogate pair.
+
+        ***********************************************************************/
+
+        final uint lastIndexOf (wchar c, uint start=uint.max)
+        {
+                pinIndex (start);
+                wchar* s = u_memrchr (content.ptr, c, start);
+                if (s)
+                    return s - content.ptr;
+                return uint.max;
+        }
+
+        /***********************************************************************
+
+                Find the last occurrence of a BMP code point in a string.
+                A surrogate code point is found only if its match in the
+                text is not part of a surrogate pair.
+
+        ***********************************************************************/
+
+        final uint lastIndexOf (UStringView other, uint start=uint.max)
+        {
+                return lastIndexOf (other.get, start);
+        }
+
+        /***********************************************************************
+
+                Find the last occurrence of a substring in a string.
+
+                The substring is found at code point boundaries. That means
+                that if the substring begins with a trail surrogate or ends
+                with a lead surrogate, then it is found only if these
+                surrogates stand alone in the text. Otherwise, the substring
+                edge units would be matched against halves of surrogate pairs.
+
+        ***********************************************************************/
+
+        final uint lastIndexOf (wchar[] chars, uint start=uint.max)
+        {
+                pinIndex (start);
+                wchar* s = u_strFindLast (content.ptr, start, chars.ptr, chars.length);
+                if (s)
+                    return s - content.ptr;
+                return uint.max;
+        }
+
+        /***********************************************************************
+
+                Lowercase the characters into a seperate UString.
+
+                Casing is locale-dependent and context-sensitive. The
+                result may be longer or shorter than the original.
+
+                Note that the return value refers to the provided destination
+                UString.
+
+        ***********************************************************************/
+
+        final UString toLower (UString dst)
+        {
+               return toLower (dst, ULocale.Default);
+        }
+
+        /***********************************************************************
+
+                Lowercase the characters into a seperate UString.
+
+                Casing is locale-dependent and context-sensitive. The
+                result may be longer or shorter than the original.
+
+                Note that the return value refers to the provided destination
+                UString.
+
+        ***********************************************************************/
+
+        final UString toLower (UString dst, inout ULocale locale)
+        {
+                uint lower (wchar* dst, uint length, inout UErrorCode e)
+                {
+                        return u_strToLower (dst, length, content.ptr, len, ICU.toString(locale.name), e);
+                }
+
+                dst.expand (len + 32);
+                return dst.format (&lower, "toLower() failed");
+        }
+
+        /***********************************************************************
+
+                Uppercase the characters into a seperate UString.
+
+                Casing is locale-dependent and context-sensitive. The
+                result may be longer or shorter than the original.
+
+                Note that the return value refers to the provided destination
+                UString.
+
+        ***********************************************************************/
+
+        final UString toUpper (UString dst)
+        {
+               return toUpper (dst, ULocale.Default);
+        }
+
+        /***********************************************************************
+
+                Uppercase the characters into a seperate UString.
+
+                Casing is locale-dependent and context-sensitive. The
+                result may be longer or shorter than the original.
+
+                Note that the return value refers to the provided destination
+                UString.
+
+        ***********************************************************************/
+
+        final UString toUpper (UString dst, inout ULocale locale)
+        {
+                uint upper (wchar* dst, uint length, inout UErrorCode e)
+                {
+                        return u_strToUpper (dst, length, content.ptr, len, ICU.toString(locale.name), e);
+                }
+
+                dst.expand (len + 32);
+                return dst.format (&upper, "toUpper() failed");
+        }
+
+        /***********************************************************************
+
+                Case-fold the characters into a seperate UString.
+
+                Case-folding is locale-independent and not context-sensitive,
+                but there is an option for whether to include or exclude
+                mappings for dotted I and dotless i that are marked with 'I'
+                in CaseFolding.txt. The result may be longer or shorter than
+                the original.
+
+                Note that the return value refers to the provided destination
+                UString.
+
+        ***********************************************************************/
+
+        final UString toFolded (UString dst, CaseOption option = CaseOption.Default)
+        {
+                uint fold (wchar* dst, uint length, inout UErrorCode e)
+                {
+                        return u_strFoldCase (dst, length, content.ptr, len, option, e);
+                }
+
+                dst.expand (len + 32);
+                return dst.format (&fold, "toFolded() failed");
+        }
+
+        /***********************************************************************
+
+                Converts a sequence of wchar (UTF-16) to UTF-8 bytes. If
+                the output array is not provided, an array of appropriate
+                size will be allocated and returned. Where the output is
+                provided, it must be large enough to hold potentially four
+                bytes per character for surrogate-pairs or three bytes per
+                character for BMP only. Consider using UConverter where
+                streaming conversions are required.
+
+                Returns an array slice representing the valid UTF8 content.
+
+        ***********************************************************************/
+
+        final char[] toUtf8 (char[] dst = null)
+        {
+                uint    x;
+                UErrorCode   e;
+
+                if (! cast(char*) dst)
+                      dst = new char[len * 4];
+
+                u_strToUTF8 (dst.ptr, dst.length, &x, content.ptr, len, e);
+                testError (e, "failed to convert to UTF8");
+                return dst [0..x];
+        }
+
+        /***********************************************************************
+
+                Remove leading and trailing whitespace from this UStringView.
+                Note that we slice the content to remove leading space.
+
+        ***********************************************************************/
+
+        UStringView trim ()
+        {
+                wchar   c;
+                uint    i = len;
+
+                // cut off trailing white space
+                while (i && ((c = charAt(i-1)) == 0x20 || UChar.isWhiteSpace (c)))
+                       --i;
+                len = i;
+
+                // now remove leading whitespace
+                for (i=0; i < len && ((c = charAt(i)) == 0x20 || UChar.isWhiteSpace (c)); ++i) {}
+                if (i)
+                   {
+                   len -= i;
+                   content = content[i..$-i];
+                   }
+
+                return this;
+        }
+
+        /***********************************************************************
+
+                Unescape a string of characters and write the resulting
+                Unicode characters to the destination buffer.  The following
+                escape sequences are recognized:
+
+                  uhhhh       4 hex digits; h in [0-9A-Fa-f]
+                  Uhhhhhhhh   8 hex digits
+                  xhh         1-2 hex digits
+                  x{h...}     1-8 hex digits
+                  ooo         1-3 octal digits; o in [0-7]
+                  cX          control-X; X is masked with 0x1F
+
+                as well as the standard ANSI C escapes:
+
+                  a => U+0007, \\b => U+0008, \\t => U+0009, \\n => U+000A,
+                  v => U+000B, \\f => U+000C, \\r => U+000D, \\e => U+001B,
+                  \\" =U+0022, \\' => U+0027, \\? => U+003F, \\\\ => U+005C
+
+                Anything else following a backslash is generically escaped.
+                For example, "[a\\-z]" returns "[a-z]".
+
+                If an escape sequence is ill-formed, this method returns an
+                empty string.  An example of an ill-formed sequence is "\\u"
+                followed by fewer than 4 hex digits.
+
+         ***********************************************************************/
+
+        final UString unEscape ()
+        {
+                UString result = new UString (len);
+                for (uint i=0; i < len;)
+                    {
+                    dchar c = charAt(i++);
+                    if (c == 0x005C)
+                       {
+                       // bump index ...
+                       c = u_unescapeAt (&_charAt, &i, len, cast(void*) this);
+
+                       // error?
+                       if (c == 0xFFFFFFFF)
+                          {
+                          result.truncate ();   // return empty string
+                          break;                // invalid escape sequence
+                          }
+                       }
+                    result.append (c);
+                    }
+                return result;
+        }
+
+        /***********************************************************************
+
+                Is this code point a surrogate (U+d800..U+dfff)?
+
+        ***********************************************************************/
+
+        final static bool isSurrogate (wchar c)
+        {
+                return (c & 0xfffff800) == 0xd800;
+        }
+
+        /***********************************************************************
+
+                Is this code unit a lead surrogate (U+d800..U+dbff)?
+
+        ***********************************************************************/
+
+        final static bool isLeading (wchar c)
+        {
+                return (c & 0xfffffc00) == 0xd800;
+        }
+
+        /***********************************************************************
+
+                Is this code unit a trail surrogate (U+dc00..U+dfff)?
+
+        ***********************************************************************/
+
+        final static bool isTrailing (wchar c)
+        {
+                return (c & 0xfffffc00) == 0xdc00;
+        }
+
+        /***********************************************************************
+
+                Adjust a random-access offset to a code point boundary
+                at the start of a code point. If the offset points to
+                the trail surrogate of a surrogate pair, then the offset
+                is decremented. Otherwise, it is not modified.
+
+        ***********************************************************************/
+
+        final uint getCharStart (uint i)
+        in {
+                if (i >= len)
+                    exception ("index of out bounds");
+           }
+        body
+        {
+                if (isTrailing (content[i]) && i && isLeading (content[i-1]))
+                    --i;
+                return i;
+        }
+
+        /***********************************************************************
+
+                Adjust a random-access offset to a code point boundary
+                after a code point. If the offset is behind the lead
+                surrogate of a surrogate pair, then the offset is
+                incremented. Otherwise, it is not modified.
+
+        ***********************************************************************/
+
+        final uint getCharLimit (uint i)
+        in {
+                if (i >= len)
+                    exception ("index of out bounds");
+           }
+        body
+        {
+                if (i && isLeading(content[i-1]) && isTrailing (content[i]))
+                    ++i;
+                return i;
+        }
+
+        /***********************************************************************
+
+                Callback for C unescapeAt() function
+
+        ***********************************************************************/
+
+        extern (C)
+        {
+                typedef wchar function (uint offset, void* context) CharAt;
+
+                private static wchar _charAt (uint offset, void* context)
+                {
+                        return (cast(UString) context).charAt (offset);
+                }
+        }
+
+        /***********************************************************************
+
+                Pin the given index to a valid position.
+
+        ***********************************************************************/
+
+        final private void pinIndex (inout uint x)
+        {
+                if (x > len)
+                    x = len;
+        }
+
+        /***********************************************************************
+
+                Pin the given index and length to a valid position.
+
+        ***********************************************************************/
+
+        final private void pinIndices (inout uint start, inout uint length)
+        {
+                if (start > len)
+                    start = len;
+
+                if (length > (len - start))
+                    length = len - start;
+        }
+
+        /***********************************************************************
+
+                Helper for comparison methods
+
+        ***********************************************************************/
+
+        final private int compareFolded (wchar[] s1, wchar[] s2, CaseOption option = CaseOption.Default)
+        {
+                UErrorCode e;
+
+                int x = u_strCaseCompare (s1.ptr, s1.length, s2.ptr, s2.length, option, e);
+                testError (e, "compareFolded failed");
+                return x;
+        }
+
+
+        /***********************************************************************
+
+                Bind the ICU functions from a shared library. This is
+                complicated by the issues regarding D and DLLs on the
+                Windows platform
+
+        ***********************************************************************/
+
+        private static void* library;
+
+        /***********************************************************************
+
+        ***********************************************************************/
+
+        private static extern (C)
+        {
+                wchar* function (wchar*, uint, wchar*, uint) u_strFindFirst;
+                wchar* function (wchar*, uint, wchar*, uint) u_strFindLast;
+                wchar* function (wchar*, wchar, uint) u_memchr;
+                wchar* function (wchar*, wchar, uint) u_memrchr;
+                int    function (wchar*, uint, wchar*, uint, bool) u_strCompare;
+                int    function (wchar*, uint, wchar*, uint, uint, inout UErrorCode) u_strCaseCompare;
+                dchar  function (CharAt, uint*, uint, void*) u_unescapeAt;
+                uint   function (wchar*, uint) u_countChar32;
+                uint   function (wchar*, uint, wchar*, uint, char*, inout UErrorCode) u_strToUpper;
+                uint   function (wchar*, uint, wchar*, uint, char*, inout UErrorCode) u_strToLower;
+                uint   function (wchar*, uint, wchar*, uint, uint, inout UErrorCode) u_strFoldCase;
+                wchar* function (wchar*, uint, uint*, char*, uint, inout UErrorCode) u_strFromUTF8;
+                char*  function (char*, uint, uint*, wchar*, uint, inout UErrorCode) u_strToUTF8;
+        }
+
+        /***********************************************************************
+
+        ***********************************************************************/
+
+        static  FunctionLoader.Bind[] targets =
+                [
+                {cast(void**) &u_strFindFirst,      "u_strFindFirst"},
+                {cast(void**) &u_strFindLast,       "u_strFindLast"},
+                {cast(void**) &u_memchr,            "u_memchr"},
+                {cast(void**) &u_memrchr,           "u_memrchr"},
+                {cast(void**) &u_strCompare,        "u_strCompare"},
+                {cast(void**) &u_strCaseCompare,    "u_strCaseCompare"},
+                {cast(void**) &u_unescapeAt,        "u_unescapeAt"},
+                {cast(void**) &u_countChar32,       "u_countChar32"},
+                {cast(void**) &u_strToUpper,        "u_strToUpper"},
+                {cast(void**) &u_strToLower,        "u_strToLower"},
+                {cast(void**) &u_strFoldCase,       "u_strFoldCase"},
+                {cast(void**) &u_strFromUTF8,       "u_strFromUTF8"},
+                {cast(void**) &u_strToUTF8,         "u_strToUTF8"},
+                ];
+
+        /***********************************************************************
+
+        ***********************************************************************/
+
+        static this ()
+        {
+                library = FunctionLoader.bind (icuuc, targets);
+                //test ();
+        }
+
+        /***********************************************************************
+
+        ***********************************************************************/
+
+        static ~this ()
+        {
+                FunctionLoader.unbind (library);
+        }
+
+        /***********************************************************************
+
+        ***********************************************************************/
+
+        private static void test()
+        {
+                UString s = new UString (r"aaaqw \uabcd eaaa");
+                char[] x = "dssfsdff";
+                s ~ x ~ x;
+                wchar c = s[3];
+                s[3] = 'Q';
+                int y = s.indexOf ("qwe");
+                s.unEscape ();
+                s.toUpper (new UString);
+                s.padLeading(2).padTrailing(2).trim();
+        }
+}