Last update Fri Apr 28 11:05:24 2006
std
 std.array
 std.atomic
 std.bitarray
 std.exception
 std.intrinsic
 std.memory
 std.regexp
 std.thread
 std.traits
 std.unicode
 std.vararg
 std.math.core
 std.math.ieee
 std.math.special

std.unicode

Fast Unicode transcoders. These are particularly sensitive to minor changes on 32bit x86 devices, because the register set of those devices is so small. Beware of subtle changes which might extend the execution-period by as much as 200%. Because of this, three of the six transcoders might read past the end of input by one, two, or three bytes before arresting themselves. Note that support for streaming adds a 15% overhead to the dchar => char conversion, but has little effect on the others.

These routines were tuned on an Intel P4; other devices may work more efficiently with a slightly different approach, though this is likely to be reasonably optimal on AMD x86 CPUs also. These algorithms would benefit significantly from those extra AMD64 registers. On a 3GHz P4, the dchar/char conversions take around 2500ns to process an array of 1000 ASCII elements. Invoking the memory manager doubles that period, and quadruples the time for arrays of 100 elements. Memory allocation can slow down notably in a multi-threaded environment, so avoid that where possible.

Surrogate-pairs are dealt with in a non-optimal fashion when transcoding between utf16 and utf8. Such cases are considered to be boundary-conditions for this module.

There are three common cases where the input may be incomplete, including each 'widening' case of utf8 => utf16, utf8 => utf32, and utf16 => utf32. An edge-case is utf16 => utf8, if surrogate pairs are present. Such cases will throw an exception, unless streaming-mode is enabled ~ in the latter mode, an additional integer is returned indicating how many elements of the input have been consumed. In all cases, a correct slice of the output is returned.

For details on Unicode processing see http://www.utf-8.com/ http://www.hackcraft.net/xmlUnicode/ http://www.azillionmonkeys.com/qed/unicode.html/ http://icu.sourceforge.net/docs/papers/forms_of_unicode/

char[] toUtf8(wchar[] input, char[] output = null, uint* ate = null);
Encode Utf8 up to a maximum of 4 bytes long (five & six byte variations are not supported).

If the output is provided off the stack, it should be large enough to encompass the entire transcoding; failing to do so will cause the output to be moved onto the heap instead.

Returns a slice of the output buffer, corresponding to the converted characters. For optimum performance, the returned buffer should be specified as 'output' on subsequent calls. For example:

char[] output;

wchar[] result = toUtf8 (input, output);

// reset output after a realloc if (result.length > output.length) output = result;

wchar[] toUtf16(char[] input, wchar[] output = null, uint* ate = null);
Decode Utf8 produced by the above toUtf8() method.

If the output is provided off the stack, it should be large enough to encompass the entire transcoding; failing to do so will cause the output to be moved onto the heap instead.

Returns a slice of the output buffer, corresponding to the converted characters. For optimum performance, the returned buffer should be specified as 'output' on subsequent calls.

char[] toUtf8(dchar[] input, char[] output = null, uint* ate = null);
Encode Utf8 up to a maximum of 4 bytes long (five & six byte variations are not supported). Throws an exception where the input dchar is greater than 0x10ffff.

If the output is provided off the stack, it should be large enough to encompass the entire transcoding; failing to do so will cause the output to be moved onto the heap instead.

Returns a slice of the output buffer, corresponding to the converted characters. For optimum performance, the returned buffer should be specified as 'output' on subsequent calls.

dchar[] toUtf32(char[] input, dchar[] output = null, uint* ate = null);
Decode Utf8 produced by the above toUtf8() method.

If the output is provided off the stack, it should be large enough to encompass the entire transcoding; failing to do so will cause the output to be moved onto the heap instead.

Returns a slice of the output buffer, corresponding to the converted characters. For optimum performance, the returned buffer should be specified as 'output' on subsequent calls.

wchar[] toUtf16(dchar[] input, wchar[] output = null, uint* ate = null);
Encode Utf16 up to a maximum of 2 bytes long. Throws an exception where the input dchar is greater than 0x10ffff.

If the output is provided off the stack, it should be large enough to encompass the entire transcoding; failing to do so will cause the output to be moved onto the heap instead.

Returns a slice of the output buffer, corresponding to the converted characters. For optimum performance, the returned buffer should be specified as 'output' on subsequent calls.

dchar[] toUtf32(wchar[] input, dchar[] output = null, uint* ate = null);
Decode Utf16 produced by the above toUtf16() method.

If the output is provided off the stack, it should be large enough to encompass the entire transcoding; failing to do so will cause the output to be moved onto the heap instead.

Returns a slice of the output buffer, corresponding to the converted characters. For optimum performance, the returned buffer should be specified as 'output' on subsequent calls.

template convert(DstElem,SrcElem)


DstElem[] convert(SrcElem[] x, DstElem[] dst = null, uint* ate = null);