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Module `std.encoding`

Classes and functions for handling and transcoding between various encodings.

For cases where the encoding is known at compile-time, functions are provided for arbitrary encoding and decoding of characters, arbitrary transcoding between strings of different type, as well as validation and sanitization.

Encodings currently supported are UTF-8, UTF-16, UTF-32, ASCII, ISO-8859-1 (also known as LATIN-1), ISO-8859-2 (LATIN-2), WINDOWS-1250, WINDOWS-1251 and WINDOWS-1252.


Category	Functions
Decode	`codePoints` `decode` `decodeReverse` `safeDecode`
Conversion	`codeUnits` `sanitize` `transcode`
Classification	`canEncode` `isValid` `isValidCodePoint` `isValidCodeUnit`
BOM	`BOM` `BOMSeq` `getBOM` `utfBOM`
Length & Index	`firstSequence` `encodedLength` `index` `lastSequence` `validLength`
Encoding schemes	`encodingName` `EncodingScheme` `EncodingSchemeASCII` `EncodingSchemeLatin1` `EncodingSchemeLatin2` `EncodingSchemeUtf16Native` `EncodingSchemeUtf32Native` `EncodingSchemeUtf8` `EncodingSchemeWindows1250` `EncodingSchemeWindows1251` `EncodingSchemeWindows1252`
Representation	`AsciiChar` `AsciiString` `Latin1Char` `Latin1String` `Latin2Char` `Latin2String` `Windows1250Char` `Windows1250String` `Windows1251Char` `Windows1251String` `Windows1252Char` `Windows1252String`
Exceptions	`INVALID_SEQUENCE` `EncodingException`

For cases where the encoding is not known at compile-time, but is known at run-time, the abstract class EncodingScheme and its subclasses is provided. To construct a run-time encoder/decoder, one does e.g.

auto e = EncodingScheme.create("utf-8");

This library supplies EncodingScheme subclasses for ASCII, ISO-8859-1 (also known as LATIN-1), ISO-8859-2 (LATIN-2), WINDOWS-1250, WINDOWS-1251, WINDOWS-1252, UTF-8, and (on little-endian architectures) UTF-16LE and UTF-32LE; or (on big-endian architectures) UTF-16BE and UTF-32BE.

This library provides a mechanism whereby other modules may add EncodingScheme subclasses for any other encoding.

Functions

Name	Description
`canEncode(c)`	Returns true iff it is possible to represent the specified codepoint in the encoding.
`codePoints(s)`	Returns a foreachable struct which can bidirectionally iterate over all code points in a string.
`codeUnits(c)`	Returns a foreachable struct which can bidirectionally iterate over all code units in a code point.
`decode(s)`	Decodes a single code point.
`decodeReverse(s)`	Decodes a single code point from the end of a string.
`encode(c)`	Encodes a single code point.
`encode(c, array)`	Encodes a single code point into an array.
`encode(c, dg)`	Encodes a single code point to a delegate.
`encode(s, range)`	Encodes the contents of `s` in units of type `Tgt`, writing the result to an output range.
`encodedLength(c)`	Returns the number of code units required to encode a single code point.
`encodingName()`	Returns the name of an encoding.
`firstSequence(s)`	Returns the length of the first encoded sequence.
`getBOM(input)`	Returns a `BOMSeq` for a given `input`. If no `BOM` is present the `BOMSeq` for `BOM.none` is returned. The `BOM` sequence at the beginning of the range will not be comsumed from the passed range. If you pass a reference type range make sure that `save` creates a deep copy.
`index(s, n)`	Returns the array index at which the (n+1)th code point begins.
`isValid(s)`	Returns true if the string is encoded correctly
`isValidCodePoint(c)`	Returns true if c is a valid code point
`isValidCodeUnit(c)`	Returns true if the code unit is legal. For example, the byte 0x80 would not be legal in ASCII, because ASCII code units must always be in the range 0x00 to 0x7F.
`lastSequence(s)`	Returns the length of the last encoded sequence.
`safeDecode(s)`	Decodes a single code point. The input does not have to be valid.
`sanitize(s)`	Sanitizes a string by replacing malformed code unit sequences with valid code unit sequences. The result is guaranteed to be valid for this encoding.
`transcode(s, r)`	Convert a string from one encoding to another.
`validLength(s)`	Returns the length of the longest possible substring, starting from the first code unit, which is validly encoded.

Classes

Name	Description
`EncodingException`	The base class for exceptions thrown by this module
`EncodingScheme`	Abstract base class of all encoding schemes
`EncodingSchemeASCII`	EncodingScheme to handle ASCII
`EncodingSchemeLatin1`	EncodingScheme to handle Latin-1
`EncodingSchemeLatin2`	EncodingScheme to handle Latin-2
`EncodingSchemeUtf16Native`	EncodingScheme to handle UTF-16 in native byte order
`EncodingSchemeUtf32Native`	EncodingScheme to handle UTF-32 in native byte order
`EncodingSchemeUtf8`	EncodingScheme to handle UTF-8
`EncodingSchemeWindows1250`	EncodingScheme to handle Windows-1250
`EncodingSchemeWindows1251`	EncodingScheme to handle Windows-1251
`EncodingSchemeWindows1252`	EncodingScheme to handle Windows-1252

Enums

Name	Description
`AsciiChar`	Defines various character sets.
`BOM`	Definitions of common Byte Order Marks. The elements of the `enum` can used as indices into `bomTable` to get matching `BOMSeq`.
`Latin1Char`	Defines an Latin1-encoded character.
`Latin2Char`	Defines a Latin2-encoded character.
`Windows1250Char`	Defines a Windows1250-encoded character.
`Windows1251Char`	Defines a Windows1251-encoded character.
`Windows1252Char`	Defines a Windows1252-encoded character.

Manifest constants

Name	Type	Description
`INVALID_SEQUENCE`		Special value returned by `safeDecode`
`utfBOM`		Constant defining a fully decoded BOM

Global variables

Name	Type	Description
`bomTable`	`immutable(Tuple!(std.encoding.BOM,"schema",ubyte[],"sequence")[])`	Mapping of a byte sequence to Byte Order Mark (BOM)

Aliases

Name	Type	Description
`AsciiString`	`immutable(AsciiChar)[]`	Defines various character sets.
`BOMSeq`	`Tuple!(std.encoding.BOM,"schema",ubyte[],"sequence")`	The type stored inside `bomTable`.
`Latin1String`	`immutable(Latin1Char)[]`	Defines an Latin1-encoded string (as an array of `immutable(Latin1Char)`).
`Latin2String`	`immutable(Latin2Char)[]`	Defines an Latin2-encoded string (as an array of `immutable(Latin2Char)`).
`Windows1250String`	`immutable(Windows1250Char)[]`	Defines an Windows1250-encoded string (as an array of `immutable(Windows1250Char)`).
`Windows1251String`	`immutable(Windows1251Char)[]`	Defines an Windows1251-encoded string (as an array of `immutable(Windows1251Char)`).
`Windows1252String`	`immutable(Windows1252Char)[]`	Defines an Windows1252-encoded string (as an array of `immutable(Windows1252Char)`).

Authors

Janice Caron

License

Boost License 1.0.