Types and Traits for Character Sets, Encodings, and Character Set Encodings
Author JuliaString
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2 Years Ago
Started In
May 2018


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This provides the basic types and mode methods for dealing with character sets, encodings, and character set encodings.


Currently, there are the following types:

  • CodeUnitTypes a Union of the 3 codeunit types (UInt8, UInt16, UInt32) for convenience
  • CharSet a struct type, which is parameterized by the name of the character set and the type needed to represent a code point
  • Encoding a struct type, parameterized by the name of the encoding

Built-in Character Sets / Character Set Encodings

  • Binary For storing non-textual data as a sequence of bytes, 0-0xff

  • ASCII ASCII (Unicode subset, 0-0x7f)

  • Latin Latin-1 (ISO-8859-1) (Unicode subset, 0-0xff)

  • UCS2 UCS-2 (Unicode subset, 0-0xd7ff, 0xe000-0xffff, BMP only, no surrogates)

  • UTF32 UTF-32 (Full Unicode, 0-0xd7ff, 0xe000-0x10ffff)

  • UniPlus Unvalidated Unicode (i.e. like String, can contain invalid codepoints)

  • Text1 Unknown 1-byte character set

  • Text2 Unknown 2-byte character set

  • Text4 Unknown 4-byte character set

Built-in Encodings

  • UTF8Encoding
  • Native1Byte
  • Native2Byte
  • Native4Byte
  • NativeUTF16
  • Swapped4Byte
  • Swapped2Byte
  • SwappedUTF16
  • LE2
  • BE2
  • LE4
  • BE4
  • UTF16LE
  • UTF16BE
  • 2Byte
  • 4Byte
  • UTF16

Built-in CSEs

  • BinaryCSE, Text1CSE, ASCIICSE, LatinCSE

  • Text2CSE, UCS2CSE

  • Text4CSE, UTF32CSE

  • UTF8CSE UTF32CharSet, all valid, using UTF8Encoding, conforming to the Unicode Organization's standard, i.e. no long encodings, surrogates, or invalid bytes.

  • RawUTF8CSE UniPlusCharSet, not validated, using UTF8Encoding, may have invalid sequences, long encodings, encode surrogates and characters up to 0x7fffffff

  • UTF16CSE UTF32CharSet, all valid, using UTF16 Encoding (native order), conforming to the Unicode standard, i.e. no out of order or isolated surrogates.

Internal Unicode subset types

  • _LatinCSE Indicates has at least 1 character > 0x7f, all <= 0xff
  • _UCS2CSE Indicates has at least 1 character > 0xff, all <= 0xffff
  • _UTF32CSE Indicates has at least 1 non-BMP character


The cse function returns the character set encoding for a string type, string. Returns RawUTF8CSE as a fallback for AbstractString (i.e. same as String) The charset function returns the character set for a string type, string, character type, or character. The encoding function returns the encoding for a type or string. The codeunit function returns the code unit used for a character set encoding The cs"..." string macro creates a CharSet type with that name The enc"..." string macro creates an Encoding type with that name The @cse(cs, enc) macro creates a character set encoding with the given character set and encoding

Also Exports the helpful constant Bool flags BIG_ENDIAN and LITTLE_ENDIAN