UTF-8 is a popular character encoding scheme that allows to represent strings as sequence of code points defined in Unicode standard. Its features are:
WARNING: For the vast majority of practical purposes of format
definitions in Kaitai Struct, you'd likely NOT want to use this and
rather just use type: str with encoding: utf-8. That will use
native string implementations, which are most likely more efficient
and will give you native language strings, rather than an array of
individual codepoints. This format definition is provided mostly
for educational / research purposes.
This page hosts a formal specification of UTF-8-encoded string using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for C# generated by Kaitai Struct depends on the C# runtime library. You have to install it before you can parse data.
The C# runtime library is available in the NuGet Gallery. Installation instructions can also be found there.
Parse a local file and get structure in memory:
var data = Utf8String.FromFile("path/to/local/file.txt");
Or parse structure from a byte array:
byte[] someArray = new byte[] { ... };
var data = new Utf8String(new KaitaiStream(someArray));
After that, one can get various attributes from the structure by accessing properties like:
data.Codepoints // => get codepoints
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
using System.Collections.Generic;
namespace Kaitai
{
/// <summary>
/// UTF-8 is a popular character encoding scheme that allows to
/// represent strings as sequence of code points defined in Unicode
/// standard. Its features are:
///
/// * variable width (i.e. one code point might be represented by 1 to 4
/// bytes)
/// * backward compatiblity with ASCII
/// * basic validity checking (and thus distinguishing from other legacy
/// 8-bit encodings)
/// * maintaining sort order of codepoints if sorted as a byte array
///
/// WARNING: For the vast majority of practical purposes of format
/// definitions in Kaitai Struct, you'd likely NOT want to use this and
/// rather just use `type: str` with `encoding: utf-8`. That will use
/// native string implementations, which are most likely more efficient
/// and will give you native language strings, rather than an array of
/// individual codepoints. This format definition is provided mostly
/// for educational / research purposes.
/// </summary>
public partial class Utf8String : KaitaiStruct
{
public static Utf8String FromFile(string fileName)
{
return new Utf8String(new KaitaiStream(fileName));
}
public Utf8String(KaitaiStream p__io, KaitaiStruct p__parent = null, Utf8String p__root = null) : base(p__io)
{
m_parent = p__parent;
m_root = p__root ?? this;
_read();
}
private void _read()
{
_codepoints = new List<Utf8Codepoint>();
{
var i = 0;
while (!m_io.IsEof) {
_codepoints.Add(new Utf8Codepoint(M_Io.Pos, m_io, this, m_root));
i++;
}
}
}
public partial class Utf8Codepoint : KaitaiStruct
{
public Utf8Codepoint(ulong p_ofs, KaitaiStream p__io, Utf8String p__parent = null, Utf8String p__root = null) : base(p__io)
{
m_parent = p__parent;
m_root = p__root;
_ofs = p_ofs;
f_raw1 = false;
f_lenBytes = false;
f_raw3 = false;
f_valueAsInt = false;
f_raw0 = false;
f_byte0 = false;
f_raw2 = false;
_read();
}
private void _read()
{
_bytes = m_io.ReadBytes(LenBytes);
}
private bool f_raw1;
private int? _raw1;
public int? Raw1
{
get
{
if (f_raw1)
return _raw1;
if (LenBytes >= 2) {
_raw1 = (int) ((Bytes[1] & 63));
}
f_raw1 = true;
return _raw1;
}
}
private bool f_lenBytes;
private int _lenBytes;
public int LenBytes
{
get
{
if (f_lenBytes)
return _lenBytes;
_lenBytes = (int) (((Byte0 & 128) == 0 ? 1 : ((Byte0 & 224) == 192 ? 2 : ((Byte0 & 240) == 224 ? 3 : ((Byte0 & 248) == 240 ? 4 : -1)))));
f_lenBytes = true;
return _lenBytes;
}
}
private bool f_raw3;
private int? _raw3;
public int? Raw3
{
get
{
if (f_raw3)
return _raw3;
if (LenBytes >= 4) {
_raw3 = (int) ((Bytes[3] & 63));
}
f_raw3 = true;
return _raw3;
}
}
private bool f_valueAsInt;
private int _valueAsInt;
public int ValueAsInt
{
get
{
if (f_valueAsInt)
return _valueAsInt;
_valueAsInt = (int) ((LenBytes == 1 ? Raw0 : (LenBytes == 2 ? ((Raw0 << 6) | Raw1) : (LenBytes == 3 ? (((Raw0 << 12) | (Raw1 << 6)) | Raw2) : (LenBytes == 4 ? ((((Raw0 << 18) | (Raw1 << 12)) | (Raw2 << 6)) | Raw3) : -1)))));
f_valueAsInt = true;
return _valueAsInt;
}
}
private bool f_raw0;
private int _raw0;
public int Raw0
{
get
{
if (f_raw0)
return _raw0;
_raw0 = (int) ((Bytes[0] & (LenBytes == 1 ? 127 : (LenBytes == 2 ? 31 : (LenBytes == 3 ? 15 : (LenBytes == 4 ? 7 : 0))))));
f_raw0 = true;
return _raw0;
}
}
private bool f_byte0;
private byte _byte0;
public byte Byte0
{
get
{
if (f_byte0)
return _byte0;
long _pos = m_io.Pos;
m_io.Seek(Ofs);
_byte0 = m_io.ReadU1();
m_io.Seek(_pos);
f_byte0 = true;
return _byte0;
}
}
private bool f_raw2;
private int? _raw2;
public int? Raw2
{
get
{
if (f_raw2)
return _raw2;
if (LenBytes >= 3) {
_raw2 = (int) ((Bytes[2] & 63));
}
f_raw2 = true;
return _raw2;
}
}
private byte[] _bytes;
private ulong _ofs;
private Utf8String m_root;
private Utf8String m_parent;
public byte[] Bytes { get { return _bytes; } }
public ulong Ofs { get { return _ofs; } }
public Utf8String M_Root { get { return m_root; } }
public Utf8String M_Parent { get { return m_parent; } }
}
private List<Utf8Codepoint> _codepoints;
private Utf8String m_root;
private KaitaiStruct m_parent;
public List<Utf8Codepoint> Codepoints { get { return _codepoints; } }
public Utf8String M_Root { get { return m_root; } }
public KaitaiStruct M_Parent { get { return m_parent; } }
}
}