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using System;
using System.Text;
namespace AngleSharp
{
/// <summary>
/// Various HTML encoding helpers.
/// </summary>
static class HtmlEncoding
{
public const String CHARSET = "charset";
/// <summary>
/// Tries to extract the encoding from the given http-equiv content string.
/// </summary>
/// <param name="content">The value of the attribute.</param>
/// <returns>The extracted encoding or an empty string.</returns>
public static String Extract(String content)
{
var position = 0;
content = content.ToLower();
for (int i = position; i < content.Length - 7; i++)
{
if (content.Substring(i).StartsWith(CHARSET))
{
position = i + 7;
break;
}
}
if (position > 0 && position < content.Length)
{
for (int i = position; i < content.Length - 1; i++)
{
if (Specification.IsSpaceCharacter(content[i]))
position++;
else
break;
}
if (content[position] != Specification.EQ)
return Extract(content.Substring(position));
position++;
for (int i = position; i < content.Length; i++)
{
if (Specification.IsSpaceCharacter(content[i]))
position++;
else
break;
}
if (position < content.Length)
{
if (content[position] == Specification.DQ)
{
content = content.Substring(position + 1);
var index = content.IndexOf(Specification.DQ);
if (index != -1)
return content.Substring(0, index);
}
else if (content[position] == Specification.SQ)
{
content = content.Substring(position + 1);
var index = content.IndexOf(Specification.SQ);
if (index != -1)
return content.Substring(0, index);
}
else
{
content = content.Substring(position);
var index = 0;
for (int i = 0; i < content.Length; i++)
{
if (Specification.IsSpaceCharacter(content[i]))
break;
else if (content[i] == ';')
break;
else
index++;
}
return content.Substring(0, index);
}
}
}
return String.Empty;
}
/// <summary>
/// Detects if a valid encoding has been found in the given charset string.
/// </summary>
/// <param name="charset">The parsed charset string.</param>
/// <returns>True if a valid encdoing has been found, otherwise false.</returns>
public static Boolean IsSupported(String charset)
{
return Resolve(charset) != null;
}
/// <summary>
/// Resolves an Encoding instance given by the charset string.
/// </summary>
/// <param name="charset">The charset string.</param>
/// <returns>An instance of the Encoding class or null.</returns>
public static Encoding Resolve(String charset)
{
charset = charset.ToLower();
switch (charset)
{
case "unicode-1-1-utf-8":
case "utf-8":
case "utf8":
return Encoding.UTF8;
case "utf-16be":
return Encoding.BigEndianUnicode;
case "utf-16":
case "utf-16le":
return Encoding.Unicode;
case "dos-874":
case "iso-8859-11":
case "iso8859-11":
case "iso885911":
case "tis-620":
case "windows-874":
return Encoding.GetEncoding(874);
case "cp1250":
case "windows-1250":
case "x-cp1250":
return Encoding.GetEncoding(1250);
case "cp1251":
case "windows-1251":
case "x-cp1251":
return Encoding.GetEncoding(1251);
case "ansi_x3.4-1968":
case "ascii":
case "cp1252":
case "cp819":
case "csisolatin1":
case "ibm819":
case "iso-8859-1":
case "iso-ir-100":
case "iso8859-1":
case "iso88591":
case "iso_8859-1":
case "iso_8859-1:1987":
case "l1":
case "latin1":
case "us-ascii":
case "windows-1252":
case "x-cp1252":
return Encoding.GetEncoding(1252);
case "cp1253":
case "windows-1253":
case "x-cp1253":
return Encoding.GetEncoding(1253);
case "cp1254":
case "csisolatin5":
case "iso-8859-9":
case "iso-ir-148":
case "iso8859-9":
case "iso88599":
case "iso_8859-9":
case "iso_8859-9:1989":
case "l5":
case "latin5":
case "windows-1254":
case "x-cp1254":
return Encoding.GetEncoding(1254);
case "cp1255":
case "windows-1255":
case "x-cp1255":
return Encoding.GetEncoding(1255);
case "cp1256":
case "windows-1256":
case "x-cp1256":
return Encoding.GetEncoding(1256);
case "cp1257":
case "windows-1257":
case "x-cp1257":
return Encoding.GetEncoding(1257);
case "cp1258":
case "windows-1258":
case "x-cp1258":
return Encoding.GetEncoding(1258);
case "csmacintosh":
case "mac":
case "macintosh":
case "x-mac-roman":
return Encoding.GetEncoding(10000);
case "x-mac-cyrillic":
case "x-mac-ukrainian":
return Encoding.GetEncoding(10007);
case "866":
case "cp866":
case "csibm866":
case "ibm866":
return Encoding.GetEncoding(866);
case "csisolatin2":
case "iso-8859-2":
case "iso-ir-101":
case "iso8859-2":
case "iso88592":
case "iso_8859-2":
case "iso_8859-2:1987":
case "l2":
case "latin2":
return Encoding.GetEncoding(28592);
case "csisolatin3":
case "iso-8859-3":
case "iso-ir-109":
case "iso8859-3":
case "iso88593":
case "iso_8859-3":
case "iso_8859-3:1988":
case "l3":
case "latin3":
return Encoding.GetEncoding(28593);
case "csisolatin4":
case "iso-8859-4":
case "iso-ir-110":
case "iso8859-4":
case "iso88594":
case "iso_8859-4":
case "iso_8859-4:1988":
case "l4":
case "latin4":
return Encoding.GetEncoding(28594);
case "csisolatincyrillic":
case "cyrillic":
case "iso-8859-5":
case "iso-ir-144":
case "iso8859-5":
case "iso88595":
case "iso_8859-5":
case "iso_8859-5:1988":
return Encoding.GetEncoding(28595);
case "arabic":
case "asmo-708":
case "csiso88596e":
case "csiso88596i":
case "csisolatinarabic":
case "ecma-114":
case "iso-8859-6":
case "iso-8859-6-e":
case "iso-8859-6-i":
case "iso-ir-127":
case "iso8859-6":
case "iso88596":
case "iso_8859-6":
case "iso_8859-6:1987":
return Encoding.GetEncoding(28596);
case "csisolatingreek":
case "ecma-118":
case "elot_928":
case "greek":
case "greek8":
case "iso-8859-7":
case "iso-ir-126":
case "iso8859-7":
case "iso88597":
case "iso_8859-7":
case "iso_8859-7:1987":
case "sun_eu_greek":
return Encoding.GetEncoding(28597);
case "csiso88598e":
case "csisolatinhebrew":
case "hebrew":
case "iso-8859-8":
case "iso-8859-8-e":
case "iso-ir-138":
case "iso8859-8":
case "iso88598":
case "iso_8859-8":
case "iso_8859-8:1988":
case "visual":
return Encoding.GetEncoding(28598);
case "csiso88598i":
case "iso-8859-8-i":
case "logical":
return Encoding.GetEncoding(38598);
case "iso-8859-13":
case "iso8859-13":
case "iso885913":
return Encoding.GetEncoding(28603);
case "csisolatin9":
case "iso-8859-15":
case "iso8859-15":
case "iso885915":
case "iso_8859-15":
case "l9":
return Encoding.GetEncoding(28605);
case "cskoi8r":
case "koi":
case "koi8":
case "koi8-r":
case "koi8_r":
return Encoding.GetEncoding(20866);
case "koi8-u":
return Encoding.GetEncoding(21866);
case "chinese":
case "csgb2312":
case "csiso58gb231280":
case "gb2312":
case "gb_2312":
case "gb_2312-80":
case "gbk":
case "iso-ir-58":
case "x-gbk":
return Encoding.GetEncoding(20936);
case "hz-gb-2312":
return Encoding.GetEncoding(52936);
case "gb18030":
return Encoding.GetEncoding(54936);
case "big5":
case "big5-hkscs":
case "cn-big5":
case "csbig5":
case "x-x-big5":
return Encoding.GetEncoding(950);
case "csiso2022jp":
case "iso-2022-jp":
return Encoding.GetEncoding(50222);
case "csiso2022kr":
case "iso-2022-kr":
return Encoding.GetEncoding(50225);
case "iso-2022-cn":
case "iso-2022-cn-ext":
return Encoding.GetEncoding(50220);
default:
return null;
}
}
/// <summary>
/// Suggests an Encoding for the given local.
/// </summary>
/// <param name="local">The local defined by the BCP 47 language tag.</param>
/// <returns>The suggested encoding.</returns>
public static Encoding Suggest(string local)
{
var firstTwo = local.Substring(0, 2).ToLower();
switch(firstTwo)
{
case "ar":
case "cy":
case "fa":
case "hr":
case "kk":
case "mk":
case "or":
case "ro":
case "sr":
case "vi":
return Encoding.UTF8;
case "be":
return Encoding.GetEncoding(28595);
case "bg":
case "ru":
case "uk":
return Encoding.GetEncoding(1251);
case "cs":
case "hu":
case "pl":
case "sl":
return Encoding.GetEncoding(28592);
case "tr":
case "ku":
return Encoding.GetEncoding(1254);
case "he":
return Encoding.GetEncoding(1255);
case "lv":
return Encoding.GetEncoding(28603);
case "ja":// Windows-31J ???? Replaced by something better anyway
return Encoding.UTF8;
case "ko":
return Encoding.GetEncoding(949);
case "lt":
return Encoding.GetEncoding(1257);
case "sk":
return Encoding.GetEncoding(1250);
case "th":
return Encoding.GetEncoding(874);
}
if (local.Equals("zh-CN", StringComparison.OrdinalIgnoreCase))
return Encoding.GetEncoding(54936);
else if (local.Equals("zh-TW", StringComparison.OrdinalIgnoreCase))
return Encoding.GetEncoding(950);
return Encoding.GetEncoding(1252);
}
}
}
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Florian lives in Munich, Germany. He started his programming career with Perl. After programming C/C++ for some years he discovered his favorite programming language C#. He did work at Siemens as a programmer until he decided to study Physics.
During his studies he worked as an IT consultant for various companies. After graduating with a PhD in theoretical particle Physics he is working as a senior technical consultant in the field of home automation and IoT.
Florian has been giving lectures in C#, HTML5 with CSS3 and JavaScript, software design, and other topics. He is regularly giving talks at user groups, conferences, and companies. He is actively contributing to open-source projects. Florian is the maintainer of AngleSharp, a completely managed browser engine.
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