/// <summary>
/// Decodes a string using URI encoding.
/// </summary>
/// <param name="value">The string to decode.</param>
/// <returns>The decoded string.</returns>
public static string UriDecode(string value)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
var sb = new StringBuilder();
for (int i = 0; i < value.Length; i++)
{
if (
value[i] == '%' &&
i < value.Length - 2 &&
CharEx.IsHex(value[i + 1]) &&
CharEx.IsHex(value[i + 2])
)
{
sb.Append(
(char)(CharEx.HexToInt(value[i + 1]) * 16 + CharEx.HexToInt(value[i + 2]))
);
i += 2;
}
else if (value[i] == '+')
{
sb.Append(' ');
}
else
{
sb.Append(value[i]);
}
}
return(sb.ToString());
}
/// <summary>
/// Decodes a string using HTML encoding.
/// </summary>
/// <param name="value">The string to be decoded.</param>
/// <returns>The decode string.</returns>
public static string HtmlDecode(string value)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
var sb = new StringBuilder();
for (int i = 0; i < value.Length; i++)
{
if (value[i] == '&' && value.Length > i + 2)
{
// Scan for the ;.
int maxSearch = Math.Min(value.Length, i + _longestHtmlEntity + 2);
int endPosition = -1;
for (int j = i + 1; j < maxSearch; j++)
{
if (value[j] == ';')
{
endPosition = j;
break;
}
}
// If we did not find an end separator, just skip over this
// entity and treat is at text.
if (endPosition == -1)
{
sb.Append(value[i]);
continue;
}
// Are we in a numeric separator?
if (value[i + 1] == '#')
{
int offset = 2;
bool isHexNumeric = false;
if (value[i + 2] == 'x' || value[i + 2] == 'X')
{
isHexNumeric = true;
offset++;
}
// All parts of the numeric separator must be digits.
bool isNumeric = true;
for (int j = i + offset; j < endPosition; j++)
{
if (!(
Char.IsDigit(value[j]) ||
(isHexNumeric && CharEx.IsHex(value[j]))
))
{
isNumeric = false;
break;
}
}
// If not all numeric, just skip over this
// entity and treat is at text.
if (!isNumeric)
{
sb.Append(value[i]);
continue;
}
// Convert the numeric entity to unicode.
string numericEntity = value.Substring(i + offset, endPosition - (i + offset));
sb.Append((char)int.Parse(numericEntity, isHexNumeric ? NumberStyles.HexNumber : NumberStyles.Integer));
i = endPosition;
}
else
{
string entity = value.Substring(i + 1, endPosition - (i + 1));
int codePoint;
if (_htmlEntities.TryGetValueByItem1(entity, out codePoint))
{
sb.Append((char)codePoint);
i = endPosition;
}
else
{
// If we don't know the entity, just skip over this
// entity and treat is at text.
sb.Append(value[i]);
}
}
}
else
{
sb.Append(value[i]);
}
}
return(sb.ToString());
}
public static string StringDecode(string value)
{
if (String.IsNullOrEmpty(value))
{
return(value);
}
var state = StringDecodeState.None;
var sb = new StringBuilder();
var escapeCache = new StringBuilder();
int i = 0;
while (i <= value.Length)
{
char c;
bool atEnd = i == value.Length;
if (i < value.Length)
{
c = value[i];
}
else
{
c = '\0';
}
switch (state)
{
case StringDecodeState.None:
if (!atEnd)
{
if (c == '\\')
{
state = StringDecodeState.Escape;
}
else
{
sb.Append(c);
}
}
break;
case StringDecodeState.Escape:
if (atEnd)
{
sb.Append('\\');
}
else
{
switch (Char.ToLowerInvariant(c))
{
case 'a': sb.Append('\a'); break;
case 'b': sb.Append('\b'); break;
case 't': sb.Append('\t'); break;
case 'r': sb.Append('\r'); break;
case 'v': sb.Append('\v'); break;
case 'f': sb.Append('\f'); break;
case 'n': sb.Append('\n'); break;
case 'e': sb.Append('\u001B'); break;
case '\'': sb.Append('\''); break;
case '"': sb.Append('"'); break;
case '\\': sb.Append('\\'); break;
case 'u': state = StringDecodeState.UnicodeEscape; break;
case 'x': state = StringDecodeState.HexEscape; break;
default:
if (CharEx.IsOct(c))
{
i--;
state = StringDecodeState.OctEscape;
}
else
{
sb.Append(c);
}
break;
}
if (state == StringDecodeState.Escape)
{
state = StringDecodeState.None;
}
}
break;
case StringDecodeState.OctEscape:
if (
!atEnd &&
CharEx.IsOct(c) &&
escapeCache.Length < 3
)
{
escapeCache.Append(c);
}
else
{
if (escapeCache.Length > 0)
{
sb.Append(CharEx.FromOct(escapeCache.ToString()));
}
if (!atEnd)
{
state = StringDecodeState.None;
escapeCache = new StringBuilder();
i--;
}
}
break;
case StringDecodeState.HexEscape:
case StringDecodeState.UnicodeEscape:
if (
!atEnd &&
CharEx.IsHex(c) &&
escapeCache.Length < (state == StringDecodeState.HexEscape ? 2 : 4)
)
{
escapeCache.Append(c);
}
else
{
if (escapeCache.Length == 0)
{
sb.Append(state == StringDecodeState.HexEscape ? 'x' : 'u');
}
else
{
sb.Append(CharEx.FromHex(escapeCache.ToString()));
}
if (!atEnd)
{
state = StringDecodeState.None;
escapeCache = new StringBuilder();
i--;
}
}
break;
default:
Debug.Fail("Illegal state");
return(null);
}
i++;
}
return(sb.ToString());
}
