/// <summary>
/// Parses the entity at the current position.
/// Assumes that there is a <c>&</c> at the current position.
/// </summary>
private static string ParseEntity(Subject subj)
{
int match;
string entity;
int numericEntity;
var origPos = subj.Position;
match = Scanner.scan_entity(subj.Buffer, subj.Position, subj.Length - subj.Position, out entity, out numericEntity);
if (match > 0)
{
subj.Position += match;
if (entity != null)
{
entity = EntityDecoder.DecodeEntity(entity);
if (entity != null)
{
return(entity);
}
return(subj.Buffer.Substring(origPos, match));
}
else if (numericEntity > 0)
{
entity = EntityDecoder.DecodeEntity(numericEntity);
if (entity != null)
{
return(entity);
}
}
return("\uFFFD");
}
else
{
subj.Position++;
return("&");
}
}
/// <summary>
/// Destructively unescape a string: remove backslashes before punctuation or symbol characters.
/// </summary>
/// <param name="url">The string data that will be changed by unescaping any punctuation or symbol characters.</param>
public static string Unescape(string url)
{
// remove backslashes before punctuation chars:
int searchPos = 0;
int lastPos = 0;
int match;
char c;
char[] search = new[] { '\\', '&' };
StringBuilder sb = null;
while ((searchPos = url.IndexOfAny(search, searchPos)) != -1)
{
c = url[searchPos];
if (c == '\\')
{
searchPos++;
if (url.Length == searchPos)
{
break;
}
c = url[searchPos];
if (Utilities.IsEscapableSymbol(c))
{
if (sb == null)
{
sb = new StringBuilder(url.Length);
}
sb.Append(url, lastPos, searchPos - lastPos - 1);
lastPos = searchPos;
}
}
else if (c == '&')
{
string namedEntity;
int numericEntity;
match = Scanner.scan_entity(url, searchPos, url.Length - searchPos, out namedEntity, out numericEntity);
if (match == 0)
{
searchPos++;
}
else
{
searchPos += match;
if (namedEntity != null)
{
var decoded = EntityDecoder.DecodeEntity(namedEntity);
if (decoded != null)
{
if (sb == null)
{
sb = new StringBuilder(url.Length);
}
sb.Append(url, lastPos, searchPos - match - lastPos);
sb.Append(decoded);
lastPos = searchPos;
}
}
else if (numericEntity > 0)
{
var decoded = EntityDecoder.DecodeEntity(numericEntity);
if (decoded != null)
{
if (sb == null)
{
sb = new StringBuilder(url.Length);
}
sb.Append(url, lastPos, searchPos - match - lastPos);
sb.Append(decoded);
}
else
{
if (sb == null)
{
sb = new StringBuilder(url.Length);
}
sb.Append(url, lastPos, searchPos - match - lastPos);
sb.Append('\uFFFD');
}
lastPos = searchPos;
}
}
}
}
if (sb == null)
{
return(url);
}
sb.Append(url, lastPos, url.Length - lastPos);
return(sb.ToString());
}
