private object ReadToken(MyReader source, ParseContext context)
{
ReadWhitespace(source);
Location loc = new Location(source.Line, source.Col);
int firstchar = source.Read();
if (firstchar == -1)
{
return("");
}
StringBuilder b = readTokenBuffer; readTokenBuffer.Length = 0;
b.Append((char)firstchar);
if (firstchar == '<')
{
// This is a URI or the <= verb. URIs can have \'s and <'s escaped with a backslash, plus \u and \U notation.
bool escaped = false;
while (true)
{
int c = source.Read();
if (c == -1)
{
OnError("Unexpected end of stream within a token beginning with <", loc);
}
if (b.Length == 2 && c == '=')
{
return("<="); // the <= verb
}
if (escaped)
{
ReadEscapedChar((char)c, b, source, loc, true, true, false);
// the first flag should be set true only if not NTriples, but we are flexible on reading.
// the second flag should be set true only if NTriples, but we are flexible on reading.
escaped = false;
}
else if (c == '\\')
{
escaped = true;
}
else
{
b.Append((char)c);
if (c == '>') // end of the URI
{
break;
}
}
}
}
else if (firstchar == '"')
{
// This can either be a string "..." or a longString """...""", which additionally allows embedded \n, \r, and \t, and quotes.
b.Length = 0; // get rid of the open quote
bool escaped = false;
bool triplequoted = false;
while (true)
{
int c = source.Read();
if (c == -1)
{
OnError("Unexpected end of stream within a string", loc);
}
// Check if this is started by three quotes. If we've already read three quotes, don't keep checking or we can't read """""".
if (b.Length == 0 && c == (int)'"' && source.Peek() == (int)'"' && !triplequoted)
{
triplequoted = true;
source.Read();
continue;
}
if (escaped)
{
ReadEscapedChar((char)c, b, source, loc, false, true, true); // the last flag should be set true only if N3, but we are flexible on reading
escaped = false;
}
else if (c == '\\')
{
escaped = true;
}
else
{
if (c == '"' && !triplequoted)
{
break;
}
if (c == '"' && source.Peek() == '"' && source.Peek2() == '"' && triplequoted)
{
break;
}
b.Append((char)c);
}
}
if (triplequoted) // read the extra end quotes
{
source.Read();
source.Read();
}
string litvalue = b.ToString();
string litlang = null;
string litdt = null;
// Strings can be suffixed with @langcode or ^^symbol (but not both?).
if (source.Peek() == '@')
{
source.Read();
b.Length = 0;
while (char.IsLetterOrDigit((char)source.Peek()) || source.Peek() == (int)'-')
{
b.Append((char)source.Read());
}
litlang = b.ToString();
}
else if (source.Peek() == '^' && source.Peek2() == '^')
{
loc = new Location(source.Line, source.Col);
source.Read();
source.Read();
litdt = ReadToken(source, context).ToString(); // better be a string URI
if (litdt.StartsWith("<") && litdt.EndsWith(">"))
{
litdt = litdt.Substring(1, litdt.Length - 2);
}
else if (litdt.IndexOf(":") != -1)
{
Resource r = ResolveQName(litdt, context, loc);
if (r.Uri == null)
{
OnError("A literal datatype cannot be an anonymous entity", loc);
}
litdt = r.Uri;
}
}
Literal literal = new Literal(litvalue, litlang, litdt);
ValidateLiteral(literal);
return(literal);
}
else if (char.IsLetter((char)firstchar) || firstchar == '?' || firstchar == '@' || firstchar == ':' || firstchar == '_')
{
// Something starting with @
// A QName: ([a-zA-Z_][a-zA-Z0-9_]*)?:)?([a-zA-Z_][a-zA-Z0-9_]*)?
// A variable: \?[a-zA-Z_][a-zA-Z0-9_]*
while (true)
{
int c = source.Peek();
if (c == -1 || (!Entity.ValidateUriIsIUnreserved((char)c) && c != ':') || c == '.')
{
break;
}
b.Append((char)source.Read());
}
}
else if (char.IsDigit((char)firstchar) || firstchar == '+' || firstchar == '-')
{
while (true)
{
int ci = source.Peek();
if (ci == -1)
{
break;
}
if (ci == ']' || ci == ')' || ci == '}')
{
break;
}
// punctuation followed by a space means the punctuation is
// punctuation, and not part of this token
if (!char.IsDigit((char)ci) && source.Peek2() != -1 && char.IsWhiteSpace((char)source.Peek2()))
{
break;
}
char c = (char)ci;
if (char.IsWhiteSpace(c))
{
break;
}
b.Append((char)source.Read());
}
}
else if (firstchar == '=')
{
if (source.Peek() == (int)'>')
{
b.Append((char)source.Read());
}
if (source.Peek() == (int)':' && source.Peek2() == (int)'>') // SPECIAL EXTENSION "=:>"
{
b.Append((char)source.Read());
b.Append((char)source.Read());
}
}
else if (firstchar == '[')
{
// The start of an anonymous node.
}
else if (firstchar == '{')
{
return("{");
}
else if (firstchar == '(')
{
return("(");
}
else if (firstchar == ')')
{
return(")");
}
else
{
while (true)
{
int c = source.Read();
if (c == -1)
{
break;
}
if (char.IsWhiteSpace((char)c))
{
break;
}
b.Append((char)c);
}
OnError("Invalid token: " + b.ToString(), loc);
}
return(b.ToString());
}
private object ReadToken(MyReader source, ParseContext context)
{
ReadWhitespace(source);
Location loc = new Location(source.Line, source.Col);
int firstchar = source.Read();
if (firstchar == -1)
{
return("");
}
StringBuilder b = readTokenBuffer; readTokenBuffer.Length = 0;
b.Append((char)firstchar);
if (firstchar == '<')
{
// This is a URI or the <= verb. URIs can be escaped like strings, at least in the NTriples spec.
bool escaped = false;
while (true)
{
int c = source.Read();
if (c == -1)
{
OnError("Unexpected end of stream within a token beginning with <", loc);
}
if (b.Length == 2 && c == '=')
{
return("<="); // the <= verb
}
if (escaped)
{
ReadEscapedChar((char)c, b, source, loc);
escaped = false;
}
else if (c == '\\')
{
escaped = true;
}
else
{
b.Append((char)c);
if (c == '>') // end of the URI
{
break;
}
}
}
}
else if (firstchar == '"')
{
// A string: ("""[^"\\]*(?:(?:\\.|"(?!""))[^"\\]*)*""")|("[^"\\]*(?:\\.[^"\\]*)*")
// What kind of crazy regex is this??
b.Length = 0; // get rid of the open quote
bool escaped = false;
bool triplequoted = false;
while (true)
{
int c = source.Read();
if (c == -1)
{
OnError("Unexpected end of stream within a string", loc);
}
if (b.Length == 0 && c == (int)'"' && source.Peek() == (int)'"')
{
triplequoted = true;
source.Read();
continue;
}
if (!escaped && c == '\\')
{
escaped = true;
}
else if (escaped)
{
ReadEscapedChar((char)c, b, source, loc);
escaped = false;
}
else
{
if (c == '"' && !triplequoted)
{
break;
}
if (c == '"' && source.Peek() == '"' && source.Peek2() == '"' && triplequoted)
{
break;
}
b.Append((char)c);
}
}
if (triplequoted) // read the extra end quotes
{
source.Read();
source.Read();
}
string litvalue = b.ToString();
string litlang = null;
string litdt = null;
// Strings can be suffixed with @langcode or ^^symbol (but not both?).
if (source.Peek() == '@')
{
source.Read();
b.Length = 0;
while (char.IsLetterOrDigit((char)source.Peek()) || source.Peek() == (int)'-')
{
b.Append((char)source.Read());
}
litlang = b.ToString();
}
else if (source.Peek() == '^' && source.Peek2() == '^')
{
loc = new Location(source.Line, source.Col);
source.Read();
source.Read();
litdt = ReadToken(source, context).ToString(); // better be a string URI
if (litdt.StartsWith("<") && litdt.EndsWith(">"))
{
litdt = litdt.Substring(1, litdt.Length - 2);
}
else if (litdt.IndexOf(":") != -1)
{
Resource r = ResolveQName(litdt, context, loc);
if (r.Uri == null)
{
OnError("A literal datatype cannot be an anonymous entity", loc);
}
litdt = r.Uri;
}
}
return(new Literal(litvalue, litlang, litdt));
}
else if (char.IsLetter((char)firstchar) || firstchar == '?' || firstchar == '@' || firstchar == ':' || firstchar == '_')
{
// Something starting with @
// A QName: ([a-zA-Z_][a-zA-Z0-9_]*)?:)?([a-zA-Z_][a-zA-Z0-9_]*)?
// A variable: \?[a-zA-Z_][a-zA-Z0-9_]*
while (true)
{
int c = source.Peek();
if (c == -1 || (!Entity.ValidateUriIsIUnreserved((char)c) && c != ':') || c == '.')
{
break;
}
b.Append((char)source.Read());
}
}
else if (char.IsDigit((char)firstchar) || firstchar == '+' || firstchar == '-')
{
while (true)
{
int ci = source.Peek();
if (ci == -1)
{
break;
}
if (ci == ']' || ci == ')' || ci == '}')
{
break;
}
// punctuation followed by a space means the punctuation is
// punctuation, and not part of this token
if (!char.IsDigit((char)ci) && source.Peek2() != -1 && char.IsWhiteSpace((char)source.Peek2()))
{
break;
}
char c = (char)ci;
if (char.IsWhiteSpace(c))
{
break;
}
b.Append((char)source.Read());
}
}
else if (firstchar == '=')
{
if (source.Peek() == (int)'>')
{
b.Append((char)source.Read());
}
if (source.Peek() == (int)':' && source.Peek2() == (int)'>') // SPECIAL EXTENSION "=:>"
{
b.Append((char)source.Read());
b.Append((char)source.Read());
}
}
else if (firstchar == '[')
{
// The start of an anonymous node.
}
else if (firstchar == '{')
{
return("{");
}
else if (firstchar == '(')
{
return("(");
}
else if (firstchar == ')')
{
return(")");
}
else
{
while (true)
{
int c = source.Read();
if (c == -1)
{
break;
}
if (char.IsWhiteSpace((char)c))
{
break;
}
b.Append((char)c);
}
OnError("Invalid token: " + b.ToString(), loc);
}
return(b.ToString());
}
