/// <summary>
///
/// </summary>
/// <param name="stream"></param>
/// <returns></returns>
/// <remarks>
///
/// See https://www.dmtf.org/sites/default/files/standards/documents/DSP0221_3.0.1.pdf
///
/// 5.4 Comments
///
/// Comments in a MOF file do not create, modify, or annotate language elements. They shall be treated as if
/// they were whitespace.
///
/// Comments may appear anywhere in MOF syntax where whitespace is allowed and are indicated by either
/// a leading double slash (//) or a pair of matching /* and */ character sequences. Occurrences of these
/// character sequences in string literals shall not be treated as comments.
///
/// A // comment is terminated by the end of line (see 5.3), as shown in the example below.
///
/// Integer MyProperty; // This is an example of a single-line comment
///
/// A comment that begins with /* is terminated by the next */ sequence, or by the end of the MOF file,
/// whichever comes first.
///
/// /* example of a comment between property definition tokens and a multi-line comment */
/// Integer /* 16-bit integer property */ MyProperty; /* and a multi-line
/// comment */
///
/// </remarks>
public static (CommentToken, Lexer) ReadCommentToken(SourceReader reader)
{
var thisReader = reader;
var sourceChar = default(SourceChar);
var sourceChars = new List <SourceChar>();
// read the starting '/'
(sourceChar, thisReader) = thisReader.Read('/');
sourceChars.Add(sourceChar);
switch (thisReader.Peek().Value)
{
case '/': // single-line
(sourceChar, thisReader) = thisReader.Read('/');
sourceChars.Add(sourceChar);
// read the comment text
while (!thisReader.Eof() && !thisReader.Peek(StringValidator.IsLineTerminator))
{
(sourceChar, thisReader) = thisReader.Read();
sourceChars.Add(sourceChar);
}
;
break;
case '*': // multi-line
(sourceChar, thisReader) = thisReader.Read('*');
sourceChars.Add(sourceChar);
// read the comment text
while (!thisReader.Eof())
{
(sourceChar, thisReader) = thisReader.Read();
sourceChars.Add(sourceChar);
if ((sourceChar.Value == '*') && thisReader.Peek('/'))
{
// read the closing sequence
(sourceChar, thisReader) = thisReader.Read('/');
sourceChars.Add(sourceChar);
break;
}
}
break;
default:
throw new UnexpectedCharacterException(reader.Peek());
}
// return the result
var extent = SourceExtent.From(sourceChars);
return(new CommentToken(extent), new Lexer(thisReader));
}
public ScannerResult ReadToken(SourceReader reader)
{
var peek = reader.Peek();
// make sure the rule for the next character is in the rule cache
if (!this.ScannerCache.ContainsKey(peek.Value))
{
this.ScannerCache.Add(
peek.Value,
this.Scanners.FirstOrDefault(r => r.Match.Matches(peek.Value))
?? throw new UnexpectedCharacterException(peek)
);
}
// apply the scanner for the next character
return(this.ScannerCache[peek.Value].Action.Invoke(reader));
}
public IEnumerable <Token> Scan()
{
while (!reader.EndOfStream)
{
reader.ReadWhile(Char.IsWhiteSpace);
var startLocation = reader.Location;
var lexeme = String.Empty;
var tokenKind = TokenKind.Unknown;
var c = (char)reader.Peek();
switch (c)
{
case '+':
reader.Read();
tokenKind = TokenKind.Plus;
lexeme = "+";
break;
case '-':
reader.Read();
tokenKind = TokenKind.Minus;
lexeme = "-";
break;
case '*':
reader.Read();
tokenKind = TokenKind.Mul;
lexeme = "*";
break;
case '/':
reader.Read();
tokenKind = TokenKind.Div;
lexeme = "/";
break;
case '(':
reader.Read();
tokenKind = TokenKind.LParen;
lexeme = "(";
break;
case ')':
reader.Read();
tokenKind = TokenKind.RParen;
lexeme = ")";
break;
case '[':
reader.Read();
tokenKind = TokenKind.LBracket;
lexeme = "[";
break;
case ']':
reader.Read();
tokenKind = TokenKind.RBracket;
lexeme = "]";
break;
case '{':
reader.Read();
tokenKind = TokenKind.LCurly;
lexeme = "{";
break;
case '}':
reader.Read();
tokenKind = TokenKind.RCurly;
lexeme = "}";
break;
case ',':
reader.Read();
tokenKind = TokenKind.Comma;
lexeme = ",";
break;
case '.':
reader.Read();
tokenKind = TokenKind.Period;
lexeme = ".";
break;
case ';':
reader.Read();
tokenKind = TokenKind.Semicolon;
lexeme = ";";
break;
case ':':
reader.Read();
tokenKind = TokenKind.Colon;
lexeme = ":";
break;
case '?':
reader.Read();
if (reader.Peek() == '?')
{
reader.Read();
tokenKind = TokenKind.QMark2;
lexeme = "??";
}
else
{
tokenKind = TokenKind.QMark;
lexeme = "?";
}
break;
case '!':
reader.Read();
tokenKind = TokenKind.EMark;
lexeme = "!";
break;
default:
if (Char.IsDigit(c))
{
lexeme = reader.ReadWhile(Char.IsDigit);
tokenKind = TokenKind.Number;
}
else if (Char.IsLetterOrDigit(c))
{
lexeme = reader.ReadWhile(Char.IsLetterOrDigit);
if (!keywords.TryGetValue(lexeme, out tokenKind))
{
tokenKind = TokenKind.Ident;
}
}
else
{
lexeme = reader.ReadWhile(x => !Char.IsWhiteSpace(x));
}
break;
}
yield return(new Token(tokenKind, lexeme, new TextSpan(startLocation, reader.Location)));
}
yield return(new Token(TokenKind.Eof, "end of file", new TextSpan(reader.Location, reader.Location)));
}
