public SyntaxToken Lex()
{
_start = _position;
_kind = SyntaxKind.BadToken;
_value = null;
switch (Current)
{
case '\0':
_kind = SyntaxKind.EndOfFileToken;
break;
case '+':
_kind = SyntaxKind.PlusToken;
_position++;
break;
case '-':
_kind = SyntaxKind.MinusToken;
_position++;
break;
case '*':
_position++;
if (Current != '*')
{
_kind = SyntaxKind.StarToken;
}
else
{
_position++;
_kind = SyntaxKind.StarStarToken;
}
break;
case '/':
_kind = SyntaxKind.SlashToken;
_position++;
break;
case '%':
_kind = SyntaxKind.RemainderToken;
_position++;
break;
case ':':
_kind = SyntaxKind.ColonToken;
_position++;
break;
case '<':
_position++;
if (Current != '=')
{
_kind = SyntaxKind.LessThanToken;
}
else
{
_position++;
_kind = SyntaxKind.LessOrEqualToken;
}
break;
case '>':
_position++;
if (Current != '=')
{
_kind = SyntaxKind.GreaterThanToken;
}
else
{
_position++;
_kind = SyntaxKind.GreaterOrEqualToken;
}
break;
case '(':
_kind = SyntaxKind.OpenParenthesisToken;
_position++;
break;
case ')':
_kind = SyntaxKind.CloseParenthesisToken;
_position++;
break;
case ',':
_kind = SyntaxKind.CommaToken;
_position++;
break;
case '~':
_kind = SyntaxKind.TildToken;
_position++;
break;
case '^':
_kind = SyntaxKind.HatToken;
_position++;
break;
case '{':
_kind = SyntaxKind.OpenBraceToken;
_position++;
break;
case '}':
_kind = SyntaxKind.CloseBraceToken;
_position++;
break;
case '&':
_position++;
if (Current != '&')
{
_kind = SyntaxKind.AmpersandToken;
}
else
{
_position++;
_kind = SyntaxKind.AmpersandAmpersandToken;
}
break;
case '|':
_position++;
if (Current != '|')
{
_kind = SyntaxKind.PipeToken;
}
else
{
_position++;
_kind = SyntaxKind.PipePieToken;
}
break;
case '=':
_position++;
if (Current != '=')
{
_kind = SyntaxKind.EaqlesToken;
}
else
{
_position++;
_kind = SyntaxKind.EaqulesEaqlesToken;
}
break;
case '!':
_position++;
if (Current != '=')
{
_kind = SyntaxKind.BangToken;
}
else
{
_kind = SyntaxKind.BangEaqlesToken;
_position++;
}
break;
case '\"':
ReadString();
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
ReadNumberToken();
break;
case ' ':
case '\t':
case '\n':
case '\r':
ReadWhiteSpace();
break;
default:
if (char.IsLetter(Current))
{
ReadIdentifierOrKeyword();
}
else if (char.IsWhiteSpace(Current))
{
ReadWhiteSpace();
}
else
{
_diagnostics.ReportBadCharactor(_position, Current);
_position++;
}
break;
}
var length = _position - _start;
var text = SyntaxFacts.GetText(_kind);
if (text == null)
{
text = _text.ToString(_start, length);
}
return(new SyntaxToken(_kind, _start, text, _value));
}
public SyntaxToken Lex()
{
if (_position >= _text.Length)
{
return(new SyntaxToken(SyntaxKind.EndOfFileToken, _position, "\0", null));
}
var start = _position;
// number
if (char.IsDigit(Current))
{
while (char.IsDigit(Current))
{
Next();
}
var length = _position - start;
var text = _text.Substring(start, length);
if (!int.TryParse(text, out var value))
{
_diagnostics.ReportInvalidNumber(new TextSpan(start, length), _text, typeof(int));
}
return(new SyntaxToken(SyntaxKind.NumberToken, start, text, value));
}
// whitespace
if (char.IsWhiteSpace(Current))
{
while (char.IsWhiteSpace(Current))
{
Next();
}
var length = _position - start;
var text = _text.Substring(start, length);
return(new SyntaxToken(SyntaxKind.WhitespaceToken, start, text, null));
}
if (char.IsLetter(Current))
{
while (char.IsLetter(Current))
{
Next();
}
var length = _position - start;
var text = _text.Substring(start, length);
var kind = SyntaxFacts.GetKeywordKind(text);
return(new SyntaxToken(kind, start, text, null));
}
// operator
switch (Current)
{
case '+':
return(new SyntaxToken(SyntaxKind.PlusToken, _position++, "+", null));
case '-':
return(new SyntaxToken(SyntaxKind.MinusToken, _position++, "-", null));
case '*':
return(new SyntaxToken(SyntaxKind.StarToken, _position++, "*", null));
case '/':
return(new SyntaxToken(SyntaxKind.SlashToken, _position++, "/", null));
case '(':
return(new SyntaxToken(SyntaxKind.OpenParenthesisToken, _position++, "(", null));
case ')':
return(new SyntaxToken(SyntaxKind.CloseParenthesisToken, _position++, ")", null));
case '&':
if (Lookahead == '&')
{
_position += 2;
return(new SyntaxToken(SyntaxKind.AmpersandAmpersandToken, start, "&&", null));
}
break;
case '|':
if (Lookahead == '|')
{
_position += 2;
return(new SyntaxToken(SyntaxKind.PipePipeToken, start, "||", null));
}
break;
case '=':
if (Lookahead == '=')
{
_position += 2;
return(new SyntaxToken(SyntaxKind.EqualsEqualsToken, start, "==", null));
}
break;
case '!':
if (Lookahead == '=')
{
_position += 2;
return(new SyntaxToken(SyntaxKind.BangEqualsToken, start, "!=", null));
}
else
{
_position += 1;
return(new SyntaxToken(SyntaxKind.BangToken, start, "!", null));
}
}
_diagnostics.ReportBadCharactor(_position, Current);
return(new SyntaxToken(SyntaxKind.BadToken, _position++, _text.Substring(_position - 1, 1), null));
}
