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 '*':
_kind = SyntaxKind.StarToken;
_position++;
break;
case '/':
_kind = SyntaxKind.SlashToken;
_position++;
break;
case '(':
_kind = SyntaxKind.OpenParenthesisToken;
_position++;
break;
case ')':
_kind = SyntaxKind.CloseParenthesisToken;
_position++;
break;
case '&':
if (Lookahead == '&')
{
_kind = SyntaxKind.AmpersandAmpersandToken;
_position += 2;
}
break;
case '|':
if (Lookahead == '|')
{
_kind = SyntaxKind.PipePipeToken;
_position += 2;
}
break;
case '=':
_position++;
if (Current != '=')
{
_kind = SyntaxKind.EqualsToken;
}
else
{
_kind = SyntaxKind.EqualsEqualsToken;
_position++;
}
break;
case '!':
_position++;
if (Current != '=')
{
_kind = SyntaxKind.BangToken;
}
else
{
_kind = SyntaxKind.BangEqualsToken;
_position++;
}
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
ReadNumber();
break;
case ' ':
case '\t':
case '\n':
case '\r':
ReadWhiteSpace();
break;
default:
if (char.IsLetter(Current))
{
ReadIdentifierOrKeyword();
}
else if (char.IsWhiteSpace(Current))
{
ReadWhiteSpace();
}
else
{
_diagnostics.ReportBadCharacter(_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()
{
_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 '*':
_kind = SyntaxKind.MultiplyToken;
_position++;
break;
case '/':
_kind = SyntaxKind.DivideToken;
_position++;
break;
case '(':
_kind = SyntaxKind.OpenParenthesisToken;
_position++;
break;
case ')':
_kind = SyntaxKind.CloseParenthesisToken;
_position++;
break;
case '{':
_kind = SyntaxKind.OpenBraceToken;
_position++;
break;
case '}':
_kind = SyntaxKind.CloseBraceToken;
_position++;
break;
case '~':
_kind = SyntaxKind.TildeToken;
_position++;
break;
case '^':
_kind = SyntaxKind.HatToken;
_position++;
break;
case '!':
_position++;
if (Current == '=')
{
_kind = SyntaxKind.BangEqualsToken;
_position++;
}
else
{
_kind = SyntaxKind.BangToken;
}
break;
case '&':
_position++;
if (Current != '&')
{
_kind = SyntaxKind.AmpersandToken;
}
else
{
_kind = SyntaxKind.AmpersandAmpersandToken;
_position++;
}
break;
case '|':
_position++;
if (Current == '|')
{
_kind = SyntaxKind.PipePipeToken;
_position++;
}
else
{
_kind = SyntaxKind.PipeToken;
}
break;
case '=':
_position++;
if (Current == '=')
{
_kind = SyntaxKind.EqualsEqualsToken;
_position++;
}
else
{
_kind = SyntaxKind.EqualsToken;
}
break;
case '<':
_position++;
if (Current == '=')
{
_kind = SyntaxKind.LessOrEqualsToken;
_position++;
}
else
{
_kind = SyntaxKind.LessToken;
}
break;
case '>':
_position++;
if (Current == '=')
{
_kind = SyntaxKind.GreaterOrEqualsToken;
_position++;
}
else
{
_kind = SyntaxKind.GreaterToken;
}
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 '\r':
case '\n':
ReadWhitespace();
break;
default:
{
if (char.IsLetter(Current))
{
ReadIdentifierOrKeyword();
}
else if (char.IsWhiteSpace(Current))
{
ReadWhitespace();
}
else
{
_diagnostics.ReportBadCharacter(_position, Current);
_position++;
}
}
break;
}
var text = SyntaxFacts.GetText(_kind);
if (text == null)
{
text = _text.ToString(_start, _position - _start);
}
return(new SyntaxToken(_kind, _start, text, _value));
}
internal SyntaxToken Lex()
{
_start = _position;
_kind = SyntaxKind.BadToken;
_value = null;
switch (Current)
{
case '\0':
{
_kind = SyntaxKind.EndOfFileToken;
break;
}
case '+':
{
MoveNext();
_kind = SyntaxKind.PlusToken;
break;
}
case '-':
{
MoveNext();
_kind = SyntaxKind.MinusToken;
break;
}
case '*':
{
MoveNext();
_kind = SyntaxKind.StarToken;
break;
}
case '/':
{
MoveNext();
_kind = SyntaxKind.ForwardSlashToken;
break;
}
case '(':
{
MoveNext();
_kind = SyntaxKind.OpenParenthesisToken;
break;
}
case ')':
{
MoveNext();
_kind = SyntaxKind.CloseParenthesisToken;
break;
}
case '{':
{
MoveNext();
_kind = SyntaxKind.OpenBraceToken;
break;
}
case '}':
{
MoveNext();
_kind = SyntaxKind.CloseBraceToken;
break;
}
case '~':
{
MoveNext();
_kind = SyntaxKind.TildeToken;
break;
}
case '^':
{
MoveNext();
_kind = SyntaxKind.HatToken;
break;
}
case '!':
{
if (LookAhead == '=')
{
MoveNext(2);
_kind = SyntaxKind.BangEqualsToken;
}
else
{
MoveNext();
_kind = SyntaxKind.BangToken;
}
break;
}
case '&':
{
if (LookAhead == '&')
{
MoveNext(2);
_kind = SyntaxKind.AndAndToken;
}
else
{
MoveNext();
_kind = SyntaxKind.AndToken;
}
break;
}
case '|':
{
if (LookAhead == '|')
{
MoveNext(2);
_kind = SyntaxKind.PipePipeToken;
}
else
{
MoveNext();
_kind = SyntaxKind.PipeToken;
}
break;
}
case '=':
{
if (LookAhead == '=')
{
MoveNext(2);
_kind = SyntaxKind.EqualsEqualsToken;
}
else
{
MoveNext();
_kind = SyntaxKind.EqualsToken;
}
break;
}
case '<':
{
if (LookAhead == '=')
{
MoveNext(2);
_kind = SyntaxKind.LessOrEqualsToken;
}
else
{
MoveNext();
_kind = SyntaxKind.LessToken;
}
break;
}
case '>':
{
if (LookAhead == '=')
{
MoveNext(2);
_kind = SyntaxKind.GreaterOrEqualsToken;
}
else
{
MoveNext();
_kind = SyntaxKind.GreaterToken;
}
break;
}
case '"':
{
ReadString();
break;
}
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
{
ReadNumbersToken();
break;
}
case ' ':
case '\t':
{
ReadWhitespaceTokens();
break;
}
default:
{
if (char.IsLetter(Current))
{
ReadLettersToken();
}
else if (char.IsWhiteSpace(Current))
{
ReadWhitespaceTokens();
}
else
{
_diagnostics.ReportBadCharacter(_position, Current);
MoveNext();
}
break;
}
}
{
var text = SyntaxFacts.GetText(_kind);
var length = _position - _start;
if (text is null)
{
text = _text.ToString(_start, length);
}
return(new SyntaxToken(_kind, _start, text, _value));
}
void ReadNumbersToken()
{
do
{
MoveNext();
}while (char.IsDigit(Current));
var length = _position - _start;
var text = _text.ToString(_start, length);
if (!int.TryParse(text, out var value))
{
_diagnostics.ReportInvalidNumber(new TextSpan(_start, length), text, TypeSymbol.Int);
}
_kind = SyntaxKind.NumberToken;
_value = value;
}
void ReadLettersToken()
{
do
{
MoveNext();
}while (char.IsLetter(Current));
var text = _text.ToString(_start, _position - _start);
_kind = SyntaxFacts.GetKeywordKind(text);
}
void ReadWhitespaceTokens()
{
do
{
MoveNext();
}while (char.IsWhiteSpace(Current));
_kind = SyntaxKind.WhiteSpaceToken;
}
void ReadString()
{
MoveNext();
var done = false;
var builder = new StringBuilder();
while (!done)
{
switch (Current)
{
case '\0':
case '\r':
case '\n':
var span = new TextSpan(_start, 1);
Diagnostics.ReportUnterminatedString(span);
done = true;
break;
case '\\':
{
if (LookAhead == '"')
{
MoveNext();
}
builder.Append(Current);
MoveNext();
break;
}
case '"':
{
done = true;
MoveNext();
break;
}
default:
{
builder.Append(Current);
MoveNext();
break;
}
}
}
_kind = SyntaxKind.StringToken;
_value = builder.ToString();
}
}