} /* end PrintLineAndMarkColumn */
/* --------------------------------------------------------------------------
* private method GetNewLookaheadSym()
* --------------------------------------------------------------------------
* Reads the next symbol from infile, sets currentSym and lookaheadSym.
* ----------------------------------------------------------------------- */
private void GetNewLookaheadSym()
{
Token token;
char nextChar;
uint line = 0;
uint column = 0;
/* no token yet */
token = Token.Unknown;
/* get the lookahead character */
nextChar = infile.NextChar();
while (token == Token.Unknown)
{
/* skip all whitespace and line feeds */
while ((nextChar == ASCII.SPACE) ||
(nextChar == ASCII.TAB) ||
(nextChar == ASCII.LF))
{
/* consume the character and get new lookahead */
nextChar = infile.ConsumeChar();
} /* end while */
line = infile.CurrentLine();
column = infile.CurrentColumn();
switch (nextChar)
{
case ASCII.EOT:
/* End-of-File marker */
if (infile.Status() == InfileStatus.AttemptToReadPastEOF)
{
token = Token.EndOfFile;
}
else /* invalid char */
{
// TO DO : report error with offending character
token = Token.Unknown;
} /* end if */
break;
case '!':
/* line comment */
if (Capabilities.LineComments())
{
nextChar = SkipLineComment();
}
else /* illegal character */
{
// TO DO : report error with offending character
token = Token.Unknown;
} /* end if */
break;
case '"':
/* string literal */
nextChar = GetStringLiteral(out token);
if (token == Token.MalformedString)
{
// TO DO : report error with offending position
} /* end if */
break;
case '#':
/* not-equal operator */
nextChar = infile.ConsumeChar();
token = Token.NotEqual;
break;
case '&':
/* ampersand synonym */
if (Capabilities.Synonyms())
{
nextChar = infile.ConsumeChar();
token = Token.AND;
}
else /* illegal character */
{
// TO DO : report error with offending character
token = Token.Unknown;
} /* end if */
break;
case '\'':
/* string literal */
nextChar = GetStringLiteral(out token);
if (token == Token.MalformedString)
{
// TO DO : report error with offending position
} /* end if */
break;
case '(':
/* left parenthesis */
if (infile.LA2Char() != '*')
{
nextChar = infile.ConsumeChar();
token = Token.LeftParen;
}
else /* block comment */
{
nextChar = SkipBlockComment();
token = Token.Unknown;
}
break;
case ')':
/* right parenthesis */
nextChar = infile.ConsumeChar();
token = Token.RightParen;
break;
case '*':
/* asterisk operator */
nextChar = infile.ConsumeChar();
token = Token.Asterisk;
break;
case '+':
/* plus operator */
nextChar = infile.ConsumeChar();
token = Token.Plus;
break;
case ',':
/* comma */
nextChar = infile.ConsumeChar();
token = Token.Comma;
break;
case '-':
/* minus operator */
nextChar = infile.ConsumeChar();
token = Token.Minus;
break;
case '.':
/* range or period */
nextChar = infile.ConsumeChar();
if /* range */ (nextChar == '.')
{
nextChar = infile.ConsumeChar();
token = Token.Range;
}
else /* period */
{
token = Token.Period;
} /* end if */
break;
case '/':
/* solidus operator */
nextChar = infile.ConsumeChar();
token = Token.Solidus;
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
/* number literal */
nextChar = GetNumberLiteral(out token);
if (token == Token.MalformedInteger)
{
// TO DO : report error with position
}
else if (token == Token.MalformedReal)
{
// TO DO : report error with position
} /* end if */
break;
case ':':
/* assignment or colon*/
nextChar = infile.ConsumeChar();
if /* assignment */ (nextChar == '=')
{
nextChar = infile.ConsumeChar();
token = Token.Assign;
}
else /* colon */
{
token = Token.Colon;
} /* end if */
break;
case ';':
/* semicolon */
nextChar = infile.ConsumeChar();
token = Token.Semicolon;
break;
case '<':
if (Capabilities.IsoPragmaDelimiters() && (infile.LA2Char() == '*'))
{
/* pragma */
nextChar = GetPragma();
token = Token.Pragma;
break;
} /* end if */
/* not-equal, less-equal or less operator */
nextChar = infile.ConsumeChar();
if (Capabilities.Synonyms() && (nextChar == '>'))
{
/* not-equal synonym */
nextChar = infile.ConsumeChar();
token = Token.NotEqual;
}
else if /* less-equal */ (nextChar == '=')
{
nextChar = infile.ConsumeChar();
token = Token.LessEqual;
}
else /* less */
{
token = Token.Less;
} /* end if */
break;
case '=':
/* equal operator */
nextChar = infile.ConsumeChar();
token = Token.Equal;
break;
case '>':
/* greater-equal or greater operator */
nextChar = infile.ConsumeChar();
if /* greater-equal */ (nextChar == '=')
{
nextChar = infile.ConsumeChar();
token = Token.GreaterEqual;
}
else /* greater */
{
token = Token.Greater;
} /* end if */
break;
case '?':
/* disabled code section tag */
if ((column == 1) && (infile.LA2Char() == '<'))
{
nextChar = SkipCodeSection();
}
else /* invalid character */
{
// TO DO : report error with offending character
token = Token.Unknown;
} /* end if */
break;
case 'A':
case 'B':
case 'C':
case 'D':
case 'E':
case 'F':
case 'G':
case 'H':
case 'I':
case 'J':
case 'K':
case 'L':
case 'M':
case 'N':
case 'O':
case 'P':
case 'Q':
case 'R':
case 'S':
case 'T':
case 'U':
case 'V':
case 'W':
case 'X':
case 'Y':
case 'Z':
/* identifier or reserved word */
nextChar = GetIdentOrResword(out token);
break;
case '[':
/* left bracket */
nextChar = infile.ConsumeChar();
token = Token.LeftBracket;
break;
case ASCII.BACKSLASH:
/* backslash */
if (Capabilities.BackslashSetDiffOp())
{
nextChar = infile.ConsumeChar();
token = Token.Backslash;
}
else /* illegal character */
{
// TO DO : report error with offending character
token = Token.Unknown;
} /* end if */
break;
case ']':
/* right bracket */
nextChar = infile.ConsumeChar();
token = Token.RightBracket;
break;
case '^':
/* caret */
nextChar = infile.ConsumeChar();
token = Token.Deref;
break;
case 'a':
case 'b':
case 'c':
case 'd':
case 'e':
case 'f':
case 'g':
case 'h':
case 'i':
case 'j':
case 'k':
case 'l':
case 'm':
case 'n':
case 'o':
case 'p':
case 'q':
case 'r':
case 's':
case 't':
case 'u':
case 'v':
case 'w':
case 'x':
case 'y':
case 'z':
/* identifier */
nextChar = GetIdent();
token = Token.Identifier;
break;
case '{':
/* left brace */
nextChar = infile.ConsumeChar();
token = Token.LeftBrace;
break;
case '|':
/* vertical bar */
nextChar = infile.ConsumeChar();
token = Token.Bar;
break;
case '}':
/* right brace */
nextChar = infile.ConsumeChar();
token = Token.RightBrace;
break;
case '~':
/* tilde synonym */
if (Capabilities.Synonyms())
{
nextChar = infile.ConsumeChar();
token = Token.NOT;
}
else /* illegal character */
{
// TO DO : report error with offending character
token = Token.Unknown;
} /* end if */
break;
default:
/* invalid character */
break;
} /* end switch */
} /* end while */
/* update lexer's lookahead symbol */
lookaheadSym.token = token;
lookaheadSym.line = line;
lookaheadSym.column = column;
return;
} /* end GetNewLookaheadSym */