public Token(TokenCode c, Position b, Position e, string i=null)
{
code = c;
begin = b;
end = e;
image = i;
}
public Token( TokenCode c, Position b )
{
code = c;
begin = b;
end = new Position(b.number,b.position+1);
}
private Token getToken()
{
Position begin;
Position end = null;
string image = "";
TokenCode code = TokenCode.ERROR;
char ch;
Again:
while ( true ) // skipping spaces and tabs
{
ch = source.curr();
if ( ch != ' ' && ch != '\t' ) break;
source.move();
}
begin = new Position(source.lineNo,source.linePos);
switch ( ch )
{
case '\0': code = TokenCode.EOF; break;
case '\n': source.nextLine(); goto Again; // take next line
case '.' : code = TokenCode.DOT; source.move(); image = "."; break;
case ',' : code = TokenCode.COMMA; source.move(); image = ","; break;
case ':' : code = TokenCode.COLON; source.move(); image = ":"; break;
case ';' : code = TokenCode.SEMICOLON; source.move(); image = ";"; break;
case '(' : code = TokenCode.LPAREN; source.move(); image = "("; break;
case ')' : code = TokenCode.RPAREN; source.move(); image = ")"; break;
case '{' : code = TokenCode.LBRACE; source.move(); image = "{"; break;
case '}' : code = TokenCode.RBRACE; source.move(); image = "}"; break;
case '*' : code = TokenCode.STAR; source.move(); image = "*"; break;
case '[' : code = TokenCode.LBRACKET; source.move(); image = "["; break;
case ']' : code = TokenCode.RBRACKET; source.move(); image = "]"; break;
case '<' : code = TokenCode.LESS; source.move(); image = "<"; break;
case '>' : code = TokenCode.GREATER; source.move(); image = ">="; break;
case '+' : code = TokenCode.PLUS; source.move(); image = "+"; break;
case '-' : code = TokenCode.MINUS; source.move(); image = "-"; break;
case '/' : source.move(); ch = source.curr();
if ( ch == '/' ) { source.scanTail(); goto Again; } // comment
code = TokenCode.SLASH; image = "/";
break;
case '=' : source.move(); ch = source.curr();
if ( ch == '=' ) { code = TokenCode.EQUAL; image = "=="; source.move(); }
else { code = TokenCode.ASSIGN; image = "="; }
break;
case '!' : source.move(); ch = source.curr();
if ( ch != '=' ) { errors.issue(9,""+ch); } // illegal character
source.move(); code = TokenCode.NOT_EQUAL; image = "!=";
break;
default : // identifier or integer
if ( Char.IsLetter(ch) || ch == '_' )
{
while ( Char.IsLetter(ch) || Char.IsDigit(ch) || ch == '_' )
{
image += ch;
source.move();
ch = source.curr();
}
}
if ( image != "" )
{
end = new Position(source.lineNo,source.linePos);
code = detectKeyword(image);
break;
}
while ( Char.IsDigit(ch) )
{
image += ch;
source.move();
ch = source.curr();
}
if ( image != "" )
{
end = new Position(source.lineNo,source.linePos);
code = TokenCode.NUMBER;
break;
}
// Else unknown token
errors.issue(9,""+ch); // illegal character
code = TokenCode.ERROR;
break;
}
if ( end == null )
end = new Position(begin.number,begin.position+image.Length);
return new Token(code,begin,end,image);
}