public bool Parse()
{
token = lexer.GetNextToken();
if (delayinc)
{
depth++;
delayinc = false;
}
if (token == Lexer.TokenType.EOF)
{
depth = 0;
return(false);
}
/*
* Console.WriteLine("Token: " + token.ToString() + " - " +
* lexer.TokenString);
*/
switch (token)
{
case Lexer.TokenType.CLOSE_PAREN:
if (depth == 0)
{
throw new Exception("Parse Error: unexpected )");
}
depth--;
type = LispType.END_LIST;
break;
case Lexer.TokenType.OPEN_PAREN:
type = LispType.START_LIST;
delayinc = true;
break;
case Lexer.TokenType.SYMBOL:
type = LispType.SYMBOL;
break;
case Lexer.TokenType.STRING:
type = LispType.STRING;
break;
case Lexer.TokenType.TRUE:
type = LispType.BOOLEAN;
break;
case Lexer.TokenType.INTEGER:
type = LispType.INTEGER;
break;
}
return(true);
}
public List Parse()
{
Token = Lexer.GetNextToken();
if (Token != Lexer.Token.OPEN_PAREN)
{
ParseError("file does not start with '('");
}
List Result = InternParse();
if (Token != Lexer.Token.EOF)
{
if (Token == Lexer.Token.CLOSE_PAREN)
{
ParseError("too many ')'");
}
else
{
ParseError("extra tokens at end of file");
}
}
return(Result);
}