/// <summary>
/// Initializes a new instance of the Lexer class with the specified
/// TextReader to lex.
/// </summary>
/// <param name="source">A TextReader to lex.</param>
public Lexer(TextReader source)
{
// token queue
tokens = new TokenList();
// read the file contents
reader = new CharReader(source);
}
/// <summary>
/// Returns a parsed DPL instance.
/// </summary>
/// <param name="reader">The TextReader value to be parsed.</param>
/// <returns>A parsed Program instance.</returns>
private IExpr ParseExpr(TextReader reader)
{
IExpr result=null;
Lexer lexer = new Lexer(reader);
tokens = lexer.Lex();
if (tokens.Peek().Type == TokenTypes.EQUAL)
{
tokens.Extract(); // skip over the equal
curToken = tokens.Extract(); // set up the first token
MatchExprAndOr(out result); // start with lowest precedence and work up
}
if (curToken.Type != TokenTypes.EOF)
throw new ParserException("End of expression expected." + " At column " + Convert.ToString(curToken.StartCol));
return result;
}