/// <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);
}
/// <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;
}
/// <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(Strings.Parser_ErrorP_EndExpressionExpected + GetLocationInfo(curToken));
return result;
}
// ExprAndOr:
private void MatchExprAndOr(out IExpr result)
{
TokenTypes t; // remember the type
IExpr lhs;
MatchExprNot(out lhs);
result = lhs; // in case we get no matches
while ((t = curToken.Type) == TokenTypes.AND || t == TokenTypes.OR)
{
curToken = tokens.Extract();
IExpr rhs;
MatchExprNot(out rhs);
bool bBool = (rhs.GetTypeCode() == TypeCode.Boolean &&
lhs.GetTypeCode() == TypeCode.Boolean);
if (!bBool)
{
throw new ParserException("AND/OR operations require both sides to be boolean expressions." + " At column " + Convert.ToString(curToken.StartCol));
}
switch (t)
{
case TokenTypes.AND:
result = new FunctionAnd(lhs, rhs);
break;
case TokenTypes.OR:
result = new FunctionOr(lhs, rhs);
break;
}
lhs = result; // in case we have more AND/OR s
}
}
