static Expression ParseSimpleExpression(TextReader input)
{
SwallowWhitespace(input);
if (EndOfInput(input))
{
throw new SyntaxError("Premature end of expression");
}
var c = (char)input.Peek();
if (char.IsLetter(c))
{
return(ParseIdentifierOrMember(input));
}
if (char.IsDigit(c) || c == '.')
{
return(ParseNumber(input));
}
if (c == '-')
{
input.Read();
return(UnaryOperation(Operator.Lookup("negate"), ParseSimpleExpression(input)));
}
if (c == '(')
{
input.Read();
Expression e = ParseExpression(input);
SwallowWhitespace(input);
var c2 = (char)input.Read();
if (c2 != ')')
{
throw new SyntaxError("Expected ')' after parenthesized expression");
}
return(e);
}
if (c == '"')
{
return(ParseString(input));
}
throw new SyntaxError("Syntax error beginning at '" + c + "'");
}
static Operator ReadOperator(TextReader input)
{
SwallowWhitespace(input);
return(Operator.Lookup(new string((char)input.Read(), 1)));
}
static int NextOperatorPrecedence(TextReader input)
{
return(Operator.Lookup(PeekOperator(input)).Precedence);
}
