Parsing Constants

When a digit or period is found, the parser will look for a numeric constant. Some checks are needed. A leading zero must be followed by a period or the zero is taken alone. Only one period is allowed in a constant; finding a second period will terminate the constant. Finding an “e” or “E” will cause an exponent to be scanned (an optional sign followed by digits).

Once the constant has been scanned, if the constant did not have no decimal point or exponent, then an attempt will be made to convert the string into an integer. If this fails because the value is too large, then it will be converted into a double. If the conversion to double fails (overflow or underflow) then a syntax error will reported.

When a double-quote is found, the parser will look for a string constant. Two double-quotes will be converted into a single double-quote.  The string is terminated upon reaching the ending double-quote.  A syntax error will be reported if the end of the line is reached before the ending double-quote.