Replace two loops that print leading and trailing 0s when printing a
number in fixed-width mode with a single call to `write!()` with the
appropriate formatting parameters.
Ensure that the `print_seq_integers()` function is called when the first
number and the increment are integers, regardless of the type of the
last value specified.
Change the way `seq` computes the number of digits needed to print a
number so that it works for inputs given in scientific notation.
Specifically, this commit parses the input string to determine whether
it is an integer, a float in decimal notation, or a float in scientific
notation, and then computes the number of integral digits and the number
of fractional digits based on that. This also supports floating point
negative zero, expressed in both decimal and scientific notation.
Fix a bug in `seq` where the number of characters needed to print the
number was computed incorrectly in some cases. This commit changes the
computation of the width to be after parsing the number instead of
before, in order to accommodate inputs like `1e3`, which requires four
digits when printing the number, not three.
GNU seq does not support -t, but always outputs a newline at the end.
Therefore, our default for -t should be \n.
Also removes support for escape sequences (interpreting a literal "\n"
as a newline). This is not what GNU seq is doing, and unexpected.
If we notice that we can represent all arguments as BigInts, take a
different code path. Just like GNU seq this means we can print an
infinite amount of numbers in this case.
