This is a quick hobby project that I wrote to better understand Flex and Bison, the unix lexer and parser. I never ended up using Flex because the lexing was so simple, but the use of Bison allows for efficient and correct parsing of arbitrarily deeply nested arithmetical statements, which is kind of cool.

This package requires GCC, Make, and Bison. Install these with your preferred package manager, then enter the following line in the root directory of this package:

make

This should produce the file 'roll', which can be run with the command:

./roll

or can be added to a directory included in the user's PATH and run like so:

roll

roll is a small language that does simple arithmetic (plus, minus, times, divide) on doubles. Expressions can be nested arbitrarily deeply with parentheses, and order of operations is preserved. So, for example, this code:

((1+2) * 3) / 7

produces the output:

1.2857143

In addition, arbitrarily many die rolls with whole-number-sided dice can be performed with the syntax [0-9]+d[0-9], like so:

6d12 + 33
	60

The special command D allows for rolling multiple dice and keeping the m number of lowest dice or the M number of highest dice:

3D6m2
	5
3D6M2
	11

The command p toggles printing of individual die rolls:

3d6
	10
p
	0
3d6
4
3
3
	10

A single q on a line will quit the program. So, a typical session might look like the following:

6d12 + 33
        60
(8.3 / 9.9) + 2
	2.8383838
q

roll can also be run in batch mode by simply directing a set of commands to standard input in one of the two following ways:

cat input.txt | roll

roll <input.txt