A library for evaluating tabletop dice roll expressions.

Sample usage: 5d6!>4 + (5d(2d10)dl - d10) * (d20 / 2) # for an unnecessarily complicated roll

Sample output: 84 for an unnecessarily complicated roll

There is also a verbose mode that outputs every individual die roll, that output looks like this: [2d10: 2,5 (7) | 5d7: -1-,6,2,4,5 (17) | 1d10: 3 (3) | 1d20: 9 (9) | 5d6: 2,2,3,*5*,*5*,2,*5*,4 (28)] 84 for an unnecessarily complicated roll

• Arithmetic: + - * / % ^ () (addition, subtraction, multiplication, division, modulus, exponent, parentheses)
• Dice: #d# (eg, 3d6, d20)
  • Rolls the left number of dice with the right number of sides. 3d6 rolls 3 six-sided dice
  • The first number is optional and defaults to 1 if omitted
• Dice modifiers:
  • Keep/Drop Highest/Lowest: kh# kl# dh# dl#
    • Keeps/Drops only the # highest/lowest dice rolls. Any that are either not kept or dropped are removed from the total
    • The number is optional and defaults to 1 if omitted
  • Exploding: ! !# !># !>=# !<# !<=#
    • Each die that rolls maximum (!), or a specific number (!#), or over/under a threshold (!># !>=# !<# !<=#), adds an additional die to the pool
      • This repeats for each die added to the pool
  • Reroll: r r# r># r>=# r<# r<=#
    • Drops and rerolls each die that rolls minimum (r), or a specific number (r#), or over/under a threshold (r># r>=# r<# r<=#)
      • This repeats for each die rerolled. You can make it only reroll each die once with ro instead of r
  • Sorting: s sa sd
    • Sorts the dice rolls in ascending (s sa) or descending (sd) order
    • This still applies in non-verbose mode but you won't see any visible effect
• Comments: # your comment here
  • Adds a comment to the end of the output, so you can describe what the roll is for. eg: d20+5 # for initiative
  • The # is a literal hash, not a number this time :)

If you have more ideas for operators, suggestions and pull requests are welcome!