grammar.md

Grammar

1. expression → simple_expression repeat | fcount ( die , condition_list )
2. repeat → { num } | ε
3. simple_expression → term simple_expression'
4. simple_expression' → addop term simple_expression' | ε
5. term → factor term'
6. term' → mulop factor term' | ε
7. factor → num factor' | [ num d num addop extrema ] |( simple_expression ) | min | max
8. factor' → d num | ε
9. min → fmin ( simple_expression , simple_expression )
10. max → fmax ( simple_expression , simple_expression )
11. condition_list → condition condition_list'
12. condition_list' → , condition condition_list' | ε
13. condition → relop num

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tokens

1. num → [1-9][0-9]*
2. d → d|D
3. addop → + | -
4. mulop → * | /
5. relop → > | < | >= | <= | =
6. extrema → MIN | MAX
7. min → min
8. max → max
9. count → count

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machines

1. whitespace
2. num
3. d
4. relop
5. extrema
6. min
7. max
8. count
9. catchall

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example valid strings

1d20 + 4 + min([2d4-MAX], 3)

max(10, 1d20 + 4) # evaluate 2 simple_expressions, return max value
min(2d20, 15)

max(10, max(1d10, 1d20))

[4d6 - MIN] # roll 4 six-sided dice, subtract the lowest value
[4d6 - MAX] # roll 4 six-sided dice, subtract the highest value

count(4d6, >4)
count(10d6, >=5, =1, =6, <=4)