11 releases
0.9.10 | Jul 28, 2023 |
---|---|
0.9.9 | May 3, 2021 |
0.9.8 | Apr 12, 2021 |
0.9.1 | Mar 31, 2021 |
#65 in Game dev
46 downloads per month
69KB
1K
SLoC
About
Parses dice notation and evaluate algebraic manipulation of sets of dice rolls.
This module provides Dice
and RollSet
structs, which implement FromStr
for
converting from strings. It also provides error types directly related to
parsing dice-related strings.
Examples
Dice Examples
Rolling Dice
Creating Dice
from a string literal:
use ndm::Dice;
let d6 = "1d6".parse::<Dice>().unwrap();
You can create them directly:
use ndm::Dice;
let d4 = Dice::new(1, 4);
Exploding Dice
Creating exploding dice (which roll again when the highest number is rolled):
use ndm::Dice;
let exploding_d20 = "1d20!".parse::<Dice>().unwrap();
let exploding_d6 = Dice::new_exploding(1, 6, 6);
Exploding dice can explode on any number greater than 1:
use ndm::Dice;
let exploding_d13 = "1d13!2".parse::<Dice>().unwrap();
More Complicated Examples
Rolling multiple Dice
at a time:
use ndm::Dice;
let dice = Dice::new(3, 8);
let dice = Dice::new_exploding(2, 4, 4);
Keeping High or Low Rolls
Keeping the three highest dice:
use ndm::Dice;
let wis = Dice::new_keep_n(4, 6, 3);
let dex: Dice = "4d6/H3".parse().unwrap();
Or the lowest roll:
use ndm::Dice;
let disadvantage = Dice::new_keep_n(2, 20, -1);
let minimum: Dice = "4d7/L1".parse().unwrap();
(String parsing isn't case-sensitive.)
Keeping exploding dice:
use ndm::Dice;
let dice = Dice::new_extended(4, 7, 5, 3);
// or
let dice = "4d7/H3!5".parse::<Dice>().unwrap();
Formatting Dice
Dice
can be formatted with the normal {}
operator:
use ndm::Dice;
println!("{}", Dice::new(2, 10).unwrap());
Parse Errors
Strings which cannot be parsed cause DiceParseError
s. String parsing is more
strict than the constructors, which currently don't fail, but instead ignore
invalid parameters.
Combinations
Sets of dice, such as multiple sizes of dice, and mathematical operations upon
dice, are represented by RollSet
s.
RollSet
s can only be created by parsing string slices:
use ndm::RollSet;
let roll_set: RollSet = "3d6".parse().unwrap();
RollSet
s can contain any combinations of valid Dice
and whole numbers,
joined by +
or -
(or −). These combinations can also be multiplied
by floating-point numbers, using *
(or x
or X
or ×).
use ndm::RollSet;
let roll_set: RollSet = "1d20+4".parse().unwrap();
let empowered = "4d6 * 1.5".parse::<RollSet>().unwrap();
let sneak = "3d8 + 2d6".parse::<RollSet>().unwrap();
Extraneous text can be included:
use ndm::RollSet;
let roll_set = "2d8 slashing + 3d6 fire".parse::<RollSet>().unwrap();
End-comments can be indicated by #
, which will prevent additional parsing:
use ndm::RollSet;
// Only the 4d6 will be parsed, the 8d6 is just a comment.
let roll_set: RollSet = "4d6 # 8d6 on a critical".parse().unwrap();
RollSet
s can also be formatted using {}
, and totals will appear before an
end-of-line comment, if any.
use ndm::RollSet;
// Prints something like: `3d6 [ 2, 4, 5: 11] slashing + 4 = 15`
println!("{}", "3d6 slashing + 4".parse::<RollSet>().unwrap());
// Prints something like `3d6 [ 3, 5, 6: 14] + 4 = 18 # slashing`
println!("{}", "3d6+4 # slashing".parse::<RollSet>().unwrap());
Parse Errors
Errors are returned using RollParseError
. In general, RollSet
s treat
anything that isn't Dice
, operators, or numbers as comments, but will fail if
there isn't a roll anywhere in the string. Some combinations of operators are
also invalid: Dice
can't be multiplied by other Dice
, text can't be added to
numbers, etc.
More Information
Dice math is from left to right, regardless of operator. For example,
4d6 + 12 * 1.5
ranges from 24 ((4 + 12) * 1.5) to 54 ((24 + 12) * 1.5), not
from 22 to 42.
Addition and subtraction can be done with whole numbers, dice rolls, and results
of previous operations. Multiplication can be done upon all of the above, but
the right hand side must be a number (either whole or floating-point). Also,
the result of floating-point math is truncated: 1d6 * 4.9
ranges from 4 to 29,
not from 4.9 to 29.4.
Exploding dice get rerolled as long as they roll at least as high as the “fuse” (which defaults to the highest value on the die, but may be as low as 2).
You can construct Dice
directly, or complex expressions of RollSet
s.
The dice notation parsed by this library is:
[count]d
<sides>[/
<H
|L
><keep>][!
[fuse]]
count
is the number of dice to roll, is optional, and defaults to 1sides
is the number of sides on the dice and is required- If numeric, it must be non-negative
f
orF
may be used to represent Fudge/Fate dice
- Optionally,
/
, followed byH
(orh
) orL
(orl
) and- a positive number less than or equal to the number of dice rolled
- Optionally,
!
, optionally followed by thefuse
as a whole number- If the fuse is provided, it must be at least 2
- Otherwise, it defaults to the highest possible roll for the die
Dice can be added with +
, subtracted with -
[or −], or multiplied
with *
[or x
or X
or ×]. Other text is treated as comments.
Dice
can be combined with each other by addition or subtraction. You can also
add or subtract whole numbers and multiply results by floating point numbers.
(Division isn't currently supported directly, but you can multiply by the
reciprocal.)
License
Licensed, at your option, under either the Apache License, Version 2.0 or the MIT license.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache License, Version 2.0, shall be dual licensed as above, without any additional terms or conditions.
Dependencies
~3–5MB
~93K SLoC