Crate critfail

Evaluation and rolling of D&D 5e die roll expressions.

The RollExpression trait provides methods for dealing with the various kinds of rolls. Roll provides the simplest text-in, text-out interface for rolling expressions an printing the result regardless of the type of roll.

use critfail::{RollExpression, Roll};

let check = Roll::new("r-3").unwrap();
let check_outcome = check.roll();
print!("{}", check_outcome); // eg. "11"
print!("{:?}", check_outcome); // eg. "(14)-3"

let damage = Roll::new("2d8+6").unwrap();
let damage_outcome = damage.roll();
print!("{}", damage_outcome); // eg. "13"
print!("{:?}", damage_outcome); // eg. "[2+5]+6"

let attack = Roll::new("r+1?2d6+4").unwrap();
let attack_outcome = attack.roll();
print!("{}", attack_outcome); // eg. "10 ? 16"
print!("{:?}", attack_outcome); // eg. "(9)+1 ? [6+6]+4"

In order to handle the outcome of a Roll programatically, roll expressions are split into Check rolls, Damage rolls, and Attack rolls, each with their own outcome type which provides methods for determining the score and makeup of the results for each.

Features

• wasm-bindgen: Enable this when compiling for wasm32 targets, or random number generation won't work.

Structs

Attack	An attack roll consisting of a check and a damage roll.
AttackOutcome	The outcome of an attack roll.
AttackOutcomeBuilder	This is used to create a 'fudged' AttackOutcome without actually randomly generating anything.
Check	An ability check - roll a d20, potentially with modifiers or advantage.
CheckOutcome	The outcome of a check roll.
CheckOutcomeBuilder	This is used to create a 'fudged' CheckOutcome without actually randomly generating anything.
Damage	A list of dice to roll and modifiers to add, usually used for damage.
DamageOutcome	The outcome of a check roll.
DamageOutcomeBuilder	This is used to create a 'fudged' DamageOutcome without actually randomly generating anything.
ParseError	Represents an error parsing a roll expression.

Enums

AdvState	The advantage state of an ability check.
CritScore	The score of a roll that could be a critical hit/failure
OutcomePart	Enum representing the different kinds of values that can be returned for damage or the modifier on a check.
Roll	Any kind of roll—either a check, damage, or attack roll.
RollOutcome	The outcome of rolling a check, damage, or attack roll.

Traits

RollExpression

Used for structs defining a set of dice that can be rolled.

Type Definitions

Score	The number type that is used when reporting the score of a roll
Sides	The number type that is used for specifying the number of sides on a die