tenebrous-dicebot/src/parser.rs

165 lines
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Rust
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2020-04-20 06:32:57 +00:00
use nom::{
alt,
tag,
complete,
named,
many0,
IResult,
bytes::complete::{tag, take_while},
character::complete::digit1,
sequence::tuple
};
#[derive(Debug, PartialEq, Eq)]
struct Dice {
count: u32,
sides: u32,
}
impl Dice {
fn new(count: u32, sides: u32) -> Dice {
Dice {
count,
sides,
}
}
}
#[derive(Debug, PartialEq, Eq)]
enum Element {
Dice(Dice),
Bonus(u32),
}
#[derive(Debug, PartialEq, Eq)]
enum Sign {
Plus,
Minus,
}
#[derive(Debug, PartialEq, Eq)]
enum SignedElement {
Positive(Element),
Negative(Element),
}
#[derive(Debug, PartialEq, Eq)]
struct ElementExpression(Vec<SignedElement>);
fn is_whitespace(input: char) -> bool {
input == ' ' || input == '\n' || input == '\t' || input == '\r'
}
fn eat_whitespace(input: &str) -> IResult<&str, ()> {
let (input, _) = take_while(is_whitespace)(input)?;
Ok((input, ()))
}
// Parse a dice expression. Does not eat whitespace
fn parse_dice(input: &str) -> IResult<&str, Dice> {
let (input, (count, _, sides)) = tuple((digit1, tag("d"), digit1))(input)?;
Ok((input, Dice::new(count.parse().unwrap(), sides.parse().unwrap())))
}
// Parse a single digit expression. Does not eat whitespace
fn parse_bonus(input: &str) -> IResult<&str, u32> {
let (input, bonus) = digit1(input)?;
Ok((input, bonus.parse().unwrap()))
}
// Parse a sign expression. Eats whitespace.
fn parse_sign(input: &str) -> IResult<&str, Sign> {
let (input, _) = eat_whitespace(input)?;
named!(sign(&str) -> Sign, alt!(
tag!("+") => { |_| Sign::Plus } |
tag!("-") => { |_| Sign::Minus }
));
let (input, sign) = sign(input)?;
Ok((input, sign))
}
// Parse an element expression. Eats whitespace.
fn parse_element(input: &str) -> IResult<&str, Element> {
let (input, _) = eat_whitespace(input)?;
named!(element(&str) -> Element, alt!(
parse_dice => { |d| Element::Dice(d) } |
parse_bonus => { |b| Element::Bonus(b) }
));
let (input, element) = element(input)?;
Ok((input, element))
}
// Parse a signed element expression. Eats whitespace.
fn parse_signed_element(input: &str) -> IResult<&str, SignedElement> {
let (input, _) = eat_whitespace(input)?;
let (input, sign) = parse_sign(input)?;
let (input, _) = eat_whitespace(input)?;
let (input, element) = parse_element(input)?;
let element = match sign {
Sign::Plus => SignedElement::Positive(element),
Sign::Minus => SignedElement::Negative(element),
};
Ok((input, element))
}
// Parse a full element expression. Eats whitespace.
fn parse_element_expression(input: &str) -> IResult<&str, ElementExpression> {
named!(first_element(&str) -> SignedElement, alt!(
parse_signed_element => { |e| e } |
parse_element => { |e| SignedElement::Positive(e) }
));
let (input, first) = first_element(input)?;
let (input, rest) = if input.trim().is_empty() {
(input, vec![first])
} else {
named!(rest_elements(&str) -> Vec<SignedElement>, many0!(complete!(parse_signed_element)));
let (input, mut rest) = rest_elements(input)?;
rest.insert(0, first);
(input, rest)
};
Ok((input, ElementExpression(rest)))
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn dice_test() {
assert_eq!(parse_dice("2d4"), Ok(("", Dice::new(2, 4))));
assert_eq!(parse_dice("20d40"), Ok(("", Dice::new(20, 40))));
assert_eq!(parse_dice("8d7"), Ok(("", Dice::new(8, 7))));
}
#[test]
fn element_test() {
assert_eq!(parse_element(" \t\n\r\n 8d7 \n"), Ok((" \n", Element::Dice(Dice::new(8, 7)))));
assert_eq!(parse_element(" \t\n\r\n 8 \n"), Ok((" \n", Element::Bonus(8))));
}
#[test]
fn signed_element_test() {
assert_eq!(parse_signed_element("+ 7"), Ok(("", SignedElement::Positive(Element::Bonus(7)))));
assert_eq!(parse_signed_element(" \t\n\r\n- 8 \n"), Ok((" \n", SignedElement::Negative(Element::Bonus(8)))));
assert_eq!(parse_signed_element(" \t\n\r\n- 8d4 \n"), Ok((" \n", SignedElement::Negative(Element::Dice(Dice::new(8, 4))))));
assert_eq!(parse_signed_element(" \t\n\r\n+ 8d4 \n"), Ok((" \n", SignedElement::Positive(Element::Dice(Dice::new(8, 4))))));
}
#[test]
fn element_expression_test() {
assert_eq!(parse_element_expression("8d4"), Ok(("", ElementExpression(vec![SignedElement::Positive(Element::Dice(Dice::new(8, 4)))]))));
assert_eq!(parse_element_expression(" - 8d4 \n "), Ok((" \n ", ElementExpression(vec![SignedElement::Negative(Element::Dice(Dice::new(8, 4)))]))));
assert_eq!(parse_element_expression("\t3d4 + 7 - 5 - 6d12 + 1d1 + 53 1d5 "), Ok((" 1d5 ", ElementExpression(vec![
SignedElement::Positive(Element::Dice(Dice::new(3, 4))),
SignedElement::Positive(Element::Bonus(7)),
SignedElement::Negative(Element::Bonus(5)),
SignedElement::Negative(Element::Dice(Dice::new(6, 12))),
SignedElement::Positive(Element::Dice(Dice::new(1, 1))),
SignedElement::Positive(Element::Bonus(53)),
]))));
}
}