tenebrous-dicebot/src/parser.rs

180 lines
4.9 KiB
Rust

use combine::parser::char::{digit, letter, spaces};
use combine::{many, many1, one_of, Parser};
use thiserror::Error;
//******************************
//New hotness
//******************************
#[derive(Debug, Clone, Copy, PartialEq, Error)]
pub enum DiceParsingError {
#[error("invalid amount")]
InvalidAmount,
#[error("modifiers not specified properly")]
InvalidModifiers,
#[error("extraneous input detected")]
UnconsumedInput,
#[error("{0}")]
InternalParseError(#[from] combine::error::StringStreamError),
}
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum Operator {
Plus,
Minus,
}
impl Operator {
pub fn mult(&self) -> i32 {
match self {
Operator::Plus => 1,
Operator::Minus => -1,
}
}
}
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum Element {
Variable(String),
Number(i32),
}
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Amount {
pub operator: Operator,
pub element: Element,
}
/// Parse an expression of numbers and/or variables into elements
/// coupled with operators, where an operator is "+" or "-", and an
/// element is either a number or variable name. The first element
/// should not have an operator, but every one after that should.
/// Accepts expressions like "8", "10 + variablename", "variablename -
/// 3", etc. This function is currently common to systems that don't
/// deal with XdY rolls. Support for that will be added later. Parsers
/// utilzing this function should layer their own checks on top of
/// this; perhaps they do not want more than one expression, or some
/// other rules.
pub fn parse_amounts(input: &str) -> Result<Vec<Amount>, DiceParsingError> {
let input = input.trim();
let plus_or_minus = one_of("+-".chars());
let maybe_sign = plus_or_minus.map(|sign: char| match sign {
'+' => Operator::Plus,
'-' => Operator::Minus,
_ => Operator::Plus,
});
//TODO make this a macro or something
let first = many1(letter())
.or(many1(digit()))
.skip(spaces().silent()) //Consume any space after first amount
.map(|value: String| match value.parse::<i32>() {
Ok(num) => Amount {
operator: Operator::Plus,
element: Element::Number(num),
},
_ => Amount {
operator: Operator::Plus,
element: Element::Variable(value),
},
});
let variable_or_number =
many1(letter())
.or(many1(digit()))
.map(|value: String| match value.parse::<i32>() {
Ok(num) => Element::Number(num),
_ => Element::Variable(value),
});
let sign_and_word = maybe_sign
.skip(spaces().silent())
.and(variable_or_number)
.skip(spaces().silent())
.map(|parsed: (Operator, Element)| Amount {
operator: parsed.0,
element: parsed.1,
});
let rest = many(sign_and_word).map(|expr: Vec<_>| expr);
let mut parser = first.and(rest);
//Maps the found expression into a Vec of Amount instances,
//tacking the first one on.
type ParsedAmountExpr = (Amount, Vec<Amount>);
let (results, rest) = parser
.parse(input)
.map(|mut results: (ParsedAmountExpr, &str)| {
let mut amounts = vec![(results.0).0];
amounts.append(&mut (results.0).1);
(amounts, results.1)
})?;
if rest.len() == 0 {
Ok(results)
} else {
Err(DiceParsingError::UnconsumedInput)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn parse_single_number_amount_test() {
let result = parse_amounts("1");
assert!(result.is_ok());
assert_eq!(
result.unwrap(),
vec![Amount {
operator: Operator::Plus,
element: Element::Number(1)
}]
);
let result = parse_amounts("10");
assert!(result.is_ok());
assert_eq!(
result.unwrap(),
vec![Amount {
operator: Operator::Plus,
element: Element::Number(10)
}]
);
}
#[test]
fn parse_single_variable_amount_test() {
let result = parse_amounts("asdf");
assert!(result.is_ok());
assert_eq!(
result.unwrap(),
vec![Amount {
operator: Operator::Plus,
element: Element::Variable("asdf".to_string())
}]
);
let result = parse_amounts("nosis");
assert!(result.is_ok());
assert_eq!(
result.unwrap(),
vec![Amount {
operator: Operator::Plus,
element: Element::Variable("nosis".to_string())
}]
);
}
#[test]
fn parse_complex_amount_expression() {
assert!(parse_amounts("1 + myvariable - 2").is_ok());
}
}