tenebrous-dicebot/src/commands/parser.rs

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use crate::cofd::parser::{create_chance_die, parse_dice_pool};
use crate::commands::{Command, HelpCommand, PoolRollCommand, RollCommand};
use crate::dice::parser::parse_element_expression;
use crate::help::parse_help_topic;
use nom::{bytes::complete::tag, character::complete::alpha1, IResult};
// Parse a roll expression.
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fn parse_roll(input: &str) -> IResult<&str, Box<dyn Command>> {
let (input, expression) = parse_element_expression(input)?;
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Ok((input, Box::new(RollCommand(expression))))
}
fn parse_pool_roll(input: &str) -> IResult<&str, Box<dyn Command>> {
let (input, pool) = parse_dice_pool(input)?;
Ok((input, Box::new(PoolRollCommand(pool))))
}
fn chance_die() -> IResult<&'static str, Box<dyn Command>> {
let (input, pool) = create_chance_die()?;
Ok((input, Box::new(PoolRollCommand(pool))))
}
fn help(topic: &str) -> IResult<&str, Box<dyn Command>> {
let topic = parse_help_topic(topic);
Ok(("", Box::new(HelpCommand(topic))))
}
/// Split an input string into its constituent command and "everything
/// else" parts. Extracts the command separately from its input (i.e.
/// rest of the line) and returns a tuple of (command_input, command).
/// Whitespace at the start and end of the command input is removed.
fn split_command(input: &str) -> IResult<&str, &str> {
//let (input, _) = eat_whitespace(input)?;
let input = input.trim_start();
let (input, _) = tag("!")(input)?;
let (mut command_input, command) = alpha1(input)?;
command_input = command_input.trim();
Ok((command_input, command))
}
/// Potentially parse a command expression. If we recognize the
/// command, an error should be raised if the command is misparsed. If
/// we don't recognize the command, ignore it and return none
pub fn parse_command(input: &str) -> IResult<&str, Option<Box<dyn Command>>> {
let (cmd_input, cmd) = split_command(input)?;
match cmd {
"r" | "roll" => parse_roll(cmd_input).map(|(input, command)| (input, Some(command))),
"rp" | "pool" => parse_pool_roll(cmd_input).map(|(input, command)| (input, Some(command))),
"chance" => chance_die().map(|(input, command)| (input, Some(command))),
"help" => help(cmd_input).map(|(input, command)| (input, Some(command))),
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// No recognized command, ignore this.
_ => Ok((input, None)),
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn basic_command_test() {
assert_eq!(
("1d4", "roll"),
split_command("!roll 1d4").expect("got parsing error")
);
}
#[test]
fn whitespace_at_start_test() {
assert_eq!(
("1d4", "roll"),
split_command(" !roll 1d4").expect("got parsing error")
);
}
#[test]
fn whitespace_at_end_test() {
//TODO currently it does not chop whitespace off the end.
assert_eq!(
("1d4", "roll"),
split_command("!roll 1d4 ").expect("got parsing error")
);
}
#[test]
fn whitespace_on_both_ends_test() {
assert_eq!(
("1d4", "roll"),
split_command(" !roll 1d4 ").expect("got parsing error")
);
}
#[test]
fn single_command_test() {
assert_eq!(
("", "roll"),
split_command("!roll").expect("got parsing error")
);
assert_eq!(
("", "thisdoesnotexist"),
split_command("!thisdoesnotexist").expect("got parsing error")
);
}
#[test]
fn bad_command_test() {
assert!(split_command("roll 1d4").is_err());
assert!(split_command("roll").is_err());
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}
}