66 lines
2.6 KiB
Rust
66 lines
2.6 KiB
Rust
use nom::{alt, complete, named, tag, take_while, tuple, IResult};
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use crate::cofd::parser::{create_chance_die, parse_dice_pool};
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use crate::commands::{Command, HelpCommand, PoolRollCommand, RollCommand};
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use crate::dice::parser::parse_element_expression;
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use crate::help::parse_help_topic;
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use crate::parser::{eat_whitespace, trim};
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// Parse a roll expression.
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fn parse_roll(input: &str) -> IResult<&str, Box<dyn Command>> {
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let (input, _) = eat_whitespace(input)?;
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let (input, expression) = parse_element_expression(input)?;
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Ok((input, Box::new(RollCommand(expression))))
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}
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fn parse_pool_roll(input: &str) -> IResult<&str, Box<dyn Command>> {
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let (input, _) = eat_whitespace(input)?;
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let (input, pool) = parse_dice_pool(input)?;
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Ok((input, Box::new(PoolRollCommand(pool))))
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}
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fn chance_die() -> IResult<&'static str, Box<dyn Command>> {
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let (input, pool) = create_chance_die()?;
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Ok((input, Box::new(PoolRollCommand(pool))))
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}
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fn help(topic: &str) -> IResult<&str, Box<dyn Command>> {
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let (topic, _) = eat_whitespace(topic)?;
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let topic = parse_help_topic(&trim(topic));
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Ok(("", Box::new(HelpCommand(topic))))
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}
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/// Potentially parse a command expression. If we recognize the command, an error should be raised
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/// if the command is misparsed. If we don't recognize the command, ignore it and return none
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pub fn parse_command(original_input: &str) -> IResult<&str, Option<Box<dyn Command>>> {
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let (input, _) = eat_whitespace(original_input)?;
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//Parser understands either specific !commands with no input, or any !command with extra input.
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named!(command(&str) -> (&str, &str), tuple!(
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complete!(tag!("!")),
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alt!(
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//TODO figure out how to gracefully handle arbitrary single commands.
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complete!(tag!("chance")) |
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complete!(tag!("help")) |
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complete!(take_while!(char::is_alphabetic))
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)
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));
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let (input, command) = match command(input) {
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// Strip the exclamation mark
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Ok((input, (_, result))) => (input, result),
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Err(_e) => {
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return Ok((original_input, None));
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}
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};
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match command {
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"r" | "roll" => parse_roll(input).map(|(input, command)| (input, Some(command))),
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"rp" | "pool" => parse_pool_roll(input).map(|(input, command)| (input, Some(command))),
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"chance" => chance_die().map(|(input, command)| (input, Some(command))),
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"help" => help(input).map(|(input, command)| (input, Some(command))),
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// No recognized command, ignore this.
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_ => Ok((original_input, None)),
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}
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}
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