bms-rs 1.0.0

The BMS format parser.
Documentation 
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//! This module handles the tokens:
//!
//! - `#VOLWAV n` - Changes the score's volume at `n`%.
//! - `#xxx97:` - BGM volume change channel. It changes BGM notes volume at `[01-FF]`. Obsolete.
//! - `#xxx98:` - Key volume change channel. It changes key notes volume at `[01-FF]`. Obsolete.

use super::{super::prompt::Prompter, ProcessContext, TokenProcessor, parse_hex_values};
use crate::bms::ParseErrorWithRange;
use crate::bms::{
    model::volume::VolumeObjects,
    parse::{ParseWarning, Result},
    prelude::*,
};

/// It processes `#VOLWAV` definitions and objects on `BgmVolume` and `KeyVolume` channels.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct VolumeProcessor;

impl TokenProcessor for VolumeProcessor {
    type Output = VolumeObjects;

    fn process<P: Prompter>(
        &self,
        ctx: &mut ProcessContext<'_, '_, P>,
    ) -> core::result::Result<Self::Output, ParseErrorWithRange> {
        let mut objects = VolumeObjects::default();
        ctx.all_tokens(|token, prompter| match token.content() {
            Token::Header { name, args } => {
                Ok(Self::on_header(name.as_ref(), args.as_ref(), &mut objects)
                    .map_or_else(|warn| vec![warn.into_wrapper(token)], |()| Vec::new()))
            }
            Token::Message {
                track,
                channel,
                message,
            } => Ok(Self::on_message(
                *track,
                *channel,
                &message.as_ref().into_wrapper(token),
                prompter,
                &mut objects,
            )
            .unwrap_or_else(|warn| vec![warn.into_wrapper(token)])),
            Token::NotACommand(_) => Ok(Vec::new()),
        })?;
        Ok(objects)
    }
}

impl VolumeProcessor {
    fn on_header(name: &str, args: &str, volume: &mut VolumeObjects) -> Result<()> {
        if name.eq_ignore_ascii_case("VOLWAV") {
            let volume_value = args
                .parse()
                .map_err(|_| ParseWarning::SyntaxError("expected integer".into()))?;
            let volume_obj = Volume {
                relative_percent: volume_value,
            };
            volume.volume = volume_obj;
        }
        Ok(())
    }

    fn on_message(
        track: Track,
        channel: Channel,
        message: &SourceRangeMixin<&str>,
        prompter: &impl Prompter,
        objects: &mut VolumeObjects,
    ) -> Result<Vec<ParseWarningWithRange>> {
        let mut warnings: Vec<ParseWarningWithRange> = Vec::new();
        match channel {
            Channel::BgmVolume => {
                let (pairs, w) = parse_hex_values(track, message);
                warnings.extend(w);
                for (time, volume_value) in pairs {
                    objects.push_bgm_volume_change(
                        BgmVolumeObj {
                            time,
                            volume: volume_value,
                        },
                        prompter,
                    )?;
                }
            }
            Channel::KeyVolume => {
                let (pairs, w) = parse_hex_values(track, message);
                warnings.extend(w);
                for (time, volume_value) in pairs {
                    objects.push_key_volume_change(
                        KeyVolumeObj {
                            time,
                            volume: volume_value,
                        },
                        prompter,
                    )?;
                }
            }
            _ => {}
        }
        Ok(warnings)
    }
}