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|
use std::{iter::Peekable, str::FromStr, vec::IntoIter};
use super::{
Result,
lexer::{Token, TokenKind},
util::{SpanParserError, TokenError},
};
use crate::program::{ChanSpec, Instruction};
use TokenKind as K;
pub struct Parser<'s> {
tokens: Peekable<IntoIter<Token<'s>>>,
spec: Option<ChanSpec>,
eof: Token<'s>,
}
impl<'s> Parser<'s> {
pub fn new(tokens: Vec<Token<'s>>) -> Self {
let eof = Token {
span: tokens[tokens.len() - 1].span,
content: "",
kind: K::Eof,
};
Self {
tokens: tokens.into_iter().peekable(),
spec: None,
eof,
}
}
fn next(&mut self) -> Token<'s> {
self.tokens.next().unwrap_or(self.eof)
}
fn peek(&mut self) -> Token<'s> {
self.tokens.peek().cloned().unwrap_or(self.eof)
}
fn expect(&mut self, kind: TokenKind) -> Result<Token<'s>> {
let token = self.next();
if token.kind == kind {
Ok(token)
} else {
token.token_err(format!("expected {kind}, got {}", token.kind))
}
}
fn parse_int<T>(&mut self) -> Result<T>
where
T: FromStr,
<T as FromStr>::Err: std::error::Error,
{
let token = self.expect(K::Integer)?;
token.content.parse().span_err(token.span)
}
fn parse_note(&mut self) -> Result<u8> {
if self.peek().kind == K::Integer {
return self.parse_int();
}
let ident = self.expect(K::Identifier)?;
let str = ident.content;
let str_len = str.len();
let last = str.chars().last().unwrap_or_default();
let note_str = &str[..1];
let note = match note_str {
"a" => 80,
"b" => 82,
"c" => 83,
"d" => 85,
"e" => 87,
"f" => 88,
"g" => 90,
_ => return ident.token_err("invalid note"),
};
let octave_str = if last.is_ascii_digit() {
&str[1..str_len]
} else {
&str[1..str_len - 1]
};
let octave = if !octave_str.is_empty() {
octave_str.parse().span_err(ident.span)?
} else {
4
};
let off = match last {
'b' | 'f' => -1,
'#' | 's' => 1,
_ => 0,
};
let pitch_u32 = (note + octave * 12) + off;
let pitch = u8::try_from(pitch_u32).span_err(ident.span)?;
Ok(pitch)
}
fn parse_bool(&mut self) -> Result<bool> {
let n = self.parse_int::<u8>()?;
Ok(n > 0)
}
fn parse_chan_ins(&mut self) -> Result<Instruction> {
let token = self.next();
let Some(spec) = self.spec else {
return token.token_err("missing channel specifier");
};
let ins = match token.kind {
K::Volume => {
let volume = self.parse_int()?;
Instruction::SetVolume(spec, volume)
}
K::Pitch => {
let pitch = self.parse_note()?;
Instruction::SetPitch(spec, pitch)
}
K::DutyCycle if spec == ChanSpec::PulseA => {
let cycle = self.parse_int()?;
Instruction::SetPulseDutyA(cycle)
}
K::DutyCycle if spec == ChanSpec::PulseB => {
let cycle = self.parse_int()?;
Instruction::SetPulseDutyB(cycle)
}
K::DutyCycle => {
return token.token_err("cannot set duty cycle for this channel");
}
K::Mode if spec == ChanSpec::Noise => {
let mode = self.parse_bool()?;
Instruction::SetNoiseMode(mode)
}
K::Mode => return token.token_err("cannot set mode for this channel"),
_ => return token.token_err("invalid channel argument"),
};
Ok(ins)
}
fn parse_pause_len(&mut self) -> Result<Instruction> {
self.next();
let num = self.parse_int()?;
Ok(Instruction::PauseLen(num))
}
fn parse_pause(&mut self) -> Result<Instruction> {
self.next();
let next = self.peek();
let ins = if next.kind == K::Integer {
let num = self.parse_int()?;
Instruction::Pause(num)
} else {
Instruction::Pause(1)
};
Ok(ins)
}
fn parse_ins(&mut self) -> Result<Instruction> {
let token = self.peek();
let spec = self.spec.take();
match token.kind {
K::PulseA => {
self.spec = Some(ChanSpec::PulseA);
self.next();
self.parse_chan_ins()
}
K::PulseB => {
self.spec = Some(ChanSpec::PulseB);
self.next();
self.parse_chan_ins()
}
K::Triangle => {
self.spec = Some(ChanSpec::Triangle);
self.next();
self.parse_chan_ins()
}
K::Noise => {
self.spec = Some(ChanSpec::Noise);
self.next();
self.parse_chan_ins()
}
K::PauseLen => self.parse_pause_len(),
K::Dash => self.parse_pause(),
_ => {
self.spec = spec;
self.parse_chan_ins()
}
}
}
pub fn parse(&mut self) -> Result<Vec<Instruction>> {
let mut prog = vec![];
loop {
let token = self.peek();
match token.kind {
K::Eof => break,
K::LineSeparator => {
self.next();
}
_ => prog.push(self.parse_ins()?),
}
}
Ok(prog)
}
}
|
