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use crate::lexer::token::Token;
use crate::lexer::Lexer;
use crate::parser::TokenStream;
use moore_common::errors::*;
use moore_common::grind::Grinder;
use moore_common::source::*;
use std::collections::VecDeque;
pub struct BasicParser<T>
where
T: Grinder<Item = Option<u8>, Error = DiagBuilder2>,
{
input: Lexer<T>,
queue: VecDeque<Spanned<Token>>,
last_span: Span,
severity: Severity,
consumed: usize,
}
impl<T> TokenStream<Token> for BasicParser<T>
where
T: Grinder<Item = Option<u8>, Error = DiagBuilder2>,
{
fn peek(&mut self, offset: usize) -> Spanned<Token> {
self.ensure_queue_filled(offset);
if offset < self.queue.len() {
self.queue[offset]
} else {
*self
.queue
.back()
.expect("At least an Eof token should be in the queue")
}
}
fn bump(&mut self) {
if self.queue.is_empty() {
self.ensure_queue_filled(1);
}
if let Some(Spanned { value, span }) = self.queue.pop_front() {
assert!(value != Token::Eof);
self.last_span = span;
self.consumed += 1;
}
}
fn consumed(&self) -> usize {
self.consumed
}
fn last_span(&self) -> Span {
self.last_span
}
fn emit(&mut self, diag: DiagBuilder2) {
use std::cmp::max;
self.severity = max(self.severity, diag.get_severity());
self.input.emit(diag);
}
fn severity(&self) -> Severity {
self.severity
}
}
impl<T> BasicParser<T>
where
T: Grinder<Item = Option<u8>, Error = DiagBuilder2>,
{
pub fn new(input: Lexer<T>) -> BasicParser<T> {
BasicParser {
input: input,
queue: VecDeque::new(),
last_span: INVALID_SPAN,
severity: Severity::Note,
consumed: 0,
}
}
fn ensure_queue_filled(&mut self, min_tokens: usize) {
if let Some(&Spanned {
value: Token::Eof, ..
}) = self.queue.back()
{
return;
}
while self.queue.len() <= min_tokens {
match self.input.next() {
Some(t) => self.queue.push_back(t),
None => {
self.queue
.push_back(Spanned::new(Token::Eof, self.last_span.end().into()));
break;
}
}
}
}
}