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|
mod event;
pub(crate) mod input;
use std::cell::Cell;
use crate::{
syntax_error::ParseError,
parsing::{
TreeSink, TokenSource, TokenPos,
lexer::Token,
parser_api::Parser,
parser_impl::event::{Event, EventProcessor},
},
};
use crate::SyntaxKind::{self, EOF, TOMBSTONE};
/// Parse a sequence of tokens into the representative node tree
pub(super) fn parse_with<S: TreeSink>(
sink: S,
text: &str,
tokens: &[Token],
parser: fn(&mut Parser),
) -> S::Tree {
let mut events = {
let input = input::ParserInput::new(text, tokens);
let parser_impl = ParserImpl::new(&input);
let mut parser_api = Parser(parser_impl);
parser(&mut parser_api);
parser_api.0.into_events()
};
EventProcessor::new(sink, text, tokens, &mut events).process().finish()
}
/// Implementation details of `Parser`, extracted
/// to a separate struct in order not to pollute
/// the public API of the `Parser`.
pub(super) struct ParserImpl<'a> {
token_source: &'a dyn TokenSource,
pos: TokenPos,
events: Vec<Event>,
steps: Cell<u32>,
}
impl<'a> ParserImpl<'a> {
fn new(token_source: &'a dyn TokenSource) -> ParserImpl<'a> {
ParserImpl {
token_source,
pos: TokenPos::default(),
events: Vec::new(),
steps: Cell::new(0),
}
}
fn into_events(self) -> Vec<Event> {
assert_eq!(self.nth(0), EOF);
self.events
}
pub(super) fn current2(&self) -> Option<(SyntaxKind, SyntaxKind)> {
let c1 = self.token_source.token_kind(self.pos);
let c2 = self.token_source.token_kind(self.pos + 1);
if self.token_source.is_token_joint_to_next(self.pos) {
Some((c1, c2))
} else {
None
}
}
pub(super) fn current3(&self) -> Option<(SyntaxKind, SyntaxKind, SyntaxKind)> {
let c1 = self.token_source.token_kind(self.pos);
let c2 = self.token_source.token_kind(self.pos + 1);
let c3 = self.token_source.token_kind(self.pos + 2);
if self.token_source.is_token_joint_to_next(self.pos)
&& self.token_source.is_token_joint_to_next(self.pos + 1)
{
Some((c1, c2, c3))
} else {
None
}
}
/// Get the syntax kind of the nth token.
pub(super) fn nth(&self, n: u32) -> SyntaxKind {
let steps = self.steps.get();
assert!(steps <= 10_000_000, "the parser seems stuck");
self.steps.set(steps + 1);
self.token_source.token_kind(self.pos + n)
}
pub(super) fn at_kw(&self, kw: &str) -> bool {
self.token_source.is_keyword(self.pos, kw)
}
/// Start parsing right behind the last event.
pub(super) fn start(&mut self) -> u32 {
let pos = self.events.len() as u32;
self.push_event(Event::tombstone());
pos
}
/// Advances the parser by one token unconditionally.
pub(super) fn bump(&mut self) {
let kind = self.nth(0);
if kind == EOF {
return;
}
self.do_bump(kind, 1);
}
pub(super) fn bump_remap(&mut self, kind: SyntaxKind) {
if self.nth(0) == EOF {
// TODO: panic!?
return;
}
self.do_bump(kind, 1);
}
pub(super) fn bump_compound(&mut self, kind: SyntaxKind, n: u8) {
self.do_bump(kind, n);
}
fn do_bump(&mut self, kind: SyntaxKind, n_raw_tokens: u8) {
self.pos += u32::from(n_raw_tokens);
self.push_event(Event::Token { kind, n_raw_tokens });
}
/// Append one Error event to the back of events.
pub(super) fn error(&mut self, msg: String) {
self.push_event(Event::Error { msg: ParseError(msg) })
}
/// Complete an event with appending a `Finish` event.
pub(super) fn complete(&mut self, pos: u32, kind: SyntaxKind) {
match self.events[pos as usize] {
Event::Start { kind: ref mut slot, .. } => {
*slot = kind;
}
_ => unreachable!(),
}
self.push_event(Event::Finish);
}
/// Ignore the dummy `Start` event.
pub(super) fn abandon(&mut self, pos: u32) {
let idx = pos as usize;
if idx == self.events.len() - 1 {
match self.events.pop() {
Some(Event::Start { kind: TOMBSTONE, forward_parent: None }) => (),
_ => unreachable!(),
}
}
}
/// Save the relative distance of a completed event to its forward_parent.
pub(super) fn precede(&mut self, pos: u32) -> u32 {
let new_pos = self.start();
match self.events[pos as usize] {
Event::Start { ref mut forward_parent, .. } => {
*forward_parent = Some(new_pos - pos);
}
_ => unreachable!(),
}
new_pos
}
fn push_event(&mut self, event: Event) {
self.events.push(event)
}
}
|
