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|
mod event;
mod input;
use std::cell::Cell;
use {
lexer::Token,
parser_api::Parser,
parser_impl::{
event::{process, Event},
input::{InputPosition, ParserInput},
},
TextUnit,
};
use SyntaxKind::{self, EOF, TOMBSTONE};
pub(crate) trait Sink<'a> {
type Tree;
fn new(text: &'a str) -> Self;
fn leaf(&mut self, kind: SyntaxKind, len: TextUnit);
fn start_internal(&mut self, kind: SyntaxKind);
fn finish_internal(&mut self);
fn error(&mut self, err: String);
fn finish(self) -> Self::Tree;
}
/// Parse a sequence of tokens into the representative node tree
pub(crate) fn parse_with<'a, S: Sink<'a>>(
text: &'a str,
tokens: &[Token],
parser: fn(&mut Parser),
) -> S::Tree {
let 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()
};
let mut sink = S::new(text);
process(&mut sink, tokens, events);
sink.finish()
}
/// Implementation details of `Parser`, extracted
/// to a separate struct in order not to pollute
/// the public API of the `Parser`.
pub(crate) struct ParserImpl<'t> {
inp: &'t ParserInput<'t>,
pos: InputPosition,
events: Vec<Event>,
steps: Cell<u32>,
}
impl<'t> ParserImpl<'t> {
pub(crate) fn new(inp: &'t ParserInput<'t>) -> ParserImpl<'t> {
ParserImpl {
inp,
pos: InputPosition::new(),
events: Vec::new(),
steps: Cell::new(0),
}
}
pub(crate) fn into_events(self) -> Vec<Event> {
assert_eq!(self.nth(0), EOF);
self.events
}
pub(super) fn next2(&self) -> Option<(SyntaxKind, SyntaxKind)> {
let c1 = self.inp.kind(self.pos);
let c2 = self.inp.kind(self.pos + 1);
if self.inp.start(self.pos + 1) == self.inp.start(self.pos) + self.inp.len(self.pos) {
Some((c1, c2))
} else {
None
}
}
pub(super) fn next3(&self) -> Option<(SyntaxKind, SyntaxKind, SyntaxKind)> {
let c1 = self.inp.kind(self.pos);
let c2 = self.inp.kind(self.pos + 1);
let c3 = self.inp.kind(self.pos + 2);
if self.inp.start(self.pos + 1) == self.inp.start(self.pos) + self.inp.len(self.pos)
&& self.inp.start(self.pos + 2) == self.inp.start(self.pos + 1) + self.inp.len(self.pos + 1){
Some((c1, c2, c3))
} else {
None
}
}
pub(super) fn nth(&self, n: u32) -> SyntaxKind {
let steps = self.steps.get();
if steps > 10_000_000 {
panic!("the parser seems stuck");
}
self.steps.set(steps + 1);
self.inp.kind(self.pos + n)
}
pub(super) fn at_kw(&self, t: &str) -> bool {
self.inp.text(self.pos) == t
}
pub(super) fn start(&mut self) -> u32 {
let pos = self.events.len() as u32;
self.event(Event::Start {
kind: TOMBSTONE,
forward_parent: None,
});
pos
}
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.event(Event::Token {
kind,
n_raw_tokens,
});
}
pub(super) fn error(&mut self, msg: String) {
self.event(Event::Error { msg })
}
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.event(Event::Finish);
}
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!(),
}
}
}
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 event(&mut self, event: Event) {
self.events.push(event)
}
}
|
