From d334b5a1db9ec6a57f54077d422a3f4b3c8c1178 Mon Sep 17 00:00:00 2001 From: Aleksey Kladov Date: Thu, 21 Feb 2019 13:27:45 +0300 Subject: move parser to a separate crate --- crates/ra_syntax/src/parsing/parser.rs | 270 --------------------------------- 1 file changed, 270 deletions(-) delete mode 100644 crates/ra_syntax/src/parsing/parser.rs (limited to 'crates/ra_syntax/src/parsing/parser.rs') diff --git a/crates/ra_syntax/src/parsing/parser.rs b/crates/ra_syntax/src/parsing/parser.rs deleted file mode 100644 index 923b0f2b2..000000000 --- a/crates/ra_syntax/src/parsing/parser.rs +++ /dev/null @@ -1,270 +0,0 @@ -use std::cell::Cell; - -use drop_bomb::DropBomb; - -use crate::{ - SyntaxKind::{self, ERROR, EOF, TOMBSTONE}, - parsing::{ - TokenSource, ParseError, - token_set::TokenSet, - event::Event, - }, -}; - -/// `Parser` struct provides the low-level API for -/// navigating through the stream of tokens and -/// constructing the parse tree. The actual parsing -/// happens in the `grammar` module. -/// -/// However, the result of this `Parser` is not a real -/// tree, but rather a flat stream of events of the form -/// "start expression, consume number literal, -/// finish expression". See `Event` docs for more. -pub(crate) struct Parser<'t> { - token_source: &'t dyn TokenSource, - token_pos: usize, - events: Vec, - steps: Cell, -} - -impl<'t> Parser<'t> { - pub(super) fn new(token_source: &'t dyn TokenSource) -> Parser<'t> { - Parser { token_source, token_pos: 0, events: Vec::new(), steps: Cell::new(0) } - } - - pub(crate) fn finish(self) -> Vec { - self.events - } - - /// Returns the kind of the current token. - /// If parser has already reached the end of input, - /// the special `EOF` kind is returned. - pub(crate) fn current(&self) -> SyntaxKind { - self.nth(0) - } - - /// Returns the kinds of the current two tokens, if they are not separated - /// by trivia. - /// - /// Useful for parsing things like `>>`. - pub(crate) fn current2(&self) -> Option<(SyntaxKind, SyntaxKind)> { - let c1 = self.token_source.token_kind(self.token_pos); - let c2 = self.token_source.token_kind(self.token_pos + 1); - if self.token_source.is_token_joint_to_next(self.token_pos) { - Some((c1, c2)) - } else { - None - } - } - - /// Returns the kinds of the current three tokens, if they are not separated - /// by trivia. - /// - /// Useful for parsing things like `=>>`. - pub(crate) fn current3(&self) -> Option<(SyntaxKind, SyntaxKind, SyntaxKind)> { - let c1 = self.token_source.token_kind(self.token_pos); - let c2 = self.token_source.token_kind(self.token_pos + 1); - let c3 = self.token_source.token_kind(self.token_pos + 2); - if self.token_source.is_token_joint_to_next(self.token_pos) - && self.token_source.is_token_joint_to_next(self.token_pos + 1) - { - Some((c1, c2, c3)) - } else { - None - } - } - - /// Lookahead operation: returns the kind of the next nth - /// token. - pub(crate) fn nth(&self, n: usize) -> 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.token_pos + n) - } - - /// Checks if the current token is `kind`. - pub(crate) fn at(&self, kind: SyntaxKind) -> bool { - self.current() == kind - } - - /// Checks if the current token is in `kinds`. - pub(crate) fn at_ts(&self, kinds: TokenSet) -> bool { - kinds.contains(self.current()) - } - - /// Checks if the current token is contextual keyword with text `t`. - pub(crate) fn at_contextual_kw(&self, kw: &str) -> bool { - self.token_source.is_keyword(self.token_pos, kw) - } - - /// Starts a new node in the syntax tree. All nodes and tokens - /// consumed between the `start` and the corresponding `Marker::complete` - /// belong to the same node. - pub(crate) fn start(&mut self) -> Marker { - let pos = self.events.len() as u32; - self.push_event(Event::tombstone()); - Marker::new(pos) - } - - /// Advances the parser by one token unconditionally. - pub(crate) fn bump(&mut self) { - let kind = self.nth(0); - if kind == EOF { - return; - } - self.do_bump(kind, 1); - } - - /// Advances the parser by one token, remapping its kind. - /// This is useful to create contextual keywords from - /// identifiers. For example, the lexer creates an `union` - /// *identifier* token, but the parser remaps it to the - /// `union` keyword, and keyword is what ends up in the - /// final tree. - pub(crate) fn bump_remap(&mut self, kind: SyntaxKind) { - if self.nth(0) == EOF { - // TODO: panic!? - return; - } - self.do_bump(kind, 1); - } - - /// Advances the parser by `n` tokens, remapping its kind. - /// This is useful to create compound tokens from parts. For - /// example, an `<<` token is two consecutive remapped `<` tokens - pub(crate) fn bump_compound(&mut self, kind: SyntaxKind, n: u8) { - self.do_bump(kind, n); - } - - /// Emit error with the `message` - /// TODO: this should be much more fancy and support - /// structured errors with spans and notes, like rustc - /// does. - pub(crate) fn error>(&mut self, message: T) { - let msg = ParseError(message.into()); - self.push_event(Event::Error { msg }) - } - - /// Consume the next token if `kind` matches. - pub(crate) fn eat(&mut self, kind: SyntaxKind) -> bool { - if !self.at(kind) { - return false; - } - self.bump(); - true - } - - /// Consume the next token if it is `kind` or emit an error - /// otherwise. - pub(crate) fn expect(&mut self, kind: SyntaxKind) -> bool { - if self.eat(kind) { - return true; - } - self.error(format!("expected {:?}", kind)); - false - } - - /// Create an error node and consume the next token. - pub(crate) fn err_and_bump(&mut self, message: &str) { - self.err_recover(message, TokenSet::empty()); - } - - /// Create an error node and consume the next token. - pub(crate) fn err_recover(&mut self, message: &str, recovery: TokenSet) { - if self.at(SyntaxKind::L_CURLY) || self.at(SyntaxKind::R_CURLY) || self.at_ts(recovery) { - self.error(message); - } else { - let m = self.start(); - self.error(message); - self.bump(); - m.complete(self, ERROR); - }; - } - - fn do_bump(&mut self, kind: SyntaxKind, n_raw_tokens: u8) { - self.token_pos += usize::from(n_raw_tokens); - self.push_event(Event::Token { kind, n_raw_tokens }); - } - - fn push_event(&mut self, event: Event) { - self.events.push(event) - } -} - -/// See `Parser::start`. -pub(crate) struct Marker { - pos: u32, - bomb: DropBomb, -} - -impl Marker { - fn new(pos: u32) -> Marker { - Marker { pos, bomb: DropBomb::new("Marker must be either completed or abandoned") } - } - - /// Finishes the syntax tree node and assigns `kind` to it, - /// and mark the create a `CompletedMarker` for possible future - /// operation like `.precede()` to deal with forward_parent. - pub(crate) fn complete(mut self, p: &mut Parser, kind: SyntaxKind) -> CompletedMarker { - self.bomb.defuse(); - let idx = self.pos as usize; - match p.events[idx] { - Event::Start { kind: ref mut slot, .. } => { - *slot = kind; - } - _ => unreachable!(), - } - p.push_event(Event::Finish); - CompletedMarker::new(self.pos, kind) - } - - /// Abandons the syntax tree node. All its children - /// are attached to its parent instead. - pub(crate) fn abandon(mut self, p: &mut Parser) { - self.bomb.defuse(); - let idx = self.pos as usize; - if idx == p.events.len() - 1 { - match p.events.pop() { - Some(Event::Start { kind: TOMBSTONE, forward_parent: None }) => (), - _ => unreachable!(), - } - } - } -} - -pub(crate) struct CompletedMarker(u32, SyntaxKind); - -impl CompletedMarker { - fn new(pos: u32, kind: SyntaxKind) -> Self { - CompletedMarker(pos, kind) - } - - /// This method allows to create a new node which starts - /// *before* the current one. That is, parser could start - /// node `A`, then complete it, and then after parsing the - /// whole `A`, decide that it should have started some node - /// `B` before starting `A`. `precede` allows to do exactly - /// that. See also docs about `forward_parent` in `Event::Start`. - /// - /// Given completed events `[START, FINISH]` and its corresponding - /// `CompletedMarker(pos: 0, _)`. - /// Append a new `START` events as `[START, FINISH, NEWSTART]`, - /// then mark `NEWSTART` as `START`'s parent with saving its relative - /// distance to `NEWSTART` into forward_parent(=2 in this case); - pub(crate) fn precede(self, p: &mut Parser) -> Marker { - let new_pos = p.start(); - let idx = self.0 as usize; - match p.events[idx] { - Event::Start { ref mut forward_parent, .. } => { - *forward_parent = Some(new_pos.pos - self.0); - } - _ => unreachable!(), - } - new_pos - } - - pub(crate) fn kind(&self) -> SyntaxKind { - self.1 - } -} -- cgit v1.2.3