Merge #867

867: This moves the parser to separate crate r=matklad a=matklad

That makes parser independent form both the token and the tree representation. 

Co-authored-by: Aleksey Kladov <[email protected]>

1 files changed, 0 insertions, 128 deletions

diff --git a/crates/ra_syntax/src/parsing/event.rs b/crates/ra_syntax/src/parsing/event.rs
deleted file mode 100644
index d6cbdffe0..000000000
--- a/crates/ra_syntax/src/parsing/event.rs
+++ /dev/null
@@ -1,128 +0,0 @@
-//! This module provides a way to construct a `File`.
-//! It is intended to be completely decoupled from the
-//! parser, so as to allow to evolve the tree representation
-//! and the parser algorithm independently.
-//!
-//! The `TreeSink` trait is the bridge between the parser and the
-//! tree builder: the parser produces a stream of events like
-//! `start node`, `finish node`, and `FileBuilder` converts
-//! this stream to a real tree.
-use std::mem;
-
-use crate::{
-    SyntaxKind::{self, *},
-    parsing::{ParseError, TreeSink},
-};
-
-/// `Parser` produces a flat list of `Event`s.
-/// They are converted to a tree-structure in
-/// a separate pass, via `TreeBuilder`.
-#[derive(Debug)]
-pub(crate) enum Event {
-    /// This event signifies the start of the node.
-    /// It should be either abandoned (in which case the
-    /// `kind` is `TOMBSTONE`, and the event is ignored),
-    /// or completed via a `Finish` event.
-    ///
-    /// All tokens between a `Start` and a `Finish` would
-    /// become the children of the respective node.
-    ///
-    /// For left-recursive syntactic constructs, the parser produces
-    /// a child node before it sees a parent. `forward_parent`
-    /// saves the position of current event's parent.
-    ///
-    /// Consider this path
-    ///
-    /// foo::bar
-    ///
-    /// The events for it would look like this:
-    ///
-    ///
-    /// START(PATH) IDENT('foo') FINISH START(PATH) COLONCOLON IDENT('bar') FINISH
-    ///       |                          /\
-    ///       |                          |
-    ///       +------forward-parent------+
-    ///
-    /// And the tree would look like this
-    ///
-    ///    +--PATH---------+
-    ///    |   |           |
-    ///    |   |           |
-    ///    |  '::'       'bar'
-    ///    |
-    ///   PATH
-    ///    |
-    ///   'foo'
-    ///
-    /// See also `CompletedMarker::precede`.
-    Start {
-        kind: SyntaxKind,
-        forward_parent: Option<u32>,
-    },
-
-    /// Complete the previous `Start` event
-    Finish,
-
-    /// Produce a single leaf-element.
-    /// `n_raw_tokens` is used to glue complex contextual tokens.
-    /// For example, lexer tokenizes `>>` as `>`, `>`, and
-    /// `n_raw_tokens = 2` is used to produced a single `>>`.
-    Token {
-        kind: SyntaxKind,
-        n_raw_tokens: u8,
-    },
-
-    Error {
-        msg: ParseError,
-    },
-}
-
-impl Event {
-    pub(crate) fn tombstone() -> Self {
-        Event::Start { kind: TOMBSTONE, forward_parent: None }
-    }
-}
-
-/// Generate the syntax tree with the control of events.
-pub(super) fn process(sink: &mut impl TreeSink, mut events: Vec<Event>) {
-    let mut forward_parents = Vec::new();
-
-    for i in 0..events.len() {
-        match mem::replace(&mut events[i], Event::tombstone()) {
-            Event::Start { kind: TOMBSTONE, .. } => (),
-
-            Event::Start { kind, forward_parent } => {
-                // For events[A, B, C], B is A's forward_parent, C is B's forward_parent,
-                // in the normal control flow, the parent-child relation: `A -> B -> C`,
-                // while with the magic forward_parent, it writes: `C <- B <- A`.
-
-                // append `A` into parents.
-                forward_parents.push(kind);
-                let mut idx = i;
-                let mut fp = forward_parent;
-                while let Some(fwd) = fp {
-                    idx += fwd as usize;
-                    // append `A`'s forward_parent `B`
-                    fp = match mem::replace(&mut events[idx], Event::tombstone()) {
-                        Event::Start { kind, forward_parent } => {
-                            forward_parents.push(kind);
-                            forward_parent
-                        }
-                        _ => unreachable!(),
-                    };
-                    // append `B`'s forward_parent `C` in the next stage.
-                }
-
-                for (j, kind) in forward_parents.drain(..).rev().enumerate() {
-                    let is_root_node = i == 0 && j == 0;
-                    sink.start_branch(kind, is_root_node);
-                }
-            }
-            Event::Finish => sink.finish_branch(i == events.len() - 1),
-            Event::Token { kind, n_raw_tokens } => {
-                sink.leaf(kind, n_raw_tokens);
-            }
-            Event::Error { msg } => sink.error(msg),
-        }
-    }
-}