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Diffstat (limited to 'crates/libsyntax2/src/parser_impl/event.rs')
| -rw-r--r-- | crates/libsyntax2/src/parser_impl/event.rs | 154 |
1 files changed, 0 insertions, 154 deletions
diff --git a/crates/libsyntax2/src/parser_impl/event.rs b/crates/libsyntax2/src/parser_impl/event.rs deleted file mode 100644 index 9fd56b996..000000000 --- a/crates/libsyntax2/src/parser_impl/event.rs +++ /dev/null | |||
| @@ -1,154 +0,0 @@ | |||
| 1 | //! This module provides a way to construct a `File`. | ||
| 2 | //! It is intended to be completely decoupled from the | ||
| 3 | //! parser, so as to allow to evolve the tree representation | ||
| 4 | //! and the parser algorithm independently. | ||
| 5 | //! | ||
| 6 | //! The `Sink` trait is the bridge between the parser and the | ||
| 7 | //! tree builder: the parser produces a stream of events like | ||
| 8 | //! `start node`, `finish node`, and `FileBuilder` converts | ||
| 9 | //! this stream to a real tree. | ||
| 10 | use std::mem; | ||
| 11 | use { | ||
| 12 | lexer::Token, | ||
| 13 | parser_impl::Sink, | ||
| 14 | SyntaxKind::{self, TOMBSTONE}, | ||
| 15 | }; | ||
| 16 | |||
| 17 | |||
| 18 | /// `Parser` produces a flat list of `Event`s. | ||
| 19 | /// They are converted to a tree-structure in | ||
| 20 | /// a separate pass, via `TreeBuilder`. | ||
| 21 | #[derive(Debug)] | ||
| 22 | pub(crate) enum Event { | ||
| 23 | /// This event signifies the start of the node. | ||
| 24 | /// It should be either abandoned (in which case the | ||
| 25 | /// `kind` is `TOMBSTONE`, and the event is ignored), | ||
| 26 | /// or completed via a `Finish` event. | ||
| 27 | /// | ||
| 28 | /// All tokens between a `Start` and a `Finish` would | ||
| 29 | /// become the children of the respective node. | ||
| 30 | /// | ||
| 31 | /// For left-recursive syntactic constructs, the parser produces | ||
| 32 | /// a child node before it sees a parent. `forward_parent` | ||
| 33 | /// exists to allow to tweak parent-child relationships. | ||
| 34 | /// | ||
| 35 | /// Consider this path | ||
| 36 | /// | ||
| 37 | /// foo::bar | ||
| 38 | /// | ||
| 39 | /// The events for it would look like this: | ||
| 40 | /// | ||
| 41 | /// | ||
| 42 | /// START(PATH) IDENT('foo') FINISH START(PATH) COLONCOLON IDENT('bar') FINISH | ||
| 43 | /// | /\ | ||
| 44 | /// | | | ||
| 45 | /// +------forward-parent------+ | ||
| 46 | /// | ||
| 47 | /// And the tree would look like this | ||
| 48 | /// | ||
| 49 | /// +--PATH---------+ | ||
| 50 | /// | | | | ||
| 51 | /// | | | | ||
| 52 | /// | '::' 'bar' | ||
| 53 | /// | | ||
| 54 | /// PATH | ||
| 55 | /// | | ||
| 56 | /// 'foo' | ||
| 57 | /// | ||
| 58 | /// See also `CompletedMarker::precede`. | ||
| 59 | Start { | ||
| 60 | kind: SyntaxKind, | ||
| 61 | forward_parent: Option<u32>, | ||
| 62 | }, | ||
| 63 | |||
| 64 | /// Complete the previous `Start` event | ||
| 65 | Finish, | ||
| 66 | |||
| 67 | /// Produce a single leaf-element. | ||
| 68 | /// `n_raw_tokens` is used to glue complex contextual tokens. | ||
| 69 | /// For example, lexer tokenizes `>>` as `>`, `>`, and | ||
| 70 | /// `n_raw_tokens = 2` is used to produced a single `>>`. | ||
| 71 | Token { | ||
| 72 | kind: SyntaxKind, | ||
| 73 | n_raw_tokens: u8, | ||
| 74 | }, | ||
| 75 | |||
| 76 | Error { | ||
| 77 | msg: String, | ||
| 78 | }, | ||
| 79 | } | ||
| 80 | |||
| 81 | |||
| 82 | pub(super) fn process<'a, S: Sink<'a>>(builder: &mut S, tokens: &[Token], mut events: Vec<Event>) { | ||
| 83 | fn tombstone() -> Event { | ||
| 84 | Event::Start { kind: TOMBSTONE, forward_parent: None } | ||
| 85 | } | ||
| 86 | let eat_ws = |idx: &mut usize, builder: &mut S| { | ||
| 87 | while let Some(token) = tokens.get(*idx) { | ||
| 88 | if !token.kind.is_trivia() { | ||
| 89 | break; | ||
| 90 | } | ||
| 91 | builder.leaf(token.kind, token.len); | ||
| 92 | *idx += 1 | ||
| 93 | } | ||
| 94 | }; | ||
| 95 | |||
| 96 | let events: &mut [Event] = &mut events; | ||
| 97 | let mut depth = 0; | ||
| 98 | let mut forward_parents = Vec::new(); | ||
| 99 | let mut next_tok_idx = 0; | ||
| 100 | for i in 0..events.len() { | ||
| 101 | match mem::replace(&mut events[i], tombstone()) { | ||
| 102 | Event::Start { | ||
| 103 | kind: TOMBSTONE, .. | ||
| 104 | } => (), | ||
| 105 | |||
| 106 | Event::Start { kind, forward_parent } => { | ||
| 107 | forward_parents.push(kind); | ||
| 108 | let mut idx = i; | ||
| 109 | let mut fp = forward_parent; | ||
| 110 | while let Some(fwd) = fp { | ||
| 111 | idx += fwd as usize; | ||
| 112 | fp = match mem::replace(&mut events[idx], tombstone()) { | ||
| 113 | Event::Start { | ||
| 114 | kind, | ||
| 115 | forward_parent, | ||
| 116 | } => { | ||
| 117 | forward_parents.push(kind); | ||
| 118 | forward_parent | ||
| 119 | }, | ||
| 120 | _ => unreachable!(), | ||
| 121 | }; | ||
| 122 | } | ||
| 123 | for kind in forward_parents.drain(..).rev() { | ||
| 124 | if depth > 0 { | ||
| 125 | eat_ws(&mut next_tok_idx, builder); | ||
| 126 | } | ||
| 127 | depth += 1; | ||
| 128 | builder.start_internal(kind); | ||
| 129 | } | ||
| 130 | } | ||
| 131 | Event::Finish => { | ||
| 132 | depth -= 1; | ||
| 133 | if depth == 0 { | ||
| 134 | eat_ws(&mut next_tok_idx, builder); | ||
| 135 | } | ||
| 136 | |||
| 137 | builder.finish_internal(); | ||
| 138 | } | ||
| 139 | Event::Token { | ||
| 140 | kind, | ||
| 141 | mut n_raw_tokens, | ||
| 142 | } => { | ||
| 143 | eat_ws(&mut next_tok_idx, builder); | ||
| 144 | let mut len = 0.into(); | ||
| 145 | for _ in 0..n_raw_tokens { | ||
| 146 | len += tokens[next_tok_idx].len; | ||
| 147 | next_tok_idx += 1; | ||
| 148 | } | ||
| 149 | builder.leaf(kind, len); | ||
| 150 | } | ||
| 151 | Event::Error { msg } => builder.error(msg), | ||
| 152 | } | ||
| 153 | } | ||
| 154 | } | ||