148 lines
4.5 KiB
Rust
148 lines
4.5 KiB
Rust
use {ErrorMsg, File, FileBuilder, Sink, SyntaxKind, TextUnit, Token};
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use syntax_kinds::TOMBSTONE;
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use super::is_insignificant;
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/// `Parser` produces a flat list of `Event`s.
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/// They are converted to a tree-structure in
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/// a separate pass, via `TreeBuilder`.
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#[derive(Debug)]
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pub(crate) enum Event {
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/// This event signifies the start of the node.
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/// It should be either abandoned (in which case the
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/// `kind` is `TOMBSTONE`, and the event is ignored),
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/// or completed via a `Finish` event.
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///
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/// All tokens between a `Start` and a `Finish` would
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/// become the children of the respective node.
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///
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/// For left-recursive syntactic constructs, the parser produces
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/// a child node before it sees a parent. `forward_parent`
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/// exists to allow to tweak parent-child relationships.
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///
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/// Consider this path
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///
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/// foo::bar
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///
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/// The events for it would look like this:
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///
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///
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/// START(PATH) IDENT('foo') FINISH START(PATH) COLONCOLON IDENT('bar') FINISH
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/// | /\
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/// | |
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/// +------forward-parent------+
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///
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/// And the tree would look like this
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///
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/// +--PATH---------+
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/// | | |
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/// | | |
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/// | '::' 'bar'
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/// |
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/// PATH
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/// |
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/// 'foo'
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///
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/// See also `CompletedMarker::precede`.
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Start {
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kind: SyntaxKind,
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forward_parent: Option<u32>,
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},
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/// Complete the previous `Start` event
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Finish,
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/// Produce a single leaf-element.
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/// `n_raw_tokens` is used to glue complex contextual tokens.
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/// For example, lexer tokenizes `>>` as `>`, `>`, and
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/// `n_raw_tokens = 2` is used to produced a single `>>`.
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Token {
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kind: SyntaxKind,
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n_raw_tokens: u8,
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},
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Error {
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msg: String,
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},
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}
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pub(super) fn to_file(text: String, tokens: &[Token], events: Vec<Event>) -> File {
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let mut builder = FileBuilder::new(text);
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let mut idx = 0;
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let mut holes = Vec::new();
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let mut forward_parents = Vec::new();
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for (i, event) in events.iter().enumerate() {
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if holes.last() == Some(&i) {
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holes.pop();
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continue;
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}
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match event {
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&Event::Start {
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kind: TOMBSTONE, ..
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} => (),
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&Event::Start { .. } => {
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forward_parents.clear();
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let mut idx = i;
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loop {
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let (kind, fwd) = match events[idx] {
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Event::Start {
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kind,
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forward_parent,
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} => (kind, forward_parent),
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_ => unreachable!(),
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};
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forward_parents.push((idx, kind));
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if let Some(fwd) = fwd {
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idx += fwd as usize;
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} else {
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break;
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}
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}
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for &(idx, kind) in forward_parents.iter().into_iter().rev() {
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builder.start_internal(kind);
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holes.push(idx);
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}
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holes.pop();
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}
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&Event::Finish => {
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while idx < tokens.len() {
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let token = tokens[idx];
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if is_insignificant(token.kind) {
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idx += 1;
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builder.leaf(token.kind, token.len);
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} else {
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break;
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}
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}
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builder.finish_internal()
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}
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&Event::Token {
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kind,
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mut n_raw_tokens,
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} => {
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// FIXME: currently, we attach whitespace to some random node
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// this should be done in a sensible manner instead
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loop {
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let token = tokens[idx];
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if !is_insignificant(token.kind) {
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break;
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}
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builder.leaf(token.kind, token.len);
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idx += 1
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}
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let mut len = TextUnit::new(0);
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for _ in 0..n_raw_tokens {
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len += tokens[idx].len;
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idx += 1;
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}
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builder.leaf(kind, len);
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}
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&Event::Error { ref msg } => builder.error(ErrorMsg { msg: msg.clone() }),
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}
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}
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builder.finish()
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}
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