442 lines
11 KiB
Rust
442 lines
11 KiB
Rust
//! Implementation of incremental re-parsing.
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//!
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//! We use two simple strategies for this:
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//! - if the edit modifies only a single token (like changing an identifier's
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//! letter), we replace only this token.
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//! - otherwise, we search for the nearest `{}` block which contains the edit
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//! and try to parse only this block.
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use parser::Reparser;
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use text_edit::Indel;
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use crate::{
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parsing::build_tree,
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syntax_node::{GreenNode, GreenToken, NodeOrToken, SyntaxElement, SyntaxNode},
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SyntaxError,
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SyntaxKind::*,
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TextRange, TextSize, T,
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};
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pub(crate) fn incremental_reparse(
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node: &SyntaxNode,
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edit: &Indel,
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errors: Vec<SyntaxError>,
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) -> Option<(GreenNode, Vec<SyntaxError>, TextRange)> {
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if let Some((green, new_errors, old_range)) = reparse_token(node, edit) {
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return Some((green, merge_errors(errors, new_errors, old_range, edit), old_range));
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}
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if let Some((green, new_errors, old_range)) = reparse_block(node, edit) {
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return Some((green, merge_errors(errors, new_errors, old_range, edit), old_range));
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}
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None
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}
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fn reparse_token(
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root: &SyntaxNode,
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edit: &Indel,
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) -> Option<(GreenNode, Vec<SyntaxError>, TextRange)> {
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let prev_token = root.covering_element(edit.delete).as_token()?.clone();
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let prev_token_kind = prev_token.kind();
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match prev_token_kind {
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WHITESPACE | COMMENT | IDENT | STRING => {
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if prev_token_kind == WHITESPACE || prev_token_kind == COMMENT {
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// removing a new line may extends previous token
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let deleted_range = edit.delete - prev_token.text_range().start();
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if prev_token.text()[deleted_range].contains('\n') {
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return None;
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}
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}
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let mut new_text = get_text_after_edit(prev_token.clone().into(), edit);
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let (new_token_kind, new_err) = parser::LexedStr::single_token(&new_text)?;
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if new_token_kind != prev_token_kind
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|| (new_token_kind == IDENT && is_contextual_kw(&new_text))
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{
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return None;
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}
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// Check that edited token is not a part of the bigger token.
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// E.g. if for source code `bruh"str"` the user removed `ruh`, then
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// `b` no longer remains an identifier, but becomes a part of byte string literal
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if let Some(next_char) = root.text().char_at(prev_token.text_range().end()) {
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new_text.push(next_char);
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let token_with_next_char = parser::LexedStr::single_token(&new_text);
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if let Some((_kind, _error)) = token_with_next_char {
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return None;
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}
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new_text.pop();
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}
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let new_token = GreenToken::new(rowan::SyntaxKind(prev_token_kind.into()), &new_text);
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let range = TextRange::up_to(TextSize::of(&new_text));
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Some((
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prev_token.replace_with(new_token),
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new_err.into_iter().map(|msg| SyntaxError::new(msg, range)).collect(),
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prev_token.text_range(),
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))
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}
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_ => None,
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}
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}
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fn reparse_block(
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root: &SyntaxNode,
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edit: &Indel,
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) -> Option<(GreenNode, Vec<SyntaxError>, TextRange)> {
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let (node, reparser) = find_reparsable_node(root, edit.delete)?;
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let text = get_text_after_edit(node.clone().into(), edit);
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let lexed = parser::LexedStr::new(text.as_str());
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let parser_input = lexed.to_input();
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if !is_balanced(&lexed) {
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return None;
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}
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let tree_traversal = reparser.parse(&parser_input);
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let (green, new_parser_errors, _eof) = build_tree(lexed, tree_traversal);
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Some((node.replace_with(green), new_parser_errors, node.text_range()))
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}
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fn get_text_after_edit(element: SyntaxElement, edit: &Indel) -> String {
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let edit = Indel::replace(edit.delete - element.text_range().start(), edit.insert.clone());
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let mut text = match element {
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NodeOrToken::Token(token) => token.text().to_string(),
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NodeOrToken::Node(node) => node.text().to_string(),
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};
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edit.apply(&mut text);
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text
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}
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fn is_contextual_kw(text: &str) -> bool {
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matches!(text, "auto" | "default" | "union")
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}
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fn find_reparsable_node(node: &SyntaxNode, range: TextRange) -> Option<(SyntaxNode, Reparser)> {
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let node = node.covering_element(range);
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node.ancestors().find_map(|node| {
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let first_child = node.first_child_or_token().map(|it| it.kind());
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let parent = node.parent().map(|it| it.kind());
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Reparser::for_node(node.kind(), first_child, parent).map(|r| (node, r))
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})
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}
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fn is_balanced(lexed: &parser::LexedStr<'_>) -> bool {
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if lexed.is_empty() || lexed.kind(0) != T!['{'] || lexed.kind(lexed.len() - 1) != T!['}'] {
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return false;
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}
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let mut balance = 0usize;
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for i in 1..lexed.len() - 1 {
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match lexed.kind(i) {
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T!['{'] => balance += 1,
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T!['}'] => {
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balance = match balance.checked_sub(1) {
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Some(b) => b,
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None => return false,
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}
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}
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_ => (),
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}
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}
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balance == 0
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}
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fn merge_errors(
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old_errors: Vec<SyntaxError>,
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new_errors: Vec<SyntaxError>,
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range_before_reparse: TextRange,
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edit: &Indel,
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) -> Vec<SyntaxError> {
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let mut res = Vec::new();
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for old_err in old_errors {
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let old_err_range = old_err.range();
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if old_err_range.end() <= range_before_reparse.start() {
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res.push(old_err);
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} else if old_err_range.start() >= range_before_reparse.end() {
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let inserted_len = TextSize::of(&edit.insert);
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res.push(old_err.with_range((old_err_range + inserted_len) - edit.delete.len()));
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// Note: extra parens are intentional to prevent uint underflow, HWAB (here was a bug)
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}
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}
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res.extend(new_errors.into_iter().map(|new_err| {
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// fighting borrow checker with a variable ;)
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let offseted_range = new_err.range() + range_before_reparse.start();
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new_err.with_range(offseted_range)
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}));
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res
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}
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#[cfg(test)]
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mod tests {
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use test_utils::{assert_eq_text, extract_range};
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use super::*;
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use crate::{AstNode, Parse, SourceFile};
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fn do_check(before: &str, replace_with: &str, reparsed_len: u32) {
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let (range, before) = extract_range(before);
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let edit = Indel::replace(range, replace_with.to_owned());
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let after = {
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let mut after = before.clone();
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edit.apply(&mut after);
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after
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};
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let fully_reparsed = SourceFile::parse(&after);
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let incrementally_reparsed: Parse<SourceFile> = {
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let before = SourceFile::parse(&before);
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let (green, new_errors, range) =
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incremental_reparse(before.tree().syntax(), &edit, before.errors.to_vec()).unwrap();
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assert_eq!(range.len(), reparsed_len.into(), "reparsed fragment has wrong length");
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Parse::new(green, new_errors)
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};
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assert_eq_text!(
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&format!("{:#?}", fully_reparsed.tree().syntax()),
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&format!("{:#?}", incrementally_reparsed.tree().syntax()),
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);
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assert_eq!(fully_reparsed.errors(), incrementally_reparsed.errors());
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}
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#[test] // FIXME: some test here actually test token reparsing
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fn reparse_block_tests() {
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do_check(
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r"
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fn foo() {
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let x = foo + $0bar$0
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}
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",
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"baz",
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3,
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);
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do_check(
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r"
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fn foo() {
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let x = foo$0 + bar$0
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}
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",
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"baz",
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25,
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);
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do_check(
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r"
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struct Foo {
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f: foo$0$0
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}
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",
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",\n g: (),",
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14,
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);
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do_check(
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r"
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fn foo {
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let;
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1 + 1;
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$092$0;
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}
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",
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"62",
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31, // FIXME: reparse only int literal here
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);
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do_check(
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r"
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mod foo {
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fn $0$0
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}
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",
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"bar",
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11,
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);
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do_check(
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r"
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trait Foo {
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type $0Foo$0;
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}
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",
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"Output",
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3,
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);
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do_check(
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r"
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impl IntoIterator<Item=i32> for Foo {
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f$0$0
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}
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",
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"n next(",
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9,
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);
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do_check(r"use a::b::{foo,$0,bar$0};", "baz", 10);
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do_check(
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r"
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pub enum A {
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Foo$0$0
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}
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",
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"\nBar;\n",
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11,
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);
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do_check(
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r"
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foo!{a, b$0$0 d}
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",
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", c[3]",
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8,
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);
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do_check(
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r"
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fn foo() {
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vec![$0$0]
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}
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",
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"123",
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14,
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);
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do_check(
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r"
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extern {
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fn$0;$0
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}
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",
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" exit(code: c_int)",
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11,
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);
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}
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#[test]
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fn reparse_token_tests() {
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do_check(
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r"$0$0
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fn foo() -> i32 { 1 }
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",
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"\n\n\n \n",
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1,
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);
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do_check(
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r"
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fn foo() -> $0$0 {}
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",
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" \n",
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2,
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);
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do_check(
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r"
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fn $0foo$0() -> i32 { 1 }
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",
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"bar",
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3,
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);
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do_check(
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r"
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fn foo$0$0foo() { }
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",
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"bar",
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6,
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);
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do_check(
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r"
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fn foo /* $0$0 */ () {}
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",
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"some comment",
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6,
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);
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do_check(
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r"
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fn baz $0$0 () {}
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",
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" \t\t\n\n",
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2,
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);
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do_check(
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r"
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fn baz $0$0 () {}
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",
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" \t\t\n\n",
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2,
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);
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do_check(
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r"
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/// foo $0$0omment
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mod { }
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",
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"c",
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14,
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);
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do_check(
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r#"
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fn -> &str { "Hello$0$0" }
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"#,
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", world",
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7,
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);
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do_check(
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r#"
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fn -> &str { // "Hello$0$0"
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"#,
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", world",
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10,
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);
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do_check(
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r##"
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fn -> &str { r#"Hello$0$0"#
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"##,
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", world",
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10,
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);
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do_check(
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r"
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#[derive($0Copy$0)]
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enum Foo {
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}
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",
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"Clone",
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4,
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);
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}
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#[test]
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fn reparse_str_token_with_error_unchanged() {
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do_check(r#""$0Unclosed$0 string literal"#, "Still unclosed", 24);
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}
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#[test]
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fn reparse_str_token_with_error_fixed() {
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do_check(r#""unterinated$0$0"#, "\"", 12);
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}
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#[test]
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fn reparse_block_with_error_in_middle_unchanged() {
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do_check(
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r#"fn main() {
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if {}
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32 + 4$0$0
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return
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if {}
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}"#,
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"23",
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105,
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)
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}
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#[test]
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fn reparse_block_with_error_in_middle_fixed() {
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do_check(
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r#"fn main() {
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if {}
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32 + 4$0$0
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return
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if {}
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}"#,
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";",
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105,
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)
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}
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}
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