660 lines
18 KiB
Rust
660 lines
18 KiB
Rust
//! Collection of assorted algorithms for syntax trees.
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use std::hash::BuildHasherDefault;
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use indexmap::IndexMap;
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use itertools::Itertools;
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use rustc_hash::FxHashMap;
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use text_edit::TextEditBuilder;
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use crate::{
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AstNode, Direction, NodeOrToken, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange,
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TextSize,
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};
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/// Returns ancestors of the node at the offset, sorted by length. This should
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/// do the right thing at an edge, e.g. when searching for expressions at `{
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/// $0foo }` we will get the name reference instead of the whole block, which
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/// we would get if we just did `find_token_at_offset(...).flat_map(|t|
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/// t.parent().ancestors())`.
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pub fn ancestors_at_offset(
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node: &SyntaxNode,
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offset: TextSize,
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) -> impl Iterator<Item = SyntaxNode> {
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node.token_at_offset(offset)
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.map(|token| token.parent_ancestors())
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.kmerge_by(|node1, node2| node1.text_range().len() < node2.text_range().len())
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}
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/// Finds a node of specific Ast type at offset. Note that this is slightly
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/// imprecise: if the cursor is strictly between two nodes of the desired type,
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/// as in
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///
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/// ```no_run
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/// struct Foo {}|struct Bar;
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/// ```
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///
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/// then the shorter node will be silently preferred.
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pub fn find_node_at_offset<N: AstNode>(syntax: &SyntaxNode, offset: TextSize) -> Option<N> {
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ancestors_at_offset(syntax, offset).find_map(N::cast)
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}
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pub fn find_node_at_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
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syntax.covering_element(range).ancestors().find_map(N::cast)
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}
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/// Skip to next non `trivia` token
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pub fn skip_trivia_token(mut token: SyntaxToken, direction: Direction) -> Option<SyntaxToken> {
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while token.kind().is_trivia() {
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token = match direction {
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Direction::Next => token.next_token()?,
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Direction::Prev => token.prev_token()?,
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}
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}
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Some(token)
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}
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/// Skip to next non `whitespace` token
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pub fn skip_whitespace_token(mut token: SyntaxToken, direction: Direction) -> Option<SyntaxToken> {
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while token.kind() == SyntaxKind::WHITESPACE {
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token = match direction {
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Direction::Next => token.next_token()?,
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Direction::Prev => token.prev_token()?,
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}
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}
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Some(token)
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}
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/// Finds the first sibling in the given direction which is not `trivia`
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pub fn non_trivia_sibling(element: SyntaxElement, direction: Direction) -> Option<SyntaxElement> {
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return match element {
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NodeOrToken::Node(node) => node.siblings_with_tokens(direction).skip(1).find(not_trivia),
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NodeOrToken::Token(token) => token.siblings_with_tokens(direction).skip(1).find(not_trivia),
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};
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fn not_trivia(element: &SyntaxElement) -> bool {
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match element {
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NodeOrToken::Node(_) => true,
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NodeOrToken::Token(token) => !token.kind().is_trivia(),
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}
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}
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}
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pub fn least_common_ancestor(u: &SyntaxNode, v: &SyntaxNode) -> Option<SyntaxNode> {
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if u == v {
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return Some(u.clone());
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}
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let u_depth = u.ancestors().count();
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let v_depth = v.ancestors().count();
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let keep = u_depth.min(v_depth);
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let u_candidates = u.ancestors().skip(u_depth - keep);
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let v_candidates = v.ancestors().skip(v_depth - keep);
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let (res, _) = u_candidates.zip(v_candidates).find(|(x, y)| x == y)?;
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Some(res)
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}
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pub fn neighbor<T: AstNode>(me: &T, direction: Direction) -> Option<T> {
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me.syntax().siblings(direction).skip(1).find_map(T::cast)
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}
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pub fn has_errors(node: &SyntaxNode) -> bool {
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node.children().any(|it| it.kind() == SyntaxKind::ERROR)
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}
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type FxIndexMap<K, V> = IndexMap<K, V, BuildHasherDefault<rustc_hash::FxHasher>>;
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#[derive(Debug, Hash, PartialEq, Eq)]
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enum TreeDiffInsertPos {
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After(SyntaxElement),
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AsFirstChild(SyntaxElement),
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}
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#[derive(Debug)]
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pub struct TreeDiff {
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replacements: FxHashMap<SyntaxElement, SyntaxElement>,
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deletions: Vec<SyntaxElement>,
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// the vec as well as the indexmap are both here to preserve order
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insertions: FxIndexMap<TreeDiffInsertPos, Vec<SyntaxElement>>,
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}
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impl TreeDiff {
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pub fn into_text_edit(&self, builder: &mut TextEditBuilder) {
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let _p = tracing::span!(tracing::Level::INFO, "into_text_edit").entered();
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for (anchor, to) in &self.insertions {
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let offset = match anchor {
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TreeDiffInsertPos::After(it) => it.text_range().end(),
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TreeDiffInsertPos::AsFirstChild(it) => it.text_range().start(),
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};
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to.iter().for_each(|to| builder.insert(offset, to.to_string()));
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}
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for (from, to) in &self.replacements {
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builder.replace(from.text_range(), to.to_string());
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}
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for text_range in self.deletions.iter().map(SyntaxElement::text_range) {
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builder.delete(text_range);
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}
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}
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pub fn is_empty(&self) -> bool {
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self.replacements.is_empty() && self.deletions.is_empty() && self.insertions.is_empty()
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}
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}
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/// Finds a (potentially minimal) diff, which, applied to `from`, will result in `to`.
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///
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/// Specifically, returns a structure that consists of a replacements, insertions and deletions
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/// such that applying this map on `from` will result in `to`.
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///
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/// This function tries to find a fine-grained diff.
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pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff {
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let _p = tracing::span!(tracing::Level::INFO, "diff").entered();
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let mut diff = TreeDiff {
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replacements: FxHashMap::default(),
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insertions: FxIndexMap::default(),
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deletions: Vec::new(),
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};
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let (from, to) = (from.clone().into(), to.clone().into());
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if !syntax_element_eq(&from, &to) {
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go(&mut diff, from, to);
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}
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return diff;
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fn syntax_element_eq(lhs: &SyntaxElement, rhs: &SyntaxElement) -> bool {
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lhs.kind() == rhs.kind()
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&& lhs.text_range().len() == rhs.text_range().len()
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&& match (&lhs, &rhs) {
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(NodeOrToken::Node(lhs), NodeOrToken::Node(rhs)) => {
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lhs == rhs || lhs.text() == rhs.text()
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}
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(NodeOrToken::Token(lhs), NodeOrToken::Token(rhs)) => lhs.text() == rhs.text(),
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_ => false,
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}
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}
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// FIXME: this is horribly inefficient. I bet there's a cool algorithm to diff trees properly.
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fn go(diff: &mut TreeDiff, lhs: SyntaxElement, rhs: SyntaxElement) {
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let (lhs, rhs) = match lhs.as_node().zip(rhs.as_node()) {
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Some((lhs, rhs)) => (lhs, rhs),
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_ => {
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cov_mark::hit!(diff_node_token_replace);
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diff.replacements.insert(lhs, rhs);
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return;
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}
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};
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let mut look_ahead_scratch = Vec::default();
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let mut rhs_children = rhs.children_with_tokens();
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let mut lhs_children = lhs.children_with_tokens();
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let mut last_lhs = None;
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loop {
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let lhs_child = lhs_children.next();
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match (lhs_child.clone(), rhs_children.next()) {
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(None, None) => break,
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(None, Some(element)) => {
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let insert_pos = match last_lhs.clone() {
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Some(prev) => {
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cov_mark::hit!(diff_insert);
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TreeDiffInsertPos::After(prev)
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}
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// first iteration, insert into out parent as the first child
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None => {
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cov_mark::hit!(diff_insert_as_first_child);
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TreeDiffInsertPos::AsFirstChild(lhs.clone().into())
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}
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};
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diff.insertions.entry(insert_pos).or_default().push(element);
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}
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(Some(element), None) => {
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cov_mark::hit!(diff_delete);
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diff.deletions.push(element);
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}
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(Some(ref lhs_ele), Some(ref rhs_ele)) if syntax_element_eq(lhs_ele, rhs_ele) => {}
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(Some(lhs_ele), Some(rhs_ele)) => {
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// nodes differ, look for lhs_ele in rhs, if its found we can mark everything up
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// until that element as insertions. This is important to keep the diff minimal
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// in regards to insertions that have been actually done, this is important for
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// use insertions as we do not want to replace the entire module node.
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look_ahead_scratch.push(rhs_ele.clone());
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let mut rhs_children_clone = rhs_children.clone();
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let mut insert = false;
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for rhs_child in &mut rhs_children_clone {
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if syntax_element_eq(&lhs_ele, &rhs_child) {
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cov_mark::hit!(diff_insertions);
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insert = true;
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break;
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}
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look_ahead_scratch.push(rhs_child);
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}
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let drain = look_ahead_scratch.drain(..);
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if insert {
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let insert_pos = if let Some(prev) = last_lhs.clone().filter(|_| insert) {
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TreeDiffInsertPos::After(prev)
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} else {
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cov_mark::hit!(insert_first_child);
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TreeDiffInsertPos::AsFirstChild(lhs.clone().into())
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};
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diff.insertions.entry(insert_pos).or_default().extend(drain);
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rhs_children = rhs_children_clone;
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} else {
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go(diff, lhs_ele, rhs_ele);
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}
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}
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}
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last_lhs = lhs_child.or(last_lhs);
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use expect_test::{expect, Expect};
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use itertools::Itertools;
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use parser::{Edition, SyntaxKind};
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use text_edit::TextEdit;
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use crate::{AstNode, SyntaxElement};
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#[test]
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fn replace_node_token() {
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cov_mark::check!(diff_node_token_replace);
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check_diff(
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r#"use node;"#,
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r#"ident"#,
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expect![[r#"
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insertions:
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replacements:
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Line 0: Token(USE_KW@0..3 "use") -> ident
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deletions:
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Line 1: " "
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Line 1: node
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Line 1: ;
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"#]],
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);
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}
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#[test]
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fn replace_parent() {
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cov_mark::check!(diff_insert_as_first_child);
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check_diff(
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r#""#,
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r#"use foo::bar;"#,
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expect![[r#"
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insertions:
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Line 0: AsFirstChild(Node(SOURCE_FILE@0..0))
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-> use foo::bar;
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replacements:
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deletions:
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"#]],
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);
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}
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#[test]
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fn insert_last() {
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cov_mark::check!(diff_insert);
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check_diff(
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r#"
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use foo;
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use bar;"#,
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r#"
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use foo;
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use bar;
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use baz;"#,
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expect![[r#"
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insertions:
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Line 2: After(Node(USE@10..18))
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-> "\n"
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-> use baz;
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replacements:
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deletions:
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"#]],
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);
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}
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#[test]
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fn insert_middle() {
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check_diff(
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r#"
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use foo;
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use baz;"#,
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r#"
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use foo;
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use bar;
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use baz;"#,
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expect![[r#"
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insertions:
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Line 2: After(Token(WHITESPACE@9..10 "\n"))
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-> use bar;
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-> "\n"
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replacements:
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deletions:
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"#]],
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)
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}
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#[test]
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fn insert_first() {
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check_diff(
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r#"
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use bar;
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use baz;"#,
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r#"
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use foo;
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use bar;
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use baz;"#,
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expect![[r#"
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insertions:
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Line 0: After(Token(WHITESPACE@0..1 "\n"))
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-> use foo;
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-> "\n"
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replacements:
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deletions:
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"#]],
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)
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}
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#[test]
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fn first_child_insertion() {
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cov_mark::check!(insert_first_child);
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check_diff(
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r#"fn main() {
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stdi
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}"#,
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r#"use foo::bar;
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fn main() {
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stdi
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}"#,
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expect![[r#"
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insertions:
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Line 0: AsFirstChild(Node(SOURCE_FILE@0..30))
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-> use foo::bar;
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-> "\n\n "
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replacements:
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deletions:
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"#]],
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);
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}
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#[test]
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fn delete_last() {
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cov_mark::check!(diff_delete);
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check_diff(
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r#"use foo;
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use bar;"#,
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r#"use foo;"#,
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expect![[r#"
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insertions:
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replacements:
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deletions:
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Line 1: "\n "
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Line 2: use bar;
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"#]],
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);
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}
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#[test]
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fn delete_middle() {
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cov_mark::check!(diff_insertions);
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check_diff(
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r#"
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use expect_test::{expect, Expect};
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use text_edit::TextEdit;
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use crate::AstNode;
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"#,
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r#"
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use expect_test::{expect, Expect};
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use crate::AstNode;
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"#,
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expect![[r#"
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insertions:
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Line 1: After(Node(USE@1..35))
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-> "\n\n"
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-> use crate::AstNode;
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replacements:
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deletions:
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Line 2: use text_edit::TextEdit;
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Line 3: "\n\n"
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Line 4: use crate::AstNode;
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Line 5: "\n"
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"#]],
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)
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}
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#[test]
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fn delete_first() {
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check_diff(
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r#"
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use text_edit::TextEdit;
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use crate::AstNode;
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"#,
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r#"
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use crate::AstNode;
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"#,
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expect![[r#"
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insertions:
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replacements:
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Line 2: Token(IDENT@5..14 "text_edit") -> crate
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Line 2: Token(IDENT@16..24 "TextEdit") -> AstNode
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Line 2: Token(WHITESPACE@25..27 "\n\n") -> "\n"
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deletions:
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Line 3: use crate::AstNode;
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Line 4: "\n"
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"#]],
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)
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}
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#[test]
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fn merge_use() {
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check_diff(
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r#"
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use std::{
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fmt,
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hash::BuildHasherDefault,
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ops::{self, RangeInclusive},
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};
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"#,
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r#"
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use std::fmt;
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use std::hash::BuildHasherDefault;
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use std::ops::{self, RangeInclusive};
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"#,
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expect![[r#"
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insertions:
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Line 2: After(Node(PATH_SEGMENT@5..8))
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-> ::
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-> fmt
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Line 6: After(Token(WHITESPACE@86..87 "\n"))
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-> use std::hash::BuildHasherDefault;
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-> "\n"
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-> use std::ops::{self, RangeInclusive};
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-> "\n"
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replacements:
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Line 2: Token(IDENT@5..8 "std") -> std
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deletions:
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Line 2: ::
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Line 2: {
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fmt,
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hash::BuildHasherDefault,
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ops::{self, RangeInclusive},
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}
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"#]],
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)
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}
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#[test]
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fn early_return_assist() {
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check_diff(
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r#"
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fn main() {
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if let Ok(x) = Err(92) {
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foo(x);
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}
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}
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"#,
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r#"
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fn main() {
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let x = match Err(92) {
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Ok(it) => it,
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_ => return,
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};
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foo(x);
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}
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"#,
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expect![[r#"
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insertions:
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Line 3: After(Node(BLOCK_EXPR@40..63))
|
|
-> " "
|
|
-> match Err(92) {
|
|
Ok(it) => it,
|
|
_ => return,
|
|
}
|
|
-> ;
|
|
Line 3: After(Node(IF_EXPR@17..63))
|
|
-> "\n "
|
|
-> foo(x);
|
|
|
|
replacements:
|
|
|
|
Line 3: Token(IF_KW@17..19 "if") -> let
|
|
Line 3: Token(LET_KW@20..23 "let") -> x
|
|
Line 3: Node(BLOCK_EXPR@40..63) -> =
|
|
|
|
deletions:
|
|
|
|
Line 3: " "
|
|
Line 3: Ok(x)
|
|
Line 3: " "
|
|
Line 3: =
|
|
Line 3: " "
|
|
Line 3: Err(92)
|
|
"#]],
|
|
)
|
|
}
|
|
|
|
fn check_diff(from: &str, to: &str, expected_diff: Expect) {
|
|
let from_node = crate::SourceFile::parse(from, Edition::CURRENT).tree().syntax().clone();
|
|
let to_node = crate::SourceFile::parse(to, Edition::CURRENT).tree().syntax().clone();
|
|
let diff = super::diff(&from_node, &to_node);
|
|
|
|
let line_number =
|
|
|syn: &SyntaxElement| from[..syn.text_range().start().into()].lines().count();
|
|
|
|
let fmt_syntax = |syn: &SyntaxElement| match syn.kind() {
|
|
SyntaxKind::WHITESPACE => format!("{:?}", syn.to_string()),
|
|
_ => format!("{syn}"),
|
|
};
|
|
|
|
let insertions =
|
|
diff.insertions.iter().format_with("\n", |(k, v), f| -> Result<(), std::fmt::Error> {
|
|
f(&format!(
|
|
"Line {}: {:?}\n-> {}",
|
|
line_number(match k {
|
|
super::TreeDiffInsertPos::After(syn) => syn,
|
|
super::TreeDiffInsertPos::AsFirstChild(syn) => syn,
|
|
}),
|
|
k,
|
|
v.iter().format_with("\n-> ", |v, f| f(&fmt_syntax(v)))
|
|
))
|
|
});
|
|
|
|
let replacements = diff
|
|
.replacements
|
|
.iter()
|
|
.sorted_by_key(|(syntax, _)| syntax.text_range().start())
|
|
.format_with("\n", |(k, v), f| {
|
|
f(&format!("Line {}: {k:?} -> {}", line_number(k), fmt_syntax(v)))
|
|
});
|
|
|
|
let deletions = diff
|
|
.deletions
|
|
.iter()
|
|
.format_with("\n", |v, f| f(&format!("Line {}: {}", line_number(v), &fmt_syntax(v))));
|
|
|
|
let actual = format!(
|
|
"insertions:\n\n{insertions}\n\nreplacements:\n\n{replacements}\n\ndeletions:\n\n{deletions}\n"
|
|
);
|
|
expected_diff.assert_eq(&actual);
|
|
|
|
let mut from = from.to_owned();
|
|
let mut text_edit = TextEdit::builder();
|
|
diff.into_text_edit(&mut text_edit);
|
|
text_edit.finish().apply(&mut from);
|
|
assert_eq!(&*from, to, "diff did not turn `from` to `to`");
|
|
}
|
|
}
|