rust/crates/ide-ssr/src/search.rs
2024-01-18 13:59:49 +01:00

290 lines
12 KiB
Rust

//! Searching for matches.
use crate::{
matching,
resolving::{ResolvedPath, ResolvedPattern, ResolvedRule},
Match, MatchFinder,
};
use ide_db::{
base_db::{FileId, FileRange},
defs::Definition,
search::{SearchScope, UsageSearchResult},
FxHashSet,
};
use syntax::{ast, AstNode, SyntaxKind, SyntaxNode};
/// A cache for the results of find_usages. This is for when we have multiple patterns that have the
/// same path. e.g. if the pattern was `foo::Bar` that can parse as a path, an expression, a type
/// and as a pattern. In each, the usages of `foo::Bar` are the same and we'd like to avoid finding
/// them more than once.
#[derive(Default)]
pub(crate) struct UsageCache {
usages: Vec<(Definition, UsageSearchResult)>,
}
impl MatchFinder<'_> {
/// Adds all matches for `rule` to `matches_out`. Matches may overlap in ways that make
/// replacement impossible, so further processing is required in order to properly nest matches
/// and remove overlapping matches. This is done in the `nesting` module.
pub(crate) fn find_matches_for_rule(
&self,
rule: &ResolvedRule,
usage_cache: &mut UsageCache,
matches_out: &mut Vec<Match>,
) {
if rule.pattern.contains_self {
// If the pattern contains `self` we restrict the scope of the search to just the
// current method. No other method can reference the same `self`. This makes the
// behavior of `self` consistent with other variables.
if let Some(current_function) = self.resolution_scope.current_function() {
self.slow_scan_node(&current_function, rule, &None, matches_out);
}
return;
}
if pick_path_for_usages(&rule.pattern).is_none() {
self.slow_scan(rule, matches_out);
return;
}
self.find_matches_for_pattern_tree(rule, &rule.pattern, usage_cache, matches_out);
}
fn find_matches_for_pattern_tree(
&self,
rule: &ResolvedRule,
pattern: &ResolvedPattern,
usage_cache: &mut UsageCache,
matches_out: &mut Vec<Match>,
) {
if let Some(resolved_path) = pick_path_for_usages(pattern) {
let definition: Definition = resolved_path.resolution.into();
for file_range in self.find_usages(usage_cache, definition).file_ranges() {
for node_to_match in self.find_nodes_to_match(resolved_path, file_range) {
if !is_search_permitted_ancestors(&node_to_match) {
cov_mark::hit!(use_declaration_with_braces);
continue;
}
self.try_add_match(rule, &node_to_match, &None, matches_out);
}
}
}
}
fn find_nodes_to_match(
&self,
resolved_path: &ResolvedPath,
file_range: FileRange,
) -> Vec<SyntaxNode> {
let file = self.sema.parse(file_range.file_id);
let depth = resolved_path.depth as usize;
let offset = file_range.range.start();
let mut paths = self
.sema
.find_nodes_at_offset_with_descend::<ast::Path>(file.syntax(), offset)
.peekable();
if paths.peek().is_some() {
paths
.filter_map(|path| {
self.sema.ancestors_with_macros(path.syntax().clone()).nth(depth)
})
.collect::<Vec<_>>()
} else {
self.sema
.find_nodes_at_offset_with_descend::<ast::MethodCallExpr>(file.syntax(), offset)
.filter_map(|path| {
// If the pattern contained a path and we found a reference to that path that wasn't
// itself a path, but was a method call, then we need to adjust how far up to try
// matching by how deep the path was within a CallExpr. The structure would have been
// CallExpr, PathExpr, Path - i.e. a depth offset of 2. We don't need to check if the
// path was part of a CallExpr because if it wasn't then all that will happen is we'll
// fail to match, which is the desired behavior.
const PATH_DEPTH_IN_CALL_EXPR: usize = 2;
if depth < PATH_DEPTH_IN_CALL_EXPR {
return None;
}
self.sema
.ancestors_with_macros(path.syntax().clone())
.nth(depth - PATH_DEPTH_IN_CALL_EXPR)
})
.collect::<Vec<_>>()
}
}
fn find_usages<'a>(
&self,
usage_cache: &'a mut UsageCache,
definition: Definition,
) -> &'a UsageSearchResult {
// Logically if a lookup succeeds we should just return it. Unfortunately returning it would
// extend the lifetime of the borrow, then we wouldn't be able to do the insertion on a
// cache miss. This is a limitation of NLL and is fixed with Polonius. For now we do two
// lookups in the case of a cache hit.
if usage_cache.find(&definition).is_none() {
let usages = definition.usages(&self.sema).in_scope(&self.search_scope()).all();
usage_cache.usages.push((definition, usages));
return &usage_cache.usages.last().unwrap().1;
}
usage_cache.find(&definition).unwrap()
}
/// Returns the scope within which we want to search. We don't want un unrestricted search
/// scope, since we don't want to find references in external dependencies.
fn search_scope(&self) -> SearchScope {
// FIXME: We should ideally have a test that checks that we edit local roots and not library
// roots. This probably would require some changes to fixtures, since currently everything
// seems to get put into a single source root.
let mut files = Vec::new();
self.search_files_do(|file_id| {
files.push(file_id);
});
SearchScope::files(&files)
}
fn slow_scan(&self, rule: &ResolvedRule, matches_out: &mut Vec<Match>) {
self.search_files_do(|file_id| {
let file = self.sema.parse(file_id);
let code = file.syntax();
self.slow_scan_node(code, rule, &None, matches_out);
})
}
fn search_files_do(&self, mut callback: impl FnMut(FileId)) {
if self.restrict_ranges.is_empty() {
// Unrestricted search.
use ide_db::base_db::SourceDatabaseExt;
use ide_db::symbol_index::SymbolsDatabase;
for &root in self.sema.db.local_roots().iter() {
let sr = self.sema.db.source_root(root);
for file_id in sr.iter() {
callback(file_id);
}
}
} else {
// Search is restricted, deduplicate file IDs (generally only one).
let mut files = FxHashSet::default();
for range in &self.restrict_ranges {
if files.insert(range.file_id) {
callback(range.file_id);
}
}
}
}
fn slow_scan_node(
&self,
code: &SyntaxNode,
rule: &ResolvedRule,
restrict_range: &Option<FileRange>,
matches_out: &mut Vec<Match>,
) {
if !is_search_permitted(code) {
return;
}
self.try_add_match(rule, code, restrict_range, matches_out);
// If we've got a macro call, we already tried matching it pre-expansion, which is the only
// way to match the whole macro, now try expanding it and matching the expansion.
if let Some(macro_call) = ast::MacroCall::cast(code.clone()) {
if let Some(expanded) = self.sema.expand(&macro_call) {
if let Some(tt) = macro_call.token_tree() {
// When matching within a macro expansion, we only want to allow matches of
// nodes that originated entirely from within the token tree of the macro call.
// i.e. we don't want to match something that came from the macro itself.
self.slow_scan_node(
&expanded,
rule,
&Some(self.sema.original_range(tt.syntax())),
matches_out,
);
}
}
}
for child in code.children() {
self.slow_scan_node(&child, rule, restrict_range, matches_out);
}
}
fn try_add_match(
&self,
rule: &ResolvedRule,
code: &SyntaxNode,
restrict_range: &Option<FileRange>,
matches_out: &mut Vec<Match>,
) {
if !self.within_range_restrictions(code) {
cov_mark::hit!(replace_nonpath_within_selection);
return;
}
if let Ok(m) = matching::get_match(false, rule, code, restrict_range, &self.sema) {
matches_out.push(m);
}
}
/// Returns whether `code` is within one of our range restrictions if we have any. No range
/// restrictions is considered unrestricted and always returns true.
fn within_range_restrictions(&self, code: &SyntaxNode) -> bool {
if self.restrict_ranges.is_empty() {
// There is no range restriction.
return true;
}
let node_range = self.sema.original_range(code);
for range in &self.restrict_ranges {
if range.file_id == node_range.file_id && range.range.contains_range(node_range.range) {
return true;
}
}
false
}
}
/// Returns whether we support matching within `node` and all of its ancestors.
fn is_search_permitted_ancestors(node: &SyntaxNode) -> bool {
if let Some(parent) = node.parent() {
if !is_search_permitted_ancestors(&parent) {
return false;
}
}
is_search_permitted(node)
}
/// Returns whether we support matching within this kind of node.
fn is_search_permitted(node: &SyntaxNode) -> bool {
// FIXME: Properly handle use declarations. At the moment, if our search pattern is `foo::bar`
// and the code is `use foo::{baz, bar}`, we'll match `bar`, since it resolves to `foo::bar`.
// However we'll then replace just the part we matched `bar`. We probably need to instead remove
// `bar` and insert a new use declaration.
node.kind() != SyntaxKind::USE
}
impl UsageCache {
fn find(&mut self, definition: &Definition) -> Option<&UsageSearchResult> {
// We expect a very small number of cache entries (generally 1), so a linear scan should be
// fast enough and avoids the need to implement Hash for Definition.
for (d, refs) in &self.usages {
if d == definition {
return Some(refs);
}
}
None
}
}
/// Returns a path that's suitable for path resolution. We exclude builtin types, since they aren't
/// something that we can find references to. We then somewhat arbitrarily pick the path that is the
/// longest as this is hopefully more likely to be less common, making it faster to find.
fn pick_path_for_usages(pattern: &ResolvedPattern) -> Option<&ResolvedPath> {
// FIXME: Take the scope of the resolved path into account. e.g. if there are any paths that are
// private to the current module, then we definitely would want to pick them over say a path
// from std. Possibly we should go further than this and intersect the search scopes for all
// resolved paths then search only in that scope.
pattern
.resolved_paths
.iter()
.filter(|(_, p)| {
!matches!(p.resolution, hir::PathResolution::Def(hir::ModuleDef::BuiltinType(_)))
})
.map(|(node, resolved)| (node.text().len(), resolved))
.max_by(|(a, _), (b, _)| a.cmp(b))
.map(|(_, resolved)| resolved)
}