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|
//! Searching for matches.
use crate::{
matching,
resolving::{ResolvedPath, ResolvedPattern, ResolvedRule},
Match, MatchFinder,
};
use ra_db::FileRange;
use ra_ide_db::{
defs::Definition,
search::{Reference, SearchScope},
};
use ra_syntax::{ast, AstNode, 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, Vec<Reference>)>,
}
impl<'db> MatchFinder<'db> {
/// 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 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(first_path) = pick_path_for_usages(pattern) {
let definition: Definition = first_path.resolution.clone().into();
for reference in self.find_usages(usage_cache, definition) {
let file = self.sema.parse(reference.file_range.file_id);
if let Some(path) = self.sema.find_node_at_offset_with_descend::<ast::Path>(
file.syntax(),
reference.file_range.range.start(),
) {
if let Some(node_to_match) = self
.sema
.ancestors_with_macros(path.syntax().clone())
.skip(first_path.depth as usize)
.next()
{
if let Ok(m) =
matching::get_match(false, rule, &node_to_match, &None, &self.sema)
{
matches_out.push(m);
}
}
}
}
}
}
fn find_usages<'a>(
&self,
usage_cache: &'a mut UsageCache,
definition: Definition,
) -> &'a [Reference] {
// 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.find_usages(&self.sema, Some(self.search_scope()));
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.
use ra_db::SourceDatabaseExt;
use ra_ide_db::symbol_index::SymbolsDatabase;
let mut files = Vec::new();
for &root in self.sema.db.local_roots().iter() {
let sr = self.sema.db.source_root(root);
files.extend(sr.iter());
}
SearchScope::files(&files)
}
fn slow_scan(&self, rule: &ResolvedRule, matches_out: &mut Vec<Match>) {
use ra_db::SourceDatabaseExt;
use ra_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() {
let file = self.sema.parse(file_id);
let code = file.syntax();
self.slow_scan_node(code, rule, &None, matches_out);
}
}
}
fn slow_scan_node(
&self,
code: &SyntaxNode,
rule: &ResolvedRule,
restrict_range: &Option<FileRange>,
matches_out: &mut Vec<Match>,
) {
if let Ok(m) = matching::get_match(false, rule, &code, restrict_range, &self.sema) {
matches_out.push(m);
}
// 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(¯o_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);
}
}
}
impl UsageCache {
fn find(&mut self, definition: &Definition) -> Option<&[Reference]> {
// 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)
}
|
