1 //! Structural Search Replace
3 //! Allows searching the AST for code that matches one or more patterns and then replacing that code
4 //! based on a template.
6 // Feature: Structural Search and Replace
8 // Search and replace with named wildcards that will match any expression, type, path, pattern or item.
9 // The syntax for a structural search replace command is `<search_pattern> ==>> <replace_pattern>`.
10 // A `$<name>` placeholder in the search pattern will match any AST node and `$<name>` will reference it in the replacement.
11 // Within a macro call, a placeholder will match up until whatever token follows the placeholder.
13 // All paths in both the search pattern and the replacement template must resolve in the context
14 // in which this command is invoked. Paths in the search pattern will then match the code if they
15 // resolve to the same item, even if they're written differently. For example if we invoke the
16 // command in the module `foo` with a pattern of `Bar`, then code in the parent module that refers
17 // to `foo::Bar` will match.
19 // Paths in the replacement template will be rendered appropriately for the context in which the
20 // replacement occurs. For example if our replacement template is `foo::Bar` and we match some
21 // code in the `foo` module, we'll insert just `Bar`.
23 // Inherent method calls should generally be written in UFCS form. e.g. `foo::Bar::baz($s, $a)` will
24 // match `$s.baz($a)`, provided the method call `baz` resolves to the method `foo::Bar::baz`. When a
25 // placeholder is the receiver of a method call in the search pattern (e.g. `$s.foo()`), but not in
26 // the replacement template (e.g. `bar($s)`), then *, & and &mut will be added as needed to mirror
27 // whatever autoderef and autoref was happening implicitly in the matched code.
29 // The scope of the search / replace will be restricted to the current selection if any, otherwise
30 // it will apply to the whole workspace.
32 // Placeholders may be given constraints by writing them as `${<name>:<constraint1>:<constraint2>...}`.
34 // Supported constraints:
37 // | Constraint | Restricts placeholder
39 // | kind(literal) | Is a literal (e.g. `42` or `"forty two"`)
40 // | not(a) | Negates the constraint `a`
43 // Available via the command `rust-analyzer.ssr`.
46 // // Using structural search replace command [foo($a, $b) ==>> ($a).foo($b)]
49 // String::from(foo(y + 5, z))
52 // String::from((y + 5).foo(z))
56 // | Editor | Action Name
58 // | VS Code | **Rust Analyzer: Structural Search Replace**
61 // Also available as an assist, by writing a comment containing the structural
62 // search and replace rule. You will only see the assist if the comment can
63 // be parsed as a valid structural search and replace rule.
66 // // Place the cursor on the line below to see the assist 💡.
67 // // foo($a, $b) ==>> ($a).foo($b)
82 use crate::errors::bail;
83 pub use crate::errors::SsrError;
84 pub use crate::from_comment::ssr_from_comment;
85 pub use crate::matching::Match;
86 use crate::matching::MatchFailureReason;
88 use ide_db::base_db::{FileId, FilePosition, FileRange};
89 use resolving::ResolvedRule;
90 use rustc_hash::FxHashMap;
91 use syntax::{ast, AstNode, SyntaxNode, TextRange};
92 use text_edit::TextEdit;
94 // A structured search replace rule. Create by calling `parse` on a str.
97 /// A structured pattern that we're searching for.
98 pattern: parsing::RawPattern,
99 /// What we'll replace it with.
100 template: parsing::RawPattern,
101 parsed_rules: Vec<parsing::ParsedRule>,
105 pub struct SsrPattern {
106 raw: parsing::RawPattern,
107 parsed_rules: Vec<parsing::ParsedRule>,
110 #[derive(Debug, Default)]
111 pub struct SsrMatches {
112 pub matches: Vec<Match>,
115 /// Searches a crate for pattern matches and possibly replaces them with something else.
116 pub struct MatchFinder<'db> {
117 /// Our source of information about the user's code.
118 sema: Semantics<'db, ide_db::RootDatabase>,
119 rules: Vec<ResolvedRule>,
120 resolution_scope: resolving::ResolutionScope<'db>,
121 restrict_ranges: Vec<FileRange>,
124 impl<'db> MatchFinder<'db> {
125 /// Constructs a new instance where names will be looked up as if they appeared at
126 /// `lookup_context`.
128 db: &'db ide_db::RootDatabase,
129 lookup_context: FilePosition,
130 mut restrict_ranges: Vec<FileRange>,
131 ) -> MatchFinder<'db> {
132 restrict_ranges.retain(|range| !range.range.is_empty());
133 let sema = Semantics::new(db);
134 let resolution_scope = resolving::ResolutionScope::new(&sema, lookup_context);
135 MatchFinder { sema, rules: Vec::new(), resolution_scope, restrict_ranges }
138 /// Constructs an instance using the start of the first file in `db` as the lookup context.
139 pub fn at_first_file(db: &'db ide_db::RootDatabase) -> Result<MatchFinder<'db>, SsrError> {
140 use ide_db::base_db::SourceDatabaseExt;
141 use ide_db::symbol_index::SymbolsDatabase;
142 if let Some(first_file_id) = db
146 .and_then(|root| db.source_root(root.clone()).iter().next())
148 Ok(MatchFinder::in_context(
150 FilePosition { file_id: first_file_id, offset: 0.into() },
154 bail!("No files to search");
158 /// Adds a rule to be applied. The order in which rules are added matters. Earlier rules take
159 /// precedence. If a node is matched by an earlier rule, then later rules won't be permitted to
161 pub fn add_rule(&mut self, rule: SsrRule) -> Result<(), SsrError> {
162 for parsed_rule in rule.parsed_rules {
163 self.rules.push(ResolvedRule::new(
165 &self.resolution_scope,
172 /// Finds matches for all added rules and returns edits for all found matches.
173 pub fn edits(&self) -> FxHashMap<FileId, TextEdit> {
174 use ide_db::base_db::SourceDatabaseExt;
175 let mut matches_by_file = FxHashMap::default();
176 for m in self.matches().matches {
178 .entry(m.range.file_id)
179 .or_insert_with(|| SsrMatches::default())
185 .map(|(file_id, matches)| {
188 replacing::matches_to_edit(
190 &self.sema.db.file_text(file_id),
198 /// Adds a search pattern. For use if you intend to only call `find_matches_in_file`. If you
199 /// intend to do replacement, use `add_rule` instead.
200 pub fn add_search_pattern(&mut self, pattern: SsrPattern) -> Result<(), SsrError> {
201 for parsed_rule in pattern.parsed_rules {
202 self.rules.push(ResolvedRule::new(
204 &self.resolution_scope,
211 /// Returns matches for all added rules.
212 pub fn matches(&self) -> SsrMatches {
213 let mut matches = Vec::new();
214 let mut usage_cache = search::UsageCache::default();
215 for rule in &self.rules {
216 self.find_matches_for_rule(rule, &mut usage_cache, &mut matches);
218 nester::nest_and_remove_collisions(matches, &self.sema)
221 /// Finds all nodes in `file_id` whose text is exactly equal to `snippet` and attempts to match
222 /// them, while recording reasons why they don't match. This API is useful for command
223 /// line-based debugging where providing a range is difficult.
224 pub fn debug_where_text_equal(&self, file_id: FileId, snippet: &str) -> Vec<MatchDebugInfo> {
225 use ide_db::base_db::SourceDatabaseExt;
226 let file = self.sema.parse(file_id);
227 let mut res = Vec::new();
228 let file_text = self.sema.db.file_text(file_id);
229 let mut remaining_text = file_text.as_str();
231 let len = snippet.len() as u32;
232 while let Some(offset) = remaining_text.find(snippet) {
233 let start = base + offset as u32;
234 let end = start + len;
235 self.output_debug_for_nodes_at_range(
237 FileRange { file_id, range: TextRange::new(start.into(), end.into()) },
241 remaining_text = &remaining_text[offset + snippet.len()..];
247 fn output_debug_for_nodes_at_range(
251 restrict_range: &Option<FileRange>,
252 out: &mut Vec<MatchDebugInfo>,
254 for node in node.children() {
255 let node_range = self.sema.original_range(&node);
256 if node_range.file_id != range.file_id || !node_range.range.contains_range(range.range)
260 if node_range.range == range.range {
261 for rule in &self.rules {
262 // For now we ignore rules that have a different kind than our node, otherwise
263 // we get lots of noise. If at some point we add support for restricting rules
264 // to a particular kind of thing (e.g. only match type references), then we can
265 // relax this. We special-case expressions, since function calls can match
267 if rule.pattern.node.kind() != node.kind()
268 && !(ast::Expr::can_cast(rule.pattern.node.kind())
269 && ast::Expr::can_cast(node.kind()))
273 out.push(MatchDebugInfo {
274 matched: matching::get_match(true, rule, &node, restrict_range, &self.sema)
275 .map_err(|e| MatchFailureReason {
276 reason: e.reason.unwrap_or_else(|| {
277 "Match failed, but no reason was given".to_owned()
280 pattern: rule.pattern.node.clone(),
284 } else if let Some(macro_call) = ast::MacroCall::cast(node.clone()) {
285 if let Some(expanded) = self.sema.expand(¯o_call) {
286 if let Some(tt) = macro_call.token_tree() {
287 self.output_debug_for_nodes_at_range(
290 &Some(self.sema.original_range(tt.syntax())),
296 self.output_debug_for_nodes_at_range(&node, range, restrict_range, out);
301 pub struct MatchDebugInfo {
303 /// Our search pattern parsed as an expression or item, etc
305 matched: Result<Match, MatchFailureReason>,
308 impl std::fmt::Debug for MatchDebugInfo {
309 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
310 match &self.matched {
311 Ok(_) => writeln!(f, "Node matched")?,
312 Err(reason) => writeln!(f, "Node failed to match because: {}", reason.reason)?,
316 "============ AST ===========\n\
320 writeln!(f, "========= PATTERN ==========")?;
321 writeln!(f, "{:#?}", self.pattern)?;
322 writeln!(f, "============================")?;
328 /// Returns `self` with any nested matches removed and made into top-level matches.
329 pub fn flattened(self) -> SsrMatches {
330 let mut out = SsrMatches::default();
331 self.flatten_into(&mut out);
335 fn flatten_into(self, out: &mut SsrMatches) {
336 for mut m in self.matches {
337 for p in m.placeholder_values.values_mut() {
338 std::mem::replace(&mut p.inner_matches, SsrMatches::default()).flatten_into(out);
346 pub fn matched_text(&self) -> String {
347 self.matched_node.text().to_string()
351 impl std::error::Error for SsrError {}
354 impl MatchDebugInfo {
355 pub(crate) fn match_failure_reason(&self) -> Option<&str> {
356 self.matched.as_ref().err().map(|r| r.reason.as_str())