SSR: Match paths based on what they resolve to

Also render template paths appropriately for their context.

Author: davidlattimore

crates/ra_ide/src/ssr.rs

@@ -11,6 +11,16 @@ use ra_ssr::{MatchFinder, SsrError, SsrRule};
 // A `$<name>` placeholder in the search pattern will match any AST node and `$<name>` will reference it in the replacement.
 // Within a macro call, a placeholder will match up until whatever token follows the placeholder.
 //
+// All paths in both the search pattern and the replacement template must resolve in the context
+// in which this command is invoked. Paths in the search pattern will then match the code if they
+// resolve to the same item, even if they're written differently. For example if we invoke the
+// command in the module `foo` with a pattern of `Bar`, then code in the parent module that refers
+// to `foo::Bar` will match.
+//
+// Paths in the replacement template will be rendered appropriately for the context in which the
+// replacement occurs. For example if our replacement template is `foo::Bar` and we match some
+// code in the `foo` module, we'll insert just `Bar`.
+//
 // Placeholders may be given constraints by writing them as `${<name>:<constraint1>:<constraint2>...}`.
 //
 // Supported constraints:
@@ -47,7 +57,7 @@ pub fn parse_search_replace(
 ) -> Result<Vec<SourceFileEdit>, SsrError> {
     let rule: SsrRule = rule.parse()?;
     let mut match_finder = MatchFinder::in_context(db, position);
-    match_finder.add_rule(rule);
+    match_finder.add_rule(rule)?;
     if parse_only {
         return Ok(Vec::new());
     }

crates/ra_ssr/src/lib.rs

@@ -7,6 +7,7 @@ mod matching;
 mod nester;
 mod parsing;
 mod replacing;
+mod resolving;
 mod search;
 #[macro_use]
 mod errors;
@@ -21,6 +22,7 @@ use hir::Semantics;
 use ra_db::{FileId, FilePosition, FileRange};
 use ra_ide_db::source_change::SourceFileEdit;
 use ra_syntax::{ast, AstNode, SyntaxNode, TextRange};
+use resolving::ResolvedRule;
 use rustc_hash::FxHashMap;
 
 // A structured search replace rule. Create by calling `parse` on a str.
@@ -48,18 +50,34 @@ pub struct SsrMatches {
 pub struct MatchFinder<'db> {
     /// Our source of information about the user's code.
     sema: Semantics<'db, ra_ide_db::RootDatabase>,
-    rules: Vec<parsing::ParsedRule>,
+    rules: Vec<ResolvedRule>,
+    scope: hir::SemanticsScope<'db>,
+    hygiene: hir::Hygiene,
 }
 
 impl<'db> MatchFinder<'db> {
     /// Constructs a new instance where names will be looked up as if they appeared at
     /// `lookup_context`.
     pub fn in_context(
         db: &'db ra_ide_db::RootDatabase,
-        _lookup_context: FilePosition,
+        lookup_context: FilePosition,
     ) -> MatchFinder<'db> {
-        // FIXME: Use lookup_context
-        MatchFinder { sema: Semantics::new(db), rules: Vec::new() }
+        let sema = Semantics::new(db);
+        let file = sema.parse(lookup_context.file_id);
+        // Find a node at the requested position, falling back to the whole file.
+        let node = file
+            .syntax()
+            .token_at_offset(lookup_context.offset)
+            .left_biased()
+            .map(|token| token.parent())
+            .unwrap_or_else(|| file.syntax().clone());
+        let scope = sema.scope(&node);
+        MatchFinder {
+            sema: Semantics::new(db),
+            rules: Vec::new(),
+            scope,
+            hygiene: hir::Hygiene::new(db, lookup_context.file_id.into()),
+        }
     }
 
     /// Constructs an instance using the start of the first file in `db` as the lookup context.
@@ -84,8 +102,16 @@ impl<'db> MatchFinder<'db> {
     /// Adds a rule to be applied. The order in which rules are added matters. Earlier rules take
     /// precedence. If a node is matched by an earlier rule, then later rules won't be permitted to
     /// match to it.
-    pub fn add_rule(&mut self, rule: SsrRule) {
-        self.add_parsed_rules(rule.parsed_rules);
+    pub fn add_rule(&mut self, rule: SsrRule) -> Result<(), SsrError> {
+        for parsed_rule in rule.parsed_rules {
+            self.rules.push(ResolvedRule::new(
+                parsed_rule,
+                &self.scope,
+                &self.hygiene,
+                self.rules.len(),
+            )?);
+        }
+        Ok(())
     }
 
     /// Finds matches for all added rules and returns edits for all found matches.
@@ -110,8 +136,16 @@ impl<'db> MatchFinder<'db> {
 
     /// Adds a search pattern. For use if you intend to only call `find_matches_in_file`. If you
     /// intend to do replacement, use `add_rule` instead.
-    pub fn add_search_pattern(&mut self, pattern: SsrPattern) {
-        self.add_parsed_rules(pattern.parsed_rules);
+    pub fn add_search_pattern(&mut self, pattern: SsrPattern) -> Result<(), SsrError> {
+        for parsed_rule in pattern.parsed_rules {
+            self.rules.push(ResolvedRule::new(
+                parsed_rule,
+                &self.scope,
+                &self.hygiene,
+                self.rules.len(),
+            )?);
+        }
+        Ok(())
     }
 
     /// Returns matches for all added rules.
@@ -149,13 +183,6 @@ impl<'db> MatchFinder<'db> {
         res
     }
 
-    fn add_parsed_rules(&mut self, parsed_rules: Vec<parsing::ParsedRule>) {
-        for mut parsed_rule in parsed_rules {
-            parsed_rule.index = self.rules.len();
-            self.rules.push(parsed_rule);
-        }
-    }
-
     fn output_debug_for_nodes_at_range(
         &self,
         node: &SyntaxNode,
@@ -175,7 +202,7 @@ impl<'db> MatchFinder<'db> {
                     // we get lots of noise. If at some point we add support for restricting rules
                     // to a particular kind of thing (e.g. only match type references), then we can
                     // relax this.
-                    if rule.pattern.kind() != node.kind() {
+                    if rule.pattern.node.kind() != node.kind() {
                         continue;
                     }
                     out.push(MatchDebugInfo {
@@ -185,7 +212,7 @@ impl<'db> MatchFinder<'db> {
                                     "Match failed, but no reason was given".to_owned()
                                 }),
                             }),
-                        pattern: rule.pattern.clone(),
+                        pattern: rule.pattern.node.clone(),
                         node: node.clone(),
                     });
                 }

crates/ra_ssr/src/matching.rs

@@ -2,7 +2,8 @@
 //! process of matching, placeholder values are recorded.
 
 use crate::{
-    parsing::{Constraint, NodeKind, ParsedRule, Placeholder},
+    parsing::{Constraint, NodeKind, Placeholder},
+    resolving::{ResolvedPattern, ResolvedRule},
     SsrMatches,
 };
 use hir::Semantics;
@@ -51,6 +52,8 @@ pub struct Match {
     pub(crate) rule_index: usize,
     /// The depth of matched_node.
     pub(crate) depth: usize,
+    // Each path in the template rendered for the module in which the match was found.
+    pub(crate) rendered_template_paths: FxHashMap<SyntaxNode, hir::ModPath>,
 }
 
 /// Represents a `$var` in an SSR query.
@@ -86,7 +89,7 @@ pub(crate) struct MatchFailed {
 /// parent module, we don't populate nested matches.
 pub(crate) fn get_match(
     debug_active: bool,
-    rule: &ParsedRule,
+    rule: &ResolvedRule,
     code: &SyntaxNode,
     restrict_range: &Option<FileRange>,
     sema: &Semantics<ra_ide_db::RootDatabase>,
@@ -102,7 +105,7 @@ struct Matcher<'db, 'sema> {
     /// If any placeholders come from anywhere outside of this range, then the match will be
     /// rejected.
     restrict_range: Option<FileRange>,
-    rule: &'sema ParsedRule,
+    rule: &'sema ResolvedRule,
 }
 
 /// Which phase of matching we're currently performing. We do two phases because most attempted
@@ -117,14 +120,14 @@ enum Phase<'a> {
 
 impl<'db, 'sema> Matcher<'db, 'sema> {
     fn try_match(
-        rule: &ParsedRule,
+        rule: &ResolvedRule,
         code: &SyntaxNode,
         restrict_range: &Option<FileRange>,
         sema: &'sema Semantics<'db, ra_ide_db::RootDatabase>,
     ) -> Result<Match, MatchFailed> {
         let match_state = Matcher { sema, restrict_range: restrict_range.clone(), rule };
         // First pass at matching, where we check that node types and idents match.
-        match_state.attempt_match_node(&mut Phase::First, &rule.pattern, code)?;
+        match_state.attempt_match_node(&mut Phase::First, &rule.pattern.node, code)?;
         match_state.validate_range(&sema.original_range(code))?;
         let mut the_match = Match {
             range: sema.original_range(code),
@@ -133,11 +136,19 @@ impl<'db, 'sema> Matcher<'db, 'sema> {
             ignored_comments: Vec::new(),
             rule_index: rule.index,
             depth: 0,
+            rendered_template_paths: FxHashMap::default(),
         };
         // Second matching pass, where we record placeholder matches, ignored comments and maybe do
         // any other more expensive checks that we didn't want to do on the first pass.
-        match_state.attempt_match_node(&mut Phase::Second(&mut the_match), &rule.pattern, code)?;
+        match_state.attempt_match_node(
+            &mut Phase::Second(&mut the_match),
+            &rule.pattern.node,
+            code,
+        )?;
         the_match.depth = sema.ancestors_with_macros(the_match.matched_node.clone()).count();
+        if let Some(template) = &rule.template {
+            the_match.render_template_paths(template, sema)?;
+        }
         Ok(the_match)
     }
 
@@ -195,6 +206,7 @@ impl<'db, 'sema> Matcher<'db, 'sema> {
                 self.attempt_match_record_field_list(phase, pattern, code)
             }
             SyntaxKind::TOKEN_TREE => self.attempt_match_token_tree(phase, pattern, code),
+            SyntaxKind::PATH => self.attempt_match_path(phase, pattern, code),
             _ => self.attempt_match_node_children(phase, pattern, code),
         }
     }
@@ -311,6 +323,64 @@ impl<'db, 'sema> Matcher<'db, 'sema> {
         Ok(())
     }
 
+    /// Paths are matched based on whether they refer to the same thing, even if they're written
+    /// differently.
+    fn attempt_match_path(
+        &self,
+        phase: &mut Phase,
+        pattern: &SyntaxNode,
+        code: &SyntaxNode,
+    ) -> Result<(), MatchFailed> {
+        if let Some(pattern_resolved) = self.rule.pattern.resolved_paths.get(pattern) {
+            let pattern_path = ast::Path::cast(pattern.clone()).unwrap();
+            let code_path = ast::Path::cast(code.clone()).unwrap();
+            if let (Some(pattern_segment), Some(code_segment)) =
+                (pattern_path.segment(), code_path.segment())
+            {
+                // Match everything within the segment except for the name-ref, which is handled
+                // separately via comparing what the path resolves to below.
+                self.attempt_match_opt(
+                    phase,
+                    pattern_segment.type_arg_list(),
+                    code_segment.type_arg_list(),
+                )?;
+                self.attempt_match_opt(
+                    phase,
+                    pattern_segment.param_list(),
+                    code_segment.param_list(),
+                )?;
+            }
+            if matches!(phase, Phase::Second(_)) {
+                let resolution = self
+                    .sema
+                    .resolve_path(&code_path)
+                    .ok_or_else(|| match_error!("Failed to resolve path `{}`", code.text()))?;
+                if pattern_resolved.resolution != resolution {
+                    fail_match!("Pattern had path `{}` code had `{}`", pattern.text(), code.text());
+                }
+            }
+        } else {
+            return self.attempt_match_node_children(phase, pattern, code);
+        }
+        Ok(())
+    }
+
+    fn attempt_match_opt<T: AstNode>(
+        &self,
+        phase: &mut Phase,
+        pattern: Option<T>,
+        code: Option<T>,
+    ) -> Result<(), MatchFailed> {
+        match (pattern, code) {
+            (Some(p), Some(c)) => self.attempt_match_node(phase, &p.syntax(), &c.syntax()),
+            (None, None) => Ok(()),
+            (Some(p), None) => fail_match!("Pattern `{}` had nothing to match", p.syntax().text()),
+            (None, Some(c)) => {
+                fail_match!("Nothing in pattern to match code `{}`", c.syntax().text())
+            }
+        }
+    }
+
     /// We want to allow the records to match in any order, so we have special matching logic for
     /// them.
     fn attempt_match_record_field_list(
@@ -449,6 +519,28 @@ impl<'db, 'sema> Matcher<'db, 'sema> {
     }
 }
 
+impl Match {
+    fn render_template_paths(
+        &mut self,
+        template: &ResolvedPattern,
+        sema: &Semantics<ra_ide_db::RootDatabase>,
+    ) -> Result<(), MatchFailed> {
+        let module = sema
+            .scope(&self.matched_node)
+            .module()
+            .ok_or_else(|| match_error!("Matched node isn't in a module"))?;
+        for (path, resolved_path) in &template.resolved_paths {
+            if let hir::PathResolution::Def(module_def) = resolved_path.resolution {
+                let mod_path = module.find_use_path(sema.db, module_def).ok_or_else(|| {
+                    match_error!("Failed to render template path `{}` at match location")
+                })?;
+                self.rendered_template_paths.insert(path.clone(), mod_path);
+            }
+        }
+        Ok(())
+    }
+}
+
 impl Phase<'_> {
     fn next_non_trivial(&mut self, code_it: &mut SyntaxElementChildren) -> Option<SyntaxElement> {
         loop {
@@ -578,7 +670,7 @@ mod tests {
 
         let (db, position) = crate::tests::single_file(input);
         let mut match_finder = MatchFinder::in_context(&db, position);
-        match_finder.add_rule(rule);
+        match_finder.add_rule(rule).unwrap();
         let matches = match_finder.matches();
         assert_eq!(matches.matches.len(), 1);
         assert_eq!(matches.matches[0].matched_node.text(), "foo(1+2)");

crates/ra_ssr/src/parsing.rs

@@ -7,7 +7,7 @@
 
 use crate::errors::bail;
 use crate::{SsrError, SsrPattern, SsrRule};
-use ra_syntax::{ast, AstNode, SmolStr, SyntaxKind, SyntaxNode, SyntaxToken, T};
+use ra_syntax::{ast, AstNode, SmolStr, SyntaxKind, SyntaxNode, T};
 use rustc_hash::{FxHashMap, FxHashSet};
 use std::str::FromStr;
 
@@ -16,7 +16,6 @@ pub(crate) struct ParsedRule {
     pub(crate) placeholders_by_stand_in: FxHashMap<SmolStr, Placeholder>,
     pub(crate) pattern: SyntaxNode,
     pub(crate) template: Option<SyntaxNode>,
-    pub(crate) index: usize,
 }
 
 #[derive(Debug)]
@@ -93,16 +92,11 @@ impl RuleBuilder {
                 placeholders_by_stand_in: self.placeholders_by_stand_in.clone(),
                 pattern: pattern.syntax().clone(),
                 template: Some(template.syntax().clone()),
-                // For now we give the rule an index of 0. It's given a proper index when the rule
-                // is added to the SsrMatcher. Using an Option<usize>, instead would be slightly
-                // more correct, but we delete this field from ParsedRule in a subsequent commit.
-                index: 0,
             }),
             (Ok(pattern), None) => self.rules.push(ParsedRule {
                 placeholders_by_stand_in: self.placeholders_by_stand_in.clone(),
                 pattern: pattern.syntax().clone(),
                 template: None,
-                index: 0,
             }),
             _ => {}
         }
@@ -171,15 +165,6 @@ impl RawPattern {
     }
 }
 
-impl ParsedRule {
-    pub(crate) fn get_placeholder(&self, token: &SyntaxToken) -> Option<&Placeholder> {
-        if token.kind() != SyntaxKind::IDENT {
-            return None;
-        }
-        self.placeholders_by_stand_in.get(token.text())
-    }
-}
-
 impl FromStr for SsrPattern {
     type Err = SsrError;