[clangd] Index API and implementations for relations

Summary:
This builds on the relations support added in D59407, D62459,
and D62471 to expose relations in SymbolIndex and its
implementations.

Reviewers: kadircet

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62839

llvm-svn: 363481

1 files changed, 19 insertions, 0 deletions

diff --git a/clang-tools-extra/clangd/index/Index.h b/clang-tools-extra/clangd/index/Index.h
index 87a777e72df..8ccadf20653 100644
--- a/clang-tools-extra/clangd/index/Index.h
+++ b/clang-tools-extra/clangd/index/Index.h
@@ -73,6 +73,13 @@ struct RefsRequest {
   llvm::Optional<uint32_t> Limit;
 };
 
+struct RelationsRequest {
+  llvm::DenseSet<SymbolID> Subjects;
+  index::SymbolRole Predicate;
+  /// If set, limit the number of relations returned from the index.
+  llvm::Optional<uint32_t> Limit;
+};
+
 /// Interface for symbol indexes that can be used for searching or
 /// matching symbols among a set of symbols based on names or unique IDs.
 class SymbolIndex {
@@ -103,6 +110,14 @@ public:
   virtual void refs(const RefsRequest &Req,
                     llvm::function_ref<void(const Ref &)> Callback) const = 0;
 
+  /// Finds all relations (S, P, O) stored in the index such that S is among
+  /// Req.Subjects and P is Req.Predicate, and invokes \p Callback for (S, O) in
+  /// each.
+  virtual void relations(
+      const RelationsRequest &Req,
+      llvm::function_ref<void(const SymbolID &Subject, const Symbol &Object)>
+          Callback) const = 0;
+
   /// Returns estimated size of index (in bytes).
   virtual size_t estimateMemoryUsage() const = 0;
 };
@@ -123,6 +138,10 @@ public:
               llvm::function_ref<void(const Symbol &)>) const override;
   void refs(const RefsRequest &,
             llvm::function_ref<void(const Ref &)>) const override;
+  void relations(const RelationsRequest &,
+                 llvm::function_ref<void(const SymbolID &, const Symbol &)>)
+      const override;
+
   size_t estimateMemoryUsage() const override;
 
 private: