Index: clang-tools-extra/clangd/index/dex/Iterator.h
===================================================================
--- clang-tools-extra/clangd/index/dex/Iterator.h
+++ clang-tools-extra/clangd/index/dex/Iterator.h
@@ -101,8 +101,14 @@
   virtual llvm::raw_ostream &dump(llvm::raw_ostream &OS) const = 0;
 };
 
-/// Advances the iterator until it is either exhausted or the number of
-/// requested items is reached. The result contains sorted DocumentIDs.
+/// Advances given iterator until it is exhausted or the requested number of
+/// symbols is already seen while using callback on each processed DocID.
+void matchSymbols(Iterator &It,
+                  llvm::function_ref<void(const DocID &)> Callback,
+                  size_t Limit = std::numeric_limits<size_t>::max());
+
+/// Advances given iterator until it is either exhausted or the number of
+/// requested items is reached and returns all seen DocIDs.
 std::vector<DocID> consume(Iterator &It,
                            size_t Limit = std::numeric_limits<size_t>::max());
 
Index: clang-tools-extra/clangd/index/dex/Iterator.cpp
===================================================================
--- clang-tools-extra/clangd/index/dex/Iterator.cpp
+++ clang-tools-extra/clangd/index/dex/Iterator.cpp
@@ -220,10 +220,16 @@
 
 std::vector<DocID> consume(Iterator &It, size_t Limit) {
   std::vector<DocID> Result;
+  matchSymbols(It, [&](const DocID &ID) { Result.push_back(ID); }, Limit);
+  return Result;
+}
+
+void matchSymbols(Iterator &It,
+                  llvm::function_ref<void(const DocID &)> Callback,
+                  size_t Limit) {
   for (size_t Retrieved = 0; !It.reachedEnd() && Retrieved < Limit;
        It.advance(), ++Retrieved)
-    Result.push_back(It.peek());
-  return Result;
+    Callback(It.peek());
 }
 
 std::unique_ptr<Iterator> create(PostingListRef Documents) {