SERVER-45530 Implement $match and $project duplication and pushdown across $unionWith

1 files changed, 13 insertions, 0 deletions

diff --git a/src/mongo/db/pipeline/document_source_match.h b/src/mongo/db/pipeline/document_source_match.h
index a684c4c82f8..ecdda5dc274 100644
--- a/src/mongo/db/pipeline/document_source_match.h
+++ b/src/mongo/db/pipeline/document_source_match.h
@@ -30,16 +30,24 @@
 #pragma once
 
 #include <memory>
+#include <type_traits>
 #include <utility>
 
 #include "mongo/client/connpool.h"
 #include "mongo/db/matcher/matcher.h"
 #include "mongo/db/pipeline/document_source.h"
+#include "mongo/util/intrusive_counter.h"
 
 namespace mongo {
 
 class DocumentSourceMatch : public DocumentSource {
 public:
+    template <typename T, typename... Args, typename>
+    friend boost::intrusive_ptr<T> make_intrusive(Args&&...);
+    virtual boost::intrusive_ptr<DocumentSourceMatch> clone() const {
+        return make_intrusive<std::decay_t<decltype(*this)>>(*this);
+    }
+
     static constexpr StringData kStageName = "$match"_sd;
     /**
      * Convenience method for creating a $match stage.
@@ -170,6 +178,11 @@ public:
     }
 
 protected:
+    DocumentSourceMatch(const DocumentSourceMatch& other)
+        : DocumentSourceMatch(
+              other.serialize().getDocument().toBson().firstElement().embeddedObject(),
+              other.pExpCtx) {}
+
     GetNextResult doGetNext() override;
     DocumentSourceMatch(const BSONObj& query,
                         const boost::intrusive_ptr<ExpressionContext>& expCtx);