SERVER-24508 DocumentComparator and ValueComparator

 - Changes the Document/Value library to require comparisons
   to be made in the context of a comparator object. This is
   prep work for full collation support in the aggregation
   system.
 - Adds injectExpressionContext() to propagate the
   ExpressionContext containing the comparator object to all
   DocumentSource, Accumulator, and Expression instances
   involved in the Pipeline.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/mongo/db/pipeline/parsed_inclusion_projection.h b/src/mongo/db/pipeline/parsed_inclusion_projection.h
index 7236d8f85eb..d762d6d7ede 100644
--- a/src/mongo/db/pipeline/parsed_inclusion_projection.h
+++ b/src/mongo/db/pipeline/parsed_inclusion_projection.h
@@ -33,6 +33,7 @@
 #include <unordered_set>
 
 #include "mongo/db/pipeline/expression.h"
+#include "mongo/db/pipeline/expression_context.h"
 #include "mongo/db/pipeline/parsed_aggregation_projection.h"
 #include "mongo/stdx/memory.h"
 
@@ -118,6 +119,8 @@ public:
         return _pathToNode;
     }
 
+    void injectExpressionContext(const boost::intrusive_ptr<ExpressionContext>& expCtx);
+
 private:
     // Helpers for the Document versions above. These will apply the transformation recursively to
     // each element of any arrays, and ensure non-documents are handled appropriately.
@@ -202,6 +205,10 @@ public:
         _root->optimize();
     }
 
+    void injectExpressionContext(const boost::intrusive_ptr<ExpressionContext>& expCtx) final {
+        _root->injectExpressionContext(expCtx);
+    }
+
     void addDependencies(DepsTracker* deps) const final {
         _root->addDependencies(deps);
     }