SERVER-15926: Implement $round function and allow a precision argument for $trunc

Closes #1297

Signed-off-by: Charlie Swanson <charlie.swanson@mongodb.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/src/mongo/db/pipeline/expression.h b/src/mongo/db/pipeline/expression.h
index 33e2781c296..5b79fafe1ad 100644
--- a/src/mongo/db/pipeline/expression.h
+++ b/src/mongo/db/pipeline/expression.h
@@ -1755,6 +1755,14 @@ public:
     const char* getOpName() const final;
 };
 
+class ExpressionRound final : public ExpressionRangedArity<ExpressionRound, 1, 2> {
+public:
+    explicit ExpressionRound(const boost::intrusive_ptr<ExpressionContext>& expCtx)
+        : ExpressionRangedArity<ExpressionRound, 1, 2>(expCtx) {}
+
+    Value evaluate(const Document& root) const final;
+    const char* getOpName() const final;
+};
 
 class ExpressionSplit final : public ExpressionFixedArity<ExpressionSplit, 2> {
 public:
@@ -1949,12 +1957,12 @@ private:
 };
 
 
-class ExpressionTrunc final : public ExpressionSingleNumericArg<ExpressionTrunc> {
+class ExpressionTrunc final : public ExpressionRangedArity<ExpressionTrunc, 1, 2> {
 public:
     explicit ExpressionTrunc(const boost::intrusive_ptr<ExpressionContext>& expCtx)
-        : ExpressionSingleNumericArg<ExpressionTrunc>(expCtx) {}
+        : ExpressionRangedArity<ExpressionTrunc, 1, 2>(expCtx) {}
 
-    Value evaluateNumericArg(const Value& numericArg) const final;
+    Value evaluate(const Document& root) const final;
     const char* getOpName() const final;
 };