SERVER-53399 Parse individual window functions

2 files changed, 36 insertions, 9 deletions

diff --git a/src/mongo/db/query/datetime/date_time_support.cpp b/src/mongo/db/query/datetime/date_time_support.cpp
index 425a4349abc..ea2f603b8bf 100644
--- a/src/mongo/db/query/datetime/date_time_support.cpp
+++ b/src/mongo/db/query/datetime/date_time_support.cpp
@@ -722,18 +722,40 @@ long long dateDiff(Date_t startDate, Date_t endDate, TimeUnit unit, const TimeZo
     }
 }
 
-TimeUnit parseTimeUnit(const std::string_view unitName) {
-    const StringData unitNameAsStringData{unitName.data(), unitName.length()};
-    auto iterator = timeUnitNameToTimeUnitMap.find(unitNameAsStringData);
+TimeUnit parseTimeUnit(StringData unitName) {
+    auto iterator = timeUnitNameToTimeUnitMap.find(unitName);
     uassert(ErrorCodes::FailedToParse,
-            str::stream() << "unknown time unit value: " << unitNameAsStringData,
+            str::stream() << "unknown time unit value: " << unitName,
             iterator != timeUnitNameToTimeUnitMap.end());
     return iterator->second;
 }
 
-bool isValidTimeUnit(const std::string_view unitName) {
-    return timeUnitNameToTimeUnitMap.find(StringData{unitName.data(), unitName.length()}) !=
-        timeUnitNameToTimeUnitMap.end();
+bool isValidTimeUnit(StringData unitName) {
+    return timeUnitNameToTimeUnitMap.find(unitName) != timeUnitNameToTimeUnitMap.end();
+}
+
+StringData serializeTimeUnit(TimeUnit unit) {
+    switch (unit) {
+        case TimeUnit::year:
+            return "year"_sd;
+        case TimeUnit::quarter:
+            return "quarter"_sd;
+        case TimeUnit::month:
+            return "month"_sd;
+        case TimeUnit::week:
+            return "week"_sd;
+        case TimeUnit::day:
+            return "day"_sd;
+        case TimeUnit::hour:
+            return "hour"_sd;
+        case TimeUnit::minute:
+            return "minute"_sd;
+        case TimeUnit::second:
+            return "second"_sd;
+        case TimeUnit::millisecond:
+            return "millisecond"_sd;
+    }
+    MONGO_UNREACHABLE_TASSERT(5339900);
 }
 
 void TimelibRelTimeDeleter::operator()(timelib_rel_time* relTime) {
diff --git a/src/mongo/db/query/datetime/date_time_support.h b/src/mongo/db/query/datetime/date_time_support.h
index 640ba01c5a6..43bc84d54fb 100644
--- a/src/mongo/db/query/datetime/date_time_support.h
+++ b/src/mongo/db/query/datetime/date_time_support.h
@@ -496,14 +496,19 @@ private:
  * TimeUnit. Throws an exception with error code ErrorCodes::FailedToParse when passed an invalid
  * name.
  */
-TimeUnit parseTimeUnit(const std::string_view unitName);
+TimeUnit parseTimeUnit(StringData unitName);
 
 /**
  * Returns true if 'unitName' is a valid time unit, meaning that it can be parsed by the
  * 'parseTimeUnit()' function into one of the units represented by the 'TimeUnit' enum. Otherwise
  * returns 'false'.
  */
-bool isValidTimeUnit(const std::string_view unitName);
+bool isValidTimeUnit(StringData unitName);
+
+/**
+ * Inverse of parseTimeUnit.
+ */
+StringData serializeTimeUnit(TimeUnit unit);
 
 /**
  * A custom-deleter which destructs a timelib_rel_time* when it goes out of scope.