1 files changed, 43 insertions, 0 deletions
diff --git a/src/mongo/db/exec/sbe/values/value.cpp b/src/mongo/db/exec/sbe/values/value.cpp
index 4ed55ffb75c..aa9efdeb687 100644
--- a/src/mongo/db/exec/sbe/values/value.cpp
+++ b/src/mongo/db/exec/sbe/values/value.cpp
@@ -34,6 +34,7 @@
 #include <pcrecpp.h>
 
 #include "mongo/db/exec/sbe/values/bson.h"
+#include "mongo/db/exec/sbe/values/value_builder.h"
 #include "mongo/db/storage/key_string.h"
 
 namespace mongo {
@@ -613,6 +614,48 @@ std::string_view ObjectEnumerator::getFieldName() const {
     }
 }
 
+void readKeyStringValueIntoAccessors(const KeyString::Value& keyString,
+                                     const Ordering& ordering,
+                                     BufBuilder* valueBufferBuilder,
+                                     std::vector<ViewOfValueAccessor>* accessors,
+                                     boost::optional<IndexKeysInclusionSet> indexKeysToInclude) {
+    ValueBuilder valBuilder(valueBufferBuilder);
+    invariant(!indexKeysToInclude || indexKeysToInclude->count() == accessors->size());
+
+    BufReader reader(keyString.getBuffer(), keyString.getSize());
+    KeyString::TypeBits typeBits(keyString.getTypeBits());
+    KeyString::TypeBits::Reader typeBitsReader(typeBits);
+
+    bool keepReading = true;
+    size_t componentIndex = 0;
+    do {
+        // In the edge case that 'componentIndex' indicates that we have already read
+        // 'kMaxCompoundIndexKeys' components, we expect that the next 'readSBEValue()' will return
+        // false (to indicate EOF), so the value of 'inverted' does not matter.
+        bool inverted = (componentIndex < Ordering::kMaxCompoundIndexKeys)
+            ? (ordering.get(componentIndex) == -1)
+            : false;
+
+        keepReading = KeyString::readSBEValue(
+            &reader, &typeBitsReader, inverted, typeBits.version, &valBuilder);
+
+        invariant(componentIndex < Ordering::kMaxCompoundIndexKeys || !keepReading);
+
+        // If 'indexKeysToInclude' indicates that this index key component is not part of the
+        // projection, remove it from the list of values that will be fed to the 'accessors' list.
+        // Note that, even when we are excluding a key component, we can't skip the call to
+        // 'KeyString::readSBEValue()' because it is needed to advance the 'reader' and
+        // 'typeBitsReader' stream.
+        if (indexKeysToInclude && (componentIndex < Ordering::kMaxCompoundIndexKeys) &&
+            !(*indexKeysToInclude)[componentIndex]) {
+            valBuilder.popValue();
+        }
+        ++componentIndex;
+    } while (keepReading && valBuilder.numValues() < accessors->size());
+
+    valBuilder.readValues(accessors);
+}
+
 }  // namespace value
 }  // namespace sbe
 }  // namespace mongo