1 files changed, 55 insertions, 0 deletions
diff --git a/src/mongo/gotools/common/json/objectid.go b/src/mongo/gotools/common/json/objectid.go
new file mode 100644
index 00000000000..c38f4df5225
--- /dev/null
+++ b/src/mongo/gotools/common/json/objectid.go
@@ -0,0 +1,55 @@
+package json
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// Transition functions for recognizing ObjectId.
+// Adapted from encoding/json/scanner.go.
+
+// stateO is the state after reading `O`.
+func stateO(s *scanner, c int) int {
+	if c == 'b' {
+		s.step = generateState("ObjectId", []byte("jectId"), stateConstructor)
+		return scanContinue
+	}
+	return s.error(c, "in literal ObjectId (expecting 'b')")
+}
+
+// Decodes an ObjectId literal stored in the underlying byte data into v.
+func (d *decodeState) storeObjectId(v reflect.Value) {
+	op := d.scanWhile(scanSkipSpace)
+	if op != scanBeginCtor {
+		d.error(fmt.Errorf("expected beginning of constructor"))
+	}
+
+	args, err := d.ctor("ObjectId", []reflect.Type{objectIdType})
+	if err != nil {
+		d.error(err)
+	}
+	switch kind := v.Kind(); kind {
+	case reflect.Interface:
+		v.Set(args[0])
+	default:
+		d.error(fmt.Errorf("cannot store %v value into %v type", objectIdType, kind))
+	}
+}
+
+// Returns an ObjectId literal from the underlying byte data.
+func (d *decodeState) getObjectId() interface{} {
+	op := d.scanWhile(scanSkipSpace)
+	if op != scanBeginCtor {
+		d.error(fmt.Errorf("expected beginning of constructor"))
+	}
+
+	args := d.ctorInterface()
+	if err := ctorNumArgsMismatch("ObjectId", 1, len(args)); err != nil {
+		d.error(err)
+	}
+	arg0, ok := args[0].(string)
+	if !ok {
+		d.error(fmt.Errorf("expected string for first argument of ObjectId constructor"))
+	}
+	return ObjectId(arg0)
+}