Initial (incomplete) implementation of f:f:core::Filter (#1495)

And RelationFilter subclass.

Used to implement the next step in core::Query.

1 files changed, 9 insertions, 0 deletions

diff --git a/Firestore/core/src/firebase/firestore/model/field_value.h b/Firestore/core/src/firebase/firestore/model/field_value.h
index 09c8531..697d5b3 100644
--- a/Firestore/core/src/firebase/firestore/model/field_value.h
+++ b/Firestore/core/src/firebase/firestore/model/field_value.h
@@ -108,6 +108,15 @@ class FieldValue {
     return tag_;
   }
 
+  /**
+   * PORTING NOTE: This deviates from the other platforms that define TypeOrder.
+   * Since we already define Type for union types, we use it together with this
+   * function to achieve the equivalent order of types i.e.
+   *     i) if two types are comparable, then they are of equal order;
+   *    ii) otherwise, their order is the same as the order of their Type.
+   */
+  static bool Comparable(Type lhs, Type rhs);
+
   bool boolean_value() const {
     HARD_ASSERT(tag_ == Type::Boolean);
     return boolean_value_;