Move Emptiable and MaybeEmpty to scylla_cql::value

Old locations are kept until 2.0 for backwards compatibility.
The change is done because we will implement serialization for
MaybeEmpty.

scylla-cql/src/deserialize/value.rs

@@ -27,6 +27,15 @@ use crate::value::{
     CqlTimeuuid, CqlValue, CqlVarint, deser_cql_value,
 };
 
+// Re-export for backwards compatibility. These types were moved to crate::value module.
+// Note: deprecated doesn't work on re-exports, users won't get the warning.
+// Added it anyway for documentation purposes.
+// TODO(2.0): Remove those re-exports.
+#[deprecated(since = "1.5.0", note = "Moved to `scylla_cql::value` module")]
+pub use crate::value::Emptiable;
+#[deprecated(since = "1.5.0", note = "Moved to `scylla_cql::value` module")]
+pub use crate::value::MaybeEmpty;
+
 /// A type that can be deserialized from a column value inside a row that was
 /// returned from a query.
 ///
@@ -92,27 +101,6 @@ where
     }
 }
 
-/// Values that may be empty or not.
-///
-/// In CQL, some types can have a special value of "empty", represented as
-/// a serialized value of length 0. An example of this are integral types:
-/// the "int" type can actually hold 2^32 + 1 possible values because of this
-/// quirk. Note that this is distinct from being NULL.
-///
-/// Rust types that cannot represent an empty value (e.g. i32) should implement
-/// this trait in order to be deserialized as [MaybeEmpty].
-pub trait Emptiable {}
-
-/// A value that may be empty or not.
-///
-/// `MaybeEmpty` was introduced to help support the quirk described in [Emptiable]
-/// for Rust types which can't represent the empty, additional value.
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy)]
-pub enum MaybeEmpty<T: Emptiable> {
-    Empty,
-    Value(T),
-}
-
 impl<'frame, 'metadata, T> DeserializeValue<'frame, 'metadata> for MaybeEmpty<T>
 where
     T: DeserializeValue<'frame, 'metadata> + Emptiable,

scylla-cql/src/value.rs

@@ -57,6 +57,29 @@ impl<V> MaybeUnset<V> {
     }
 }
 
+/// Values that may be empty or not.
+///
+/// In CQL, some types can have a special value of "empty", represented as
+/// a serialized value of length 0. An example of this are integral types:
+/// the "int" type can actually hold 2^32 + 1 possible values because of this
+/// quirk. Note that this is distinct from being NULL.
+///
+/// Rust types that cannot represent an empty value (e.g. i32) should implement
+/// this trait in order to be deserialized as [`MaybeEmpty`].
+pub trait Emptiable {}
+
+/// A value that may be empty or not.
+///
+/// `MaybeEmpty` was introduced to help support the quirk described in [`Emptiable`]
+/// for Rust types which can't represent the empty, additional value.
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy)]
+pub enum MaybeEmpty<T: Emptiable> {
+    /// Represents an empty value (0 bytes in the serialized form).
+    Empty,
+    /// Represents a non-empty value.
+    Value(T),
+}
+
 /// Represents timeuuid (uuid V1) value
 ///
 /// This type has custom comparison logic which follows ScyllaDB/Cassandra semantics.

scylla/src/lib.rs

@@ -113,7 +113,8 @@ pub mod value {
     // Every `pub` item is re-exported here, apart from `deser_cql_value`.
     pub use scylla_cql::value::{
         Counter, CqlDate, CqlDecimal, CqlDecimalBorrowed, CqlDuration, CqlTime, CqlTimestamp,
-        CqlTimeuuid, CqlValue, CqlVarint, CqlVarintBorrowed, MaybeUnset, Row, Unset, ValueOverflow,
+        CqlTimeuuid, CqlValue, CqlVarint, CqlVarintBorrowed, Emptiable, MaybeEmpty, MaybeUnset,
+        Row, Unset, ValueOverflow,
     };
 }
 
@@ -226,12 +227,18 @@ pub mod deserialize {
     pub mod value {
         pub use scylla_cql::deserialize::value::{
             BuiltinDeserializationError, BuiltinDeserializationErrorKind, BuiltinTypeCheckError,
-            BuiltinTypeCheckErrorKind, DeserializeValue, Emptiable, ListlikeIterator,
-            MapDeserializationErrorKind, MapIterator, MapTypeCheckErrorKind, MaybeEmpty,
+            BuiltinTypeCheckErrorKind, DeserializeValue, ListlikeIterator,
+            MapDeserializationErrorKind, MapIterator, MapTypeCheckErrorKind,
             SetOrListDeserializationErrorKind, SetOrListTypeCheckErrorKind,
             TupleDeserializationErrorKind, TupleTypeCheckErrorKind, UdtIterator,
             UdtTypeCheckErrorKind,
         };
+
+        // Note: deprecated doesn't work on re-exports, users won't get the warning.
+        // Added it anyway for documentation purposes.
+        // TODO(2.0): Remove those re-exports.
+        #[deprecated(since = "1.5.0", note = "Moved to `scylla::value` module")]
+        pub use scylla_cql::deserialize::value::{Emptiable, MaybeEmpty};
     }
 
     // Shorthands for better readability.