frame: adjust serialized values iterator to return RawValue

Currently, the SerializedValues' `iter()` method treats both null and
unset values as None, and `iter_name_value_pairs()` just assumes that
values are never null/unset and panics if they are.

Make the interface more correct by adjusting both methods to return
RawValue. The iterators will be used in the next commit to implement the
fallback that allows to implement `SerializeRow`/`SerializeCql` via
legacy `ValueList`/`Value` traits.

scylla-cql/src/frame/value.rs

@@ -16,6 +16,7 @@ use chrono::{DateTime, NaiveDate, NaiveTime, TimeZone, Utc};
 
 use super::response::result::CqlValue;
 use super::types::vint_encode;
+use super::types::RawValue;
 
 #[cfg(feature = "secret")]
 use secrecy::{ExposeSecret, Secret, Zeroize};
@@ -366,7 +367,7 @@ impl SerializedValues {
         Ok(())
     }
 
-    pub fn iter(&self) -> impl Iterator<Item = Option<&[u8]>> {
+    pub fn iter(&self) -> impl Iterator<Item = RawValue> {
         SerializedValuesIterator {
             serialized_values: &self.serialized_values,
             contains_names: self.contains_names,
@@ -410,15 +411,15 @@ impl SerializedValues {
         })
     }
 
-    pub fn iter_name_value_pairs(&self) -> impl Iterator<Item = (Option<&str>, &[u8])> {
+    pub fn iter_name_value_pairs(&self) -> impl Iterator<Item = (Option<&str>, RawValue)> {
         let mut buf = &self.serialized_values[..];
         (0..self.values_num).map(move |_| {
             // `unwrap()`s here are safe, as we assume type-safety: if `SerializedValues` exits,
             // we have a guarantee that the layout of the serialized values is valid.
             let name = self
                 .contains_names
                 .then(|| types::read_string(&mut buf).unwrap());
-            let serialized = types::read_bytes(&mut buf).unwrap();
+            let serialized = types::read_value(&mut buf).unwrap();
             (name, serialized)
         })
     }
@@ -431,7 +432,7 @@ pub struct SerializedValuesIterator<'a> {
 }
 
 impl<'a> Iterator for SerializedValuesIterator<'a> {
-    type Item = Option<&'a [u8]>;
+    type Item = RawValue<'a>;
 
     fn next(&mut self) -> Option<Self::Item> {
         if self.serialized_values.is_empty() {
@@ -443,7 +444,7 @@ impl<'a> Iterator for SerializedValuesIterator<'a> {
             types::read_short_bytes(&mut self.serialized_values).expect("badly encoded value name");
         }
 
-        Some(types::read_bytes_opt(&mut self.serialized_values).expect("badly encoded value"))
+        Some(types::read_value(&mut self.serialized_values).expect("badly encoded value"))
     }
 }
 

scylla-cql/src/frame/value_tests.rs

@@ -1,4 +1,4 @@
-use crate::frame::value::BatchValuesIterator;
+use crate::frame::{types::RawValue, value::BatchValuesIterator};
 
 use super::value::{
     BatchValues, CqlDate, CqlTime, CqlTimestamp, MaybeUnset, SerializeValuesError,
@@ -421,7 +421,10 @@ fn serialized_values() {
         values.write_to_request(&mut request);
         assert_eq!(request, vec![0, 1, 0, 0, 0, 1, 8]);
 
-        assert_eq!(values.iter().collect::<Vec<_>>(), vec![Some([8].as_ref())]);
+        assert_eq!(
+            values.iter().collect::<Vec<_>>(),
+            vec![RawValue::Value([8].as_ref())]
+        );
     }
 
     // Add second value
@@ -436,7 +439,10 @@ fn serialized_values() {
 
         assert_eq!(
             values.iter().collect::<Vec<_>>(),
-            vec![Some([8].as_ref()), Some([0, 16].as_ref())]
+            vec![
+                RawValue::Value([8].as_ref()),
+                RawValue::Value([0, 16].as_ref())
+            ]
         );
     }
 
@@ -468,7 +474,10 @@ fn serialized_values() {
 
         assert_eq!(
             values.iter().collect::<Vec<_>>(),
-            vec![Some([8].as_ref()), Some([0, 16].as_ref())]
+            vec![
+                RawValue::Value([8].as_ref()),
+                RawValue::Value([0, 16].as_ref())
+            ]
         );
     }
 }
@@ -498,9 +507,9 @@ fn slice_value_list() {
     assert_eq!(
         serialized.iter().collect::<Vec<_>>(),
         vec![
-            Some([0, 0, 0, 1].as_ref()),
-            Some([0, 0, 0, 2].as_ref()),
-            Some([0, 0, 0, 3].as_ref())
+            RawValue::Value([0, 0, 0, 1].as_ref()),
+            RawValue::Value([0, 0, 0, 2].as_ref()),
+            RawValue::Value([0, 0, 0, 3].as_ref())
         ]
     );
 }
@@ -515,9 +524,9 @@ fn vec_value_list() {
     assert_eq!(
         serialized.iter().collect::<Vec<_>>(),
         vec![
-            Some([0, 0, 0, 1].as_ref()),
-            Some([0, 0, 0, 2].as_ref()),
-            Some([0, 0, 0, 3].as_ref())
+            RawValue::Value([0, 0, 0, 1].as_ref()),
+            RawValue::Value([0, 0, 0, 2].as_ref()),
+            RawValue::Value([0, 0, 0, 3].as_ref())
         ]
     );
 }
@@ -530,7 +539,7 @@ fn tuple_value_list() {
 
         let serialized_vals: Vec<u8> = serialized
             .iter()
-            .map(|o: Option<&[u8]>| o.unwrap()[0])
+            .map(|o: RawValue| o.as_value().unwrap()[0])
             .collect();
 
         let expected: Vec<u8> = expected.collect();
@@ -604,9 +613,9 @@ fn ref_value_list() {
     assert_eq!(
         serialized.iter().collect::<Vec<_>>(),
         vec![
-            Some([0, 0, 0, 1].as_ref()),
-            Some([0, 0, 0, 2].as_ref()),
-            Some([0, 0, 0, 3].as_ref())
+            RawValue::Value([0, 0, 0, 1].as_ref()),
+            RawValue::Value([0, 0, 0, 2].as_ref()),
+            RawValue::Value([0, 0, 0, 3].as_ref())
         ]
     );
 }

scylla/src/statement/prepared_statement.rs

@@ -1,5 +1,6 @@
 use bytes::{Bytes, BytesMut};
 use scylla_cql::errors::{BadQuery, QueryError};
+use scylla_cql::frame::types::RawValue;
 use smallvec::{smallvec, SmallVec};
 use std::convert::TryInto;
 use std::sync::Arc;
@@ -399,7 +400,7 @@ impl<'ps> PartitionKey<'ps> {
                     PartitionKeyExtractionError::NoPkIndexValue(pk_index.index, bound_values.len())
                 })?;
             // Add it in sequence order to pk_values
-            if let Some(v) = next_val {
+            if let RawValue::Value(v) = next_val {
                 let spec = &prepared_metadata.col_specs[pk_index.index as usize];
                 pk_values[pk_index.sequence as usize] = Some((v, spec));
             }

scylla/src/transport/partitioner.rs

@@ -1,4 +1,5 @@
 use bytes::Buf;
+use scylla_cql::frame::types::RawValue;
 use std::num::Wrapping;
 
 use crate::{
@@ -343,11 +344,14 @@ pub fn calculate_token_for_partition_key<P: Partitioner>(
 
     if serialized_partition_key_values.len() == 1 {
         let val = serialized_partition_key_values.iter().next().unwrap();
-        if let Some(val) = val {
+        if let RawValue::Value(val) = val {
             partitioner_hasher.write(val);
         }
     } else {
-        for val in serialized_partition_key_values.iter().flatten() {
+        for val in serialized_partition_key_values
+            .iter()
+            .filter_map(|rv| rv.as_value())
+        {
             let val_len_u16: u16 = val
                 .len()
                 .try_into()