refactor: add SchemaValidator::get_field_name

Author: timvermeulen

src/row_metadata.rs

@@ -22,7 +22,7 @@ static ROW_METADATA_CACHE: OnceCell<LockedRowMetadataCache> = OnceCell::const_ne
 #[derive(Debug, PartialEq)]
 pub(crate) enum AccessType {
     WithSeqAccess,
-    WithMapAccess(Vec<usize>),
+    WithMapAccess(Vec<usize>, Vec<&'static str>),
 }
 
 /// Contains a vector of [`Column`] objects parsed from the beginning
@@ -122,7 +122,7 @@ impl RowMetadata {
                     }
                 }
                 if should_use_map {
-                    AccessType::WithMapAccess(mapping)
+                    AccessType::WithMapAccess(mapping, T::column_names().into_iter().collect())
                 } else {
                     AccessType::WithSeqAccess
                 }
@@ -137,7 +137,7 @@ impl RowMetadata {
     #[inline]
     pub(crate) fn get_schema_index(&self, struct_idx: usize) -> usize {
         match &self.access_type {
-            AccessType::WithMapAccess(mapping) => {
+            AccessType::WithMapAccess(mapping, _) => {
                 if struct_idx < mapping.len() {
                     mapping[struct_idx]
                 } else {
@@ -149,9 +149,22 @@ impl RowMetadata {
         }
     }
 
+    #[inline]
+    pub(crate) fn get_field_name(&self, struct_idx: usize) -> Option<&'static str> {
+        match &self.access_type {
+            AccessType::WithMapAccess(mapping, field_names) => {
+                let Some(mapped) = mapping.get(struct_idx) else {
+                    return None;
+                };
+                field_names.get(*mapped).copied()
+            }
+            AccessType::WithSeqAccess => None,
+        }
+    }
+
     #[inline]
     pub(crate) fn is_field_order_wrong(&self) -> bool {
-        matches!(self.access_type, AccessType::WithMapAccess(_))
+        matches!(self.access_type, AccessType::WithMapAccess(_, _))
     }
 }
 

src/rowbinary/de.rs

@@ -287,7 +287,6 @@ where
             visitor.visit_map(RowBinaryStructAsMapAccess {
                 deserializer: self,
                 current_field_idx: 0,
-                fields,
             })
         }
     }
@@ -417,7 +416,6 @@ where
 {
     deserializer: &'de mut RowBinaryDeserializer<'cursor, 'data, R, Validator>,
     current_field_idx: usize,
-    fields: &'static [&'static str],
 }
 
 struct StructFieldIdentifier(&'static str);
@@ -475,14 +473,14 @@ where
     where
         K: DeserializeSeed<'data>,
     {
-        if self.current_field_idx >= self.fields.len() {
-            return Ok(None);
-        }
-        let schema_index = self
+        let Some(field_name) = self
             .deserializer
             .validator
-            .get_schema_index(self.current_field_idx);
-        let field_id = StructFieldIdentifier(self.fields[schema_index]);
+            .get_field_name(self.current_field_idx)
+        else {
+            return Ok(None);
+        };
+        let field_id = StructFieldIdentifier(field_name);
         self.current_field_idx += 1;
         seed.deserialize(field_id).map(Some)
     }
@@ -495,7 +493,8 @@ where
     }
 
     fn size_hint(&self) -> Option<usize> {
-        Some(self.fields.len())
+        // Some(self.fields.len())
+        None
     }
 }
 

src/rowbinary/validation.rs

@@ -28,6 +28,7 @@ pub(crate) trait SchemaValidator<R: Row>: Sized {
     /// It is used only if the crate detects that while the field names and the types are correct,
     /// the field order in the struct does not match the column order in the database schema.
     fn get_schema_index(&self, struct_idx: usize) -> usize;
+    fn get_field_name(&self, struct_idx: usize) -> Option<&'static str>;
 }
 
 pub(crate) struct DataTypeValidator<'cursor, R: Row> {
@@ -184,6 +185,10 @@ impl<'cursor, R: Row> SchemaValidator<R> for DataTypeValidator<'cursor, R> {
         self.metadata.get_schema_index(struct_idx)
     }
 
+    fn get_field_name(&self, struct_idx: usize) -> Option<&'static str> {
+        self.metadata.get_field_name(struct_idx)
+    }
+
     #[cold]
     fn validate_identifier<T: EnumOrVariantIdentifier>(&mut self, _value: T) {
         unreachable!()
@@ -393,6 +398,10 @@ impl<'cursor, R: Row> SchemaValidator<R> for Option<InnerDataTypeValidator<'_, '
     fn get_schema_index(&self, _struct_idx: usize) -> usize {
         unreachable!()
     }
+
+    fn get_field_name(&self, _struct_idx: usize) -> Option<&'static str> {
+        unreachable!()
+    }
 }
 
 impl<R: Row> Drop for InnerDataTypeValidator<'_, '_, R> {
@@ -638,6 +647,10 @@ impl<R: Row> SchemaValidator<R> for () {
     fn get_schema_index(&self, _struct_idx: usize) -> usize {
         unreachable!()
     }
+
+    fn get_field_name(&self, _struct_idx: usize) -> Option<&'static str> {
+        unreachable!()
+    }
 }
 
 /// Which Serde data type (De)serializer used for the given type.