Fokko commented on code in PR #12:
URL: https://github.com/apache/iceberg-rust/pull/12#discussion_r1276572020
##########
src/spec/datatypes.rs:
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@@ -190,21 +194,87 @@ impl fmt::Display for PrimitiveType {
}
/// DataType for a specific struct
-#[derive(Debug, Serialize, Deserialize, PartialEq, Eq, Clone)]
+#[derive(Debug, Serialize, PartialEq, Eq, Clone)]
#[serde(rename = "struct", tag = "type")]
pub struct StructType {
/// Struct fields
fields: Vec<StructField>,
+ /// Lookup for index by field id
+ #[serde(skip_serializing)]
+ id_lookup: BTreeMap<i32, usize>,
+ /// Lookup for index by field name
+ #[serde(skip_serializing)]
+ name_lookup: HashMap<String, usize>,
+}
+
+impl<'de> Deserialize<'de> for StructType {
+ fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+ where
+ D: Deserializer<'de>,
+ {
+ #[derive(Deserialize)]
+ #[serde(field_identifier, rename_all = "lowercase")]
+ enum Field {
+ Type,
+ Fields,
+ }
+
+ struct StructTypeVisitor;
+
+ impl<'de> Visitor<'de> for StructTypeVisitor {
+ type Value = StructType;
+
+ fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result
{
+ formatter.write_str("struct")
+ }
+
+ fn visit_map<V>(self, mut map: V) -> Result<StructType, V::Error>
+ where
+ V: MapAccess<'de>,
+ {
+ let mut fields = None;
+ while let Some(key) = map.next_key()? {
+ match key {
+ Field::Type => (),
+ Field::Fields => {
+ if fields.is_some() {
+ return
Err(de::Error::duplicate_field("fields"));
+ }
+ fields = Some(map.next_value()?);
+ }
+ }
+ }
+ let fields: Vec<StructField> =
+ fields.ok_or_else(|| de::Error::missing_field("fields"))?;
+
+ Ok(StructType::new(fields))
+ }
+ }
+
+ const FIELDS: &[&str] = &["type", "fields"];
+ deserializer.deserialize_struct("struct", FIELDS, StructTypeVisitor)
+ }
}
impl StructType {
+ /// Creates a struct type with the given fields.
+ pub fn new(fields: Vec<StructField>) -> Self {
+ let id_lookup = BTreeMap::from_iter(fields.iter().enumerate().map(|(i,
x)| (x.id, i)));
+ let name_lookup =
+ HashMap::from_iter(fields.iter().enumerate().map(|(i, x)|
(x.name.clone(), i)));
+ Self {
+ fields,
+ id_lookup,
+ name_lookup,
Review Comment:
I'm actually not sure if we're going to use the lookup by name at all. How
about only implementing this on the schema itself? The lookup by field-id is
useful when traversing two schemas (VisitWithPartner), for example, the file
schema and the projected schema.
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