ZENOTME commented on code in PR #731:
URL: https://github.com/apache/iceberg-rust/pull/731#discussion_r1967364613
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crates/iceberg/src/spec/schema.rs:
##########
@@ -1146,6 +1146,170 @@ impl ReassignFieldIds {
}
}
+/// A post order schema visitor with partner.
+///
+/// For order of methods called, please refer to [`visit_schema_with_partner`].
+pub trait SchemaWithPartnerVisitor<P> {
+ /// Return type of this visitor.
+ type T;
+
+ /// Called before struct field.
+ fn before_struct_field(&mut self, _field: &NestedFieldRef, _partner: &P)
-> Result<()> {
+ Ok(())
+ }
+ /// Called after struct field.
+ fn after_struct_field(&mut self, _field: &NestedFieldRef, _partner: &P) ->
Result<()> {
+ Ok(())
+ }
+ /// Called before list field.
+ fn before_list_element(&mut self, _field: &NestedFieldRef, _partner: &P)
-> Result<()> {
+ Ok(())
+ }
+ /// Called after list field.
+ fn after_list_element(&mut self, _field: &NestedFieldRef, _partner: &P) ->
Result<()> {
+ Ok(())
+ }
+ /// Called before map key field.
+ fn before_map_key(&mut self, _field: &NestedFieldRef, _partner: &P) ->
Result<()> {
+ Ok(())
+ }
+ /// Called after map key field.
+ fn after_map_key(&mut self, _field: &NestedFieldRef, _partner: &P) ->
Result<()> {
+ Ok(())
+ }
+ /// Called before map value field.
+ fn before_map_value(&mut self, _field: &NestedFieldRef, _partner: &P) ->
Result<()> {
+ Ok(())
+ }
+ /// Called after map value field.
+ fn after_map_value(&mut self, _field: &NestedFieldRef, _partner: &P) ->
Result<()> {
+ Ok(())
+ }
+
+ /// Called after schema's type visited.
+ fn schema(&mut self, schema: &Schema, partner: &P, value: Self::T) ->
Result<Self::T>;
+ /// Called after struct's field type visited.
+ fn field(&mut self, field: &NestedFieldRef, partner: &P, value: Self::T)
-> Result<Self::T>;
+ /// Called after struct's fields visited.
+ fn r#struct(
+ &mut self,
+ r#struct: &StructType,
+ partner: &P,
+ results: Vec<Self::T>,
+ ) -> Result<Self::T>;
+ /// Called after list fields visited.
+ fn list(&mut self, list: &ListType, partner: &P, value: Self::T) ->
Result<Self::T>;
+ /// Called after map's key and value fields visited.
+ fn map(
+ &mut self,
+ map: &MapType,
+ partner: &P,
+ key_value: Self::T,
+ value: Self::T,
+ ) -> Result<Self::T>;
+ /// Called when see a primitive type.
+ fn primitive(&mut self, p: &PrimitiveType, partner: &P) -> Result<Self::T>;
+}
+
+/// Accessor used to get child partner from parent partner.
+pub trait PartnerAccessor<P> {
+ /// Get the struct partner from schema partner.
+ fn struct_parner<'a>(&self, schema_partner: &'a P) -> Result<&'a P>;
+ /// Get the field partner from struct partner.
+ fn field_partner<'a>(
+ &self,
+ struct_partner: &'a P,
+ field_id: i32,
+ field_name: &str,
+ ) -> Result<&'a P>;
+ /// Get the list element partner from list partner.
+ fn list_element_partner<'a>(&self, list_partner: &'a P) -> Result<&'a P>;
+ /// Get the map key partner from map partner.
+ fn map_key_partner<'a>(&self, map_partner: &'a P) -> Result<&'a P>;
+ /// Get the map value partner from map partner.
+ fn map_value_partner<'a>(&self, map_partner: &'a P) -> Result<&'a P>;
+}
+
+/// Visiting a type in post order.
+pub fn visit_type_with_partner<P, V: SchemaWithPartnerVisitor<P>, A:
PartnerAccessor<P>>(
Review Comment:
Seems it's possible external usage to visit schema:
https://github.com/apache/iceberg-rust/blob/90f39e8c51f035c3a42638d84bc874c6db6ac630/crates/catalog/hms/src/schema.rs#L49.
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