[GitHub] [arrow-rs] viirya commented on a diff in pull request #1588: Add support for nested list arrays from parquet to arrow arrays (#993)

[GitBox <gi...@apache.org>]

viirya commented on code in PR #1588:
URL: https://github.com/apache/arrow-rs/pull/1588#discussion_r867524585


##########
parquet/src/schema/visitor.rs:
##########
@@ -27,17 +27,30 @@ pub trait TypeVisitor<R, C> {
 
     /// Default implementation when visiting a list.
     ///
-    /// It checks list type definition and calls `visit_list_with_item` with extracted
+    /// It checks list type definition and calls [`Self::visit_list_with_item`] with extracted
     /// item type.
     ///
     /// To fully understand this algorithm, please refer to
     /// [parquet doc](https://github.com/apache/parquet-format/blob/master/LogicalTypes.md).
+    ///
+    /// For example, a standard list type looks like:

Review Comment:
   nice document addition 👍 



##########
parquet/src/arrow/array_reader/list_array.rs:
##########
@@ -35,12 +35,12 @@ pub struct ListArrayReader<OffsetSize: OffsetSizeTrait> {
     item_reader: Box<dyn ArrayReader>,
     data_type: ArrowType,
     item_type: ArrowType,
-    list_def_level: i16,
-    list_rep_level: i16,
-    list_empty_def_level: i16,
-    list_null_def_level: i16,
-    def_level_buffer: Option<Buffer>,
-    rep_level_buffer: Option<Buffer>,
+    /// The definition level at which this list is not null
+    def_level: i16,
+    /// The repetition level that corresponds to a new value in this array
+    rep_level: i16,
+    /// If this list is nullable
+    nullable: bool,

Review Comment:
   The comment looks clear. 👍



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