(arrow-rs) branch main updated: [Variant] Remove dead code, add comments (#7861)

[alamb]

This is an automated email from the ASF dual-hosted git repository.

alamb pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/arrow-rs.git


The following commit(s) were added to refs/heads/main by this push:
     new c26d154b10 [Variant] Remove dead code, add comments (#7861)
c26d154b10 is described below

commit c26d154b1063a76d3a2f2df46f9f5ab85986eb8c
Author: Andrew Lamb <and...@nerdnetworks.org>
AuthorDate: Mon Jul 7 14:02:50 2025 -0400

    [Variant] Remove dead code, add comments (#7861)
    
    # Which issue does this PR close?
    
    We generally require a GitHub issue to be filed for all bug fixes and
    enhancements and this helps us generate change logs for our releases.
    You can link an issue to this PR using the GitHub syntax.
    
    - Part of #6736
    
    # Rationale for this change
    
    The `allow_deadcode` has bothered me while reviewing PRs and it also is
    hiding actually dead code
    
    # What changes are included in this PR?
    
    1. Remove clippy annotations to allow dead code
    2. Remove code clippy found as dead
    3. Add some docs (drive by docing)
    
    # Are these changes tested?
    
    By CI
    
    # Are there any user-facing changes?
    
    Just some more docs
---
 parquet-variant/src/decoder.rs | 23 ++++++++++++++---------
 parquet-variant/src/lib.rs     |  8 ++------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/parquet-variant/src/decoder.rs b/parquet-variant/src/decoder.rs
index 1b9c3bc575..e419eca6ee 100644
--- a/parquet-variant/src/decoder.rs
+++ b/parquet-variant/src/decoder.rs
@@ -22,12 +22,15 @@ use crate::ShortString;
 use arrow_schema::ArrowError;
 use chrono::{DateTime, Duration, NaiveDate, NaiveDateTime, Utc};
 
-use std::array::TryFromSliceError;
 use std::num::TryFromIntError;
 
-// Makes the code a bit more readable
-pub(crate) const VARIANT_VALUE_HEADER_BYTES: usize = 1;
-
+/// The basic type of a [`Variant`] value, encoded in the first two bits of the
+/// header byte.
+///
+/// See the [Variant Encoding specification] for details
+///
+/// [`Variant`]: crate::Variant
+/// [Variant Encoding specification]: 
https://github.com/apache/parquet-format/blob/master/VariantEncoding.md#encoding-types
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum VariantBasicType {
     Primitive = 0,
@@ -36,6 +39,13 @@ pub enum VariantBasicType {
     Array = 3,
 }
 
+/// The type of [`VariantBasicType::Primitive`], for a primitive [`Variant`]
+/// value.
+///
+/// See the [Variant Encoding specification] for details
+///
+/// [`Variant`]: crate::Variant
+/// [Variant Encoding specification]: 
https://github.com/apache/parquet-format/blob/master/VariantEncoding.md#encoding-types
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum VariantPrimitiveType {
     Null = 0,
@@ -196,11 +206,6 @@ pub(crate) fn get_primitive_type(metadata: u8) -> 
Result<VariantPrimitiveType, A
     VariantPrimitiveType::try_from(metadata >> 2)
 }
 
-/// To be used in `map_err` when unpacking an integer from a slice of bytes.
-fn map_try_from_slice_error(e: TryFromSliceError) -> ArrowError {
-    ArrowError::InvalidArgumentError(e.to_string())
-}
-
 /// Decodes an Int8 from the value section of a variant.
 pub(crate) fn decode_int8(data: &[u8]) -> Result<i8, ArrowError> {
     Ok(i8::from_le_bytes(array_from_slice(data, 0)?))
diff --git a/parquet-variant/src/lib.rs b/parquet-variant/src/lib.rs
index 7dbfff52b1..1dcd70d66a 100644
--- a/parquet-variant/src/lib.rs
+++ b/parquet-variant/src/lib.rs
@@ -27,16 +27,12 @@
 //!
 //! [Variant issue]: https://github.com/apache/arrow-rs/issues/6736
 
-// TODO: dead code removal
-#[allow(dead_code)]
-mod decoder;
-mod variant;
-// TODO: dead code removal
 mod builder;
+mod decoder;
 mod from_json;
 mod to_json;
-#[allow(dead_code)]
 mod utils;
+mod variant;
 
 pub use builder::*;
 pub use from_json::json_to_variant;