Import referenced modules at file scope and document page coordinates

Signed-off-by: Daniel King <dan@spiraldb.com>

Author: danking

encodings/pco/src/array.rs

@@ -66,6 +66,7 @@ use crate::PcoLogicalPages;
 use crate::PcoMetadata;
 use crate::PcoPageInfo;
 use crate::page_index::PageIndex;
+use crate::take::slice as decode_slice;
 
 // Overall approach here:
 // Chunk the array into Pco chunks (currently using the default recommended size
@@ -285,7 +286,7 @@ impl VTable for Pco {
     fn execute(array: Array<Self>, ctx: &mut ExecutionCtx) -> VortexResult<ExecutionResult> {
         if array.slice_start() != 0 || array.slice_stop() != array.unsliced_n_rows() {
             return Ok(ExecutionResult::done(
-                crate::take::slice(array.as_view(), ctx)?.into_array(),
+                decode_slice(array.as_view(), ctx)?.into_array(),
             ));
         }
         let unsliced_validity = array.unsliced_validity();

encodings/pco/src/range_selection_tests.rs

@@ -1,8 +1,10 @@
 // SPDX-License-Identifier: Apache-2.0
 // SPDX-FileCopyrightText: Copyright the Vortex contributors
 
+use std::iter::repeat_n;
 use std::sync::LazyLock;
 
+use pco::DEFAULT_MAX_PAGE_N;
 use rstest::rstest;
 use vortex_array::ArrayRef;
 use vortex_array::IntoArray;
@@ -17,10 +19,11 @@ use vortex_error::VortexResult;
 use vortex_session::VortexSession;
 
 use crate::Pco;
+use crate::initialize;
 
 static SESSION: LazyLock<VortexSession> = LazyLock::new(|| {
     let session = VortexSession::empty();
-    crate::initialize(&session);
+    initialize(&session);
     session
 });
 
@@ -97,7 +100,7 @@ fn rejects_invalid_indices_and_descriptors() -> VortexResult<()> {
 #[test]
 fn large_public_compressor_selections() -> VortexResult<()> {
     let mut ctx = SESSION.create_execution_ctx();
-    let len = pco::DEFAULT_MAX_PAGE_N + 257;
+    let len = DEFAULT_MAX_PAGE_N + 257;
     let input = PrimitiveArray::from_iter(
         (0..len).map(|i| u32::try_from(i).vortex_expect("fixture fits u32")),
     );
@@ -153,7 +156,7 @@ fn mixed_fragments_narrow_slices_and_compact_repeats() -> VortexResult<()> {
     )?
     .into_array();
     let expected = PrimitiveArray::from_option_iter(
-        std::iter::repeat_n(Some(11i64), 500000).chain(std::iter::repeat_n(None, 500000)),
+        repeat_n(Some(11i64), 500000).chain(repeat_n(None, 500000)),
     );
     assert_arrays_eq!(encoded.take(compact)?, expected, &mut ctx);
     let nulls = PrimitiveArray::new(vec![0i64; 100000], Validity::AllInvalid);