fix(rust): Fix inconsistency between code and comment (#21294)

crates/polars-arrow/src/array/growable/utf8.rs

@@ -20,6 +20,8 @@ impl<'a, O: Offset> GrowableUtf8<'a, O> {
     /// # Panics
     /// If `arrays` is empty.
     pub fn new(arrays: Vec<&'a Utf8Array<O>>, mut use_validity: bool, capacity: usize) -> Self {
+        assert!(!arrays.is_empty());
+
         // if any of the arrays has nulls, insertions from any array requires setting bits
         // as there is at least one array with nulls.
         if arrays.iter().any(|array| array.null_count() > 0) {

crates/polars-arrow/src/array/list/mod.rs

@@ -27,8 +27,8 @@ impl<O: Offset> ListArray<O> {
     ///
     /// # Errors
     /// This function returns an error iff:
-    /// * The last offset is not equal to the values' length.
-    /// * the validity's length is not equal to `offsets.len()`.
+    /// * `offsets.last()` is greater than `values.len()`.
+    /// * the validity's length is not equal to `offsets.len_proxy()`.
     /// * The `dtype`'s [`crate::datatypes::PhysicalType`] is not equal to either [`crate::datatypes::PhysicalType::List`] or [`crate::datatypes::PhysicalType::LargeList`].
     /// * The `dtype`'s inner field's data type is not equal to `values.dtype`.
     /// # Implementation
@@ -66,8 +66,8 @@ impl<O: Offset> ListArray<O> {
     ///
     /// # Panics
     /// This function panics iff:
-    /// * The last offset is not equal to the values' length.
-    /// * the validity's length is not equal to `offsets.len()`.
+    /// * `offsets.last()` is greater than `values.len()`.
+    /// * the validity's length is not equal to `offsets.len_proxy()`.
     /// * The `dtype`'s [`crate::datatypes::PhysicalType`] is not equal to either [`crate::datatypes::PhysicalType::List`] or [`crate::datatypes::PhysicalType::LargeList`].
     /// * The `dtype`'s inner field's data type is not equal to `values.dtype`.
     /// # Implementation

crates/polars-arrow/src/array/map/mod.rs

@@ -25,7 +25,7 @@ impl MapArray {
     /// Returns a new [`MapArray`].
     /// # Errors
     /// This function errors iff:
-    /// * The last offset is not equal to the field' length
+    /// * `offsets.last()` is greater than `field.len()`
     /// * The `dtype`'s physical type is not [`crate::datatypes::PhysicalType::Map`]
     /// * The fields' `dtype` is not equal to the inner field of `dtype`
     /// * The validity is not `None` and its length is different from `offsets.len() - 1`.
@@ -66,7 +66,7 @@ impl MapArray {
 
     /// Creates a new [`MapArray`].
     /// # Panics
-    /// * The last offset is not equal to the field' length.
+    /// * `offsets.last()` is greater than `field.len()`.
     /// * The `dtype`'s physical type is not [`crate::datatypes::PhysicalType::Map`],
     /// * The validity is not `None` and its length is different from `offsets.len() - 1`.
     pub fn new(

crates/polars-arrow/src/array/struct_/mod.rs

@@ -168,7 +168,7 @@ impl StructArray {
 
     /// Slices this [`StructArray`].
     /// # Panics
-    /// * `offset + length` must be smaller than `self.len()`.
+    /// panics iff `offset + length > self.len()`
     /// # Implementation
     /// This operation is `O(F)` where `F` is the number of fields.
     pub fn slice(&mut self, offset: usize, length: usize) {

crates/polars-arrow/src/array/utf8/mod.rs

@@ -395,7 +395,7 @@ impl<O: Offset> Utf8Array<O> {
     /// Creates a new [`Utf8Array`].
     /// # Panics
     /// This function panics iff:
-    /// * The last offset is greater than the values' length.
+    /// * `offsets.last()` is greater than `values.len()`.
     /// * the validity's length is not equal to `offsets.len_proxy()`.
     /// * The `dtype`'s [`crate::datatypes::PhysicalType`] is not equal to either `Utf8` or `LargeUtf8`.
     /// * The `values` between two consecutive `offsets` are not valid utf8

crates/polars-arrow/src/array/utf8/mutable_values.rs

@@ -66,7 +66,7 @@ impl<O: Offset> MutableUtf8ValuesArray<O> {
     ///
     /// # Errors
     /// This function returns an error iff:
-    /// * The last offset is not equal to the values' length.
+    /// * `offsets.last()` is greater than `values.len()`.
     /// * The `dtype`'s [`crate::datatypes::PhysicalType`] is not equal to either `Utf8` or `LargeUtf8`.
     /// * The `values` between two consecutive `offsets` are not valid utf8
     /// # Implementation
@@ -92,7 +92,7 @@ impl<O: Offset> MutableUtf8ValuesArray<O> {
     ///
     /// # Panic
     /// This function does not panic iff:
-    /// * The last offset is equal to the values' length.
+    /// * `offsets.last()` is greater than `values.len()`
     /// * The `dtype`'s [`crate::datatypes::PhysicalType`] is equal to either `Utf8` or `LargeUtf8`.
     ///
     /// # Safety

crates/polars-arrow/src/bitmap/immutable.rs

@@ -444,7 +444,7 @@ impl Bitmap {
 
     /// Creates a new [`Bitmap`] from a slice and length.
     /// # Panic
-    /// Panics iff `length <= bytes.len() * 8`
+    /// Panics iff `length > bytes.len() * 8`
     #[inline]
     pub fn from_u8_slice<T: AsRef<[u8]>>(slice: T, length: usize) -> Self {
         Bitmap::try_new(slice.as_ref().to_vec(), length).unwrap()

crates/polars-arrow/src/offset.rs

@@ -175,7 +175,7 @@ impl<O: Offset> Offsets<O> {
 
     /// Returns a `length` corresponding to the position `index`
     /// # Panic
-    /// This function panics iff `index >= self.len()`
+    /// This function panics iff `index >= self.len_proxy()`
     #[inline]
     pub fn length_at(&self, index: usize) -> usize {
         let (start, end) = self.start_end(index);