[GitHub] [arrow-rs] HaoYang670 commented on a diff in pull request #1684: simplify offsets checking

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

HaoYang670 commented on code in PR #1684:
URL: https://github.com/apache/arrow-rs/pull/1684#discussion_r869015456


##########
arrow/src/array/data.rs:
##########
@@ -1033,72 +1035,61 @@ impl ArrayData {
     }
 
     /// Calls the `validate(item_index, range)` function for each of
-    /// the ranges specified in the arrow offset buffer of type
+    /// the ranges specified in the arrow offsets buffer of type
     /// `T`. Also validates that each offset is smaller than
-    /// `max_offset`
+    /// `offset_limit`
+    ///
+    /// For an empty array, the offsets buffer can either be empty
+    /// or contain a single `0`.
     ///
-    /// For example, the offset buffer contained `[1, 2, 4]`, this
+    /// For example, the offsets buffer contained `[1, 2, 4]`, this
     /// function would call `validate([1,2])`, and `validate([2,4])`
     fn validate_each_offset<T, V>(
         &self,
-        offset_buffer: &Buffer,
+        offsets_buffer: &Buffer,
         offset_limit: usize,
         validate: V,
     ) -> Result<()>
     where
         T: ArrowNativeType + std::convert::TryInto<usize> + num::Num + std::fmt::Display,
         V: Fn(usize, Range<usize>) -> Result<()>,
     {
-        // An empty binary-like array can have 0 offsets
-        if self.len == 0 && offset_buffer.is_empty() {
-            return Ok(());
-        }
-
-        let offsets = self.typed_offsets::<T>(offset_buffer)?;
-
-        offsets
+        let offsets = self.typed_offsets::<T>(offsets_buffer)?
             .iter()
-            .zip(offsets.iter().skip(1))
             .enumerate()
-            .map(|(i, (&start_offset, &end_offset))| {
-                let start_offset: usize = start_offset
-                    .try_into()
-                    .map_err(|_| {
-                        ArrowError::InvalidArgumentError(format!(
-                            "Offset invariant failure: could not convert start_offset {} to usize in slot {}",
-                            start_offset, i))
-                    })?;
-                let end_offset: usize = end_offset
-                    .try_into()
-                    .map_err(|_| {
-                        ArrowError::InvalidArgumentError(format!(
-                            "Offset invariant failure: Could not convert end_offset {} to usize in slot {}",
-                            end_offset, i+1))
-                    })?;
-
-                if start_offset > offset_limit {
-                    return Err(ArrowError::InvalidArgumentError(format!(
-                        "Offset invariant failure: offset for slot {} out of bounds: {} > {}",
-                        i, start_offset, offset_limit))
-                    );
-                }
-
-                if end_offset > offset_limit {
-                    return Err(ArrowError::InvalidArgumentError(format!(
-                        "Offset invariant failure: offset for slot {} out of bounds: {} > {}",
-                        i, end_offset, offset_limit))
+            .map(|(i, x)| {
+                // check if the offset can be converted to usize
+                let r = x.to_usize().ok_or_else(|| {
+                    ArrowError::InvalidArgumentError(format!(
+                        "Offset invariant failure: Could not convert offset {} to usize at position {}",
+                        x, i))}
                     );
+                // check if the offset exceeds the limit
+                match r {
+                    Ok(n) if n <= offset_limit => Ok(n),
+                    Ok(_) => Err(ArrowError::InvalidArgumentError(format!(
+                        "Offset invariant failure: offset at position {} out of bounds: {} > {}",
+                        i, x, offset_limit))
+                    ),
+                    err => err,
                 }
+            })
+            .collect::<Result<Vec<usize>>>()?;

Review Comment:
   collect the result because I want to use the `windows` method



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