alamb commented on code in PR #7308:
URL: https://github.com/apache/arrow-rs/pull/7308#discussion_r2002053097
##########
arrow-buffer/src/builder/null.rs:
##########
@@ -179,6 +179,20 @@ impl NullBufferBuilder {
}
}
+ /// Append [`NullBuffer`] to this [`NullBufferBuilder`]
+ ///
+ /// This is useful when you want to concatenate two null buffers.
+ pub fn append_buffer(&mut self, buffer: &NullBuffer) {
+ if buffer.null_count() > 0 {
+ self.materialize_if_needed();
+ }
+ if let Some(buf) = self.bitmap_builder.as_mut() {
Review Comment:
If there are no nulls in self (so not materalized) and a `buffer` with nulls
is pushed, won't this code ignore those nulls 🤔
##########
arrow-buffer/src/builder/null.rs:
##########
@@ -339,4 +353,41 @@ mod tests {
builder.truncate(1);
assert_eq!(builder.len(), 1);
}
+
+ #[test]
+ fn test_append_buffers_with_unaligned_length() {
+ let mut builder = NullBufferBuilder::new(0);
+ let buffer = NullBuffer::from(&[true, true, false, true, false]);
+ builder.append_buffer(&buffer);
+ assert_eq!(builder.as_slice().unwrap(), &[0b01011_u8]);
+
+ let buffer = NullBuffer::from(&[false, false, true, true, true, false,
false]);
+ builder.append_buffer(&buffer);
+ assert_eq!(builder.as_slice().unwrap(), &[0b10001011_u8, 0b0011_u8]);
+ }
+
+ #[test]
+ fn test_append_empty_buffer() {
+ let mut builder = NullBufferBuilder::new(0);
+ let buffer = NullBuffer::from(&[true, true, false, true]);
+ builder.append_buffer(&buffer);
+ assert_eq!(builder.as_slice().unwrap(), &[0b1011_u8]);
+
+ let buffer = NullBuffer::from(&[]);
+ builder.append_buffer(&buffer);
+
+ assert_eq!(builder.as_slice().unwrap(), &[0b1011_u8]);
+ }
+
+ #[test]
+ fn test_should_not_materialize_when_appending_all_valid_buffers() {
+ let mut builder = NullBufferBuilder::new(0);
+ let buffer = NullBuffer::from(&[true; 10]);
+ builder.append_buffer(&buffer);
+
+ let buffer = NullBuffer::from(&[true; 2]);
+ builder.append_buffer(&buffer);
+
+ assert_eq!(builder.finish(), None);
Review Comment:
Can you also add a test that appends a null buffer of all valid, and then
appends a buffer with some valid and some not valid (my comment above)?
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