Method from_lengths

arrow-buffer/src/buffer/offset.rs:121–137

Create a new [`OffsetBuffer`] from the iterator of slice lengths ``` # use arrow_buffer::OffsetBuffer; let offsets = OffsetBuffer:: ::from_lengths([1, 3, 5]); assert_eq!(offsets.as_ref(), &[0, 1, 4, 9]); ``` If you want to create an [`OffsetBuffer`] where all lengths are the same, consider using the faster [`OffsetBuffer::from_repeated_length`] instead. # Panics Panics on overflow

(lengths: I)

    ///
    /// Panics on overflow
    pub fn from_lengths<I>(lengths: I) -> Self
    where
        I: IntoIterator<Item = usize>,
    {
        let iter = lengths.into_iter();
        let mut out = Vec::with_capacity(iter.size_hint().0 + 1);
        out.push(O::usize_as(0));

        let mut acc = 0_usize;
        for length in iter {
            acc = acc.checked_add(length).expect("usize overflow");
            out.push(O::usize_as(acc))
        }
        // Check for overflow
        O::from_usize(acc).expect("offset overflow");
        Self(out.into())
    }

    /// Create a new [`OffsetBuffer`] where each slice has the same length
    /// `length`, repeated `n` times.