Function replace

datafusion/functions/src/string/replace.rs:205–244

Replaces all occurrences in string of substring from with substring to. replace('abcdefabcdef', 'cd', 'XX') = 'abXXefabXXef'

(args: &[ArrayRef])

/// Replaces all occurrences in string of substring from with substring to.
/// replace('abcdefabcdef', 'cd', 'XX') = 'abXXefabXXef'
fn replace<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
    let string_array = as_generic_string_array::<T>(&args[0])?;
    let from_array = as_generic_string_array::<T>(&args[1])?;
    let to_array = as_generic_string_array::<T>(&args[2])?;

    let len = string_array.len();
    let mut builder = GenericStringArrayBuilder::<T>::with_capacity(len, 0);
    let nulls = NullBuffer::union_many([
        string_array.nulls(),
        from_array.nulls(),
        to_array.nulls(),
    ]);

    // Hoist the nulls.is_some() check out of the loop. LLVM unswitches this
    // automatically today, but kept explicit so the no-nulls fast path is not
    // contingent on the optimizer's cost heuristic.
    if let Some(nulls_ref) = nulls.as_ref() {
        for i in 0..len {
            if nulls_ref.is_null(i) {
                builder.append_placeholder();
                continue;
            }
            // SAFETY: union of input nulls is non-null at i, so each input is too.
            let string = unsafe { string_array.value_unchecked(i) };
            let from = unsafe { from_array.value_unchecked(i) };
            let to = unsafe { to_array.value_unchecked(i) };
            apply_replace(&mut builder, string, from, to);
        }
    } else {
        for i in 0..len {
            // SAFETY: i < len, and no input has a null buffer.
            let string = unsafe { string_array.value_unchecked(i) };
            let from = unsafe { from_array.value_unchecked(i) };
            let to = unsafe { to_array.value_unchecked(i) };
            apply_replace(&mut builder, string, from, to);
        }
    }

    Ok(Arc::new(builder.finish(nulls)?) as ArrayRef)
}

#[inline]
fn apply_replace<B: BulkNullStringArrayBuilder>(