Function string_view_trim

datafusion/functions/src/string/common.rs:144–236

Applies the trim function to the given string view array(s) and returns a new string view array with the trimmed values. Pre-computes the pattern characters once for scalar patterns to avoid repeated allocations per row.

(args: &[ArrayRef])

/// Pre-computes the pattern characters once for scalar patterns to avoid
/// repeated allocations per row.
fn string_view_trim<Tr: Trimmer>(args: &[ArrayRef]) -> Result<ArrayRef> {
    let string_view_array = as_string_view_array(&args[0])?;
    let mut views_buf = Vec::with_capacity(string_view_array.len());
    let mut null_builder = NullBufferBuilder::new(string_view_array.len());

    match args.len() {
        1 => {
            // Trim spaces by default
            for (src_str_opt, raw_view) in string_view_array
                .iter()
                .zip(string_view_array.views().iter())
            {
                if let Some(src_str) = src_str_opt {
                    let (trimmed, offset) = Tr::trim_ascii_char(src_str, b' ');
                    append_view(&mut views_buf, raw_view, trimmed, offset);
                    null_builder.append_non_null();
                } else {
                    null_builder.append_null();
                    views_buf.push(0);
                }
            }
        }
        2 => {
            let characters_array = as_string_view_array(&args[1])?;

            if characters_array.len() == 1 {
                // Scalar pattern - pre-compute pattern chars once
                if characters_array.is_null(0) {
                    return Ok(new_null_array(
                        &DataType::Utf8View,
                        string_view_array.len(),
                    ));
                }

                let pattern: Vec<char> = characters_array.value(0).chars().collect();
                for (src_str_opt, raw_view) in string_view_array
                    .iter()
                    .zip(string_view_array.views().iter())
                {
                    trim_and_append_view::<Tr>(
                        src_str_opt,
                        &pattern,
                        &mut views_buf,
                        &mut null_builder,
                        raw_view,
                    );
                }
            } else {
                // Per-row pattern - must compute pattern chars for each row
                let mut pattern: Vec<char> = Vec::new();
                for ((src_str_opt, raw_view), characters_opt) in string_view_array
                    .iter()
                    .zip(string_view_array.views().iter())
                    .zip(characters_array.iter())
                {
                    if let (Some(src_str), Some(characters)) =
                        (src_str_opt, characters_opt)
                    {