Struct arrow_cast::display::ArrayFormatter

pub struct ArrayFormatter<'a> { /* private fields */ }

A string formatter for an Array

This can be used with std::write to write type-erased dyn Array

struct MyContainer {
    values: ArrayRef,
}

impl Display for MyContainer {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        let options = FormatOptions::default();
        let formatter = ArrayFormatter::try_new(self.values.as_ref(), &options)
            .map_err(|_| std::fmt::Error)?;

        let mut iter = 0..self.values.len();
        if let Some(idx) = iter.next() {
            write!(f, "{}", formatter.value(idx))?;
        }
        for idx in iter {
            write!(f, ", {}", formatter.value(idx))?;
        }
        Ok(())
    }
}

ValueFormatter::write can also be used to get a semantic error, instead of the opaque std::fmt::Error

fn format_array(
    f: &mut dyn Write,
    array: &dyn Array,
    options: &FormatOptions,
) -> Result<(), ArrowError> {
    let formatter = ArrayFormatter::try_new(array, options)?;
    for i in 0..array.len() {
        formatter.value(i).write(f)?
    }
    Ok(())
}

Implementations

impl<'a> ArrayFormatter<'a>

pub fn try_new( array: &'a dyn Array, options: &FormatOptions<'a> ) -> Result<Self, ArrowError>

Returns an ArrayFormatter that can be used to format array

This returns an error if an array of the given data type cannot be formatted

pub fn value(&self, idx: usize) -> ValueFormatter<'_>

Returns a ValueFormatter that implements Display for the value of the array at idx