Crate size_format

size_format

This crate provides formatting for sizes.

The main goal is to provide easy formatters for data sizes.

It provides both binary and SI unit prefixes per default, though more could be added.

use size_format::{SizeFormatterBinary, SizeFormatterSI};

assert_eq!(
    format!("{}B", SizeFormatterBinary::new(42 * 1024 * 1024)),
    "42.0MiB".to_string()
);
assert_eq!(
    format!("{}B", SizeFormatterSI::new(42_000_000)),
    "42.0MB".to_string()
);

The precision can also be specified. Please note that values are always rounded down.

use size_format::SizeFormatterSI;

assert_eq!(
    format!("{:.4}B", SizeFormatterSI::new(1_999_999_999)),
    "1.9999GB".to_string()
);
assert_eq!(
    format!("{:.0}B", SizeFormatterSI::new(1_999_999_999)),
    "1GB".to_string()
);

The presented precision will also never exceed the available precision.

use size_format::SizeFormatterSI;

assert_eq!(
    format!("{:.10}B", SizeFormatterSI::new(678)),
    "678B".to_string()
);
assert_eq!(
    format!("{:.10}B", SizeFormatterSI::new(1_999)),
    "1.999kB".to_string()
);

For more flexibility, use the SizeFormatter type directly with the correct type parameters. For example the following code formats a u16 using binary prefixes and uses a comma as a separator.

use size_format::{BinaryPrefixes, CommaSeparated, SizeFormatter};

assert_eq!(
    format!("{:.2}B", SizeFormatter::<u16, BinaryPrefixes, CommaSeparated>::from(65_535u16)),
    "63,99KiB".to_string()
);

Although this crate was mainly intended for data sizes, it can also be used for other units.

It is also possible to implement the PrefixType trait to make your own prefix system.

extern crate generic_array;
extern crate size_format;

use size_format::{PointSeparated, PrefixType, SizeFormatter};
use generic_array::{typenum::U3, GenericArray};

struct Millimeter;

impl PrefixType for Millimeter {
    type N = U3;

    const PREFIX_SIZE: u32 = 1000;

    fn prefixes() -> GenericArray<&'static str, Self::N> {
        ["m", "", "k"].into()
    }
}

assert_eq!(
    format!("{}m", SizeFormatter::<u32, Millimeter, PointSeparated>::new(1)),
    "1mm".to_string()
);
assert_eq!(
    format!("{}m", SizeFormatter::<u32, Millimeter, PointSeparated>::new(1_000)),
    "1.0m".to_string()
);
assert_eq!(
    format!("{}m", SizeFormatter::<u32, Millimeter, PointSeparated>::new(1_000_000)),
    "1.0km".to_string()
);
assert_eq!(
    format!("{}m", SizeFormatter::<u64, Millimeter, PointSeparated>::new(10_000_000_000)),
    "10000.0km".to_string()
);

Structs

BinaryPrefixes	Represents the prefixes used for display file sizes using powers of 1024.
CommaSeparated	Represents a comma separation scheme for numbers (',').
PointSeparated	Represents a point or dot separation scheme for numbers ('.').
SIPrefixes	Represents the prefixes used in the SI system of measurements.
SizeFormatter	Represents a size that can be formatted.

Traits

DecimalSeparator	A trait for marker types that represent decimal separators.
PrefixType	Abstracts over the types of prefixes possible.

Type Definitions

SizeFormatterBinary	Implements Display to format the contained byte size using binary prefixes.
SizeFormatterSI	Implements Display to format the contained byte size using SI prefixes.