Trait scale_info::prelude::fmt::LowerHex

pub trait LowerHex {
    // Required method
    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>;
}

x formatting.

The LowerHex trait should format its output as a number in hexadecimal, with a through f in lower case.

For primitive signed integers (i8 to i128, and isize), negative values are formatted as the two’s complement representation.

The alternate flag, #, adds a 0x in front of the output.

For more information on formatters, see the module-level documentation.

Examples

Basic usage with i32:

let y = 42; // 42 is '2a' in hex

assert_eq!(format!("{y:x}"), "2a");
assert_eq!(format!("{y:#x}"), "0x2a");

assert_eq!(format!("{:x}", -16), "fffffff0");

Implementing LowerHex on a type:

use std::fmt;

struct Length(i32);

impl fmt::LowerHex for Length {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let val = self.0;

        fmt::LowerHex::fmt(&val, f) // delegate to i32's implementation
    }
}

let l = Length(9);

assert_eq!(format!("l as hex is: {l:x}"), "l as hex is: 9");

assert_eq!(format!("l as hex is: {l:#010x}"), "l as hex is: 0x00000009");

Required Methods

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

Errors

This function should return Err if, and only if, the provided Formatter returns Err. String formatting is considered an infallible operation; this function only returns a Result because writing to the underlying stream might fail and it must provide a way to propagate the fact that an error has occurred back up the stack.

Implementors

impl LowerHex for i8

impl LowerHex for i16

impl LowerHex for i32

impl LowerHex for i64

impl LowerHex for i128

impl LowerHex for isize

impl LowerHex for u8

impl LowerHex for u16

impl LowerHex for u32

impl LowerHex for u64

impl LowerHex for u128

impl LowerHex for usize

impl LowerHex for Bytes

impl LowerHex for BytesMut

impl<'a, T, O> LowerHex for Domain<'a, Const, T, O>

where O: BitOrder, T: BitStore,

impl<A, O> LowerHex for BitArray<A, O>

where O: BitOrder, A: BitViewSized,

impl<T> LowerHex for &T

where T: LowerHex + ?Sized,

impl<T> LowerHex for &mut T

where T: LowerHex + ?Sized,

impl<T> LowerHex for FmtBinary<T>

where T: Binary + LowerHex,

impl<T> LowerHex for FmtDisplay<T>

where T: Display + LowerHex,

impl<T> LowerHex for FmtList<T>

where &'a T: for<'a> IntoIterator, <&'a T as IntoIterator>::Item: for<'a> LowerHex,

impl<T> LowerHex for FmtLowerExp<T>

where T: LowerExp + LowerHex,

impl<T> LowerHex for FmtLowerHex<T>

where T: LowerHex,

impl<T> LowerHex for FmtOctal<T>

where T: Octal + LowerHex,

impl<T> LowerHex for FmtPointer<T>

where T: Pointer + LowerHex,

impl<T> LowerHex for FmtUpperExp<T>

where T: UpperExp + LowerHex,

impl<T> LowerHex for FmtUpperHex<T>

where T: UpperHex + LowerHex,

impl<T> LowerHex for NonZero<T>

where T: ZeroablePrimitive + LowerHex,

impl<T> LowerHex for Saturating<T>

where T: LowerHex,

impl<T> LowerHex for Wrapping<T>

where T: LowerHex,

impl<T, O> LowerHex for BitBox<T, O>

where O: BitOrder, T: BitStore,

impl<T, O> LowerHex for BitSlice<T, O>

where T: BitStore, O: BitOrder,

Bit-Slice Rendering

This implementation prints the contents of a &BitSlice in one of binary, octal, or hexadecimal. It is important to note that this does not render the raw underlying memory! They render the semantically-ordered contents of the bit-slice as numerals. This distinction matters if you use type parameters that differ from those presumed by your debugger (which is usually <u8, Msb0>).

The output separates the T elements as individual list items, and renders each element as a base- 2, 8, or 16 numeric string. When walking an element, the bits traversed by the bit-slice are considered to be stored in most-significant-bit-first ordering. This means that index [0] is the high bit of the left-most digit, and index [n] is the low bit of the right-most digit, in a given printed word.

In order to render according to expectations of the Arabic numeral system, an element being transcribed is chunked into digits from the least-significant end of its rendered form. This is most noticeable in octal, which will always have a smaller ceiling on the left-most digit in a printed word, while the right-most digit in that word is able to use the full 0 ..= 7 numeral range.

Examples

use bitvec::prelude::*;

let data = [
  0b000000_10u8,
// digits print LTR
  0b10_001_101,
// significance is computed RTL
  0b01_000000,
];
let bits = &data.view_bits::<Msb0>()[6 .. 18];

assert_eq!(format!("{:b}", bits), "[10, 10001101, 01]");
assert_eq!(format!("{:o}", bits), "[2, 215, 1]");
assert_eq!(format!("{:X}", bits), "[2, 8D, 1]");

The {:#} format modifier causes the standard 0b, 0o, or 0x prefix to be applied to each printed word. The other format specifiers are not interpreted by this implementation, and apply to the entire rendered text, not to individual words.

impl<T, O> LowerHex for BitVec<T, O>

where O: BitOrder, T: BitStore,