Trait frame_support::dispatch::fmt::UpperHex

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

X formatting.

The UpperHex trait should format its output as a number in hexadecimal, with A through F in upper 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 UpperHex on a type:

use std::fmt;

struct Length(i32);

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

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

let l = Length(i32::MAX);

assert_eq!(format!("l as hex is: {l:X}"), "l as hex is: 7FFFFFFF");

assert_eq!(format!("l as hex is: {l:#010X}"), "l as hex is: 0x7FFFFFFF");

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 UpperHex for i8

impl UpperHex for i16

impl UpperHex for i32

impl UpperHex for i64

impl UpperHex for i128

impl UpperHex for isize

impl UpperHex for u8

impl UpperHex for u16

impl UpperHex for u32

impl UpperHex for u64

impl UpperHex for u128

impl UpperHex for usize

impl UpperHex for Mnemonic

impl UpperHex for Seed

impl UpperHex for Bytes

impl UpperHex for BytesMut

impl UpperHex for Signature

impl UpperHex for FrameFlags

impl UpperHex for H128

impl UpperHex for H160

impl UpperHex for H256

impl UpperHex for H384

impl UpperHex for H512

impl UpperHex for H768

impl UpperHex for primitive_types::U128

impl UpperHex for U256

impl UpperHex for U512

impl UpperHex for CreateFlags

impl UpperHex for ReadFlags

impl UpperHex for WatchFlags

impl UpperHex for Access

impl UpperHex for AtFlags

impl UpperHex for FallocateFlags

impl UpperHex for MemfdFlags

impl UpperHex for Mode

impl UpperHex for OFlags

impl UpperHex for RenameFlags

impl UpperHex for ResolveFlags

impl UpperHex for SealFlags

impl UpperHex for StatVfsMountFlags

impl UpperHex for StatxFlags

impl UpperHex for DupFlags

impl UpperHex for FdFlags

impl UpperHex for ReadWriteFlags

impl UpperHex for MapFlags

impl UpperHex for MlockAllFlags

impl UpperHex for MlockFlags

impl UpperHex for MprotectFlags

impl UpperHex for MremapFlags

impl UpperHex for MsyncFlags

impl UpperHex for ProtFlags

impl UpperHex for UserfaultfdFlags

impl UpperHex for MountFlags

impl UpperHex for MountPropagationFlags

impl UpperHex for UnmountFlags

impl UpperHex for Flags

impl UpperHex for TimerfdFlags

impl UpperHex for TimerfdTimerFlags

impl UpperHex for IFlags

impl UpperHex for XattrFlags

impl UpperHex for MembarrierQuery

impl UpperHex for PidfdFlags

impl UpperHex for PidfdGetfdFlags

impl UpperHex for FloatingPointEmulationControl

impl UpperHex for FloatingPointExceptionMode

impl UpperHex for SpeculationFeatureControl

impl UpperHex for SpeculationFeatureState

impl UpperHex for UnalignedAccessControl

impl UpperHex for WaitOptions

impl UpperHex for WaitidOptions

impl UpperHex for CapabilityFlags

impl UpperHex for CapabilitiesSecureBits

impl UpperHex for TaggedAddressMode

impl UpperHex for ThreadNameSpaceType

impl UpperHex for UnshareFlags

impl UpperHex for Capabilities

impl UpperHex for Braced

impl UpperHex for Hyphenated

impl UpperHex for Simple

impl UpperHex for Urn

impl UpperHex for Uuid

impl UpperHex for WithdrawReasons

impl<'a, I> UpperHex for Format<'a, I>

where I: Iterator, <I as Iterator>::Item: UpperHex,

impl<'a, T> UpperHex for StyledValue<'a, T>

where T: UpperHex,

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

where O: BitOrder, T: BitStore,

impl<'s, T> UpperHex for SliceVec<'s, T>

where T: UpperHex,

impl<A> UpperHex for TinyVec<A>

where A: Array, <A as Array>::Item: UpperHex,

impl<A> UpperHex for ArrayVec<A>

where A: Array, <A as Array>::Item: UpperHex,

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

where O: BitOrder, A: BitViewSized,

impl<O> UpperHex for I16<O>

where O: ByteOrder,

impl<O> UpperHex for I32<O>

where O: ByteOrder,

impl<O> UpperHex for I64<O>

where O: ByteOrder,

impl<O> UpperHex for I128<O>

where O: ByteOrder,

impl<O> UpperHex for U16<O>

where O: ByteOrder,

impl<O> UpperHex for U32<O>

where O: ByteOrder,

impl<O> UpperHex for U64<O>

where O: ByteOrder,

impl<O> UpperHex for zerocopy::byteorder::U128<O>

where O: ByteOrder,

impl<T> UpperHex for &T

where T: UpperHex + ?Sized,

impl<T> UpperHex for &mut T

where T: UpperHex + ?Sized,

impl<T> UpperHex for GenericArray<u8, T>

where T: ArrayLength<u8> + Add, <T as Add>::Output: ArrayLength<u8>,

impl<T> UpperHex for FmtBinary<T>

where T: Binary + UpperHex,

impl<T> UpperHex for FmtDisplay<T>

where T: Display + UpperHex,

impl<T> UpperHex for FmtList<T>

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

impl<T> UpperHex for FmtLowerExp<T>

where T: LowerExp + UpperHex,

impl<T> UpperHex for FmtLowerHex<T>

where T: LowerHex + UpperHex,

impl<T> UpperHex for FmtOctal<T>

where T: Octal + UpperHex,

impl<T> UpperHex for FmtPointer<T>

where T: Pointer + UpperHex,

impl<T> UpperHex for FmtUpperExp<T>

where T: UpperExp + UpperHex,

impl<T> UpperHex for FmtUpperHex<T>

where T: UpperHex,

impl<T> UpperHex for NonZero<T>

where T: ZeroablePrimitive + UpperHex,

impl<T> UpperHex for Saturating<T>

where T: UpperHex,

impl<T> UpperHex for Wrapping<T>

where T: UpperHex,

impl<T, O> UpperHex 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.