musli-zerocopy 0.0.59

use core::fmt;

use crate::ZeroCopy;

/// The default [`TargetSize`] to use.
pub(crate) type DefaultTargetSize = u32;

#[cfg(not(any(
    target_pointer_width = "32",
    target_pointer_width = "64",
    target_pointer_width = "128"
)))]
compile_error!("musli-zerocopy is only supported on 32, 64, or 128-bit platforms");

/// Trait which defines the size of a pointer.
pub trait TargetSize: 'static + Sized + ZeroCopy + fmt::Display + Copy {
    /// The default zero pointer.
    const ZERO: Self;
    /// The max size of a pointer.
    const MAX: Self;

    /// Convert a usize to a pointer.
    fn from_usize(offset: usize) -> Option<Self>;

    /// Convert the pointer to a usize.
    fn as_usize(self) -> usize;

    /// Test if the value is zero.
    fn is_zero(self) -> bool;
}

impl TargetSize for u32 {
    const ZERO: Self = 0;
    const MAX: Self = u32::MAX;

    fn from_usize(offset: usize) -> Option<Self> {
        if offset > u32::MAX as usize {
            None
        } else {
            Some(offset as u32)
        }
    }

    fn as_usize(self) -> usize {
        self as usize
    }

    fn is_zero(self) -> bool {
        self == 0
    }
}

impl TargetSize for usize {
    const ZERO: Self = 0;
    const MAX: Self = usize::MAX;

    fn from_usize(offset: usize) -> Option<Self> {
        Some(offset)
    }

    fn as_usize(self) -> usize {
        self
    }

    fn is_zero(self) -> bool {
        self == 0
    }
}