internal_tricks.rs

use crate::ffi::{self, Py_ssize_t, PY_SSIZE_T_MAX};

macro_rules! pyo3_exception {
    ($doc: expr, $name: ident, $base: ty) => {
        #[doc = $doc]
        #[repr(transparent)]
        #[allow(non_camel_case_types)]
        pub struct $name($crate::PyAny);

        $crate::impl_exception_boilerplate!($name);

        $crate::create_exception_type_object!(pyo3_runtime, $name, $base, Some($doc));
    };
}

/// Convert an usize index into a Py_ssize_t index, clamping overflow to
/// PY_SSIZE_T_MAX.
pub(crate) fn get_ssize_index(index: usize) -> Py_ssize_t {
    index.min(PY_SSIZE_T_MAX as usize) as Py_ssize_t
}

// TODO: use ptr::from_ref on MSRV 1.76
#[inline]
pub(crate) const fn ptr_from_ref<T>(t: &T) -> *const T {
    t as *const T
}

// TODO: use ptr::from_mut on MSRV 1.76
#[inline]
pub(crate) fn ptr_from_mut<T>(t: &mut T) -> *mut T {
    t as *mut T
}

// TODO: use ptr::fn_addr_eq on MSRV 1.85
pub(crate) fn clear_eq(f: Option<ffi::inquiry>, g: ffi::inquiry) -> bool {
    #[cfg(fn_ptr_eq)]
    {
        let Some(f) = f else { return false };
        std::ptr::fn_addr_eq(f, g)
    }

    #[cfg(not(fn_ptr_eq))]
    {
        f == Some(g)
    }
}

// TODO: use ptr::fn_addr_eq on MSRV 1.85
pub(crate) fn traverse_eq(f: Option<ffi::traverseproc>, g: ffi::traverseproc) -> bool {
    #[cfg(fn_ptr_eq)]
    {
        let Some(f) = f else { return false };
        std::ptr::fn_addr_eq(f, g)
    }

    #[cfg(not(fn_ptr_eq))]
    {
        f == Some(g)
    }
}