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//! `PyClass` and related traits.
use crate::{ffi, impl_::pyclass::PyClassImpl, PyTypeInfo};
use std::{cmp::Ordering, os::raw::c_int};
mod create_type_object;
mod gc;
pub(crate) use self::create_type_object::{create_type_object, PyClassTypeObject};
pub use self::gc::{PyTraverseError, PyVisit};
/// Types that can be used as Python classes.
///
/// The `#[pyclass]` attribute implements this trait for your Rust struct -
/// you shouldn't implement this trait directly.
pub trait PyClass: PyTypeInfo + PyClassImpl {
/// Whether the pyclass is frozen.
///
/// This can be enabled via `#[pyclass(frozen)]`.
type Frozen: Frozen;
}
/// Operators for the `__richcmp__` method
#[derive(Debug, Clone, Copy)]
pub enum CompareOp {
/// The *less than* operator.
Lt = ffi::Py_LT as isize,
/// The *less than or equal to* operator.
Le = ffi::Py_LE as isize,
/// The equality operator.
Eq = ffi::Py_EQ as isize,
/// The *not equal to* operator.
Ne = ffi::Py_NE as isize,
/// The *greater than* operator.
Gt = ffi::Py_GT as isize,
/// The *greater than or equal to* operator.
Ge = ffi::Py_GE as isize,
}
impl CompareOp {
/// Conversion from the C enum.
pub fn from_raw(op: c_int) -> Option<Self> {
match op {
ffi::Py_LT => Some(CompareOp::Lt),
ffi::Py_LE => Some(CompareOp::Le),
ffi::Py_EQ => Some(CompareOp::Eq),
ffi::Py_NE => Some(CompareOp::Ne),
ffi::Py_GT => Some(CompareOp::Gt),
ffi::Py_GE => Some(CompareOp::Ge),
_ => None,
}
}
/// Returns if a Rust [`std::cmp::Ordering`] matches this ordering query.
///
/// Usage example:
///
/// ```rust
/// # use pyo3::prelude::*;
/// # use pyo3::class::basic::CompareOp;
///
/// #[pyclass]
/// struct Size {
/// size: usize,
/// }
///
/// #[pymethods]
/// impl Size {
/// fn __richcmp__(&self, other: &Size, op: CompareOp) -> bool {
/// op.matches(self.size.cmp(&other.size))
/// }
/// }
/// ```
pub fn matches(&self, result: Ordering) -> bool {
match self {
CompareOp::Eq => result == Ordering::Equal,
CompareOp::Ne => result != Ordering::Equal,
CompareOp::Lt => result == Ordering::Less,
CompareOp::Le => result != Ordering::Greater,
CompareOp::Gt => result == Ordering::Greater,
CompareOp::Ge => result != Ordering::Less,
}
}
}
/// A workaround for [associated const equality](https://github.com/rust-lang/rust/issues/92827).
///
/// This serves to have True / False values in the [`PyClass`] trait's `Frozen` type.
#[doc(hidden)]
pub mod boolean_struct {
pub(crate) mod private {
use super::*;
/// A way to "seal" the boolean traits.
pub trait Boolean {
const VALUE: bool;
}
impl Boolean for True {
const VALUE: bool = true;
}
impl Boolean for False {
const VALUE: bool = false;
}
}
pub struct True(());
pub struct False(());
}
/// A trait which is used to describe whether a `#[pyclass]` is frozen.
#[doc(hidden)]
pub trait Frozen: boolean_struct::private::Boolean {}
impl Frozen for boolean_struct::True {}
impl Frozen for boolean_struct::False {}
mod tests {
#[test]
fn test_compare_op_matches() {
use super::CompareOp;
use std::cmp::Ordering;
assert!(CompareOp::Eq.matches(Ordering::Equal));
assert!(CompareOp::Ne.matches(Ordering::Less));
assert!(CompareOp::Ge.matches(Ordering::Greater));
assert!(CompareOp::Gt.matches(Ordering::Greater));
assert!(CompareOp::Le.matches(Ordering::Equal));
assert!(CompareOp::Lt.matches(Ordering::Less));
}
}