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methods.rs
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methods.rs
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// Copyright (c) 2017-present PyO3 Project and Contributors
use crate::{ffi, PyObject, Python};
use std::ffi::{CStr, CString};
use std::fmt;
use std::os::raw::c_int;
/// `PyMethodDefType` represents different types of Python callable objects.
/// It is used by the `#[pymethods]` and `#[pyproto]` annotations.
#[derive(Debug)]
pub enum PyMethodDefType {
/// Represents class method
Class(PyMethodDef),
/// Represents static method
Static(PyMethodDef),
/// Represents normal method
Method(PyMethodDef),
/// Represents class attribute, used by `#[attribute]`
ClassAttribute(PyClassAttributeDef),
/// Represents getter descriptor, used by `#[getter]`
Getter(PyGetterDef),
/// Represents setter descriptor, used by `#[setter]`
Setter(PySetterDef),
}
#[derive(Copy, Clone, Debug)]
pub enum PyMethodType {
PyCFunction(PyCFunction),
PyCFunctionWithKeywords(PyCFunctionWithKeywords),
}
// These two newtype structs serve no purpose other than wrapping the raw ffi types (which are
// function pointers) - because function pointers aren't allowed in const fn, but types wrapping
// them are!
#[derive(Clone, Copy, Debug)]
pub struct PyCFunction(pub ffi::PyCFunction);
#[derive(Clone, Copy, Debug)]
pub struct PyCFunctionWithKeywords(pub ffi::PyCFunctionWithKeywords);
// TODO: it would be nice to use CStr in these types, but then the constructors can't be const fn
// until `CStr::from_bytes_with_nul_unchecked` is const fn.
#[derive(Clone, Debug)]
pub struct PyMethodDef {
pub(crate) ml_name: &'static str,
pub(crate) ml_meth: PyMethodType,
pub(crate) ml_flags: c_int,
pub(crate) ml_doc: &'static str,
}
#[derive(Copy, Clone)]
pub struct PyClassAttributeDef {
pub(crate) name: &'static CStr,
pub(crate) meth: for<'p> fn(Python<'p>) -> PyObject,
}
#[derive(Clone, Debug)]
pub struct PyGetterDef {
pub(crate) name: &'static CStr,
pub(crate) meth: ffi::getter,
doc: &'static CStr,
}
#[derive(Clone, Debug)]
pub struct PySetterDef {
pub(crate) name: &'static CStr,
pub(crate) meth: ffi::setter,
doc: &'static CStr,
}
unsafe impl Sync for PyMethodDef {}
unsafe impl Sync for PyGetterDef {}
unsafe impl Sync for PySetterDef {}
impl PyMethodDef {
/// Define a function with no `*args` and `**kwargs`.
pub const fn cfunction(name: &'static str, cfunction: PyCFunction, doc: &'static str) -> Self {
Self {
ml_name: name,
ml_meth: PyMethodType::PyCFunction(cfunction),
ml_flags: ffi::METH_NOARGS,
ml_doc: doc,
}
}
/// Define a function that can take `*args` and `**kwargs`.
pub const fn cfunction_with_keywords(
name: &'static str,
cfunction: PyCFunctionWithKeywords,
flags: c_int,
doc: &'static str,
) -> Self {
Self {
ml_name: name,
ml_meth: PyMethodType::PyCFunctionWithKeywords(cfunction),
ml_flags: flags | ffi::METH_VARARGS | ffi::METH_KEYWORDS,
ml_doc: doc,
}
}
/// Convert `PyMethodDef` to Python method definition struct `ffi::PyMethodDef`
pub fn as_method_def(&self) -> Result<ffi::PyMethodDef, NulByteInString> {
let meth = match self.ml_meth {
PyMethodType::PyCFunction(meth) => meth.0,
PyMethodType::PyCFunctionWithKeywords(meth) => unsafe { std::mem::transmute(meth.0) },
};
Ok(ffi::PyMethodDef {
ml_name: get_name(self.ml_name)?.as_ptr(),
ml_meth: Some(meth),
ml_flags: self.ml_flags,
ml_doc: get_doc(self.ml_doc)?.as_ptr(),
})
}
}
impl PyClassAttributeDef {
/// Define a class attribute.
pub fn new(name: &'static str, meth: for<'p> fn(Python<'p>) -> PyObject) -> Self {
Self {
name: get_name(name).unwrap(),
meth,
}
}
}
// Manual implementation because `Python<'_>` does not implement `Debug` and
// trait bounds on `fn` compiler-generated derive impls are too restrictive.
impl fmt::Debug for PyClassAttributeDef {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("PyClassAttributeDef")
.field("name", &self.name)
.finish()
}
}
impl PyGetterDef {
/// Define a getter.
pub fn new(name: &'static str, getter: ffi::getter, doc: &'static str) -> Self {
Self {
name: get_name(name).unwrap(),
meth: getter,
doc: get_doc(doc).unwrap(),
}
}
/// Copy descriptor information to `ffi::PyGetSetDef`
pub fn copy_to(&self, dst: &mut ffi::PyGetSetDef) {
if dst.name.is_null() {
dst.name = self.name.as_ptr() as _;
}
if dst.doc.is_null() {
dst.doc = self.doc.as_ptr() as _;
}
dst.get = Some(self.meth);
}
}
impl PySetterDef {
/// Define a setter.
pub fn new(name: &'static str, setter: ffi::setter, doc: &'static str) -> Self {
Self {
name: get_name(name).unwrap(),
meth: setter,
doc: get_doc(doc).unwrap(),
}
}
/// Copy descriptor information to `ffi::PyGetSetDef`
pub fn copy_to(&self, dst: &mut ffi::PyGetSetDef) {
if dst.name.is_null() {
dst.name = self.name.as_ptr() as _;
}
if dst.doc.is_null() {
dst.doc = self.doc.as_ptr() as _;
}
dst.set = Some(self.meth);
}
}
/// Implementation detail. Only to be used through our proc macro code.
/// Method storage for `#[pyclass]`.
/// Allows arbitrary `#[pymethod]/#[pyproto]` blocks to submit their methods,
/// which are eventually collected by `#[pyclass]`.
#[doc(hidden)]
#[cfg(feature = "macros")]
pub trait PyMethodsInventory: inventory::Collect {
/// Create a new instance
fn new(methods: Vec<PyMethodDefType>) -> Self;
/// Returns the methods for a single `#[pymethods] impl` block
fn get(&'static self) -> &'static [PyMethodDefType];
}
/// Implemented for `#[pyclass]` in our proc macro code.
/// Indicates that the pyclass has its own method storage.
#[doc(hidden)]
#[cfg(feature = "macros")]
pub trait HasMethodsInventory {
type Methods: PyMethodsInventory;
}
#[derive(Debug)]
pub struct NulByteInString(pub(crate) &'static str);
fn get_name(name: &'static str) -> Result<&'static CStr, NulByteInString> {
extract_cstr_or_leak_cstring(name, "Function name cannot contain contain NULL byte.")
}
fn get_doc(doc: &'static str) -> Result<&'static CStr, NulByteInString> {
extract_cstr_or_leak_cstring(doc, "Document cannot contain contain NULL byte.")
}
fn extract_cstr_or_leak_cstring(
src: &'static str,
err_msg: &'static str,
) -> Result<&'static CStr, NulByteInString> {
CStr::from_bytes_with_nul(src.as_bytes())
.or_else(|_| {
CString::new(src.as_bytes()).map(|c_string| &*Box::leak(c_string.into_boxed_c_str()))
})
.map_err(|_| NulByteInString(err_msg))
}