pyo3_macros_backend/
method.rs

1use std::borrow::Cow;
2use std::ffi::CString;
3use std::fmt::Display;
4
5use proc_macro2::{Span, TokenStream};
6use quote::{format_ident, quote, quote_spanned, ToTokens};
7use syn::{ext::IdentExt, spanned::Spanned, Ident, Result};
8
9use crate::pyfunction::{PyFunctionWarning, WarningFactory};
10use crate::pyversions::is_abi3_before;
11use crate::utils::{expr_to_python, Ctx, LitCStr};
12use crate::{
13    attributes::{FromPyWithAttribute, TextSignatureAttribute, TextSignatureAttributeValue},
14    params::{impl_arg_params, Holders},
15    pyfunction::{
16        FunctionSignature, PyFunctionArgPyO3Attributes, PyFunctionOptions, SignatureAttribute,
17    },
18    quotes,
19    utils::{self, PythonDoc},
20};
21
22#[derive(Clone, Debug)]
23pub struct RegularArg<'a> {
24    pub name: Cow<'a, syn::Ident>,
25    pub ty: &'a syn::Type,
26    pub from_py_with: Option<FromPyWithAttribute>,
27    pub default_value: Option<syn::Expr>,
28    pub option_wrapped_type: Option<&'a syn::Type>,
29    #[cfg(feature = "experimental-inspect")]
30    pub annotation: Option<String>,
31}
32
33impl RegularArg<'_> {
34    pub fn default_value(&self) -> String {
35        if let Self {
36            default_value: Some(arg_default),
37            ..
38        } = self
39        {
40            expr_to_python(arg_default)
41        } else if let RegularArg {
42            option_wrapped_type: Some(..),
43            ..
44        } = self
45        {
46            // functions without a `#[pyo3(signature = (...))]` option
47            // will treat trailing `Option<T>` arguments as having a default of `None`
48            "None".to_string()
49        } else {
50            "...".to_string()
51        }
52    }
53}
54
55/// Pythons *args argument
56#[derive(Clone, Debug)]
57pub struct VarargsArg<'a> {
58    pub name: Cow<'a, syn::Ident>,
59    pub ty: &'a syn::Type,
60    #[cfg(feature = "experimental-inspect")]
61    pub annotation: Option<String>,
62}
63
64/// Pythons **kwarg argument
65#[derive(Clone, Debug)]
66pub struct KwargsArg<'a> {
67    pub name: Cow<'a, syn::Ident>,
68    pub ty: &'a syn::Type,
69    #[cfg(feature = "experimental-inspect")]
70    pub annotation: Option<String>,
71}
72
73#[derive(Clone, Debug)]
74pub struct CancelHandleArg<'a> {
75    pub name: &'a syn::Ident,
76    pub ty: &'a syn::Type,
77}
78
79#[derive(Clone, Debug)]
80pub struct PyArg<'a> {
81    pub name: &'a syn::Ident,
82    pub ty: &'a syn::Type,
83}
84
85#[allow(clippy::large_enum_variant)] // See #5039
86#[derive(Clone, Debug)]
87pub enum FnArg<'a> {
88    Regular(RegularArg<'a>),
89    VarArgs(VarargsArg<'a>),
90    KwArgs(KwargsArg<'a>),
91    Py(PyArg<'a>),
92    CancelHandle(CancelHandleArg<'a>),
93}
94
95impl<'a> FnArg<'a> {
96    pub fn name(&self) -> &syn::Ident {
97        match self {
98            FnArg::Regular(RegularArg { name, .. }) => name,
99            FnArg::VarArgs(VarargsArg { name, .. }) => name,
100            FnArg::KwArgs(KwargsArg { name, .. }) => name,
101            FnArg::Py(PyArg { name, .. }) => name,
102            FnArg::CancelHandle(CancelHandleArg { name, .. }) => name,
103        }
104    }
105
106    pub fn ty(&self) -> &'a syn::Type {
107        match self {
108            FnArg::Regular(RegularArg { ty, .. }) => ty,
109            FnArg::VarArgs(VarargsArg { ty, .. }) => ty,
110            FnArg::KwArgs(KwargsArg { ty, .. }) => ty,
111            FnArg::Py(PyArg { ty, .. }) => ty,
112            FnArg::CancelHandle(CancelHandleArg { ty, .. }) => ty,
113        }
114    }
115
116    #[allow(clippy::wrong_self_convention)]
117    pub fn from_py_with(&self) -> Option<&FromPyWithAttribute> {
118        if let FnArg::Regular(RegularArg { from_py_with, .. }) = self {
119            from_py_with.as_ref()
120        } else {
121            None
122        }
123    }
124
125    pub fn to_varargs_mut(&mut self) -> Result<&mut Self> {
126        if let Self::Regular(RegularArg {
127            name,
128            ty,
129            option_wrapped_type: None,
130            #[cfg(feature = "experimental-inspect")]
131            annotation,
132            ..
133        }) = self
134        {
135            *self = Self::VarArgs(VarargsArg {
136                name: name.clone(),
137                ty,
138                #[cfg(feature = "experimental-inspect")]
139                annotation: annotation.clone(),
140            });
141            Ok(self)
142        } else {
143            bail_spanned!(self.name().span() => "args cannot be optional")
144        }
145    }
146
147    pub fn to_kwargs_mut(&mut self) -> Result<&mut Self> {
148        if let Self::Regular(RegularArg {
149            name,
150            ty,
151            option_wrapped_type: Some(..),
152            #[cfg(feature = "experimental-inspect")]
153            annotation,
154            ..
155        }) = self
156        {
157            *self = Self::KwArgs(KwargsArg {
158                name: name.clone(),
159                ty,
160                #[cfg(feature = "experimental-inspect")]
161                annotation: annotation.clone(),
162            });
163            Ok(self)
164        } else {
165            bail_spanned!(self.name().span() => "kwargs must be Option<_>")
166        }
167    }
168
169    /// Transforms a rust fn arg parsed with syn into a method::FnArg
170    pub fn parse(arg: &'a mut syn::FnArg) -> Result<Self> {
171        match arg {
172            syn::FnArg::Receiver(recv) => {
173                bail_spanned!(recv.span() => "unexpected receiver")
174            } // checked in parse_fn_type
175            syn::FnArg::Typed(cap) => {
176                if let syn::Type::ImplTrait(_) = &*cap.ty {
177                    bail_spanned!(cap.ty.span() => IMPL_TRAIT_ERR);
178                }
179
180                let PyFunctionArgPyO3Attributes {
181                    from_py_with,
182                    cancel_handle,
183                } = PyFunctionArgPyO3Attributes::from_attrs(&mut cap.attrs)?;
184                let ident = match &*cap.pat {
185                    syn::Pat::Ident(syn::PatIdent { ident, .. }) => ident,
186                    other => return Err(handle_argument_error(other)),
187                };
188
189                if utils::is_python(&cap.ty) {
190                    return Ok(Self::Py(PyArg {
191                        name: ident,
192                        ty: &cap.ty,
193                    }));
194                }
195
196                if cancel_handle.is_some() {
197                    // `PyFunctionArgPyO3Attributes::from_attrs` validates that
198                    // only compatible attributes are specified, either
199                    // `cancel_handle` or `from_py_with`, dublicates and any
200                    // combination of the two are already rejected.
201                    return Ok(Self::CancelHandle(CancelHandleArg {
202                        name: ident,
203                        ty: &cap.ty,
204                    }));
205                }
206
207                Ok(Self::Regular(RegularArg {
208                    name: Cow::Borrowed(ident),
209                    ty: &cap.ty,
210                    from_py_with,
211                    default_value: None,
212                    option_wrapped_type: utils::option_type_argument(&cap.ty),
213                    #[cfg(feature = "experimental-inspect")]
214                    annotation: None,
215                }))
216            }
217        }
218    }
219
220    pub fn default_value(&self) -> String {
221        if let Self::Regular(args) = self {
222            args.default_value()
223        } else {
224            "...".to_string()
225        }
226    }
227}
228
229fn handle_argument_error(pat: &syn::Pat) -> syn::Error {
230    let span = pat.span();
231    let msg = match pat {
232        syn::Pat::Wild(_) => "wildcard argument names are not supported",
233        syn::Pat::Struct(_)
234        | syn::Pat::Tuple(_)
235        | syn::Pat::TupleStruct(_)
236        | syn::Pat::Slice(_) => "destructuring in arguments is not supported",
237        _ => "unsupported argument",
238    };
239    syn::Error::new(span, msg)
240}
241
242/// Represents what kind of a function a pyfunction or pymethod is
243#[derive(Clone, Debug)]
244pub enum FnType {
245    /// Represents a pymethod annotated with `#[getter]`
246    Getter(SelfType),
247    /// Represents a pymethod annotated with `#[setter]`
248    Setter(SelfType),
249    /// Represents a regular pymethod
250    Fn(SelfType),
251    /// Represents a pymethod annotated with `#[new]`, i.e. the `__new__` dunder.
252    FnNew,
253    /// Represents a pymethod annotated with both `#[new]` and `#[classmethod]` (in either order)
254    FnNewClass(Span),
255    /// Represents a pymethod annotated with `#[classmethod]`, like a `@classmethod`
256    FnClass(Span),
257    /// Represents a pyfunction or a pymethod annotated with `#[staticmethod]`, like a `@staticmethod`
258    FnStatic,
259    /// Represents a pyfunction annotated with `#[pyo3(pass_module)]
260    FnModule(Span),
261    /// Represents a pymethod or associated constant annotated with `#[classattr]`
262    ClassAttribute,
263}
264
265impl FnType {
266    pub fn skip_first_rust_argument_in_python_signature(&self) -> bool {
267        match self {
268            FnType::Getter(_)
269            | FnType::Setter(_)
270            | FnType::Fn(_)
271            | FnType::FnClass(_)
272            | FnType::FnNewClass(_)
273            | FnType::FnModule(_) => true,
274            FnType::FnNew | FnType::FnStatic | FnType::ClassAttribute => false,
275        }
276    }
277
278    pub fn signature_attribute_allowed(&self) -> bool {
279        match self {
280            FnType::Fn(_)
281            | FnType::FnNew
282            | FnType::FnStatic
283            | FnType::FnClass(_)
284            | FnType::FnNewClass(_)
285            | FnType::FnModule(_) => true,
286            // Setter, Getter and ClassAttribute all have fixed signatures (either take 0 or 1
287            // arguments) so cannot have a `signature = (...)` attribute.
288            FnType::Getter(_) | FnType::Setter(_) | FnType::ClassAttribute => false,
289        }
290    }
291
292    pub fn self_arg(
293        &self,
294        cls: Option<&syn::Type>,
295        error_mode: ExtractErrorMode,
296        holders: &mut Holders,
297        ctx: &Ctx,
298    ) -> Option<TokenStream> {
299        let Ctx { pyo3_path, .. } = ctx;
300        match self {
301            FnType::Getter(st) | FnType::Setter(st) | FnType::Fn(st) => {
302                let mut receiver = st.receiver(
303                    cls.expect("no class given for Fn with a \"self\" receiver"),
304                    error_mode,
305                    holders,
306                    ctx,
307                );
308                syn::Token![,](Span::call_site()).to_tokens(&mut receiver);
309                Some(receiver)
310            }
311            FnType::FnClass(span) | FnType::FnNewClass(span) => {
312                let py = syn::Ident::new("py", Span::call_site());
313                let slf: Ident = syn::Ident::new("_slf", Span::call_site());
314                let pyo3_path = pyo3_path.to_tokens_spanned(*span);
315                let ret = quote_spanned! { *span =>
316                    #[allow(clippy::useless_conversion)]
317                    ::std::convert::Into::into(
318                        #pyo3_path::impl_::pymethods::BoundRef::ref_from_ptr(#py, &*(&#slf as *const _ as *const *mut _))
319                            .downcast_unchecked::<#pyo3_path::types::PyType>()
320                    )
321                };
322                Some(quote! { unsafe { #ret }, })
323            }
324            FnType::FnModule(span) => {
325                let py = syn::Ident::new("py", Span::call_site());
326                let slf: Ident = syn::Ident::new("_slf", Span::call_site());
327                let pyo3_path = pyo3_path.to_tokens_spanned(*span);
328                let ret = quote_spanned! { *span =>
329                    #[allow(clippy::useless_conversion)]
330                    ::std::convert::Into::into(
331                        #pyo3_path::impl_::pymethods::BoundRef::ref_from_ptr(#py, &*(&#slf as *const _ as *const *mut _))
332                            .downcast_unchecked::<#pyo3_path::types::PyModule>()
333                    )
334                };
335                Some(quote! { unsafe { #ret }, })
336            }
337            FnType::FnNew | FnType::FnStatic | FnType::ClassAttribute => None,
338        }
339    }
340}
341
342#[derive(Clone, Debug)]
343pub enum SelfType {
344    Receiver { mutable: bool, span: Span },
345    TryFromBoundRef(Span),
346}
347
348#[derive(Clone, Copy)]
349pub enum ExtractErrorMode {
350    NotImplemented,
351    Raise,
352}
353
354impl ExtractErrorMode {
355    pub fn handle_error(self, extract: TokenStream, ctx: &Ctx) -> TokenStream {
356        let Ctx { pyo3_path, .. } = ctx;
357        match self {
358            ExtractErrorMode::Raise => quote! { #extract? },
359            ExtractErrorMode::NotImplemented => quote! {
360                match #extract {
361                    ::std::result::Result::Ok(value) => value,
362                    ::std::result::Result::Err(_) => { return #pyo3_path::impl_::callback::convert(py, py.NotImplemented()); },
363                }
364            },
365        }
366    }
367}
368
369impl SelfType {
370    pub fn receiver(
371        &self,
372        cls: &syn::Type,
373        error_mode: ExtractErrorMode,
374        holders: &mut Holders,
375        ctx: &Ctx,
376    ) -> TokenStream {
377        // Due to use of quote_spanned in this function, need to bind these idents to the
378        // main macro callsite.
379        let py = syn::Ident::new("py", Span::call_site());
380        let slf = syn::Ident::new("_slf", Span::call_site());
381        let Ctx { pyo3_path, .. } = ctx;
382        let bound_ref =
383            quote! { unsafe { #pyo3_path::impl_::pymethods::BoundRef::ref_from_ptr(#py, &#slf) } };
384        match self {
385            SelfType::Receiver { span, mutable } => {
386                let method = if *mutable {
387                    syn::Ident::new("extract_pyclass_ref_mut", *span)
388                } else {
389                    syn::Ident::new("extract_pyclass_ref", *span)
390                };
391                let holder = holders.push_holder(*span);
392                let pyo3_path = pyo3_path.to_tokens_spanned(*span);
393                error_mode.handle_error(
394                    quote_spanned! { *span =>
395                        #pyo3_path::impl_::extract_argument::#method::<#cls>(
396                            #bound_ref.0,
397                            &mut #holder,
398                        )
399                    },
400                    ctx,
401                )
402            }
403            SelfType::TryFromBoundRef(span) => {
404                let pyo3_path = pyo3_path.to_tokens_spanned(*span);
405                error_mode.handle_error(
406                    quote_spanned! { *span =>
407                        #bound_ref.downcast::<#cls>()
408                            .map_err(::std::convert::Into::<#pyo3_path::PyErr>::into)
409                            .and_then(
410                                #[allow(unknown_lints, clippy::unnecessary_fallible_conversions)]  // In case slf is Py<Self> (unknown_lints can be removed when MSRV is 1.75+)
411                                |bound| ::std::convert::TryFrom::try_from(bound).map_err(::std::convert::Into::into)
412                            )
413
414                    },
415                    ctx
416                )
417            }
418        }
419    }
420}
421
422/// Determines which CPython calling convention a given FnSpec uses.
423#[derive(Clone, Debug)]
424pub enum CallingConvention {
425    Noargs,   // METH_NOARGS
426    Varargs,  // METH_VARARGS | METH_KEYWORDS
427    Fastcall, // METH_FASTCALL | METH_KEYWORDS (not compatible with `abi3` feature before 3.10)
428    TpNew,    // special convention for tp_new
429}
430
431impl CallingConvention {
432    /// Determine default calling convention from an argument signature.
433    ///
434    /// Different other slots (tp_call, tp_new) can have other requirements
435    /// and are set manually (see `parse_fn_type` below).
436    pub fn from_signature(signature: &FunctionSignature<'_>) -> Self {
437        if signature.python_signature.has_no_args() {
438            Self::Noargs
439        } else if signature.python_signature.kwargs.is_none() && !is_abi3_before(3, 10) {
440            // For functions that accept **kwargs, always prefer varargs for now based on
441            // historical performance testing.
442            //
443            // FASTCALL not compatible with `abi3` before 3.10
444            Self::Fastcall
445        } else {
446            Self::Varargs
447        }
448    }
449}
450
451#[derive(Clone)]
452pub struct FnSpec<'a> {
453    pub tp: FnType,
454    // Rust function name
455    pub name: &'a syn::Ident,
456    // Wrapped python name. This should not have any leading r#.
457    // r# can be removed by syn::ext::IdentExt::unraw()
458    pub python_name: syn::Ident,
459    pub signature: FunctionSignature<'a>,
460    pub convention: CallingConvention,
461    pub text_signature: Option<TextSignatureAttribute>,
462    pub asyncness: Option<syn::Token![async]>,
463    pub unsafety: Option<syn::Token![unsafe]>,
464    pub warnings: Vec<PyFunctionWarning>,
465    #[cfg(feature = "experimental-inspect")]
466    pub output: syn::ReturnType,
467}
468
469pub fn parse_method_receiver(arg: &syn::FnArg) -> Result<SelfType> {
470    match arg {
471        syn::FnArg::Receiver(
472            recv @ syn::Receiver {
473                reference: None, ..
474            },
475        ) => {
476            bail_spanned!(recv.span() => RECEIVER_BY_VALUE_ERR);
477        }
478        syn::FnArg::Receiver(recv @ syn::Receiver { mutability, .. }) => Ok(SelfType::Receiver {
479            mutable: mutability.is_some(),
480            span: recv.span(),
481        }),
482        syn::FnArg::Typed(syn::PatType { ty, .. }) => {
483            if let syn::Type::ImplTrait(_) = &**ty {
484                bail_spanned!(ty.span() => IMPL_TRAIT_ERR);
485            }
486            Ok(SelfType::TryFromBoundRef(ty.span()))
487        }
488    }
489}
490
491impl<'a> FnSpec<'a> {
492    /// Parser function signature and function attributes
493    pub fn parse(
494        // Signature is mutable to remove the `Python` argument.
495        sig: &'a mut syn::Signature,
496        meth_attrs: &mut Vec<syn::Attribute>,
497        options: PyFunctionOptions,
498    ) -> Result<FnSpec<'a>> {
499        let PyFunctionOptions {
500            text_signature,
501            name,
502            signature,
503            warnings,
504            ..
505        } = options;
506
507        let mut python_name = name.map(|name| name.value.0);
508
509        let fn_type = Self::parse_fn_type(sig, meth_attrs, &mut python_name)?;
510        ensure_signatures_on_valid_method(&fn_type, signature.as_ref(), text_signature.as_ref())?;
511
512        let name = &sig.ident;
513        let python_name = python_name.as_ref().unwrap_or(name).unraw();
514
515        let arguments: Vec<_> = sig
516            .inputs
517            .iter_mut()
518            .skip(if fn_type.skip_first_rust_argument_in_python_signature() {
519                1
520            } else {
521                0
522            })
523            .map(FnArg::parse)
524            .collect::<Result<_>>()?;
525
526        let signature = if let Some(signature) = signature {
527            FunctionSignature::from_arguments_and_attribute(arguments, signature)?
528        } else {
529            FunctionSignature::from_arguments(arguments)
530        };
531
532        let convention = if matches!(fn_type, FnType::FnNew | FnType::FnNewClass(_)) {
533            CallingConvention::TpNew
534        } else {
535            CallingConvention::from_signature(&signature)
536        };
537
538        Ok(FnSpec {
539            tp: fn_type,
540            name,
541            convention,
542            python_name,
543            signature,
544            text_signature,
545            asyncness: sig.asyncness,
546            unsafety: sig.unsafety,
547            warnings,
548            #[cfg(feature = "experimental-inspect")]
549            output: sig.output.clone(),
550        })
551    }
552
553    pub fn null_terminated_python_name(&self, ctx: &Ctx) -> LitCStr {
554        let name = self.python_name.to_string();
555        let name = CString::new(name).unwrap();
556        LitCStr::new(name, self.python_name.span(), ctx)
557    }
558
559    fn parse_fn_type(
560        sig: &syn::Signature,
561        meth_attrs: &mut Vec<syn::Attribute>,
562        python_name: &mut Option<syn::Ident>,
563    ) -> Result<FnType> {
564        let mut method_attributes = parse_method_attributes(meth_attrs)?;
565
566        let name = &sig.ident;
567        let parse_receiver = |msg: &'static str| {
568            let first_arg = sig
569                .inputs
570                .first()
571                .ok_or_else(|| err_spanned!(sig.span() => msg))?;
572            parse_method_receiver(first_arg)
573        };
574
575        // strip get_ or set_
576        let strip_fn_name = |prefix: &'static str| {
577            name.unraw()
578                .to_string()
579                .strip_prefix(prefix)
580                .map(|stripped| syn::Ident::new(stripped, name.span()))
581        };
582
583        let mut set_name_to_new = || {
584            if let Some(name) = &python_name {
585                bail_spanned!(name.span() => "`name` not allowed with `#[new]`");
586            }
587            *python_name = Some(syn::Ident::new("__new__", Span::call_site()));
588            Ok(())
589        };
590
591        let fn_type = match method_attributes.as_mut_slice() {
592            [] => FnType::Fn(parse_receiver(
593                "static method needs #[staticmethod] attribute",
594            )?),
595            [MethodTypeAttribute::StaticMethod(_)] => FnType::FnStatic,
596            [MethodTypeAttribute::ClassAttribute(_)] => FnType::ClassAttribute,
597            [MethodTypeAttribute::New(_)] => {
598                set_name_to_new()?;
599                FnType::FnNew
600            }
601            [MethodTypeAttribute::New(_), MethodTypeAttribute::ClassMethod(span)]
602            | [MethodTypeAttribute::ClassMethod(span), MethodTypeAttribute::New(_)] => {
603                set_name_to_new()?;
604                FnType::FnNewClass(*span)
605            }
606            [MethodTypeAttribute::ClassMethod(_)] => {
607                // Add a helpful hint if the classmethod doesn't look like a classmethod
608                let span = match sig.inputs.first() {
609                    // Don't actually bother checking the type of the first argument, the compiler
610                    // will error on incorrect type.
611                    Some(syn::FnArg::Typed(first_arg)) => first_arg.ty.span(),
612                    Some(syn::FnArg::Receiver(_)) | None => bail_spanned!(
613                        sig.paren_token.span.join() => "Expected `&Bound<PyType>` or `Py<PyType>` as the first argument to `#[classmethod]`"
614                    ),
615                };
616                FnType::FnClass(span)
617            }
618            [MethodTypeAttribute::Getter(_, name)] => {
619                if let Some(name) = name.take() {
620                    ensure_spanned!(
621                        python_name.replace(name).is_none(),
622                        python_name.span() => "`name` may only be specified once"
623                    );
624                } else if python_name.is_none() {
625                    // Strip off "get_" prefix if needed
626                    *python_name = strip_fn_name("get_");
627                }
628
629                FnType::Getter(parse_receiver("expected receiver for `#[getter]`")?)
630            }
631            [MethodTypeAttribute::Setter(_, name)] => {
632                if let Some(name) = name.take() {
633                    ensure_spanned!(
634                        python_name.replace(name).is_none(),
635                        python_name.span() => "`name` may only be specified once"
636                    );
637                } else if python_name.is_none() {
638                    // Strip off "set_" prefix if needed
639                    *python_name = strip_fn_name("set_");
640                }
641
642                FnType::Setter(parse_receiver("expected receiver for `#[setter]`")?)
643            }
644            [first, rest @ .., last] => {
645                // Join as many of the spans together as possible
646                let span = rest
647                    .iter()
648                    .fold(first.span(), |s, next| s.join(next.span()).unwrap_or(s));
649                let span = span.join(last.span()).unwrap_or(span);
650                // List all the attributes in the error message
651                let mut msg = format!("`{first}` may not be combined with");
652                let mut is_first = true;
653                for attr in &*rest {
654                    msg.push_str(&format!(" `{attr}`"));
655                    if is_first {
656                        is_first = false;
657                    } else {
658                        msg.push(',');
659                    }
660                }
661                if !rest.is_empty() {
662                    msg.push_str(" and");
663                }
664                msg.push_str(&format!(" `{last}`"));
665                bail_spanned!(span => msg)
666            }
667        };
668        Ok(fn_type)
669    }
670
671    /// Return a C wrapper function for this signature.
672    pub fn get_wrapper_function(
673        &self,
674        ident: &proc_macro2::Ident,
675        cls: Option<&syn::Type>,
676        ctx: &Ctx,
677    ) -> Result<TokenStream> {
678        let Ctx {
679            pyo3_path,
680            output_span,
681        } = ctx;
682        let mut cancel_handle_iter = self
683            .signature
684            .arguments
685            .iter()
686            .filter(|arg| matches!(arg, FnArg::CancelHandle(..)));
687        let cancel_handle = cancel_handle_iter.next();
688        if let Some(FnArg::CancelHandle(CancelHandleArg { name, .. })) = cancel_handle {
689            ensure_spanned!(self.asyncness.is_some(), name.span() => "`cancel_handle` attribute can only be used with `async fn`");
690            if let Some(FnArg::CancelHandle(CancelHandleArg { name, .. })) =
691                cancel_handle_iter.next()
692            {
693                bail_spanned!(name.span() => "`cancel_handle` may only be specified once");
694            }
695        }
696
697        let rust_call = |args: Vec<TokenStream>, holders: &mut Holders| {
698            let mut self_arg = || self.tp.self_arg(cls, ExtractErrorMode::Raise, holders, ctx);
699
700            let call = if self.asyncness.is_some() {
701                let throw_callback = if cancel_handle.is_some() {
702                    quote! { Some(__throw_callback) }
703                } else {
704                    quote! { None }
705                };
706                let python_name = &self.python_name;
707                let qualname_prefix = match cls {
708                    Some(cls) => quote!(Some(<#cls as #pyo3_path::PyTypeInfo>::NAME)),
709                    None => quote!(None),
710                };
711                let arg_names = (0..args.len())
712                    .map(|i| format_ident!("arg_{}", i))
713                    .collect::<Vec<_>>();
714                let future = match self.tp {
715                    FnType::Fn(SelfType::Receiver { mutable: false, .. }) => {
716                        quote! {{
717                            #(let #arg_names = #args;)*
718                            let __guard = unsafe { #pyo3_path::impl_::coroutine::RefGuard::<#cls>::new(&#pyo3_path::impl_::pymethods::BoundRef::ref_from_ptr(py, &_slf))? };
719                            async move { function(&__guard, #(#arg_names),*).await }
720                        }}
721                    }
722                    FnType::Fn(SelfType::Receiver { mutable: true, .. }) => {
723                        quote! {{
724                            #(let #arg_names = #args;)*
725                            let mut __guard = unsafe { #pyo3_path::impl_::coroutine::RefMutGuard::<#cls>::new(&#pyo3_path::impl_::pymethods::BoundRef::ref_from_ptr(py, &_slf))? };
726                            async move { function(&mut __guard, #(#arg_names),*).await }
727                        }}
728                    }
729                    _ => {
730                        if let Some(self_arg) = self_arg() {
731                            quote! {
732                                function(
733                                    // NB #self_arg includes a comma, so none inserted here
734                                    #self_arg
735                                    #(#args),*
736                                )
737                            }
738                        } else {
739                            quote! { function(#(#args),*) }
740                        }
741                    }
742                };
743                let mut call = quote! {{
744                    let future = #future;
745                    #pyo3_path::impl_::coroutine::new_coroutine(
746                        #pyo3_path::intern!(py, stringify!(#python_name)),
747                        #qualname_prefix,
748                        #throw_callback,
749                        async move {
750                            let fut = future.await;
751                            #pyo3_path::impl_::wrap::converter(&fut).wrap(fut)
752                        },
753                    )
754                }};
755                if cancel_handle.is_some() {
756                    call = quote! {{
757                        let __cancel_handle = #pyo3_path::coroutine::CancelHandle::new();
758                        let __throw_callback = __cancel_handle.throw_callback();
759                        #call
760                    }};
761                }
762                call
763            } else if let Some(self_arg) = self_arg() {
764                quote! {
765                    function(
766                        // NB #self_arg includes a comma, so none inserted here
767                        #self_arg
768                        #(#args),*
769                    )
770                }
771            } else {
772                quote! { function(#(#args),*) }
773            };
774
775            // We must assign the output_span to the return value of the call,
776            // but *not* of the call itself otherwise the spans get really weird
777            let ret_ident = Ident::new("ret", *output_span);
778            let ret_expr = quote! { let #ret_ident = #call; };
779            let return_conversion =
780                quotes::map_result_into_ptr(quotes::ok_wrap(ret_ident.to_token_stream(), ctx), ctx);
781            quote! {
782                {
783                    #ret_expr
784                    #return_conversion
785                }
786            }
787        };
788
789        let func_name = &self.name;
790        let rust_name = if let Some(cls) = cls {
791            quote!(#cls::#func_name)
792        } else {
793            quote!(#func_name)
794        };
795
796        let warnings = self.warnings.build_py_warning(ctx);
797
798        Ok(match self.convention {
799            CallingConvention::Noargs => {
800                let mut holders = Holders::new();
801                let args = self
802                    .signature
803                    .arguments
804                    .iter()
805                    .map(|arg| match arg {
806                        FnArg::Py(..) => quote!(py),
807                        FnArg::CancelHandle(..) => quote!(__cancel_handle),
808                        _ => unreachable!("`CallingConvention::Noargs` should not contain any arguments (reaching Python) except for `self`, which is handled below."),
809                    })
810                    .collect();
811                let call = rust_call(args, &mut holders);
812                let init_holders = holders.init_holders(ctx);
813                quote! {
814                    unsafe fn #ident<'py>(
815                        py: #pyo3_path::Python<'py>,
816                        _slf: *mut #pyo3_path::ffi::PyObject,
817                    ) -> #pyo3_path::PyResult<*mut #pyo3_path::ffi::PyObject> {
818                        let function = #rust_name; // Shadow the function name to avoid #3017
819                        #init_holders
820                        #warnings
821                        let result = #call;
822                        result
823                    }
824                }
825            }
826            CallingConvention::Fastcall => {
827                let mut holders = Holders::new();
828                let (arg_convert, args) = impl_arg_params(self, cls, true, &mut holders, ctx);
829                let call = rust_call(args, &mut holders);
830                let init_holders = holders.init_holders(ctx);
831
832                quote! {
833                    unsafe fn #ident<'py>(
834                        py: #pyo3_path::Python<'py>,
835                        _slf: *mut #pyo3_path::ffi::PyObject,
836                        _args: *const *mut #pyo3_path::ffi::PyObject,
837                        _nargs: #pyo3_path::ffi::Py_ssize_t,
838                        _kwnames: *mut #pyo3_path::ffi::PyObject
839                    ) -> #pyo3_path::PyResult<*mut #pyo3_path::ffi::PyObject> {
840                        let function = #rust_name; // Shadow the function name to avoid #3017
841                        #arg_convert
842                        #init_holders
843                        #warnings
844                        let result = #call;
845                        result
846                    }
847                }
848            }
849            CallingConvention::Varargs => {
850                let mut holders = Holders::new();
851                let (arg_convert, args) = impl_arg_params(self, cls, false, &mut holders, ctx);
852                let call = rust_call(args, &mut holders);
853                let init_holders = holders.init_holders(ctx);
854
855                quote! {
856                    unsafe fn #ident<'py>(
857                        py: #pyo3_path::Python<'py>,
858                        _slf: *mut #pyo3_path::ffi::PyObject,
859                        _args: *mut #pyo3_path::ffi::PyObject,
860                        _kwargs: *mut #pyo3_path::ffi::PyObject
861                    ) -> #pyo3_path::PyResult<*mut #pyo3_path::ffi::PyObject> {
862                        let function = #rust_name; // Shadow the function name to avoid #3017
863                        #arg_convert
864                        #init_holders
865                        #warnings
866                        let result = #call;
867                        result
868                    }
869                }
870            }
871            CallingConvention::TpNew => {
872                let mut holders = Holders::new();
873                let (arg_convert, args) = impl_arg_params(self, cls, false, &mut holders, ctx);
874                let self_arg = self
875                    .tp
876                    .self_arg(cls, ExtractErrorMode::Raise, &mut holders, ctx);
877                let call = quote_spanned! {*output_span=> #rust_name(#self_arg #(#args),*) };
878                let init_holders = holders.init_holders(ctx);
879                quote! {
880                    unsafe fn #ident(
881                        py: #pyo3_path::Python<'_>,
882                        _slf: *mut #pyo3_path::ffi::PyTypeObject,
883                        _args: *mut #pyo3_path::ffi::PyObject,
884                        _kwargs: *mut #pyo3_path::ffi::PyObject
885                    ) -> #pyo3_path::PyResult<*mut #pyo3_path::ffi::PyObject> {
886                        use #pyo3_path::impl_::callback::IntoPyCallbackOutput;
887                        let function = #rust_name; // Shadow the function name to avoid #3017
888                        #arg_convert
889                        #init_holders
890                        #warnings
891                        let result = #call;
892                        let initializer: #pyo3_path::PyClassInitializer::<#cls> = result.convert(py)?;
893                        #pyo3_path::impl_::pymethods::tp_new_impl(py, initializer, _slf)
894                    }
895                }
896            }
897        })
898    }
899
900    /// Return a `PyMethodDef` constructor for this function, matching the selected
901    /// calling convention.
902    pub fn get_methoddef(&self, wrapper: impl ToTokens, doc: &PythonDoc, ctx: &Ctx) -> TokenStream {
903        let Ctx { pyo3_path, .. } = ctx;
904        let python_name = self.null_terminated_python_name(ctx);
905        match self.convention {
906            CallingConvention::Noargs => quote! {
907                #pyo3_path::impl_::pymethods::PyMethodDef::noargs(
908                    #python_name,
909                    {
910                        unsafe extern "C" fn trampoline(
911                            _slf: *mut #pyo3_path::ffi::PyObject,
912                            _args: *mut #pyo3_path::ffi::PyObject,
913                        ) -> *mut #pyo3_path::ffi::PyObject
914                        {
915                            unsafe {
916                                #pyo3_path::impl_::trampoline::noargs(
917                                    _slf,
918                                    _args,
919                                    #wrapper
920                                )
921                            }
922                        }
923                        trampoline
924                    },
925                    #doc,
926                )
927            },
928            CallingConvention::Fastcall => quote! {
929                #pyo3_path::impl_::pymethods::PyMethodDef::fastcall_cfunction_with_keywords(
930                    #python_name,
931                    {
932                        unsafe extern "C" fn trampoline(
933                            _slf: *mut #pyo3_path::ffi::PyObject,
934                            _args: *const *mut #pyo3_path::ffi::PyObject,
935                            _nargs: #pyo3_path::ffi::Py_ssize_t,
936                            _kwnames: *mut #pyo3_path::ffi::PyObject
937                        ) -> *mut #pyo3_path::ffi::PyObject
938                        {
939                            #pyo3_path::impl_::trampoline::fastcall_with_keywords(
940                                _slf,
941                                _args,
942                                _nargs,
943                                _kwnames,
944                                #wrapper
945                            )
946                        }
947                        trampoline
948                    },
949                    #doc,
950                )
951            },
952            CallingConvention::Varargs => quote! {
953                #pyo3_path::impl_::pymethods::PyMethodDef::cfunction_with_keywords(
954                    #python_name,
955                    {
956                        unsafe extern "C" fn trampoline(
957                            _slf: *mut #pyo3_path::ffi::PyObject,
958                            _args: *mut #pyo3_path::ffi::PyObject,
959                            _kwargs: *mut #pyo3_path::ffi::PyObject,
960                        ) -> *mut #pyo3_path::ffi::PyObject
961                        {
962                            #pyo3_path::impl_::trampoline::cfunction_with_keywords(
963                                _slf,
964                                _args,
965                                _kwargs,
966                                #wrapper
967                            )
968                        }
969                        trampoline
970                    },
971                    #doc,
972                )
973            },
974            CallingConvention::TpNew => unreachable!("tp_new cannot get a methoddef"),
975        }
976    }
977
978    /// Forwards to [utils::get_doc] with the text signature of this spec.
979    pub fn get_doc(&self, attrs: &[syn::Attribute], ctx: &Ctx) -> syn::Result<PythonDoc> {
980        let text_signature = self
981            .text_signature_call_signature()
982            .map(|sig| format!("{}{}", self.python_name, sig));
983        utils::get_doc(attrs, text_signature, ctx)
984    }
985
986    /// Creates the parenthesised arguments list for `__text_signature__` snippet based on this spec's signature
987    /// and/or attributes. Prepend the callable name to make a complete `__text_signature__`.
988    pub fn text_signature_call_signature(&self) -> Option<String> {
989        let self_argument = match &self.tp {
990            // Getters / Setters / ClassAttribute are not callables on the Python side
991            FnType::Getter(_) | FnType::Setter(_) | FnType::ClassAttribute => return None,
992            FnType::Fn(_) => Some("self"),
993            FnType::FnModule(_) => Some("module"),
994            FnType::FnClass(_) | FnType::FnNewClass(_) => Some("cls"),
995            FnType::FnStatic | FnType::FnNew => None,
996        };
997
998        match self.text_signature.as_ref().map(|attr| &attr.value) {
999            Some(TextSignatureAttributeValue::Str(s)) => Some(s.value()),
1000            None => Some(self.signature.text_signature(self_argument)),
1001            Some(TextSignatureAttributeValue::Disabled(_)) => None,
1002        }
1003    }
1004}
1005
1006enum MethodTypeAttribute {
1007    New(Span),
1008    ClassMethod(Span),
1009    StaticMethod(Span),
1010    Getter(Span, Option<Ident>),
1011    Setter(Span, Option<Ident>),
1012    ClassAttribute(Span),
1013}
1014
1015impl MethodTypeAttribute {
1016    fn span(&self) -> Span {
1017        match self {
1018            MethodTypeAttribute::New(span)
1019            | MethodTypeAttribute::ClassMethod(span)
1020            | MethodTypeAttribute::StaticMethod(span)
1021            | MethodTypeAttribute::Getter(span, _)
1022            | MethodTypeAttribute::Setter(span, _)
1023            | MethodTypeAttribute::ClassAttribute(span) => *span,
1024        }
1025    }
1026
1027    /// Attempts to parse a method type attribute.
1028    ///
1029    /// If the attribute does not match one of the attribute names, returns `Ok(None)`.
1030    ///
1031    /// Otherwise will either return a parse error or the attribute.
1032    fn parse_if_matching_attribute(attr: &syn::Attribute) -> Result<Option<Self>> {
1033        fn ensure_no_arguments(meta: &syn::Meta, ident: &str) -> syn::Result<()> {
1034            match meta {
1035                syn::Meta::Path(_) => Ok(()),
1036                syn::Meta::List(l) => bail_spanned!(
1037                    l.span() => format!(
1038                        "`#[{ident}]` does not take any arguments\n= help: did you mean `#[{ident}] #[pyo3({meta})]`?",
1039                        ident = ident,
1040                        meta = l.tokens,
1041                    )
1042                ),
1043                syn::Meta::NameValue(nv) => {
1044                    bail_spanned!(nv.eq_token.span() => format!(
1045                        "`#[{}]` does not take any arguments\n= note: this was previously accepted and ignored",
1046                        ident
1047                    ))
1048                }
1049            }
1050        }
1051
1052        fn extract_name(meta: &syn::Meta, ident: &str) -> Result<Option<Ident>> {
1053            match meta {
1054                syn::Meta::Path(_) => Ok(None),
1055                syn::Meta::NameValue(nv) => bail_spanned!(
1056                    nv.eq_token.span() => format!("expected `#[{}(name)]` to set the name", ident)
1057                ),
1058                syn::Meta::List(l) => {
1059                    if let Ok(name) = l.parse_args::<syn::Ident>() {
1060                        Ok(Some(name))
1061                    } else if let Ok(name) = l.parse_args::<syn::LitStr>() {
1062                        name.parse().map(Some)
1063                    } else {
1064                        bail_spanned!(l.tokens.span() => "expected ident or string literal for property name");
1065                    }
1066                }
1067            }
1068        }
1069
1070        let meta = &attr.meta;
1071        let path = meta.path();
1072
1073        if path.is_ident("new") {
1074            ensure_no_arguments(meta, "new")?;
1075            Ok(Some(MethodTypeAttribute::New(path.span())))
1076        } else if path.is_ident("classmethod") {
1077            ensure_no_arguments(meta, "classmethod")?;
1078            Ok(Some(MethodTypeAttribute::ClassMethod(path.span())))
1079        } else if path.is_ident("staticmethod") {
1080            ensure_no_arguments(meta, "staticmethod")?;
1081            Ok(Some(MethodTypeAttribute::StaticMethod(path.span())))
1082        } else if path.is_ident("classattr") {
1083            ensure_no_arguments(meta, "classattr")?;
1084            Ok(Some(MethodTypeAttribute::ClassAttribute(path.span())))
1085        } else if path.is_ident("getter") {
1086            let name = extract_name(meta, "getter")?;
1087            Ok(Some(MethodTypeAttribute::Getter(path.span(), name)))
1088        } else if path.is_ident("setter") {
1089            let name = extract_name(meta, "setter")?;
1090            Ok(Some(MethodTypeAttribute::Setter(path.span(), name)))
1091        } else {
1092            Ok(None)
1093        }
1094    }
1095}
1096
1097impl Display for MethodTypeAttribute {
1098    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
1099        match self {
1100            MethodTypeAttribute::New(_) => "#[new]".fmt(f),
1101            MethodTypeAttribute::ClassMethod(_) => "#[classmethod]".fmt(f),
1102            MethodTypeAttribute::StaticMethod(_) => "#[staticmethod]".fmt(f),
1103            MethodTypeAttribute::Getter(_, _) => "#[getter]".fmt(f),
1104            MethodTypeAttribute::Setter(_, _) => "#[setter]".fmt(f),
1105            MethodTypeAttribute::ClassAttribute(_) => "#[classattr]".fmt(f),
1106        }
1107    }
1108}
1109
1110fn parse_method_attributes(attrs: &mut Vec<syn::Attribute>) -> Result<Vec<MethodTypeAttribute>> {
1111    let mut new_attrs = Vec::new();
1112    let mut found_attrs = Vec::new();
1113
1114    for attr in attrs.drain(..) {
1115        match MethodTypeAttribute::parse_if_matching_attribute(&attr)? {
1116            Some(attr) => found_attrs.push(attr),
1117            None => new_attrs.push(attr),
1118        }
1119    }
1120
1121    *attrs = new_attrs;
1122
1123    Ok(found_attrs)
1124}
1125
1126const IMPL_TRAIT_ERR: &str = "Python functions cannot have `impl Trait` arguments";
1127const RECEIVER_BY_VALUE_ERR: &str =
1128    "Python objects are shared, so 'self' cannot be moved out of the Python interpreter.
1129Try `&self`, `&mut self, `slf: PyClassGuard<'_, Self>` or `slf: PyClassGuardMut<'_, Self>`.";
1130
1131fn ensure_signatures_on_valid_method(
1132    fn_type: &FnType,
1133    signature: Option<&SignatureAttribute>,
1134    text_signature: Option<&TextSignatureAttribute>,
1135) -> syn::Result<()> {
1136    if let Some(signature) = signature {
1137        match fn_type {
1138            FnType::Getter(_) => {
1139                debug_assert!(!fn_type.signature_attribute_allowed());
1140                bail_spanned!(signature.kw.span() => "`signature` not allowed with `getter`")
1141            }
1142            FnType::Setter(_) => {
1143                debug_assert!(!fn_type.signature_attribute_allowed());
1144                bail_spanned!(signature.kw.span() => "`signature` not allowed with `setter`")
1145            }
1146            FnType::ClassAttribute => {
1147                debug_assert!(!fn_type.signature_attribute_allowed());
1148                bail_spanned!(signature.kw.span() => "`signature` not allowed with `classattr`")
1149            }
1150            _ => debug_assert!(fn_type.signature_attribute_allowed()),
1151        }
1152    }
1153    if let Some(text_signature) = text_signature {
1154        match fn_type {
1155            FnType::Getter(_) => {
1156                bail_spanned!(text_signature.kw.span() => "`text_signature` not allowed with `getter`")
1157            }
1158            FnType::Setter(_) => {
1159                bail_spanned!(text_signature.kw.span() => "`text_signature` not allowed with `setter`")
1160            }
1161            FnType::ClassAttribute => {
1162                bail_spanned!(text_signature.kw.span() => "`text_signature` not allowed with `classattr`")
1163            }
1164            _ => {}
1165        }
1166    }
1167    Ok(())
1168}
pyo3_macros_backend/method.rs

pyo3_macros_backend/
method.rs
