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Copy pathpyclass.rs
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2825 lines (2632 loc) · 97.9 KB
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use super::Diagnostic;
use crate::util::{
ALL_ALLOWED_NAMES, ClassItemMeta, ContentItem, ContentItemInner, ErrorVec, ExceptionItemMeta,
ItemMeta, ItemMetaInner, ItemNursery, SimpleItemMeta, internal_doc_tokens,
pyclass_ident_and_attrs, pyexception_ident_and_attrs,
};
use core::str::FromStr;
use proc_macro2::{Delimiter, Group, Span, TokenStream, TokenTree};
use quote::{ToTokens, quote, quote_spanned};
use std::collections::{HashMap, HashSet};
use syn::{Attribute, Ident, Item, Result, parse_quote, spanned::Spanned};
use syn_ext::ext::*;
use syn_ext::types::*;
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum AttrName {
Method,
ClassMethod,
StaticMethod,
GetSet,
Slot,
Attr,
ExtendClass,
Member,
}
impl core::fmt::Display for AttrName {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
let s = match self {
Self::Method => "pymethod",
Self::ClassMethod => "pyclassmethod",
Self::StaticMethod => "pystaticmethod",
Self::GetSet => "pygetset",
Self::Slot => "pyslot",
Self::Attr => "pyattr",
Self::ExtendClass => "extend_class",
Self::Member => "pymember",
};
s.fmt(f)
}
}
impl FromStr for AttrName {
type Err = String;
fn from_str(s: &str) -> core::result::Result<Self, Self::Err> {
Ok(match s {
"pymethod" => Self::Method,
"pyclassmethod" => Self::ClassMethod,
"pystaticmethod" => Self::StaticMethod,
"pygetset" => Self::GetSet,
"pyslot" => Self::Slot,
"pyattr" => Self::Attr,
"extend_class" => Self::ExtendClass,
"pymember" => Self::Member,
s => {
return Err(s.to_owned());
}
})
}
}
#[derive(Default)]
struct ImplContext {
is_trait: bool,
attribute_items: ItemNursery,
method_items: MethodNursery,
getset_items: GetSetNursery,
extend_slots_items: ItemNursery,
class_extensions: Vec<TokenStream>,
errors: Vec<syn::Error>,
/// Set when the impl has no generic parameters, so `Self` in argument
/// types can be replaced before it appears in a nested const.
self_ty_subst: Option<syn::Type>,
/// Set when `self` in this impl is the payload rather than the object:
/// an impl for `T` rather than `Py<T>` or `PyRef<T>`, or a trait.
self_is_payload: bool,
}
fn extract_items_into_context<'a, Item>(
context: &mut ImplContext,
items: impl Iterator<Item = &'a mut Item>,
) where
Item: ItemLike + ToTokens + GetIdent + syn_ext::ext::ItemAttrExt + 'a,
{
for item in items {
let r = item.try_split_attr_mut(|attrs, item| {
let (py_items, cfgs) = attrs_to_content_items(attrs, impl_item_new::<Item>)?;
for py_item in py_items.iter().rev() {
let r = py_item.gen_impl_item(ImplItemArgs::<Item> {
item,
attrs,
context,
cfgs: cfgs.as_slice(),
});
context.errors.ok_or_push(r);
}
Ok(())
});
context.errors.ok_or_push(r);
}
context.errors.ok_or_push(context.method_items.validate());
context.errors.ok_or_push(context.getset_items.validate());
}
pub(crate) fn impl_pyclass_impl(attr: PunctuatedNestedMeta, item: Item) -> Result<TokenStream> {
let mut context = ImplContext::default();
let mut tokens = match item {
Item::Impl(mut imp) => {
if imp.generics.params.is_empty() {
context.self_ty_subst = Some((*imp.self_ty).clone());
context.getset_items.class_ty = context.self_ty_subst.clone();
}
context.self_is_payload = !matches!(
imp.self_ty.as_ref(),
syn::Type::Path(syn::TypePath { path, .. })
if path.segments.last().is_some_and(|segment| {
segment.ident == "Py" || segment.ident == "PyRef"
})
);
extract_items_into_context(&mut context, imp.items.iter_mut());
let attr_nonempty = !attr.is_empty();
let (impl_ty, payload_guess, wrapped) = match imp.self_ty.as_ref() {
syn::Type::Path(syn::TypePath {
path: syn::Path { segments, .. },
..
}) if segments.len() == 1 => {
let segment = &segments[0];
let payload_ty = if segment.ident == "Py" || segment.ident == "PyRef" {
match &segment.arguments {
syn::PathArguments::AngleBracketed(
syn::AngleBracketedGenericArguments { args, .. },
) if args.len() == 1 => {
let arg = &args[0];
match arg {
syn::GenericArgument::Type(syn::Type::Path(
syn::TypePath {
path: syn::Path { segments, .. },
..
},
)) if segments.len() == 1 => segments[0].ident.clone(),
_ => {
return Err(syn::Error::new_spanned(
segment,
"Py{Ref}<T> is expected but Py{Ref}<?> is found",
));
}
}
}
_ => {
return Err(syn::Error::new_spanned(
segment,
"Py{Ref}<T> is expected but Py{Ref}? is found",
));
}
}
} else {
if !matches!(segment.arguments, syn::PathArguments::None) {
return Err(syn::Error::new_spanned(
segment,
"PyImpl can only be implemented for Py{Ref}<T> or T",
));
}
segment.ident.clone()
};
let wrapped = segment.ident == "Py" || segment.ident == "PyRef";
(segment.ident.clone(), payload_ty, wrapped)
}
_ => {
return Err(syn::Error::new_spanned(
imp.self_ty,
"PyImpl can only be implemented for Py{Ref}<T> or T",
));
}
};
let ExtractedImplAttrs {
payload: attr_payload,
flags,
with_impl,
with_method_defs,
with_slots,
itemsize,
sig_initializer,
sig_constructor,
sig_structseq,
} = extract_impl_attrs(attr, &impl_ty)?;
let payload_ty = attr_payload.unwrap_or(payload_guess);
let method_def = &context.method_items;
let getset_impl = &context.getset_items;
let extend_impl = context.attribute_items.validate()?;
let slots_impl = context.extend_slots_items.validate()?;
let class_extensions = &context.class_extensions;
let extra_methods = [
parse_quote! {
const __OWN_METHOD_DEFS: &'static [::rustpython_vm::function::PyMethodDef] = &#method_def;
},
parse_quote! {
fn __extend_py_class(
ctx: &'static ::rustpython_vm::Context,
class: &'static ::rustpython_vm::Py<::rustpython_vm::builtins::PyType>,
) {
#getset_impl
#extend_impl
#(#class_extensions)*
}
},
{
let itemsize_impl = itemsize.as_ref().map(|size| {
quote! {
slots.itemsize = #size;
}
});
parse_quote! {
fn __extend_slots(slots: &mut ::rustpython_vm::types::PyTypeSlots) {
#itemsize_impl
#slots_impl
}
}
},
];
imp.items.extend(extra_methods);
// `#[pyclass(...)] impl Py<T>` with attributes is the class impl.
// A bare `#[pyclass] impl Py<T>` stays a method extension pulled in
// by `with(Py)` on the payload impl.
let is_main_impl = !wrapped || attr_nonempty;
let holder = if wrapped {
quote!(#impl_ty::<#payload_ty>)
} else {
quote!(#impl_ty)
};
if is_main_impl {
let method_defs = if with_method_defs.is_empty() {
quote!(#holder::__OWN_METHOD_DEFS)
} else {
quote!(::rustpython_vm::__cfg_doc!({
::rustpython_vm::function::PyMethodDef::concat_with_attr_docs::<
{ #holder::__OWN_METHOD_DEFS.len() #(+ #with_method_defs.len())* },
>(
&[#holder::__OWN_METHOD_DEFS, #(#with_method_defs,)*],
<#payload_ty as ::rustpython_vm::class::PyClassDef>::ATTR_DOCS,
)
} else {
::rustpython_vm::function::PyMethodDef::__const_concat_arrays::<
{ #holder::__OWN_METHOD_DEFS.len() #(+ #with_method_defs.len())* },
>(&[#holder::__OWN_METHOD_DEFS, #(#with_method_defs,)*])
}))
};
let internal_doc = class_internal_doc(
&payload_ty,
sig_initializer,
sig_constructor,
sig_structseq,
);
quote! {
#imp
impl ::rustpython_vm::class::PyClassImpl for #payload_ty {
const TP_FLAGS: ::rustpython_vm::types::PyTypeFlags = #flags;
const INTERNAL_DOC: ::rustpython_vm::function::ItemDoc = #internal_doc;
fn impl_extend_class(
ctx: &'static ::rustpython_vm::Context,
class: &'static ::rustpython_vm::Py<::rustpython_vm::builtins::PyType>,
) {
#holder::__extend_py_class(ctx, class);
#with_impl
}
const METHOD_DEFS: &'static [::rustpython_vm::function::PyMethodDef] = &#method_defs;
fn extend_slots(slots: &mut ::rustpython_vm::types::PyTypeSlots) {
#with_slots
#holder::__extend_slots(slots);
}
}
}
} else {
imp.into_token_stream()
}
}
Item::Trait(mut trai) => {
context.is_trait = true;
context.self_is_payload = true;
let mut has_extend_slots = false;
for item in &trai.items {
let has = match item {
syn::TraitItem::Fn(item) => item.sig.ident == "extend_slots",
_ => false,
};
if has {
has_extend_slots = has;
break;
}
}
extract_items_into_context(&mut context, trai.items.iter_mut());
let ExtractedImplAttrs {
with_impl,
with_slots,
..
} = extract_impl_attrs(attr, &trai.ident)?;
let method_def = &context.method_items;
let getset_impl = &context.getset_items;
let extend_impl = &context.attribute_items.validate()?;
let slots_impl = &context.extend_slots_items.validate()?;
let class_extensions = &context.class_extensions;
let call_extend_slots = if has_extend_slots {
quote! {
Self::extend_slots(slots);
}
} else {
quote! {}
};
let extra_methods = [
parse_quote! {
const __OWN_METHOD_DEFS: &'static [::rustpython_vm::function::PyMethodDef] = &#method_def;
},
parse_quote! {
fn __extend_py_class(
ctx: &'static ::rustpython_vm::Context,
class: &'static ::rustpython_vm::Py<::rustpython_vm::builtins::PyType>,
) {
#getset_impl
#extend_impl
#with_impl
#(#class_extensions)*
}
},
parse_quote! {
fn __extend_slots(slots: &mut ::rustpython_vm::types::PyTypeSlots) {
#with_slots
#slots_impl
#call_extend_slots
}
},
];
trai.items.extend(extra_methods);
trai.into_token_stream()
}
item => item.into_token_stream(),
};
if let Some(error) = context.errors.into_error() {
let error = Diagnostic::from(error);
tokens = quote! {
#tokens
#error
}
}
Ok(tokens)
}
/// Validates that when a base class is specified, the struct has the base type as its first
/// *declared* field. Returns a token naming that field (e.g. `_base` or `0` for tuple structs)
/// so the caller can emit compile-time layout assertions.
fn validate_base_field(item: &Item, base_path: &syn::Path) -> Result<TokenStream> {
let Item::Struct(item_struct) = item else {
bail_span!(item, "#[pyclass] with base requires a struct");
};
// Get the base type name for error messages
let base_name = base_path
.segments
.last()
.map_or_else(|| quote!(#base_path).to_string(), |s| s.ident.to_string());
match &item_struct.fields {
syn::Fields::Named(fields) => {
let Some(first_field) = fields.named.first() else {
bail_span!(
item_struct,
"#[pyclass] with base = {base_name} requires the first field to be of type {base_name}, but the struct has no fields"
);
};
if !type_matches_path(&first_field.ty, base_path) {
bail_span!(
first_field,
"#[pyclass] with base = {base_name} requires the first field to be of type {base_name}"
);
}
let ident = first_field
.ident
.as_ref()
.expect("named fields always have identifiers");
Ok(quote! { #ident })
}
syn::Fields::Unnamed(fields) => {
let Some(first_field) = fields.unnamed.first() else {
bail_span!(
item_struct,
"#[pyclass] with base = {base_name} requires the first field to be of type {base_name}, but the struct has no fields"
);
};
if !type_matches_path(&first_field.ty, base_path) {
bail_span!(
first_field,
"#[pyclass] with base = {base_name} requires the first field to be of type {base_name}"
);
}
Ok(quote! { 0 })
}
syn::Fields::Unit => {
bail_span!(
item_struct,
"#[pyclass] with base = {base_name} requires the first field to be of type {base_name}, but the struct is a unit struct"
);
}
}
}
/// Adds `#[repr(C)]` to a derived pyclass struct when no explicit `#[repr(…)]` is present.
///
/// The inherited getter dispatcher reinterprets the derived object pointer as `*Base`, which
/// is only valid when the base field is at offset 0. Under `#[repr(Rust)]` the compiler may
/// reorder fields to minimise padding, silently displacing the base field. `#[repr(C)]`
/// preserves declaration order, guaranteeing offset 0 for the first field.
fn ensure_repr_c(mut item: Item) -> Item {
let Item::Struct(ref mut s) = item else {
return item;
};
let has_repr = s.attrs.iter().any(|attr| attr.path().is_ident("repr"));
if !has_repr {
s.attrs.push(parse_quote!(#[repr(C)]));
}
item
}
/// Check if a type matches a given path (handles simple cases like `Foo` or `path::to::Foo`)
fn class_def_ty(self_ty: Option<&syn::Type>) -> Option<TokenStream> {
let ty = self_ty?;
if let syn::Type::Path(type_path) = ty
&& let Some(segment) = type_path.path.segments.last()
&& (segment.ident == "Py" || segment.ident == "PyRef")
&& let syn::PathArguments::AngleBracketed(args) = &segment.arguments
&& let Some(syn::GenericArgument::Type(inner)) = args.args.first()
{
return Some(quote!(#inner));
}
Some(quote!(#ty))
}
/// Const `ItemDoc`. A non-empty Rust doc is the docstring.
/// The attribute table is used only when there is no Rust doc. Generic impls
/// cannot name `Self` from a nested const, so without a Rust doc they store none.
fn attr_doc_expr(self_ty: Option<&syn::Type>, attr: &str, rust_doc: Option<String>) -> TokenStream {
if let Some(doc) = rust_doc.filter(|doc| !doc.is_empty()) {
return quote!(::rustpython_vm::function::ItemDoc::static_text(#doc));
}
let Some(ty) = class_def_ty(self_ty) else {
return quote!(::rustpython_vm::function::ItemDoc::NONE);
};
quote! {
::rustpython_vm::__cfg_doc!({
{
const FOUND: Option<(u32, u32)> = ::rustpython_vm::class::attr_doc(
<#ty as ::rustpython_vm::class::PyClassDef>::ATTR_DOCS,
#attr,
);
if let Some((offset, len)) = FOUND {
if len != 0 {
::rustpython_vm::function::ItemDoc {
text: None,
offset,
len,
}
} else if offset == u32::MAX {
::rustpython_vm::function::ItemDoc::EMPTY
} else {
::rustpython_vm::function::ItemDoc::NONE
}
} else {
::rustpython_vm::function::ItemDoc::NONE
}
}
} else {
::rustpython_vm::function::ItemDoc::NONE
})
}
}
/// True when the method body is still taken from the owning class's table.
/// A non-empty Rust doc is the body. Otherwise the span is resolved here when
/// the impl can name its class; a missing class or a missing span stays pending.
fn doc_body_pending_expr(
self_ty: Option<&syn::Type>,
attr: &str,
rust_doc: Option<String>,
) -> TokenStream {
if rust_doc.as_ref().is_some_and(|doc| !doc.is_empty()) {
return quote!(false);
}
let Some(ty) = class_def_ty(self_ty) else {
return quote!(true);
};
quote! {
{
const FOUND: Option<(u32, u32)> = ::rustpython_vm::class::attr_doc(
<#ty as ::rustpython_vm::class::PyClassDef>::ATTR_DOCS,
#attr,
);
match FOUND {
Some((_, len)) if len != 0 => false,
_ => true,
}
}
}
}
fn type_matches_path(ty: &syn::Type, path: &syn::Path) -> bool {
// Compare by converting both to string representation for macro hygiene
let ty_str = quote!(#ty).to_string().replace(' ', "");
let path_str = quote!(#path).to_string().replace(' ', "");
// Check if both are the same or if the type ends with the path's last segment
if ty_str == path_str {
return true;
}
// Also match if just the last segment matches (e.g., foo::Bar matches Bar)
let syn::Type::Path(type_path) = ty else {
return false;
};
let Some(type_last) = type_path.path.segments.last() else {
return false;
};
let Some(path_last) = path.segments.last() else {
return false;
};
type_last.ident == path_last.ident
}
struct MemberTableTokens<'a> {
members: &'a TokenStream,
parts: &'a TokenStream,
checks: &'a TokenStream,
}
struct ClassDefExtras<'a> {
attrs: &'a [Attribute],
member_table: MemberTableTokens<'a>,
}
fn generate_class_def(
ident: &Ident,
name: &str,
module_name: Option<&str>,
base: Option<syn::Path>,
metaclass: Option<String>,
unhashable: bool,
extras: ClassDefExtras<'_>,
) -> Result<TokenStream> {
let attrs = extras.attrs;
let module_key = module_name.unwrap_or("builtins");
let (attr_docs, attr_names) = crate::class_docs::attr_docs_tokens(module_name, name);
let rust_doc = attrs.doc().filter(|doc| !doc.is_empty());
let db_doc = if rust_doc.is_some() {
None
} else {
rustpython_doc::get_qualified(module_key, name, None, true)
};
let doc = crate::class_docs::item_doc_tokens(db_doc, rust_doc);
let module_class_name = if let Some(module_name) = module_name {
format!("{module_name}.{name}")
} else {
name.to_owned()
};
let module_name = match module_name {
Some(v) => quote!(Some(#v) ),
None => quote!(None),
};
let unhashable = if unhashable {
quote!(true)
} else {
quote!(false)
};
let is_pystruct = attrs.iter().any(|attr| {
attr.path().is_ident("derive")
&& if let Ok(Meta::List(l)) = attr.parse_meta() {
l.nested
.into_iter()
.any(|n| n.get_ident().is_some_and(|p| p == "PyStructSequence"))
} else {
false
}
});
// Check if the type has #[repr(transparent)] - only then we can safely
// generate PySubclass impl (requires same memory layout as base type)
let is_repr_transparent = attrs.iter().any(|attr| {
attr.path().is_ident("repr")
&& if let Ok(Meta::List(l)) = attr.parse_meta() {
l.nested
.into_iter()
.any(|n| n.get_ident().is_some_and(|p| p == "transparent"))
} else {
false
}
});
// If repr(transparent) with a base, the type has the same memory layout as base,
// so basicsize stays 0 and type creation copies the base's full tp_basicsize.
// Otherwise, include any alignment padding between the header and payload.
let basicsize = if is_repr_transparent && base.is_some() {
quote!(0)
} else {
quote!(
::rustpython_vm::object::payload_offset::<#ident>() + ::core::mem::size_of::<#ident>()
)
};
if base.is_some() && is_pystruct {
bail_span!(ident, "PyStructSequence cannot have `base` class attr",);
}
let base_class = if is_pystruct {
Some(quote! { rustpython_vm::builtins::PyTuple })
} else {
base.as_ref().map(|typ| {
quote_spanned! { ident.span() => #typ }
})
}
.map(|typ| {
quote! {
fn static_baseclass() -> &'static ::rustpython_vm::Py<::rustpython_vm::builtins::PyType> {
use rustpython_vm::class::StaticType;
#typ::static_type()
}
}
});
let meta_class = metaclass.map(|typ| {
let typ = Ident::new(&typ, ident.span());
quote! {
fn static_metaclass() -> &'static ::rustpython_vm::Py<::rustpython_vm::builtins::PyType> {
use rustpython_vm::class::StaticType;
#typ::static_type()
}
}
});
let base_or_object = if let Some(ref base) = base {
quote! { #base }
} else {
quote! { ::rustpython_vm::builtins::PyBaseObject }
};
// Generate PySubclass impl for #[repr(transparent)] types with base class
// (tuple struct assumed, so &self.0 works)
let subclass_impl = if !is_pystruct && is_repr_transparent {
base.as_ref().map(|typ| {
quote! {
// SAFETY: the transparent base field has the same layout as Self;
// pyclass also checks the object payload offsets and alignment.
unsafe impl ::rustpython_vm::class::PySubclass for #ident {
type Base = #typ;
#[inline]
fn as_base(&self) -> &Self::Base {
&self.0
}
}
}
})
} else {
None
};
let MemberTableTokens {
members,
parts: member_parts_impl,
checks: member_checks,
} = extras.member_table;
let native_layout = if is_repr_transparent {
base.as_ref().map(|base| {
quote! {
const NATIVE_LAYOUT_ID: ::core::any::TypeId =
<#base as ::rustpython_vm::class::PyClassDef>::NATIVE_LAYOUT_ID;
}
})
} else {
None
};
let tokens = quote! {
impl ::rustpython_vm::class::PyClassDef for #ident {
const NAME: &'static str = #name;
#native_layout
const MODULE_NAME: Option<&'static str> = #module_name;
const TP_NAME: &'static str = #module_class_name;
const DOC: ::rustpython_vm::function::ItemDoc = #doc;
::rustpython_vm::__cfg_doc! {{
const ATTR_DOCS: &'static [(&'static str, u32, u32)] = #attr_docs;
} else {
const ATTR_DOCS: &'static [&'static str] = #attr_names;
}}
const BASICSIZE: usize = #basicsize;
const UNHASHABLE: bool = #unhashable;
const MEMBERS: &'static [::rustpython_vm::builtins::descriptor::PyMemberSpec] = #members;
type Base = #base_or_object;
fn assert_member_layout() {
#member_checks
}
}
#member_parts_impl
impl ::rustpython_vm::class::StaticType for #ident {
fn static_cell() -> &'static ::rustpython_vm::common::static_cell::StaticCell<::rustpython_vm::builtins::PyTypeRef> {
::rustpython_vm::common::static_cell! {
static CELL: ::rustpython_vm::builtins::PyTypeRef;
}
&CELL
}
#meta_class
#base_class
}
#subclass_impl
};
Ok(tokens)
}
pub(crate) fn impl_pyclass(attr: PunctuatedNestedMeta, item: Item) -> Result<TokenStream> {
if matches!(item, syn::Item::Use(_)) {
return Ok(quote!(#item));
}
let fake_ident = Ident::new("pyclass", item.span());
let (class_meta, class_name, module_name, base, metaclass, unhashable) = {
let (ident, _) = pyclass_ident_and_attrs(&item)?;
let class_meta = ClassItemMeta::from_nested(ident.clone(), fake_ident, attr.into_iter())?;
let class_name = class_meta.class_name()?;
let module_name = class_meta.module()?;
let base = class_meta.base()?;
let metaclass = class_meta.metaclass()?;
let unhashable = class_meta.unhashable()?;
(
class_meta,
class_name,
module_name,
base,
metaclass,
unhashable,
)
};
// When a base is specified:
// 1. Validate that the first *declared* field has the base type.
// 2. Auto-insert #[repr(C)] so the compiler preserves declaration order,
// keeping the base field at offset 0 as the inherited getter dispatcher requires.
// 3. Emit a compile-time offset_of! assertion as a safety net for structs that
// already carry an explicit repr that does not guarantee offset 0.
// 4. Require the payload to start at the same offset in Py<Base> and Py<Derived>.
// 5. Require Py<Derived> to meet Py<Base>'s alignment, including packed payloads.
let base_field_token = if let Some(ref base_path) = base {
Some(validate_base_field(&item, base_path)?)
} else {
None
};
let mut item = if base.is_some() {
ensure_repr_c(item)
} else {
item
};
let (members, member_parts, member_checks) = extract_py_members(&mut item)?;
let (ident, attrs) = pyclass_ident_and_attrs(&item)?;
let offset_assert = match (&base, &base_field_token) {
(Some(base_type), Some(field)) => quote! {
const _: () = ::core::assert!(
::core::mem::offset_of!(#ident, #field) == 0,
concat!(
"The base field of `", stringify!(#ident), "` is not at offset 0. \
Add `#[repr(C)]` (or `#[repr(transparent)]`) to the struct so the \
compiler preserves declaration order and inherited getter dispatch \
reads the correct memory."
)
);
const _: () = ::core::assert!(
::rustpython_vm::object::payload_offset::<#ident>()
== ::rustpython_vm::object::payload_offset::<#base_type>(),
concat!(
"The payload offsets of `", stringify!(#ident), "` and its base `",
stringify!(#base_type), "` differ inside `Py<T>`. \
Adjust the payload alignment so inherited methods read the same address. \
A base field at offset 0 alone is not sufficient."
)
);
const _: () = ::core::assert!(
::core::mem::align_of::<::rustpython_vm::Py<#ident>>()
>= ::core::mem::align_of::<::rustpython_vm::Py<#base_type>>(),
concat!(
"The object alignment of `", stringify!(#ident), "` is smaller than its base `",
stringify!(#base_type), "`. Packed payloads must not weaken the base object's alignment."
)
);
},
_ => quote! {},
};
let class_def = generate_class_def(
ident,
&class_name,
module_name.as_deref(),
base.clone(),
metaclass,
unhashable,
ClassDefExtras {
attrs,
member_table: MemberTableTokens {
members: &members,
parts: &member_parts,
checks: &member_checks,
},
},
)?;
const ALLOWED_TRAVERSE_OPTS: &[&str] = &["manual"];
// Generate MaybeTraverse impl with both traverse and clear support
//
// For traverse:
// 1. no `traverse` at all: HAS_TRAVERSE = false, try_traverse does nothing
// 2. `traverse = "manual"`: HAS_TRAVERSE = true, but no #[derive(Traverse)]
// 3. `traverse`: HAS_TRAVERSE = true, and #[derive(Traverse)]
//
// For clear (tp_clear):
// 1. no `clear`: HAS_CLEAR = HAS_TRAVERSE (default: same as traverse)
// 2. `clear` or `clear = true`: HAS_CLEAR = true, try_clear calls Traverse::clear
// 3. `clear = false`: HAS_CLEAR = false (rare: traverse without clear)
let has_traverse = class_meta.inner().contains_key("traverse");
let has_clear = if class_meta.inner().contains_key("clear") {
// If clear attribute is present, use its value
class_meta.inner()._bool("clear")?
} else {
// If clear attribute is absent, default to same as traverse
has_traverse
};
let derive_trace = if has_traverse {
// _optional_str returns Err when key exists without value (e.g., `traverse` vs `traverse = "manual"`)
// We want to derive Traverse in that case, so we handle Err as Ok(None)
let value = class_meta.inner()._optional_str("traverse").ok().flatten();
if let Some(s) = value {
if !ALLOWED_TRAVERSE_OPTS.contains(&s.as_str()) {
bail_span!(
item,
"traverse attribute only accept {ALLOWED_TRAVERSE_OPTS:?} as value or no value at all",
);
}
assert_eq!(s, "manual");
quote! {}
} else {
quote! {#[derive(Traverse)]}
}
} else {
quote! {}
};
let maybe_traverse_code = {
let try_traverse_body = if has_traverse {
quote! {
::rustpython_vm::object::Traverse::traverse(self, tracer_fn);
}
} else {
quote! {
// do nothing
}
};
let try_clear_body = if has_clear {
quote! {
::rustpython_vm::object::Traverse::clear(self, out);
}
} else {
quote! {
// do nothing
}
};
quote! {
impl ::rustpython_vm::object::MaybeTraverse for #ident {
const HAS_TRAVERSE: bool = #has_traverse;
const HAS_CLEAR: bool = #has_clear;
fn try_traverse(&self, tracer_fn: &mut ::rustpython_vm::object::TraverseFn) {
#try_traverse_body
}
fn try_clear(&mut self, out: &mut ::std::vec::Vec<::rustpython_vm::PyObjectRef>) {
#try_clear_body
}
}
}
};
// Generate PyPayload impl based on whether base exists
#[allow(clippy::collapsible_else_if)]
let impl_payload = if class_meta.manual_payload()? {
quote! {}
} else if let Some(base_type) = &base {
let class_fn = if let Some(ctx_type_name) = class_meta.ctx_name()? {
let ctx_type_ident = Ident::new(&ctx_type_name, ident.span());
quote! { ctx.types.#ctx_type_ident }
} else {
quote! { <Self as ::rustpython_vm::class::StaticType>::static_type() }
};
quote! {
// static_assertions::const_assert!(std::mem::size_of::<#base_type>() <= std::mem::size_of::<#ident>());
impl ::rustpython_vm::PyPayload for #ident {
const PAYLOAD_TYPE_ID: ::core::any::TypeId = <#base_type as ::rustpython_vm::PyPayload>::PAYLOAD_TYPE_ID;
fn supports_native_layout(layout: ::core::any::TypeId) -> bool {
layout == <Self as ::rustpython_vm::class::PyClassDef>::NATIVE_LAYOUT_ID
|| <#base_type as ::rustpython_vm::PyPayload>::supports_native_layout(layout)
}
#[inline]
unsafe fn validate_downcastable_from(obj: &::rustpython_vm::PyObject) -> bool {
obj.supports_native_layout(<Self as ::rustpython_vm::class::PyClassDef>::NATIVE_LAYOUT_ID) && obj.class().fast_issubclass(<Self as ::rustpython_vm::class::StaticType>::static_type())
}
fn class(ctx: &::rustpython_vm::vm::Context) -> &'static ::rustpython_vm::Py<::rustpython_vm::builtins::PyType> {
#class_fn
}
}
}
} else {
if let Some(ctx_type_name) = class_meta.ctx_name()? {
let ctx_type_ident = Ident::new(&ctx_type_name, ident.span());
quote! {
impl ::rustpython_vm::PyPayload for #ident {
fn class(ctx: &::rustpython_vm::vm::Context) -> &'static ::rustpython_vm::Py<::rustpython_vm::builtins::PyType> {
ctx.types.#ctx_type_ident
}
}
}
} else {
quote! {}
}
};
let empty_impl = if let Some(attrs) = class_meta.impl_attrs()? {
let attrs: Meta = parse_quote! (#attrs);
quote! {
#[pyclass(#attrs)]
impl #ident {}
}
} else {
quote! {}
};
let ret = quote! {
#derive_trace
#item
#offset_assert
#maybe_traverse_code
#class_def
#impl_payload
#empty_impl
};
Ok(ret)
}
/// Special macro to create exception types.
///
/// Why do we need it and why can't we just use `pyclass` macro instead?
/// We generate exception types with a `macro_rules`,
/// similar to how CPython does it.
/// But, inside `macro_rules` we don't have an opportunity
/// to add non-literal attributes to `pyclass`.
/// That's why we have to use this proxy.
pub(crate) fn impl_pyexception(attr: PunctuatedNestedMeta, item: &Item) -> Result<TokenStream> {
let (ident, _attrs) = pyexception_ident_and_attrs(item)?;
let fake_ident = Ident::new("pyclass", item.span());
let class_meta = ExceptionItemMeta::from_nested(ident.clone(), fake_ident, attr.into_iter())?;
let class_name = class_meta.class_name()?;
let base_class_name = class_meta.base()?;
let impl_pyclass = if class_meta.has_impl()? {
quote! {
#[pyexception]
impl #ident {}
}
} else {
quote! {}
};
// Forward a `traverse` option to the generated `#[pyclass]` so exception
// payloads with a manual `Traverse` impl are GC-tracked and traversed.
let traverse_attr = match class_meta.inner()._optional_str("traverse").ok().flatten() {
Some(value) => quote! { , traverse = #value },
None => quote! {},