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Copy pathpyclass.rs
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2045 lines (1882 loc) · 69.7 KB
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use super::Diagnostic;
use crate::util::{
ALL_ALLOWED_NAMES, ClassItemMeta, ContentItem, ContentItemInner, ErrorVec, ExceptionItemMeta,
ItemMeta, ItemMetaInner, ItemNursery, SimpleItemMeta, format_doc, infer_native_call_flags,
pyclass_ident_and_attrs, pyexception_ident_and_attrs, text_signature,
};
use core::str::FromStr;
use proc_macro2::{Delimiter, Group, Span, TokenStream, TokenTree};
use quote::{ToTokens, quote, quote_spanned};
use rustpython_doc::DB;
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)]
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,
member_items: MemberNursery,
extend_slots_items: ItemNursery,
class_extensions: Vec<TokenStream>,
errors: Vec<syn::Error>,
}
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());
context.errors.ok_or_push(context.member_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) => {
extract_items_into_context(&mut context, imp.items.iter_mut());
let (impl_ty, payload_guess) = 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()
};
(segment.ident.clone(), payload_ty)
}
_ => {
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,
} = 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 member_impl = &context.member_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
#member_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);
let is_main_impl = impl_ty == payload_ty;
if is_main_impl {
let method_defs = if with_method_defs.is_empty() {
quote!(#impl_ty::__OWN_METHOD_DEFS)
} else {
quote!(
rustpython_vm::function::PyMethodDef::__const_concat_arrays::<
{ #impl_ty::__OWN_METHOD_DEFS.len() #(+ #with_method_defs.len())* },
>(&[#impl_ty::__OWN_METHOD_DEFS, #(#with_method_defs,)*])
)
};
quote! {
#imp
impl ::rustpython_vm::class::PyClassImpl for #payload_ty {
const TP_FLAGS: ::rustpython_vm::types::PyTypeFlags = #flags;
fn impl_extend_class(
ctx: &'static ::rustpython_vm::Context,
class: &'static ::rustpython_vm::Py<::rustpython_vm::builtins::PyType>,
) {
#impl_ty::__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
#impl_ty::__extend_slots(slots);
}
}
}
} else {
imp.into_token_stream()
}
}
Item::Trait(mut trai) => {
let mut context = ImplContext {
is_trait: true,
..Default::default()
};
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 member_impl = &context.member_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
#member_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 a compile-time `offset_of!` assertion, or `None` for non-structs.
fn validate_base_field(item: &Item, base_path: &syn::Path) -> Result<Option<TokenStream>> {
let Item::Struct(item_struct) = item else {
// Only validate structs - enums with base are already an error elsewhere
return Ok(None);
};
// 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().map(|id| quote! { #id });
Ok(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(Some(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 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
}
fn generate_class_def(
ident: &Ident,
name: &str,
module_name: Option<&str>,
base: Option<syn::Path>,
metaclass: Option<String>,
unhashable: bool,
attrs: &[Attribute],
) -> Result<TokenStream> {
let doc = attrs.doc().or_else(|| {
let module_name = module_name.unwrap_or("builtins");
DB.get(&format!("{module_name}.{name}"))
.copied()
.map(str::to_owned)
});
let doc = if let Some(doc) = doc {
quote!(Some(#doc))
} else {
quote!(None)
};
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 should be 0 (no additional space beyond the base type)
// Otherwise, basicsize = sizeof(payload). The header size is added in __basicsize__ getter.
let basicsize = if is_repr_transparent && base.is_some() {
quote!(0)
} else {
quote!(std::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! {
impl ::rustpython_vm::class::PySubclass for #ident {
type Base = #typ;
#[inline]
fn as_base(&self) -> &Self::Base {
&self.0
}
}
}
})
} else {
None
};
let tokens = quote! {
impl ::rustpython_vm::class::PyClassDef for #ident {
const NAME: &'static str = #name;
const MODULE_NAME: Option<&'static str> = #module_name;
const TP_NAME: &'static str = #module_class_name;
const DOC: Option<&'static str> = #doc;
const BASICSIZE: usize = #basicsize;
const UNHASHABLE: bool = #unhashable;
type Base = #base_or_object;
}
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.
let base_field_token = if let Some(ref base_path) = base {
validate_base_field(&item, base_path)?
} else {
None
};
let item = if base.is_some() {
ensure_repr_c(item)
} else {
item
};
let (ident, attrs) = pyclass_ident_and_attrs(&item)?;
let offset_assert = match (&base, &base_field_token) {
(Some(_), 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."
)
);
},
_ => quote! {},
};
let class_def = generate_class_def(
ident,
&class_name,
module_name.as_deref(),
base.clone(),
metaclass,
unhashable,
attrs,
)?;
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()._has_key("traverse");
let has_clear = if class_meta.inner()._has_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 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;
#[inline]
unsafe fn validate_downcastable_from(obj: &::rustpython_vm::PyObject) -> bool {
<Self as ::rustpython_vm::class::PyClassDef>::BASICSIZE <= obj.class().slots.basicsize && 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! {}
};
let ret = quote! {
#[pyclass(module = false, name = #class_name, base = #base_class_name)]
#item
#impl_pyclass
};
Ok(ret)
}
pub(crate) fn impl_pyexception_impl(attr: PunctuatedNestedMeta, item: Item) -> TokenStream {
let Item::Impl(imp) = item else {
return item.into_token_stream();
};
// Check if with(Constructor) is specified. If Constructor trait is used, don't generate slot_new
let mut extra_attrs = Vec::new();
let mut with_items = vec![];
for nested in &attr {
if let NestedMeta::Meta(Meta::List(MetaList { path, nested, .. })) = nested {
// If we already found the constructor trait, no need to keep looking for it
if path.is_ident("with") {
for meta in nested {
with_items.push(meta.get_ident().expect("with() has non-ident item").clone());
}
continue;
}
extra_attrs.push(NestedMeta::Meta(Meta::List(MetaList {
path: path.clone(),
paren_token: Default::default(),
nested: nested.clone(),
})));
}
}
let with_contains = |with_items: &[Ident], s: &str| {
// Check if Constructor is in the list
with_items.iter().any(|ident| ident == s)
};
let syn::ItemImpl {
generics,
self_ty,
items,
..
} = &imp;
let slot_new = if with_contains(&with_items, "Constructor") {
quote!()
} else {
with_items.push(Ident::new("Constructor", Span::call_site()));
quote! {
impl ::rustpython_vm::types::Constructor for #self_ty {
type Args = ::rustpython_vm::function::FuncArgs;
fn slot_new(
cls: ::rustpython_vm::builtins::PyTypeRef,
args: ::rustpython_vm::function::FuncArgs,
vm: &::rustpython_vm::VirtualMachine,
) -> ::rustpython_vm::PyResult {
<Self as ::rustpython_vm::class::PyClassDef>::Base::slot_new(cls, args, vm)
}
fn py_new(
_cls: &::rustpython_vm::Py<::rustpython_vm::builtins::PyType>,
_args: Self::Args,
_vm: &::rustpython_vm::VirtualMachine
) -> ::rustpython_vm::PyResult<Self> {
unreachable!("slot_new is defined")
}
}
}
};
// SimpleExtendsException: inherits BaseException_init from the base class via MRO.
// Only exceptions that explicitly specify `with(Initializer)` will have
// their own __init__ in __dict__.
let slot_init = quote!();
let extra_attrs_tokens = if extra_attrs.is_empty() {
quote!()
} else {
quote!(, #(#extra_attrs),*)
};
quote! {
#[pyclass(flags(BASETYPE, HAS_DICT), with(#(#with_items),*) #extra_attrs_tokens)]
impl #generics #self_ty {
#(#items)*
}
#slot_new
#slot_init
}
}
macro_rules! define_content_item {
(
$(#[$meta:meta])*
$vis:vis struct $name:ident
) => {
$(#[$meta])*
$vis struct $name {
inner: ContentItemInner<AttrName>,
}
impl ContentItem for $name {
type AttrName = AttrName;
fn inner(&self) -> &ContentItemInner<AttrName> {
&self.inner
}
}
};
}
define_content_item!(
/// #[pymethod] and #[pyclassmethod]
struct MethodItem
);
define_content_item!(
/// #[pygetset]
struct GetSetItem
);
define_content_item!(
/// #[pyslot]
struct SlotItem
);
define_content_item!(
/// #[pyattr]
struct AttributeItem
);
define_content_item!(
/// #[extend_class]
struct ExtendClassItem
);
define_content_item!(
/// #[pymember]
struct MemberItem
);
struct ImplItemArgs<'a, Item: ItemLike> {
item: &'a Item,
attrs: &'a mut Vec<Attribute>,
context: &'a mut ImplContext,
cfgs: &'a [Attribute],
}
trait ImplItem<Item>: ContentItem
where
Item: ItemLike + ToTokens + GetIdent,
{
fn gen_impl_item(&self, args: ImplItemArgs<'_, Item>) -> Result<()>;
}
impl<Item> ImplItem<Item> for MethodItem
where
Item: ItemLike + ToTokens + GetIdent,
{
fn gen_impl_item(&self, args: ImplItemArgs<'_, Item>) -> Result<()> {
let func = args
.item
.function_or_method()
.map_err(|_| self.new_syn_error(args.item.span(), "can only be on a method"))?;
let ident = &func.sig().ident;
let item_attr = args.attrs.remove(self.index());
let item_meta = MethodItemMeta::from_attr(ident.clone(), &item_attr)?;
let py_name = item_meta.method_name()?;
// Disallow slot methods - they should be defined via trait implementations
// These are exposed as wrapper_descriptor via add_operators from SLOT_DEFS
if !args.context.is_trait {
const FORBIDDEN_SLOT_METHODS: &[(&str, &str)] = &[
// Constructor/Initializer traits
("__new__", "Constructor"),
("__init__", "Initializer"),
// Representable trait
("__repr__", "Representable"),
// ("__str__", "???"), // allow __str__
// Hashable trait
("__hash__", "Hashable"),
// Callable trait
("__call__", "Callable"),
// GetAttr/SetAttr traits
// NOTE: __getattribute__, __setattr__, __delattr__ are intentionally NOT forbidden
// because they need pymethod for subclass override mechanism to work properly.
// GetDescriptor/SetDescriptor traits
("__get__", "GetDescriptor"),
("__set__", "SetDescriptor"),
("__delete__", "SetDescriptor"),
// AsNumber trait
("__add__", "AsNumber"),
("__radd__", "AsNumber"),
("__iadd__", "AsNumber"),
("__sub__", "AsNumber"),
("__rsub__", "AsNumber"),
("__isub__", "AsNumber"),
("__mul__", "AsNumber"),