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xso-proc: Add n = 1 flag to element meta

Browse source 
This allows exactly one arbitrary payload in any element, and is handled
after every other element with a more specific matcher has been parsed.

Both the #[xml(element(n = 1))] meta and its shortcut #[xml(element)]
are allowed and treated the exact same way.
This commit is contained in:
Emmanuel Gil Peyrot 2024-12-19 20:36:57 +01:00 • committed by Jonas Schäfer
commit c72cf3ddd1
7 changed files with 265 additions and 80 deletions
Download patch file Download diff file Expand all files Collapse all files

3
xso-proc/src/field/child.rs
View file

@ -67,10 +67,9 @@ impl Field for ChildField {
} = scope;
let from_events = from_events_fn(element_ty.clone());
let from_xml_builder = from_xml_builder_ty(element_ty.clone());
let matcher = quote! { #from_events(name, attrs) };
let builder = from_xml_builder;
let builder = from_xml_builder_ty(element_ty.clone());
(
TokenStream::default(),

160
xso-proc/src/field/element.rs
View file

@ -13,52 +13,97 @@ use proc_macro2::{Span, TokenStream};
use quote::quote;
use syn::*;
use crate::error_message::ParentRef;
use crate::error_message::{self, ParentRef};
use crate::meta::AmountConstraint;
use crate::scope::{AsItemsScope, FromEventsScope};
use crate::types::{
default_fn, element_ty, from_xml_builder_ty, into_iterator_into_iter_fn, into_iterator_iter_ty,
item_iter_ty, option_ty, ref_ty,
as_xml_iter_fn, default_fn, element_ty, from_events_fn, from_xml_builder_ty,
into_iterator_into_iter_fn, into_iterator_item_ty, into_iterator_iter_ty, item_iter_ty,
option_ty, ref_ty,
};
use super::{Field, FieldBuilderPart, FieldIteratorPart, FieldTempInit, NestedMatcher};
pub(super) struct ElementField;
pub(super) struct ElementField {
/// Number of child elements allowed.
pub(super) amount: AmountConstraint,
}
impl Field for ElementField {
fn make_builder_part(
&self,
scope: &FromEventsScope,
_container_name: &ParentRef,
container_name: &ParentRef,
member: &Member,
ty: &Type,
) -> Result<FieldBuilderPart> {
let element_ty = match self.amount {
AmountConstraint::FixedSingle(_) => ty.clone(),
AmountConstraint::Any(_) => into_iterator_item_ty(ty.clone()),
};
let FromEventsScope {
ref substate_result,
..
} = scope;
let from_events = from_events_fn(element_ty.clone());
let extra_defs = TokenStream::default();
let field_access = scope.access_field(member);
let element_ty = element_ty(Span::call_site());
let default_fn = default_fn(ty.clone());
let builder = from_xml_builder_ty(element_ty.clone());
Ok(FieldBuilderPart::Nested {
extra_defs: TokenStream::default(),
value: FieldTempInit {
init: quote! { #default_fn() },
ty: ty.clone(),
},
matcher: NestedMatcher::Fallback(quote! {
#builder::new(name, attrs)
match self.amount {
AmountConstraint::FixedSingle(_) => {
let missing_msg = error_message::on_missing_child(container_name, member);
let on_absent = quote! {
return ::core::result::Result::Err(::xso::error::Error::Other(#missing_msg).into())
};
Ok(FieldBuilderPart::Nested {
extra_defs,
value: FieldTempInit {
init: quote! { ::core::option::Option::None },
ty: option_ty(ty.clone()),
},
matcher: NestedMatcher::Selective(quote! {
if #field_access.is_some() {
::core::result::Result::Err(::xso::error::FromEventsError::Mismatch { name, attrs })
} else {
#from_events(name, attrs)
}
}),
builder,
collect: quote! {
#field_access = ::core::option::Option::Some(#substate_result);
},
finalize: quote! {
match #field_access {
::core::option::Option::Some(value) => value,
::core::option::Option::None => #on_absent,
}
},
})
}
AmountConstraint::Any(_) => Ok(FieldBuilderPart::Nested {
extra_defs,
value: FieldTempInit {
init: quote! { #default_fn() },
ty: ty.clone(),
},
matcher: NestedMatcher::Fallback(quote! {
#builder::new(name, attrs)
}),
builder,
collect: quote! {
<#ty as ::core::iter::Extend::<#element_ty>>::extend(&mut #field_access, [#substate_result]);
},
finalize: quote! {
#field_access
},
}),
builder,
collect: quote! {
<#ty as ::core::iter::Extend::<#element_ty>>::extend(&mut #field_access, [#substate_result]);
},
finalize: quote! {
#field_access
},
})
}
}
fn make_iterator_part(
@ -71,6 +116,15 @@ impl Field for ElementField {
) -> Result<FieldIteratorPart> {
let AsItemsScope { ref lifetime, .. } = scope;
let item_ty = match self.amount {
AmountConstraint::FixedSingle(_) => ty.clone(),
AmountConstraint::Any(_) => {
// This should give us the type of element stored in the
// collection.
into_iterator_item_ty(ty.clone())
}
};
let element_ty = element_ty(Span::call_site());
let iter_ty = item_iter_ty(element_ty.clone(), lifetime.clone());
let element_iter = into_iterator_iter_ty(ref_ty(ty.clone(), lifetime.clone()));
@ -78,33 +132,49 @@ impl Field for ElementField {
let state_ty = Type::Tuple(TypeTuple {
paren_token: token::Paren::default(),
elems: [element_iter, option_ty(iter_ty)].into_iter().collect(),
elems: [element_iter, option_ty(iter_ty.clone())]
.into_iter()
.collect(),
});
Ok(FieldIteratorPart::Content {
extra_defs: TokenStream::default(),
value: FieldTempInit {
init: quote! {
(#into_iter(#bound_name), ::core::option::Option::None)
let extra_defs = TokenStream::default();
let as_xml_iter = as_xml_iter_fn(item_ty.clone());
let init = quote! { #as_xml_iter(#bound_name)? };
let iter_ty = item_iter_ty(item_ty.clone(), lifetime.clone());
match self.amount {
AmountConstraint::FixedSingle(_) => Ok(FieldIteratorPart::Content {
extra_defs,
value: FieldTempInit { init, ty: iter_ty },
generator: quote! {
#bound_name.next().transpose()
},
ty: state_ty,
},
generator: quote! {
loop {
if let ::core::option::Option::Some(current) = #bound_name.1.as_mut() {
if let ::core::option::Option::Some(item) = current.next() {
break ::core::option::Option::Some(item).transpose();
}),
AmountConstraint::Any(_) => Ok(FieldIteratorPart::Content {
extra_defs,
value: FieldTempInit {
init: quote! {
(#into_iter(#bound_name), ::core::option::Option::None)
},
ty: state_ty,
},
generator: quote! {
loop {
if let ::core::option::Option::Some(current) = #bound_name.1.as_mut() {
if let ::core::option::Option::Some(item) = current.next() {
break ::core::option::Option::Some(item).transpose();
}
}
if let ::core::option::Option::Some(item) = #bound_name.0.next() {
#bound_name.1 = ::core::option::Option::Some(
<#element_ty as ::xso::AsXml>::as_xml_iter(item)?
);
} else {
break ::core::result::Result::Ok(::core::option::Option::None)
}
}
if let ::core::option::Option::Some(item) = #bound_name.0.next() {
#bound_name.1 = ::core::option::Option::Some(
<#element_ty as ::xso::AsXml>::as_xml_iter(item)?
);
} else {
break ::core::result::Result::Ok(::core::option::Option::None)
}
}
},
})
},
}),
}
}
}

19
xso-proc/src/field/mod.rs
View file

@ -358,7 +358,7 @@ fn new_field(
);
err.combine(Error::new(
*amount,
"`n` was set to a non-1 value here, which enables connection logic",
"`n` was set to a non-1 value here, which enables collection logic",
));
return Err(err);
}
@ -406,20 +406,9 @@ fn new_field(
}
#[cfg(feature = "minidom")]
XmlFieldMeta::Element { span, amount } => {
match amount {
Some(AmountConstraint::Any(_)) => (),
Some(AmountConstraint::FixedSingle(span)) => {
return Err(Error::new(
span,
"only `n = ..` is supported for #[xml(element)]` currently",
))
}
None => return Err(Error::new(span, "`n` must be set to `..` currently")),
}
Ok(Box::new(ElementField))
}
XmlFieldMeta::Element { span, amount } => Ok(Box::new(ElementField {
amount: amount.unwrap_or(AmountConstraint::FixedSingle(span)),
})),
#[cfg(not(feature = "minidom"))]
XmlFieldMeta::Element { span, amount } => {

22
xso-proc/src/meta.rs
View file

@ -1035,17 +1035,19 @@ impl XmlFieldMeta {
/// Parse a `#[xml(element)]` meta.
fn element_from_meta(meta: ParseNestedMeta<'_>) -> Result<Self> {
let mut amount = None;
meta.parse_nested_meta(|meta| {
if meta.path.is_ident("n") {
if amount.is_some() {
return Err(Error::new_spanned(meta.path, "duplicate `n` key"));
if meta.input.peek(syn::token::Paren) {
meta.parse_nested_meta(|meta| {
if meta.path.is_ident("n") {
if amount.is_some() {
return Err(Error::new_spanned(meta.path, "duplicate `n` key"));
}
amount = Some(meta.value()?.parse()?);
Ok(())
} else {
Err(Error::new_spanned(meta.path, "unsupported key"))
}
amount = Some(meta.value()?.parse()?);
Ok(())
} else {
Err(Error::new_spanned(meta.path, "unsupported key"))
}
})?;
})?;
}
Ok(Self::Element {
span: meta.path.span(),
amount,