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xso-proc: implement support for collections of children

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This commit is contained in:
Jonas Schäfer 2024-07-11 17:29:29 +02:00
commit 93ba2797be
6 changed files with 394 additions and 49 deletions
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203
xso-proc/src/field.rs
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@ -13,12 +13,13 @@ use syn::{spanned::Spanned, *};
use rxml_validation::NcName;
use crate::error_message::{self, ParentRef};
use crate::meta::{Flag, NameRef, NamespaceRef, XmlFieldMeta};
use crate::meta::{AmountConstraint, Flag, NameRef, NamespaceRef, XmlFieldMeta};
use crate::scope::{AsItemsScope, FromEventsScope};
use crate::types::{
as_optional_xml_text_fn, as_xml_iter_fn, as_xml_text_fn, default_fn, from_events_fn,
from_xml_builder_ty, from_xml_text_fn, item_iter_ty, option_ty, string_ty,
text_codec_decode_fn, text_codec_encode_fn,
as_optional_xml_text_fn, as_xml_iter_fn, as_xml_text_fn, default_fn, extend_fn, from_events_fn,
from_xml_builder_ty, from_xml_text_fn, into_iterator_into_iter_fn, into_iterator_item_ty,
into_iterator_iter_ty, item_iter_ty, option_ty, ref_ty, string_ty, text_codec_decode_fn,
text_codec_encode_fn,
};
/// Code slices necessary for declaring and initializing a temporary variable
@ -140,8 +141,8 @@ enum FieldKind {
/// The XML name of the attribute.
xml_name: NameRef,
// Flag indicating whether the value should be defaulted if the
// attribute is absent.
/// Flag indicating whether the value should be defaulted if the
/// attribute is absent.
default_: Flag,
},
@ -153,9 +154,12 @@ enum FieldKind {
/// The field maps to a child
Child {
// Flag indicating whether the value should be defaulted if the
// child is absent.
/// Flag indicating whether the value should be defaulted if the
/// child is absent.
default_: Flag,
/// Number of child elements allowed.
amount: AmountConstraint,
},
}
@ -203,7 +207,26 @@ impl FieldKind {
XmlFieldMeta::Text { codec } => Ok(Self::Text { codec }),
XmlFieldMeta::Child { default_ } => Ok(Self::Child { default_ }),
XmlFieldMeta::Child { default_, amount } => {
if let Some(AmountConstraint::Any(ref amount_span)) = amount {
if let Flag::Present(ref flag_span) = default_ {
let mut err = Error::new(
*flag_span,
"`default` has no meaning for child collections",
);
err.combine(Error::new(
*amount_span,
"the field is treated as a collection because of this `n` value",
));
return Err(err);
}
}
Ok(Self::Child {
default_,
amount: amount.unwrap_or(AmountConstraint::FixedSingle(Span::call_site())),
})
}
}
}
}
@ -345,49 +368,79 @@ impl FieldDef {
})
}
FieldKind::Child { ref default_ } => {
FieldKind::Child {
ref default_,
ref amount,
} => {
let FromEventsScope {
ref substate_result,
..
} = scope;
let field_access = scope.access_field(&self.member);
let missing_msg = error_message::on_missing_child(container_name, &self.member);
let from_events = from_events_fn(self.ty.clone());
let from_xml_builder = from_xml_builder_ty(self.ty.clone());
let on_absent = match default_ {
Flag::Absent => quote! {
return ::core::result::Result::Err(::xso::error::Error::Other(#missing_msg).into())
},
Flag::Present(_) => {
let default_ = default_fn(self.ty.clone());
quote! {
#default_()
}
}
let element_ty = match amount {
AmountConstraint::FixedSingle(_) => self.ty.clone(),
AmountConstraint::Any(_) => into_iterator_item_ty(self.ty.clone()),
};
Ok(FieldBuilderPart::Nested {
value: FieldTempInit {
init: quote! { ::std::option::Option::None },
ty: option_ty(self.ty.clone()),
},
matcher: quote! {
#from_events(name, attrs)
},
builder: from_xml_builder,
collect: quote! {
#field_access = ::std::option::Option::Some(#substate_result);
},
finalize: quote! {
match #field_access {
::std::option::Option::Some(value) => value,
::std::option::Option::None => #on_absent,
}
},
})
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;
match amount {
AmountConstraint::FixedSingle(_) => {
let missing_msg =
error_message::on_missing_child(container_name, &self.member);
let on_absent = match default_ {
Flag::Absent => quote! {
return ::core::result::Result::Err(::xso::error::Error::Other(#missing_msg).into())
},
Flag::Present(_) => {
let default_ = default_fn(self.ty.clone());
quote! {
#default_()
}
}
};
Ok(FieldBuilderPart::Nested {
value: FieldTempInit {
init: quote! { ::std::option::Option::None },
ty: option_ty(self.ty.clone()),
},
matcher,
builder,
collect: quote! {
#field_access = ::std::option::Option::Some(#substate_result);
},
finalize: quote! {
match #field_access {
::std::option::Option::Some(value) => value,
::std::option::Option::None => #on_absent,
}
},
})
}
AmountConstraint::Any(_) => {
let ty_extend = extend_fn(self.ty.clone(), element_ty.clone());
let ty_default = default_fn(self.ty.clone());
Ok(FieldBuilderPart::Nested {
value: FieldTempInit {
init: quote! { #ty_default() },
ty: self.ty.clone(),
},
matcher,
builder,
collect: quote! {
#ty_extend(&mut #field_access, [#substate_result]);
},
finalize: quote! { #field_access },
})
}
}
}
}
}
@ -442,7 +495,10 @@ impl FieldDef {
Ok(FieldIteratorPart::Text { generator })
}
FieldKind::Child { default_: _ } => {
FieldKind::Child {
default_: _,
amount: AmountConstraint::FixedSingle(_),
} => {
let AsItemsScope { ref lifetime, .. } = scope;
let as_xml_iter = as_xml_iter_fn(self.ty.clone());
@ -460,6 +516,63 @@ impl FieldDef {
},
})
}
FieldKind::Child {
default_: _,
amount: AmountConstraint::Any(_),
} => {
let AsItemsScope { ref lifetime, .. } = scope;
// This should give us the type of element stored in the
// collection.
let element_ty = into_iterator_item_ty(self.ty.clone());
// And this is the collection type we actually work with --
// as_xml_iter uses references after all.
let ty = ref_ty(self.ty.clone(), lifetime.clone());
// as_xml_iter is called on the bare type (not the ref type)
let as_xml_iter = as_xml_iter_fn(element_ty.clone());
// And thus the iterator associated with AsXml is also derived
// from the bare type.
let item_iter = item_iter_ty(element_ty.clone(), lifetime.clone());
// But the iterator for iterating over the elements inside the
// collection must use the ref type.
let element_iter = into_iterator_iter_ty(ty.clone());
// And likewise the into_iter impl.
let into_iter = into_iterator_into_iter_fn(ty.clone());
let state_ty = Type::Tuple(TypeTuple {
paren_token: token::Paren::default(),
elems: [element_iter, option_ty(item_iter)].into_iter().collect(),
});
Ok(FieldIteratorPart::Content {
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(#as_xml_iter(item)?)
} else {
break ::core::result::Result::Ok(::core::option::Option::None)
}
}
},
})
}
}
}