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xso: implement catch-all for unknown elements

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This commit is contained in:
Jonas Schäfer 2024-08-05 08:20:25 +02:00
commit 0361b5905b
10 changed files with 412 additions and 48 deletions
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62
xso-proc/src/compound.rs
View file

@ -11,7 +11,7 @@ use quote::quote;
use syn::{spanned::Spanned, *};
use crate::error_message::ParentRef;
use crate::field::{FieldBuilderPart, FieldDef, FieldIteratorPart, FieldTempInit};
use crate::field::{FieldBuilderPart, FieldDef, FieldIteratorPart, FieldTempInit, NestedMatcher};
use crate::meta::NamespaceRef;
use crate::scope::{mangle_member, AsItemsScope, FromEventsScope};
use crate::state::{AsItemsSubmachine, FromEventsSubmachine, State};
@ -109,6 +109,7 @@ impl Compound {
let mut builder_data_init = TokenStream::default();
let mut output_cons = TokenStream::default();
let mut child_matchers = TokenStream::default();
let mut fallback_child_matcher = None;
let mut text_handler = None;
let mut extra_defs = TokenStream::default();
let is_tuple = !output_name.is_path();
@ -219,18 +220,44 @@ impl Compound {
#builder_field_name: #init,
});
child_matchers.extend(quote! {
let (name, attrs) = match #matcher {
::core::result::Result::Err(::xso::error::FromEventsError::Mismatch { name, attrs }) => (name, attrs),
::core::result::Result::Err(::xso::error::FromEventsError::Invalid(e)) => return ::core::result::Result::Err(e),
::core::result::Result::Ok(#substate_data) => {
return ::core::result::Result::Ok(::core::ops::ControlFlow::Break(Self::#state_name {
#builder_data_ident,
#substate_data,
}))
match matcher {
NestedMatcher::Selective(matcher) => {
child_matchers.extend(quote! {
let (name, attrs) = match #matcher {
::core::result::Result::Err(::xso::error::FromEventsError::Mismatch { name, attrs }) => (name, attrs),
::core::result::Result::Err(::xso::error::FromEventsError::Invalid(e)) => return ::core::result::Result::Err(e),
::core::result::Result::Ok(#substate_data) => {
return ::core::result::Result::Ok(::core::ops::ControlFlow::Break(Self::#state_name {
#builder_data_ident,
#substate_data,
}))
}
};
});
}
NestedMatcher::Fallback(matcher) => {
if let Some((span, _)) = fallback_child_matcher.as_ref() {
let mut err = Error::new(
field.span(),
"more than one field is attempting to consume all unmatched child elements"
);
err.combine(Error::new(
*span,
"the previous field collecting all unmatched child elements is here"
));
return Err(err);
}
};
});
let matcher = quote! {
::core::result::Result::Ok(::core::ops::ControlFlow::Break(Self::#state_name {
#builder_data_ident,
#substate_data: { #matcher },
}))
};
fallback_child_matcher = Some((field.span(), matcher));
}
}
if is_tuple {
output_cons.extend(quote! {
@ -278,6 +305,14 @@ impl Compound {
}
};
let child_fallback = match fallback_child_matcher {
Some((_, matcher)) => matcher,
None => quote! {
let _ = (name, attrs);
::core::result::Result::Err(::xso::error::Error::Other(#unknown_child_err))
},
};
states.push(State::new_with_builder(
default_state_ident.clone(),
builder_data_ident,
@ -292,8 +327,7 @@ impl Compound {
}
::xso::exports::rxml::Event::StartElement(_, name, attrs) => {
#child_matchers
let _ = (name, attrs);
::core::result::Result::Err(::xso::error::Error::Other(#unknown_child_err))
#child_fallback
}
::xso::exports::rxml::Event::Text(_, #text) => {
#text_handler

8
xso-proc/src/field/child.rs
View file

@ -23,7 +23,7 @@ use crate::types::{
option_as_xml_ty, option_ty, ref_ty, ty_from_ident,
};
use super::{Field, FieldBuilderPart, FieldIteratorPart, FieldTempInit};
use super::{Field, FieldBuilderPart, FieldIteratorPart, FieldTempInit, NestedMatcher};
/// The field maps to a child
pub(super) struct ChildField {
@ -101,7 +101,7 @@ impl Field for ChildField {
init: quote! { ::core::option::Option::None },
ty: option_ty(ty.clone()),
},
matcher: quote! {
matcher: NestedMatcher::Selective(quote! {
match #matcher {
::core::result::Result::Ok(v) => if #field_access.is_some() {
::core::result::Result::Err(::xso::error::FromEventsError::Invalid(::xso::error::Error::Other(#duplicate_msg)))
@ -110,7 +110,7 @@ impl Field for ChildField {
},
::core::result::Result::Err(e) => ::core::result::Result::Err(e),
}
},
}),
builder,
collect: quote! {
#field_access = ::core::option::Option::Some(#fetch);
@ -132,7 +132,7 @@ impl Field for ChildField {
init: quote! { #ty_default() },
ty: ty.clone(),
},
matcher,
matcher: NestedMatcher::Selective(matcher),
builder,
collect: quote! {
#ty_extend(&mut #field_access, [#fetch]);

110
xso-proc/src/field/element.rs Normal file
View file

@ -0,0 +1,110 @@
// Copyright (c) 2024 Jonas Schäfer <jonas@zombofant.net>
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
//! This module concerns the processing of untyped `minidom::Element`
//! children.
//!
//! In particular, it provides the `#[xml(element)]` implementation.
use proc_macro2::{Span, TokenStream};
use quote::quote;
use syn::*;
use crate::error_message::ParentRef;
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,
};
use super::{Field, FieldBuilderPart, FieldIteratorPart, FieldTempInit, NestedMatcher};
pub(super) struct ElementField;
impl Field for ElementField {
fn make_builder_part(
&self,
scope: &FromEventsScope,
_container_name: &ParentRef,
member: &Member,
ty: &Type,
) -> Result<FieldBuilderPart> {
let FromEventsScope {
ref substate_result,
..
} = scope;
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)
}),
builder,
collect: quote! {
<#ty as ::core::iter::Extend::<#element_ty>>::extend(&mut #field_access, [#substate_result]);
},
finalize: quote! {
#field_access
},
})
}
fn make_iterator_part(
&self,
scope: &AsItemsScope,
_container_name: &ParentRef,
bound_name: &Ident,
_member: &Member,
ty: &Type,
) -> Result<FieldIteratorPart> {
let AsItemsScope { ref lifetime, .. } = scope;
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()));
let into_iter = into_iterator_into_iter_fn(ref_ty(ty.clone(), lifetime.clone()));
let state_ty = Type::Tuple(TypeTuple {
paren_token: token::Paren::default(),
elems: [element_iter, option_ty(iter_ty)].into_iter().collect(),
});
Ok(FieldIteratorPart::Content {
extra_defs: TokenStream::default(),
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)
}
}
},
})
}
}

75
xso-proc/src/field/mod.rs
View file

@ -18,10 +18,14 @@ use crate::scope::{AsItemsScope, FromEventsScope};
mod attribute;
mod child;
#[cfg(feature = "minidom")]
mod element;
mod text;
use self::attribute::AttributeField;
use self::child::{ChildField, ExtractDef};
#[cfg(feature = "minidom")]
use self::element::ElementField;
use self::text::TextField;
/// Code slices necessary for declaring and initializing a temporary variable
@ -34,6 +38,33 @@ pub(crate) struct FieldTempInit {
pub(crate) init: TokenStream,
}
/// Configure how a nested field builder selects child elements.
pub(crate) enum NestedMatcher {
/// Matches a specific child element fallabily.
Selective(
/// Expression which evaluates to `Result<T, FromEventsError>`,
/// consuming `name: rxml::QName` and `attrs: rxml::AttrMap`.
///
/// `T` must be the type specified in the
/// [`FieldBuilderPart::Nested::builder`] field.
TokenStream,
),
#[cfg_attr(not(feature = "minidom"), allow(dead_code))]
/// Matches any child element not matched by another matcher.
///
/// Only a single field may use this variant, otherwise an error is
/// raised during execution of the proc macro.
Fallback(
/// Expression which evaluates to `T` (or `return`s an error),
/// consuming `name: rxml::QName` and `attrs: rxml::AttrMap`.
///
/// `T` must be the type specified in the
/// [`FieldBuilderPart::Nested::builder`] field.
TokenStream,
),
}
/// Describe how a struct or enum variant's member is parsed from XML data.
///
/// This struct is returned from [`FieldDef::make_builder_part`] and
@ -73,12 +104,9 @@ pub(crate) enum FieldBuilderPart {
/// parsing.
value: FieldTempInit,
/// Expression which evaluates to `Result<T, FromEventsError>`,
/// consuming `name: rxml::QName` and `attrs: rxml::AttrMap`.
///
/// `T` must be the type specified in the
/// [`Self::Nested::builder`] field.
matcher: TokenStream,
/// Configure child matching behaviour for this field. See
/// [`NestedMatcher`] for options.
matcher: NestedMatcher,
/// Type implementing `xso::FromEventsBuilder` which parses the child
/// element.
@ -343,6 +371,31 @@ 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))
}
#[cfg(not(feature = "minidom"))]
XmlFieldMeta::Element { span, amount } => {
let _ = amount;
Err(Error::new(
span,
"#[xml(element)] requires xso to be built with the \"minidom\" feature.",
))
}
}
}
@ -351,6 +404,9 @@ fn new_field(
/// See [`Compound`][`crate::compound::Compound`] for more information on
/// compounds in general.
pub(crate) struct FieldDef {
/// A span which refers to the field's definition.
span: Span,
/// The member identifying the field.
member: Member,
@ -388,6 +444,7 @@ impl FieldDef {
let ty = field.ty.clone();
Ok(Self {
span: field_span,
inner: new_field(meta, ident, &ty, container_namespace)?,
member,
ty,
@ -406,6 +463,7 @@ impl FieldDef {
) -> Result<Self> {
let span = meta.span();
Ok(Self {
span,
member: Member::Unnamed(Index { index, span }),
ty: ty.clone(),
inner: new_field(meta, None, ty, container_namespace)?,
@ -454,4 +512,9 @@ impl FieldDef {
pub(crate) fn is_text_field(&self) -> bool {
self.inner.captures_text()
}
/// Return a span which points at the field's definition.'
pub(crate) fn span(&self) -> Span {
self.span
}
}

34
xso-proc/src/meta.rs
View file

@ -686,6 +686,17 @@ pub(crate) enum XmlFieldMeta {
/// The `fields` nested meta.
fields: Vec<XmlFieldMeta>,
},
/// `#[xml(element)]`
Element {
/// The span of the `#[xml(element)]` meta from which this was parsed.
///
/// This is useful for error messages.
span: Span,
/// The `n` flag.
amount: Option<AmountConstraint>,
},
}
impl XmlFieldMeta {
@ -906,6 +917,26 @@ 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"));
}
amount = Some(meta.value()?.parse()?);
Ok(())
} else {
Err(Error::new_spanned(meta.path, "unsupported key"))
}
})?;
Ok(Self::Element {
span: meta.path.span(),
amount,
})
}
/// Parse [`Self`] from a nestd meta, switching on the identifier
/// of that nested meta.
fn parse_from_meta(meta: ParseNestedMeta<'_>) -> Result<Self> {
@ -917,6 +948,8 @@ impl XmlFieldMeta {
Self::child_from_meta(meta)
} else if meta.path.is_ident("extract") {
Self::extract_from_meta(meta)
} else if meta.path.is_ident("element") {
Self::element_from_meta(meta)
} else {
Err(Error::new_spanned(meta.path, "unsupported field meta"))
}
@ -998,6 +1031,7 @@ impl XmlFieldMeta {
Self::Child { ref span, .. } => *span,
Self::Text { ref span, .. } => *span,
Self::Extract { ref span, .. } => *span,
Self::Element { ref span, .. } => *span,
}
}

33
xso-proc/src/types.rs
View file

@ -783,3 +783,36 @@ pub(crate) fn option_as_xml_ty(inner_ty: Type) -> Type {
},
})
}
/// Construct a [`syn::Type`] referring to `::xso::exports::minidom::Element`.
#[cfg(feature = "minidom")]
pub(crate) fn element_ty(span: Span) -> Type {
Type::Path(TypePath {
qself: None,
path: Path {
leading_colon: Some(syn::token::PathSep {
spans: [span, span],
}),
segments: [
PathSegment {
ident: Ident::new("xso", span),
arguments: PathArguments::None,
},
PathSegment {
ident: Ident::new("exports", span),
arguments: PathArguments::None,
},
PathSegment {
ident: Ident::new("minidom", span),
arguments: PathArguments::None,
},
PathSegment {
ident: Ident::new("Element", span),
arguments: PathArguments::None,
},
]
.into_iter()
.collect(),
},
})
}