xso-proc: refactor struct processing
If we are going to support structs with fields, it would be good to have that struct-related code organised a little and less splashed over the main lib.rs file.
This commit is contained in:
Jonas Schäfer
parent
2efef5ceeb
commit
bf7816d321
2 changed files with 243 additions and 143 deletions
218
xso-proc/src/structs.rs
Normal file
218
xso-proc/src/structs.rs
Normal file
|
|
@ -0,0 +1,218 @@
|
|||
// 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/.
|
||||
|
||||
//! Handling of structs
|
||||
|
||||
use proc_macro2::TokenStream;
|
||||
use quote::quote;
|
||||
use syn::*;
|
||||
|
||||
use crate::meta::{NameRef, NamespaceRef, XmlCompoundMeta};
|
||||
|
||||
/// Parts necessary to construct a `::xso::FromXml` implementation.
|
||||
pub(crate) struct FromXmlParts {
|
||||
/// Additional items necessary for the implementation.
|
||||
pub(crate) defs: TokenStream,
|
||||
|
||||
/// The body of the `::xso::FromXml::from_xml` function.
|
||||
pub(crate) from_events_body: TokenStream,
|
||||
|
||||
/// The name of the type which is the `::xso::FromXml::Builder`.
|
||||
pub(crate) builder_ty_ident: Ident,
|
||||
}
|
||||
|
||||
/// Parts necessary to construct a `::xso::IntoXml` implementation.
|
||||
pub(crate) struct IntoXmlParts {
|
||||
/// Additional items necessary for the implementation.
|
||||
pub(crate) defs: TokenStream,
|
||||
|
||||
/// The body of the `::xso::IntoXml::into_event_iter` function.
|
||||
pub(crate) into_event_iter_body: TokenStream,
|
||||
|
||||
/// The name of the type which is the `::xso::IntoXml::EventIter`.
|
||||
pub(crate) event_iter_ty_ident: Ident,
|
||||
}
|
||||
|
||||
/// Definition of a struct and how to parse it.
|
||||
pub(crate) struct StructDef {
|
||||
/// The XML namespace of the element to map the struct to.
|
||||
namespace: NamespaceRef,
|
||||
|
||||
/// The XML name of the element to map the struct to.
|
||||
name: NameRef,
|
||||
|
||||
/// Name of the target type.
|
||||
target_ty_ident: Ident,
|
||||
|
||||
/// Name of the builder type.
|
||||
builder_ty_ident: Ident,
|
||||
|
||||
/// Name of the iterator type.
|
||||
event_iter_ty_ident: Ident,
|
||||
}
|
||||
|
||||
impl StructDef {
|
||||
/// Create a new struct from its name, meta, and fields.
|
||||
pub(crate) fn new(ident: &Ident, meta: XmlCompoundMeta, fields: &Fields) -> Result<Self> {
|
||||
let Some(namespace) = meta.namespace else {
|
||||
return Err(Error::new(meta.span, "`namespace` is required on structs"));
|
||||
};
|
||||
|
||||
let Some(name) = meta.name else {
|
||||
return Err(Error::new(meta.span, "`name` is required on structs"));
|
||||
};
|
||||
|
||||
match fields {
|
||||
Fields::Unit => (),
|
||||
other => {
|
||||
return Err(Error::new_spanned(
|
||||
other,
|
||||
"cannot derive on non-unit struct (yet!)",
|
||||
))
|
||||
}
|
||||
}
|
||||
|
||||
Ok(Self {
|
||||
namespace,
|
||||
name,
|
||||
target_ty_ident: ident.clone(),
|
||||
builder_ty_ident: quote::format_ident!("{}FromXmlBuilder", ident),
|
||||
event_iter_ty_ident: quote::format_ident!("{}IntoXmlIterator", ident),
|
||||
})
|
||||
}
|
||||
|
||||
pub(crate) fn make_from_events_builder(
|
||||
&self,
|
||||
vis: &Visibility,
|
||||
name_ident: &Ident,
|
||||
attrs_ident: &Ident,
|
||||
) -> Result<FromXmlParts> {
|
||||
let xml_namespace = &self.namespace;
|
||||
let xml_name = &self.name;
|
||||
|
||||
let target_ty_ident = &self.target_ty_ident;
|
||||
let builder_ty_ident = &self.builder_ty_ident;
|
||||
let state_ty_name = quote::format_ident!("{}State", builder_ty_ident);
|
||||
|
||||
let unknown_attr_err = format!(
|
||||
"Unknown attribute in {} element.",
|
||||
xml_name.repr_to_string()
|
||||
);
|
||||
let unknown_child_err = format!("Unknown child in {} element.", xml_name.repr_to_string());
|
||||
|
||||
let docstr = format!("Build a [`{}`] from XML events", target_ty_ident);
|
||||
|
||||
Ok(FromXmlParts {
|
||||
defs: quote! {
|
||||
enum #state_ty_name {
|
||||
Default,
|
||||
}
|
||||
|
||||
#[doc = #docstr]
|
||||
#vis struct #builder_ty_ident(::core::option::Option<#state_ty_name>);
|
||||
|
||||
impl ::xso::FromEventsBuilder for #builder_ty_ident {
|
||||
type Output = #target_ty_ident;
|
||||
|
||||
fn feed(
|
||||
&mut self,
|
||||
ev: ::xso::exports::rxml::Event
|
||||
) -> ::core::result::Result<::core::option::Option<Self::Output>, ::xso::error::Error> {
|
||||
match self.0 {
|
||||
::core::option::Option::None => panic!("feed() called after it returned a non-None value"),
|
||||
::core::option::Option::Some(#state_ty_name::Default) => match ev {
|
||||
::xso::exports::rxml::Event::StartElement(..) => {
|
||||
::core::result::Result::Err(::xso::error::Error::Other(#unknown_child_err))
|
||||
}
|
||||
::xso::exports::rxml::Event::EndElement(..) => {
|
||||
self.0 = ::core::option::Option::None;
|
||||
::core::result::Result::Ok(::core::option::Option::Some(#target_ty_ident))
|
||||
}
|
||||
::xso::exports::rxml::Event::Text(..) => {
|
||||
::core::result::Result::Err(::xso::error::Error::Other("Unexpected text content".into()))
|
||||
}
|
||||
// we ignore these: a correct parser only generates
|
||||
// them at document start, and there we want to indeed
|
||||
// not worry about them being in front of the first
|
||||
// element.
|
||||
::xso::exports::rxml::Event::XmlDeclaration(_, ::xso::exports::rxml::XmlVersion::V1_0) => ::core::result::Result::Ok(::core::option::Option::None)
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
},
|
||||
from_events_body: quote! {
|
||||
if #name_ident.0 != #xml_namespace || #name_ident.1 != #xml_name {
|
||||
return ::core::result::Result::Err(::xso::error::FromEventsError::Mismatch {
|
||||
name: #name_ident,
|
||||
attrs: #attrs_ident,
|
||||
});
|
||||
}
|
||||
if attrs.len() > 0 {
|
||||
return ::core::result::Result::Err(::xso::error::Error::Other(
|
||||
#unknown_attr_err,
|
||||
).into());
|
||||
}
|
||||
::core::result::Result::Ok(#builder_ty_ident(::core::option::Option::Some(#state_ty_name::Default)))
|
||||
},
|
||||
builder_ty_ident: builder_ty_ident.clone(),
|
||||
})
|
||||
}
|
||||
|
||||
pub(crate) fn make_into_event_iter(&self, vis: &Visibility) -> Result<IntoXmlParts> {
|
||||
let xml_namespace = &self.namespace;
|
||||
let xml_name = &self.name;
|
||||
|
||||
let target_ty_ident = &self.target_ty_ident;
|
||||
let event_iter_ty_ident = &self.event_iter_ty_ident;
|
||||
let state_ty_name = quote::format_ident!("{}State", event_iter_ty_ident);
|
||||
|
||||
let docstr = format!("Decompose a [`{}`] into XML events", target_ty_ident);
|
||||
|
||||
Ok(IntoXmlParts {
|
||||
defs: quote! {
|
||||
enum #state_ty_name {
|
||||
Header,
|
||||
Footer,
|
||||
}
|
||||
|
||||
#[doc = #docstr]
|
||||
#vis struct #event_iter_ty_ident(::core::option::Option<#state_ty_name>);
|
||||
|
||||
impl ::std::iter::Iterator for #event_iter_ty_ident {
|
||||
type Item = ::core::result::Result<::xso::exports::rxml::Event, ::xso::error::Error>;
|
||||
|
||||
fn next(&mut self) -> ::core::option::Option<Self::Item> {
|
||||
match self.0 {
|
||||
::core::option::Option::Some(#state_ty_name::Header) => {
|
||||
self.0 = ::core::option::Option::Some(#state_ty_name::Footer);
|
||||
::core::option::Option::Some(::core::result::Result::Ok(::xso::exports::rxml::Event::StartElement(
|
||||
::xso::exports::rxml::parser::EventMetrics::zero(),
|
||||
(
|
||||
::xso::exports::rxml::Namespace::from_str(#xml_namespace),
|
||||
#xml_name.to_owned(),
|
||||
),
|
||||
::xso::exports::rxml::AttrMap::new(),
|
||||
)))
|
||||
}
|
||||
::core::option::Option::Some(#state_ty_name::Footer) => {
|
||||
self.0 = ::core::option::Option::None;
|
||||
::core::option::Option::Some(::core::result::Result::Ok(::xso::exports::rxml::Event::EndElement(
|
||||
::xso::exports::rxml::parser::EventMetrics::zero(),
|
||||
)))
|
||||
}
|
||||
::core::option::Option::None => ::core::option::Option::None,
|
||||
}
|
||||
}
|
||||
}
|
||||
},
|
||||
into_event_iter_body: quote! {
|
||||
::core::result::Result::Ok(#event_iter_ty_ident(::core::option::Option::Some(#state_ty_name::Header)))
|
||||
},
|
||||
event_iter_ty_ident: event_iter_ty_ident.clone(),
|
||||
})
|
||||
}
|
||||
}
|
||||
Loading…
Reference in a new issue