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https://github.com/lennart-k/rustical.git
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xml: Refactoring
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Lennart
271
crates/xml/derive/src/field.rs
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271
crates/xml/derive/src/field.rs
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@@ -0,0 +1,271 @@
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use super::{
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attrs::{ContainerAttrs, FieldAttrs, FieldType},
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get_generic_type,
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};
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use darling::FromField;
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use heck::ToKebabCase;
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use quote::quote;
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fn wrap_option_if_no_default(
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value: proc_macro2::TokenStream,
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has_default: bool,
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) -> proc_macro2::TokenStream {
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if has_default {
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value
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} else {
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quote! {Some(#value)}
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}
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}
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pub struct Field {
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pub field: syn::Field,
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pub attrs: FieldAttrs,
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pub container_attrs: ContainerAttrs,
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}
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impl Field {
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pub fn from_syn_field(field: syn::Field, container_attrs: ContainerAttrs) -> Self {
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Self {
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attrs: FieldAttrs::from_field(&field).unwrap(),
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field,
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container_attrs,
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}
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}
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/// Field name in XML
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pub fn xml_name(&self) -> syn::LitByteStr {
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self.attrs
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.common
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.rename
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.to_owned()
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.unwrap_or(syn::LitByteStr::new(
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self.field_ident().to_string().to_kebab_case().as_bytes(),
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self.field_ident().span(),
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))
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}
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/// Whether to enforce the correct XML namespace
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pub fn ns_strict(&self) -> bool {
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self.attrs.common.ns_strict.is_present() || self.container_attrs.ns_strict.is_present()
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}
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/// Field identifier
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pub fn field_ident(&self) -> &syn::Ident {
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self.field
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.ident
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.as_ref()
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.expect("tuple structs not supported")
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}
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fn is_optional(&self) -> bool {
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if let syn::Type::Path(syn::TypePath { path, .. }) = &self.field.ty {
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if path.segments.len() != 1 {
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return false;
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}
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let type_ident = &path.segments.first().unwrap().ident;
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let option: syn::Ident = syn::parse_str("Option").unwrap();
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return type_ident == &option;
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}
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false
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}
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/// The type to deserialize to
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/// - type Option<T> => optional: deserialize with T
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/// - flatten Vec<T>: deserialize with T
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/// - deserialize with T
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pub fn deserializer_type(&self) -> &syn::Type {
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if self.is_optional() {
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return get_generic_type(&self.field.ty).unwrap();
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}
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if self.attrs.flatten.is_present() {
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return get_generic_type(&self.field.ty).expect("flatten attribute only implemented for explicit generics (rustical_xml will assume the first generic as the inner type)");
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}
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&self.field.ty
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}
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/// Field in the builder struct for the deserializer
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pub fn builder_field(&self) -> proc_macro2::TokenStream {
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let field_ident = self.field_ident();
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let ty = self.deserializer_type();
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let builder_field_type = match (
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self.attrs.flatten.is_present(),
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&self.attrs.default,
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self.is_optional(),
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) {
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(_, Some(_default), true) => panic!("default value for Option<T> doesn't make sense"),
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(_, Some(_default), false) => quote! { #ty },
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(true, None, true) => panic!("cannot flatten Option<T>"),
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(true, None, false) => quote! { Vec<#ty> },
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(false, None, _) => quote! { Option<#ty> },
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};
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quote! { #field_ident: #builder_field_type }
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}
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/// Field initialiser in the builder struct for the deserializer
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pub fn builder_field_init(&self) -> proc_macro2::TokenStream {
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let field_ident = self.field_ident();
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let builder_field_initialiser = match (
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self.attrs.flatten.is_present(),
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&self.attrs.default,
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self.is_optional(),
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) {
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(_, Some(_), true) => unreachable!(),
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(_, Some(default), false) => quote! { #default() },
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(true, None, true) => unreachable!(),
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(true, None, false) => quote! { vec![] },
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(false, None, _) => quote! { None },
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};
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quote! { #field_ident: #builder_field_initialiser }
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}
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/// Map builder field to target field
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pub fn builder_field_build(&self) -> proc_macro2::TokenStream {
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let field_ident = self.field_ident();
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let builder_value = match (
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self.attrs.flatten.is_present(),
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self.attrs.default.is_some(),
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self.is_optional(),
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) {
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(true, _, true) => unreachable!(),
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(true, _, false) => {
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quote! { FromIterator::from_iter(builder.#field_ident.into_iter()) }
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}
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(false, true, true) => unreachable!(),
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(false, true, false) => quote! { builder.#field_ident },
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(false, false, true) => quote! { builder.#field_ident },
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(false, false, false) => {
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quote! { builder.#field_ident.expect("todo: handle missing field") }
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}
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};
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quote! { #field_ident: #builder_value }
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}
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pub fn named_branch(&self) -> Option<proc_macro2::TokenStream> {
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if self.attrs.xml_ty != FieldType::Tag {
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return None;
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}
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let namespace_match = if self.ns_strict() {
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if let Some(ns) = &self.attrs.common.ns {
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quote! {quick_xml::name::ResolveResult::Bound(quick_xml::name::Namespace(#ns))}
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} else {
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quote! {quick_xml::name::ResolveResult::Unbound}
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}
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} else {
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quote! {_}
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};
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let field_name = self.xml_name();
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let field_ident = self.field_ident();
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let deserializer = self.deserializer_type();
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let value = quote! { <#deserializer as rustical_xml::XmlDeserialize>::deserialize(reader, &start, empty)? };
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let assignment = match (self.attrs.flatten.is_present(), &self.attrs.default) {
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(true, _) => {
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quote! { builder.#field_ident.push(#value); }
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}
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(false, Some(_default)) => quote! { builder.#field_ident = #value; },
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(false, None) => quote! { builder.#field_ident = Some(#value); },
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};
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Some(quote! {
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(#namespace_match, #field_name) => { #assignment; }
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})
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}
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pub fn untagged_branch(&self) -> Option<proc_macro2::TokenStream> {
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if self.attrs.xml_ty != FieldType::Untagged {
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return None;
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}
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let field_ident = self.field_ident();
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let deserializer = self.deserializer_type();
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let value = quote! { <#deserializer as rustical_xml::XmlDeserialize>::deserialize(reader, &start, empty)? };
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Some(if self.attrs.flatten.is_present() {
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quote! {
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_ => { builder.#field_ident.push(#value); }
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}
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} else {
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quote! {
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_ => { builder.#field_ident = Some(#value); }
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}
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})
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}
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pub fn text_branch(&self) -> Option<proc_macro2::TokenStream> {
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if self.attrs.xml_ty != FieldType::Text {
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return None;
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}
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let field_ident = self.field_ident();
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let value = wrap_option_if_no_default(
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quote! {
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rustical_xml::Value::deserialize(text.as_ref())?
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},
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self.attrs.default.is_some(),
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);
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Some(quote! {
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builder.#field_ident = #value;
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})
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}
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pub fn attr_branch(&self) -> Option<proc_macro2::TokenStream> {
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if self.attrs.xml_ty != FieldType::Attr {
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return None;
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}
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let field_ident = self.field_ident();
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let field_name = self.xml_name();
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let value = wrap_option_if_no_default(
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quote! {
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rustical_xml::Value::deserialize(attr.unescape_value()?.as_ref())?
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},
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self.attrs.default.is_some(),
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);
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Some(quote! {
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#field_name => {
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builder.#field_ident = #value;
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}
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})
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}
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pub fn tagname_branch(&self) -> Option<proc_macro2::TokenStream> {
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if self.attrs.xml_ty != FieldType::TagName {
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return None;
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}
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let field_ident = self.field_ident();
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let value = wrap_option_if_no_default(
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quote! {
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rustical_xml::Value::deserialize(&String::from_utf8_lossy(name.as_ref()))?
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},
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self.attrs.default.is_some(),
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);
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Some(quote! {
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builder.#field_ident = #value;
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})
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}
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pub fn tag_writer(&self) -> Option<proc_macro2::TokenStream> {
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let field_ident = self.field_ident();
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let field_name = self.xml_name();
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match self.attrs.xml_ty {
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FieldType::Attr => None,
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FieldType::Text => Some(quote! {
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writer.write_event(Event::Text(BytesText::new(&self.#field_ident)))?;
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}),
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FieldType::Tag => Some(quote! {
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self.#field_ident.serialize(Some(#field_name), writer)?;
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}),
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FieldType::Untagged => Some(quote! {
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// TODO: untag!
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self.#field_ident.serialize(None, writer)?;
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}),
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// TODO: Think about what to do here
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FieldType::TagName | FieldType::Namespace => None,
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}
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}
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}
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