xml: Refactoring

crates/xml/derive/src/xml_enum.rs

@@ -0,0 +1,153 @@
+use super::{attrs::EnumAttrs, Variant};
+use crate::attrs::VariantAttrs;
+use core::panic;
+use darling::{FromDeriveInput, FromVariant};
+use quote::quote;
+use syn::{DataEnum, DeriveInput};
+
+pub struct Enum {
+    attrs: EnumAttrs,
+    variants: Vec<Variant>,
+    ident: syn::Ident,
+    generics: syn::Generics,
+}
+
+impl Enum {
+    fn impl_de_untagged(&self) -> proc_macro2::TokenStream {
+        let (impl_generics, type_generics, where_clause) = self.generics.split_for_impl();
+        let name = &self.ident;
+
+        let variant_branches = self
+            .variants
+            .iter()
+            .filter_map(|variant| variant.untagged_branch());
+
+        quote! {
+            impl #impl_generics ::rustical_xml::XmlDeserialize for #name #type_generics #where_clause {
+                fn deserialize<R: ::std::io::BufRead>(
+                    reader: &mut quick_xml::NsReader<R>,
+                    start: &quick_xml::events::BytesStart,
+                    empty: bool
+                ) -> Result<Self, rustical_xml::XmlDeError> {
+                    #(#variant_branches);*
+
+                    Err(rustical_xml::XmlDeError::UnknownError)
+                }
+            }
+        }
+    }
+
+    fn impl_de_tagged(&self) -> proc_macro2::TokenStream {
+        let (impl_generics, type_generics, where_clause) = self.generics.split_for_impl();
+        let name = &self.ident;
+
+        let variant_branches = self.variants.iter().filter_map(Variant::tagged_branch);
+
+        quote! {
+            impl #impl_generics ::rustical_xml::XmlDeserialize for #name #type_generics #where_clause {
+                fn deserialize<R: std::io::BufRead>(
+                    reader: &mut quick_xml::NsReader<R>,
+                    start: &quick_xml::events::BytesStart,
+                    empty: bool
+                ) -> Result<Self, rustical_xml::XmlDeError> {
+                    let (_ns, name) = reader.resolve_element(start.name());
+
+                    match name.as_ref() {
+                        #(#variant_branches),*
+                        name => {
+                            // Handle invalid variant name
+                            Err(rustical_xml::XmlDeError::InvalidVariant(String::from_utf8_lossy(name).to_string()))
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    pub fn impl_de(&self) -> proc_macro2::TokenStream {
+        match self.attrs.untagged.is_present() {
+            true => self.impl_de_untagged(),
+            false => self.impl_de_tagged(),
+        }
+    }
+
+    pub fn parse(input: &DeriveInput, data: &DataEnum) -> Self {
+        let attrs = EnumAttrs::from_derive_input(input).unwrap();
+
+        Self {
+            variants: data
+                .variants
+                .iter()
+                .map(|variant| Variant {
+                    attrs: VariantAttrs::from_variant(variant).unwrap(),
+                    variant: variant.to_owned(),
+                })
+                .collect(),
+            attrs,
+            ident: input.ident.to_owned(),
+            generics: input.generics.to_owned(),
+        }
+    }
+
+    pub fn impl_se(&self) -> proc_macro2::TokenStream {
+        let (impl_generics, type_generics, where_clause) = self.generics.split_for_impl();
+        let ident = &self.ident;
+
+        // TODO: Implement attributes
+        quote! {
+            impl #impl_generics ::rustical_xml::XmlSerialize for #ident #type_generics #where_clause {
+                fn serialize<W: ::std::io::Write>(
+                    &self,
+                    tag: Option<&[u8]>,
+                    writer: &mut ::quick_xml::Writer<W>
+                ) -> ::std::io::Result<()> {
+                    use ::quick_xml::events::{BytesEnd, BytesStart, BytesText, Event};
+
+                    let tag_str = tag.map(String::from_utf8_lossy);
+
+                    if let Some(tag) = &tag_str {
+                        writer.write_event(Event::Start(BytesStart::new(tag.to_owned())))?;
+                    }
+                    if let Some(tag) = &tag_str {
+                        writer.write_event(Event::End(BytesEnd::new(tag.to_owned())))?;
+                    }
+                    Ok(())
+                }
+            }
+        }
+    }
+
+    pub fn impl_xml_document(&self) -> proc_macro2::TokenStream {
+        if self.attrs.untagged.is_present() {
+            panic!("XmlDocument only supported for untagged enums");
+        }
+        let (impl_generics, type_generics, where_clause) = self.generics.split_for_impl();
+        let ident = &self.ident;
+
+        quote! {
+            impl #impl_generics ::rustical_xml::XmlDocument for #ident #type_generics #where_clause {
+                fn parse<R: ::std::io::BufRead>(mut reader: ::quick_xml::NsReader<R>) -> Result<Self, ::rustical_xml::XmlDeError>
+                where
+                    Self: ::rustical_xml::XmlDeserialize
+                {
+                    use ::quick_xml::events::Event;
+
+                    let mut buf = Vec::new();
+                    loop {
+                        let event = reader.read_event_into(&mut buf)?;
+                        let empty = matches!(event, Event::Empty(_));
+
+                        match event {
+                            Event::Decl(_) => { /* <?xml ... ?> ignore this */ }
+                            Event::Comment(_) => { /*  ignore this */ }
+                            Event::Start(start) | Event::Empty(start) => {
+                                return <Self as ::rustical_xml::XmlDeserialize>::deserialize(&mut reader, &start, empty);
+                            }
+                            _ => return Err(::rustical_xml::XmlDeError::UnknownError),
+                        };
+                    }
+                }
+            }
+        }
+    }
+}