WIP: Start implementing precondition errors

crates/xml/derive/src/xml_struct/mod.rs

@@ -0,0 +1,195 @@
+use crate::Field;
+use crate::attrs::StructAttrs;
+use core::panic;
+use darling::FromDeriveInput;
+use quote::quote;
+use syn::{DataStruct, DeriveInput};
+
+mod impl_se;
+
+fn invalid_field_branch(ident: &syn::Ident, allow: bool) -> proc_macro2::TokenStream {
+    let ident = ident.to_string();
+    if allow {
+        quote! {}
+    } else {
+        quote! {
+        return Err(XmlError::InvalidFieldName(#ident, format!("[{ns:?}]{tag}", tag = String::from_utf8_lossy(tag)))) }
+    }
+}
+
+impl NamedStruct {
+    pub fn parse(input: &DeriveInput, data: &DataStruct) -> Self {
+        let attrs = StructAttrs::from_derive_input(input).unwrap();
+
+        let fields = match &data.fields {
+            syn::Fields::Named(named) => named
+                .named
+                .iter()
+                .enumerate()
+                .map(|(i, field)| Field::from_syn_field(field.to_owned(), i))
+                .collect(),
+            syn::Fields::Unnamed(unnamed) => unnamed
+                .unnamed
+                .iter()
+                .enumerate()
+                .map(|(i, field)| Field::from_syn_field(field.to_owned(), i))
+                .collect(),
+            syn::Fields::Unit => vec![],
+        };
+
+        NamedStruct {
+            fields,
+            attrs,
+            ident: input.ident.to_owned(),
+            generics: input.generics.to_owned(),
+        }
+    }
+}
+
+pub struct NamedStruct {
+    attrs: StructAttrs,
+    fields: Vec<Field>,
+    ident: syn::Ident,
+    generics: syn::Generics,
+}
+
+impl NamedStruct {
+    pub fn impl_xml_root_tag(&self) -> proc_macro2::TokenStream {
+        let (impl_generics, type_generics, where_clause) = self.generics.split_for_impl();
+        let ident = &self.ident;
+        let root = self.attrs.root.as_ref().expect("No root attribute found");
+        let ns = match &self.attrs.ns {
+            Some(ns) => quote! { Some(#ns) },
+            None => quote! { None },
+        };
+
+        let prefixes = if self.attrs.root.is_some() {
+            self.attrs
+                .ns_prefix
+                .iter()
+                .map(|(ns, prefix)| {
+                    quote! { (#ns, #prefix.as_ref()) }
+                })
+                .collect()
+        } else {
+            vec![]
+        };
+
+        quote! {
+            impl #impl_generics ::rustical_xml::XmlRootTag for #ident #type_generics #where_clause {
+                fn root_tag() -> &'static [u8] { #root }
+                fn root_ns() -> Option<::quick_xml::name::Namespace<'static>> { #ns }
+                fn root_ns_prefixes() -> ::std::collections::HashMap<::quick_xml::name::Namespace<'static>, &'static [u8]> {
+                    ::std::collections::HashMap::from_iter(vec![
+                        #(#prefixes),*
+                    ])
+                }
+            }
+        }
+    }
+
+    pub fn impl_de(&self) -> proc_macro2::TokenStream {
+        let builder_generics = &self.generics;
+        let (impl_generics, type_generics, where_clause) = self.generics.split_for_impl();
+        let ident = &self.ident;
+
+        let builder_fields = self.fields.iter().map(Field::builder_field);
+        let builder_field_inits = self.fields.iter().map(Field::builder_field_init);
+        let named_field_branches = self.fields.iter().filter_map(Field::named_branch);
+        let untagged_field_branches: Vec<_> = self
+            .fields
+            .iter()
+            .filter_map(Field::untagged_branch)
+            .collect();
+        if untagged_field_branches.len() > 1 {
+            panic!("Currently only one untagged field supported!");
+        }
+        let text_field_branches: Vec<_> =
+            self.fields.iter().filter_map(Field::text_branch).collect();
+        let attr_field_branches = self.fields.iter().filter_map(Field::attr_branch);
+        let tagname_field_branches = self.fields.iter().filter_map(Field::tagname_branch);
+        let namespace_field_branches = self.fields.iter().filter_map(Field::namespace_branch);
+
+        let builder_field_builds = self.fields.iter().map(Field::builder_field_build);
+
+        let invalid_field_branch =
+            invalid_field_branch(ident, self.attrs.allow_invalid.is_present());
+
+        quote! {
+            impl #impl_generics ::rustical_xml::XmlDeserialize for #ident #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::XmlError> {
+                    use quick_xml::events::Event;
+                    use rustical_xml::XmlError;
+
+                    let mut buf = Vec::new();
+
+                    // initialise fields
+                    struct StructBuilder #builder_generics {
+                        #(#builder_fields),*
+                    }
+
+                    let mut builder = StructBuilder {
+                        #(#builder_field_inits),*
+                    };
+
+                    let (ns, name) = reader.resolve_element(start.name());
+                    #(#tagname_field_branches);*
+                    #(#namespace_field_branches);*
+
+                    for attr in start.attributes() {
+                        let attr = attr?;
+                        match attr.key.as_ref() {
+                            #(#attr_field_branches),*
+                            _ => { /* ignore */ }
+                        }
+                    }
+
+                    if !empty {
+                        loop {
+                            let event = reader.read_event_into(&mut buf)?;
+                            match &event {
+                                Event::End(e) if e.name() == start.name() => {
+                                    break;
+                                }
+                                Event::Eof => return Err(XmlError::Eof),
+                                // start of a child element
+                                Event::Start(start) | Event::Empty(start) => {
+                                    let empty = matches!(event, Event::Empty(_));
+                                    let (ns, name) = reader.resolve_element(start.name());
+                                    match (ns, name.as_ref()) {
+                                        #(#named_field_branches),*
+                                        #(#untagged_field_branches),*
+                                        (ns, tag) => { #invalid_field_branch }
+                                    }
+                                }
+                                Event::Text(bytes_text) => {
+                                    let text = bytes_text.unescape()?;
+                                    #(#text_field_branches)*
+                                }
+                                Event::CData(cdata) => {
+                                    let text = String::from_utf8(cdata.to_vec())?;
+                                    #(#text_field_branches)*
+                                }
+                                Event::Decl(_) => { /* <?xml ... ?> ignore this */ }
+                                Event::Comment(_) => { /* ignore */ }
+                                Event::DocType(_) => { /* ignore */ }
+                                Event::PI(_) => { /* ignore */ }
+                                Event::End(end) => {
+                                    unreachable!("Unexpected closing tag for wrong element, should be handled by quick_xml");
+                                }
+                            }
+                        }
+                    }
+
+                    Ok(Self {
+                        #(#builder_field_builds),*
+                    })
+                }
+            }
+        }
+    }
+}