smodel-proc 1.0.11

Symbol semantic modeling for Rust: procedural macros.
Documentation 
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use crate::*;

pub struct ProcessingStep3_2();

impl ProcessingStep3_2 {
    pub fn exec(&self, host: &mut SModelHost, smtype: &Symbol, field: &Rc<SmTypeField>, base_accessor: &str, asc_smtype_list: &[Symbol], field_output: &mut proc_macro2::TokenStream) -> bool {
        // 1. Create a FieldSlot.
        let slot = host.factory.create_field_slot(field.is_ref, field.name.to_string(), field.type_annotation.clone(), field.default_value.clone());

        // 2. Contribute the field slot to the type slot.
        if smtype.fields().has(&slot.name()) {
            field.name.span().unwrap().error(format!("Redefining '{}'", slot.name())).emit();
            return false;
        } else {
            smtype.fields().set(slot.name(), slot.clone());
        }

        // 3. Contribute a field to the #DATA::M structure.
        let field_name = slot.name();
        let field_name_id = Ident::new(&field_name, Span::call_site());
        let field_type = slot.field_type();
        if slot.is_ref() {
            field_output.extend(quote! {
                pub #field_name_id: ::std::cell::RefCell<#field_type>,
            });
        } else {
            field_output.extend(quote! {
                pub #field_name_id: ::std::cell::Cell<#field_type>,
            });
        }

        // 4. Define accessors
        self.define_accessors(host, smtype, &slot, &field_name, &field_type, base_accessor, asc_smtype_list);

        true
    }

    fn define_accessors(&self, _host: &mut SModelHost, smtype: &Symbol, slot: &Symbol, field_name: &str, field_type: &Type, base_accessor: &str, asc_smtype_list: &[Symbol]) {
        let getter_name = Ident::new(&field_name, Span::call_site());
        let setter_name = Ident::new(&format!("set_{}", field_name), Span::call_site());
        let fv = proc_macro2::TokenStream::from_str(&self.match_field(asc_smtype_list, 0, &format!("{base_accessor}.upgrade().unwrap()"), field_name)).unwrap();

        if slot.is_ref() {
            smtype.method_output().borrow_mut().extend(quote! {
                #[allow(non_snake_case)]
                fn #getter_name(&self) -> #field_type {
                    #fv.borrow().clone()
                }
                #[allow(non_snake_case)]
                fn #setter_name(&self, v: #field_type) {
                    #fv.replace(v);
                }
            });
        } else {
            smtype.method_output().borrow_mut().extend(quote! {
                #[allow(non_snake_case)]
                fn #getter_name(&self) -> #field_type {
                    #fv.get()
                }

                #[allow(non_snake_case)]
                fn #setter_name(&self, v: #field_type) {
                    #fv.set(v);
                }
            });
        }
    }

    /// Matches a field. `base` is assumed to be a `Rc<#DATA::M>` value.
    fn match_field(&self, asc_smtype_list: &[Symbol], smtype_index: usize, base: &str, field_name: &str) -> String {
        let (smtype, inherited) = if smtype_index + 1 >= asc_smtype_list.len() {
            (asc_smtype_list[smtype_index].clone(), None)
        } else {
            (asc_smtype_list[smtype_index + 1].clone(), Some(asc_smtype_list[smtype_index].clone()))
        };

        let Some(inherited) = inherited else {
            return format!("(&{}.{})", base, field_name);
        };
        format!("(if let {DATA}::{}::{}(o) = &{base}.{DATA_VARIANT_FIELD} {{ {} }} else {{ panic!() }})",
            DATA_VARIANT_PREFIX.to_owned() + &inherited.name(),
            DATA_PREFIX.to_owned() + &smtype.name(),
            self.match_field(asc_smtype_list, smtype_index + 1, "o", field_name))
    }
}