glib-macros: prototype porting wrapper to a proc macro

Author: jf2048

glib-macros/src/lib.rs

@@ -13,6 +13,7 @@ mod object_subclass_attribute;
 mod properties;
 mod shared_boxed_derive;
 mod variant_derive;
+mod wrapper_attribute;
 
 mod utils;
 
@@ -972,3 +973,13 @@ pub fn clone_block(_attr: TokenStream, item: TokenStream) -> TokenStream {
     clone_block_attribute::impl_clone_block(&mut item, &syn::parse_quote! { #glib }, &errors);
     errors.output_with(item).into()
 }
+
+#[proc_macro_attribute]
+#[proc_macro_error]
+pub fn wrapper(attr: TokenStream, item: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(item as syn::ItemStruct);
+    match wrapper_attribute::impl_wrapper(attr.into(), input) {
+        Ok(gen) => gen.into(),
+        Err(e) => e.into_compile_error().into(),
+    }
+}

glib-macros/src/wrapper_attribute.rs

@@ -0,0 +1,250 @@
+// Take a look at the license at the top of the repository in the LICENSE file.
+
+use std::collections::HashSet;
+
+use proc_macro2::TokenStream;
+use quote::ToTokens;
+use syn::spanned::Spanned;
+
+mod boxed;
+#[allow(dead_code)]
+mod boxed_inline {
+    #[derive(deluxe::ParseMetaItem)]
+    pub struct BoxedInline {
+        copy: Option<syn::Expr>,
+        free: Option<syn::Expr>,
+        init: Option<syn::Expr>,
+        copy_into: Option<syn::Expr>,
+        clear: Option<syn::Expr>,
+        r#type: Option<syn::Expr>,
+        #[deluxe(flatten)]
+        args: super::WrapperArgs,
+    }
+}
+#[allow(dead_code)]
+mod shared {
+    #[derive(deluxe::ParseMetaItem)]
+    pub struct Shared {
+        r#ref: syn::Expr,
+        unref: syn::Expr,
+        r#type: Option<syn::Expr>,
+        #[deluxe(flatten)]
+        args: super::WrapperArgs,
+    }
+}
+#[allow(dead_code)]
+mod object {
+    #[derive(deluxe::ParseMetaItem)]
+    pub struct Object {
+        #[deluxe(append)]
+        extends: Vec<syn::Path>,
+        #[deluxe(append)]
+        implements: Vec<syn::Path>,
+        r#type: syn::Expr,
+        #[deluxe(flatten)]
+        args: super::WrapperArgs,
+    }
+}
+#[allow(dead_code)]
+mod object_subclass {
+    #[derive(deluxe::ParseMetaItem)]
+    pub struct ObjectSubclass {
+        #[deluxe(append)]
+        extends: Vec<syn::Path>,
+        #[deluxe(append)]
+        implements: Vec<syn::Path>,
+        #[deluxe(flatten)]
+        args: super::WrapperArgs,
+    }
+}
+#[allow(dead_code)]
+mod interface {
+    #[derive(deluxe::ParseMetaItem)]
+    pub struct Interface {
+        #[deluxe(append)]
+        requires: Vec<syn::Path>,
+        r#type: syn::Expr,
+        #[deluxe(flatten)]
+        args: super::WrapperArgs,
+    }
+}
+#[allow(dead_code)]
+mod object_interface {
+    #[derive(deluxe::ParseMetaItem)]
+    pub struct ObjectInterface {
+        #[deluxe(append)]
+        requires: Vec<syn::Path>,
+        #[deluxe(flatten)]
+        args: super::WrapperArgs,
+    }
+}
+
+#[derive(deluxe::ParseMetaItem)]
+struct WrapperArgs {
+    #[deluxe(
+        append,
+        rename = skip_trait,
+        map = |s: HashSet<syn::Ident>| s.into_iter().map(|s| s.to_string()).collect(),
+    )]
+    skipped_traits: HashSet<String>,
+}
+
+enum Member<'a> {
+    Named(&'a syn::Ident),
+    Unnamed(syn::Index),
+}
+
+impl<'a> Member<'a> {
+    fn from_fields(fields: &'a syn::Fields) -> impl Iterator<Item = Member<'a>> {
+        fields
+            .iter()
+            .enumerate()
+            .map(|(index, field)| match &field.ident {
+                Some(ident) => Member::Named(ident),
+                None => Member::Unnamed(syn::Index {
+                    index: index as u32,
+                    span: field.ty.span(),
+                }),
+            })
+    }
+}
+
+impl<'a> ToTokens for Member<'a> {
+    #[inline]
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        match self {
+            Self::Named(ident) => ident.to_tokens(tokens),
+            Self::Unnamed(index) => index.to_tokens(tokens),
+        }
+    }
+}
+
+fn construct_stmt(
+    fields: &syn::Fields,
+    first_func: impl FnOnce(Member<'_>) -> TokenStream,
+    mut rest_func: impl FnMut(Member<'_>) -> TokenStream,
+) -> TokenStream {
+    let mut first_func = Some(first_func);
+    let members = fields.iter().enumerate().map(move |(index, f)| {
+        let member = match &f.ident {
+            Some(ident) => Member::Named(ident),
+            None => Member::Unnamed(syn::Index {
+                index: index as u32,
+                span: f.ty.span(),
+            }),
+        };
+        let expr: TokenStream = if index == 0 {
+            (first_func.take().unwrap())(member)
+        } else {
+            rest_func(member)
+        };
+        match &f.ident {
+            Some(ident) => quote::quote_spanned! { f.ty.span() => #ident: #expr },
+            None => expr,
+        }
+    });
+    match fields {
+        syn::Fields::Named(_) => quote::quote! { Self { #(#members),* } },
+        syn::Fields::Unnamed(_) => quote::quote! { Self(#(#members),*) },
+        _ => unreachable!(),
+    }
+}
+
+#[inline]
+fn unique_lifetime(name: &str, generics: &syn::Generics) -> syn::Lifetime {
+    let mut ident = String::from(name);
+    while generics.lifetimes().any(|l| l.lifetime.ident == ident) {
+        ident.push('_');
+    }
+    ident.insert(0, '\'');
+    syn::Lifetime::new(&ident, proc_macro2::Span::mixed_site())
+}
+
+#[inline]
+fn insert_lifetime(name: &str, generics: &mut syn::Generics) -> syn::Lifetime {
+    let lt = unique_lifetime(name, generics);
+    generics.params.insert(0, syn::parse_quote! { #lt });
+    lt
+}
+
+fn get_first_field_type_param(fields: &syn::Fields, type_index: usize) -> syn::Result<&syn::Type> {
+    fields
+        .iter()
+        .next()
+        .ok_or_else(|| fields.span())
+        .and_then(|f| match &f.ty {
+            syn::Type::Path(tp) => tp
+                .path
+                .segments
+                .last()
+                .ok_or_else(|| tp.span())
+                .and_then(|s| match &s.arguments {
+                    syn::PathArguments::AngleBracketed(ga) => ga
+                        .args
+                        .iter()
+                        .nth(type_index)
+                        .ok_or_else(|| ga.span())
+                        .and_then(|a| match a {
+                            syn::GenericArgument::Type(t) => Ok(t),
+                            t => Err(t.span()),
+                        }),
+                    a => Err(a.span()),
+                }),
+            ty => Err(ty.span()),
+        })
+        .map_err(|span| {
+            syn::Error::new(
+                span,
+                format_args!("First field missing type argument {type_index}"),
+            )
+        })
+}
+
+#[inline]
+fn get_type_name(ty: &syn::Type) -> Option<&syn::Ident> {
+    match ty {
+        syn::Type::Path(tp) => tp.path.segments.last().map(|s| &s.ident),
+        _ => None,
+    }
+}
+
+fn add_repr_transparent(item: &mut syn::ItemStruct) {
+    if item.fields.iter().skip(1).all(|f| {
+        get_type_name(&f.ty)
+            .map(|i| i == "PhantomData")
+            .unwrap_or(false)
+    }) {
+        item.attrs.extend(
+            syn::parse::Parser::parse_str(syn::Attribute::parse_outer, "#[repr(transparent)]")
+                .unwrap(),
+        );
+    }
+}
+
+pub fn impl_wrapper(attr: TokenStream, mut item: syn::ItemStruct) -> syn::Result<TokenStream> {
+    let first_field = match item.fields.iter().next() {
+        Some(f) => f,
+        None => {
+            return Err(syn::Error::new_spanned(
+                item,
+                "Wrapper struct must have at least one field",
+            ));
+        }
+    };
+    let type_name = match get_type_name(&first_field.ty) {
+        Some(n) => n,
+        None => {
+            return Err(syn::Error::new_spanned(
+                item,
+                "First field must be a type path",
+            ))
+        }
+    };
+
+    let mut tokens = match type_name.to_string().as_str() {
+        "Boxed" => deluxe::parse2::<boxed::Boxed>(attr)?.into_token_stream(&mut item)?,
+        _ => return Err(syn::Error::new_spanned(type_name, "Unknown wrapper type")),
+    };
+    item.to_tokens(&mut tokens);
+    Ok(tokens)
+}