Introduce #[cgp_impl] to simplify provider trait implementation (#174)

* Draft implement new #[cgp_impl] macro

* Finish draft #[cgp_impl] macro

* Basic test is working

* Improve impl macro

* Revert use of Refl for composite type

* Remove Refl

* Test use #[cgp_impl] in cgp-anyhow-error

* Use provider trait name directly instead

* Only replace self var when self receiver is used

* Add __ to context variable to avoid name clash

* Allow component name to be specified

* Fix clippy

Author: soareschen

crates/cgp-core/src/prelude.rs

@@ -18,7 +18,7 @@ pub use cgp_field::types::{
 };
 pub use cgp_macro::{
     BuildField, CgpData, CgpRecord, CgpVariant, ExtractField, FromVariant, HasField, HasFields,
-    Product, Sum, Symbol, cgp_auto_getter, cgp_component, cgp_context, cgp_getter,
+    Product, Sum, Symbol, cgp_auto_getter, cgp_component, cgp_context, cgp_getter, cgp_impl,
     cgp_new_provider, cgp_preset, cgp_provider, cgp_type, check_components,
     delegate_and_check_components, delegate_components, product, re_export_imports, replace_with,
 };

crates/cgp-error-anyhow/src/impls/raise_anyhow_error.rs

@@ -7,8 +7,8 @@ use cgp_core::prelude::*;
 
 pub struct RaiseAnyhowError;
 
-#[cgp_provider]
-impl<Context, E> ErrorRaiser<Context, E> for RaiseAnyhowError
+#[cgp_impl(RaiseAnyhowError)]
+impl<Context, E> ErrorRaiser<E> for Context
 where
     Context: HasErrorType<Error = Error>,
     E: StdError + Send + Sync + 'static,
@@ -18,8 +18,8 @@ where
     }
 }
 
-#[cgp_provider]
-impl<Context, Detail> ErrorWrapper<Context, Detail> for RaiseAnyhowError
+#[cgp_impl(RaiseAnyhowError)]
+impl<Context, Detail> ErrorWrapper<Detail> for Context
 where
     Context: HasErrorType<Error = Error>,
     Detail: Display + Send + Sync + 'static,

crates/cgp-macro-lib/src/derive_component/mod.rs

@@ -13,5 +13,6 @@ mod use_context_impl;
 mod use_delegate_impl;
 
 pub use derive::*;
+pub use replace_self_receiver::*;
 pub use replace_self_type::*;
 pub use snake_case::*;

crates/cgp-macro-lib/src/derive_component/provider_trait.rs

@@ -1,14 +1,15 @@
 use alloc::vec::Vec;
 
-use quote::quote;
+use quote::{ToTokens, quote};
 use syn::punctuated::Punctuated;
 use syn::token::Comma;
 use syn::{Ident, ItemTrait, TraitItem, TypeParamBound, parse2};
 
-use crate::derive_component::replace_self_receiver::replace_self_receiver;
+use crate::derive_component::replace_self_receiver::replace_self_receiver_in_signature;
 use crate::derive_component::replace_self_type::{
     iter_parse_and_replace_self_type, parse_and_replace_self_type,
 };
+use crate::derive_component::to_snake_case_ident;
 use crate::parse::parse_is_provider_params;
 
 pub fn derive_provider_trait(
@@ -89,7 +90,11 @@ pub fn derive_provider_trait(
                 parse_and_replace_self_type(item, context_type, &local_assoc_types)?;
 
             if let TraitItem::Fn(func) = &mut replaced_item {
-                replace_self_receiver(func, context_type);
+                replace_self_receiver_in_signature(
+                    &mut func.sig,
+                    &to_snake_case_ident(context_type),
+                    context_type.to_token_stream(),
+                );
             }
 
             *item = replaced_item;

crates/cgp-macro-lib/src/derive_component/replace_self_receiver.rs

@@ -1,31 +1,41 @@
-use proc_macro2::Ident;
-use syn::{FnArg, TraitItemFn, parse_quote};
+use proc_macro2::{Ident, TokenStream};
+use syn::{FnArg, Receiver, Signature, parse_quote};
 
-use crate::derive_component::snake_case::to_snake_case_ident;
-
-pub fn replace_self_receiver(func: &mut TraitItemFn, replaced_type: &Ident) {
-    if let Some(arg) = func.sig.inputs.first_mut()
+pub fn replace_self_receiver_in_signature(
+    sig: &mut Signature,
+    replaced_var: &Ident,
+    replaced_type: TokenStream,
+) {
+    if let Some(arg) = sig.inputs.first_mut()
         && let FnArg::Receiver(receiver) = arg
     {
-        let replaced_var = to_snake_case_ident(replaced_type);
+        *arg = replace_self_receiver(receiver, replaced_var, replaced_type);
+    }
+}
 
-        match (&receiver.reference, &receiver.mutability) {
-            (None, None) => {
-                *arg = parse_quote!(#replaced_var : #replaced_type);
-            }
-            (Some((_and, None)), None) => {
-                *arg = parse_quote!(#replaced_var : & #replaced_type);
-            }
-            (Some((_and, Some(life))), None) => {
-                *arg = parse_quote!(#replaced_var : & #life #replaced_type);
-            }
-            (Some((_and, None)), Some(_mut)) => {
-                *arg = parse_quote!(#replaced_var : &mut #replaced_type);
-            }
-            (Some((_and, Some(life))), Some(_mut)) => {
-                *arg = parse_quote!(#replaced_var : & #life mut #replaced_type);
-            }
-            _ => {}
+pub fn replace_self_receiver(
+    receiver: &mut Receiver,
+    replaced_var: &Ident,
+    replaced_type: TokenStream,
+) -> FnArg {
+    match (&receiver.reference, &receiver.mutability) {
+        (None, None) => {
+            parse_quote!(#replaced_var : #replaced_type)
+        }
+        (Some((_and, None)), None) => {
+            parse_quote!(#replaced_var : & #replaced_type)
+        }
+        (Some((_and, Some(life))), None) => {
+            parse_quote!(#replaced_var : & #life #replaced_type)
+        }
+        (Some((_and, None)), Some(_mut)) => {
+            parse_quote!(#replaced_var : &mut #replaced_type)
+        }
+        (Some((_and, Some(life))), Some(_mut)) => {
+            parse_quote!(#replaced_var : & #life mut #replaced_type)
+        }
+        (None, Some(_mut)) => {
+            parse_quote!(#replaced_var : mut #replaced_type)
         }
     }
 }

crates/cgp-macro-lib/src/derive_component/replace_self_type.rs

@@ -27,13 +27,17 @@ pub fn parse_and_replace_self_type<T>(
 where
     T: ToTokens + Parse,
 {
-    let stream = replace_self_type(val.to_token_stream(), replaced_ident, local_assoc_types);
+    let stream = replace_self_type(
+        val.to_token_stream(),
+        replaced_ident.to_token_stream(),
+        local_assoc_types,
+    );
     syn::parse2(stream)
 }
 
 pub fn replace_self_type(
     stream: TokenStream,
-    replaced_ident: &Ident,
+    replaced_ident: TokenStream,
     local_assoc_types: &Vec<Ident>,
 ) -> TokenStream {
     let self_type = format_ident!("Self");
@@ -57,7 +61,7 @@ pub fn replace_self_type(
                                         Some(TokenTree::Ident(assoc_type))
                                             if local_assoc_types.contains(assoc_type) =>
                                         {
-                                            ident
+                                            ident.to_token_stream()
                                         }
                                         _ => replaced_ident,
                                     }
@@ -68,14 +72,14 @@ pub fn replace_self_type(
                         _ => replaced_ident,
                     };
 
-                    result_stream.push(TokenTree::Ident(replaced));
+                    result_stream.extend(replaced);
                 } else {
                     result_stream.push(TokenTree::Ident(ident));
                 }
             }
             TokenTree::Group(group) => {
                 let replaced_stream =
-                    replace_self_type(group.stream(), replaced_ident, local_assoc_types);
+                    replace_self_type(group.stream(), replaced_ident.clone(), local_assoc_types);
                 let replaced_group = Group::new(group.delimiter(), replaced_stream);
 
                 result_stream.push(TokenTree::Group(replaced_group));

crates/cgp-macro-lib/src/derive_component/snake_case.rs

@@ -19,5 +19,8 @@ pub fn to_snake_case_str(val: &str) -> String {
 }
 
 pub fn to_snake_case_ident(val: &Ident) -> Ident {
-    Ident::new(&to_snake_case_str(&val.to_string()), Span::call_site())
+    Ident::new(
+        &format!("__{}__", to_snake_case_str(&val.to_string())),
+        Span::call_site(),
+    )
 }

crates/cgp-macro-lib/src/derive_getter/parse.rs

@@ -174,7 +174,7 @@ fn parse_receiver(context_ident: &Ident, arg: &FnArg) -> syn::Result<(ReceiverMo
             Type::Reference(ty) => {
                 let receiver = parse2(replace_self_type(
                     ty.elem.to_token_stream(),
-                    context_ident,
+                    context_ident.to_token_stream(),
                     &Vec::new(),
                 ))?;
                 Ok((ReceiverMode::Type(receiver), ty.mutability))
@@ -191,7 +191,7 @@ fn parse_return_type(context_type: &Ident, return_type: &ReturnType) -> syn::Res
     match return_type {
         ReturnType::Type(_, ty) => parse2(replace_self_type(
             ty.to_token_stream(),
-            context_type,
+            context_type.to_token_stream(),
             &Vec::new(),
         )),
         _ => Err(Error::new(

crates/cgp-macro-lib/src/entrypoints/cgp_impl.rs

@@ -0,0 +1,187 @@
+use proc_macro2::{Group, Span, TokenStream, TokenTree};
+use quote::{ToTokens, format_ident, quote};
+use syn::parse::discouraged::Speculative;
+use syn::parse::{Parse, ParseStream};
+use syn::spanned::Spanned;
+use syn::token::{Colon, For};
+use syn::{Error, FnArg, Ident, ImplItem, ItemImpl, Type, parse2};
+
+use crate::derive_component::{replace_self_receiver, replace_self_type, to_snake_case_ident};
+use crate::derive_provider::{
+    derive_component_name_from_provider_impl, derive_is_provider_for, derive_provider_struct,
+};
+use crate::parse::SimpleType;
+
+pub fn cgp_impl(attr: TokenStream, body: TokenStream) -> syn::Result<TokenStream> {
+    let spec: ImplProviderSpec = parse2(attr)?;
+    let item_impl: ItemImpl = parse2(body)?;
+
+    let consumer_trait_path = &item_impl
+        .trait_
+        .as_ref()
+        .ok_or_else(|| Error::new(item_impl.span(), "expect impl trait to contain path"))?
+        .1;
+
+    let consumer_trait_path: SimpleType = parse2(consumer_trait_path.to_token_stream())?;
+
+    let provider_impl =
+        transform_impl_trait(&item_impl, &consumer_trait_path, &spec.provider_type)?;
+
+    let component_type = match &spec.component_type {
+        Some(component_type) => component_type.clone(),
+        None => derive_component_name_from_provider_impl(&provider_impl)?,
+    };
+
+    let is_provider_for_impl: ItemImpl = derive_is_provider_for(&component_type, &provider_impl)?;
+
+    let provider_struct = if spec.new_struct {
+        Some(derive_provider_struct(&provider_impl)?)
+    } else {
+        None
+    };
+
+    Ok(quote! {
+        #provider_struct
+
+        #provider_impl
+
+        #is_provider_for_impl
+    })
+}
+
+pub struct ImplProviderSpec {
+    pub new_struct: bool,
+    pub provider_type: Type,
+    pub component_type: Option<Type>,
+}
+
+impl Parse for ImplProviderSpec {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let new_struct = {
+            let fork = input.fork();
+            let new_ident: Option<Ident> = fork.parse().ok();
+            match new_ident {
+                Some(new_ident) if new_ident == "new" => {
+                    input.advance_to(&fork);
+                    true
+                }
+                _ => false,
+            }
+        };
+
+        let provider_type = input.parse()?;
+
+        let component_type = if let Some(_colon) = input.parse::<Option<Colon>>()? {
+            let component_type: Type = input.parse()?;
+            Some(component_type)
+        } else {
+            None
+        };
+
+        Ok(ImplProviderSpec {
+            new_struct,
+            provider_type,
+            component_type,
+        })
+    }
+}
+
+pub fn transform_impl_trait(
+    item_impl: &ItemImpl,
+    consumer_trait_path: &SimpleType,
+    provider_type: &Type,
+) -> syn::Result<ItemImpl> {
+    let context_type = item_impl.self_ty.as_ref();
+
+    let context_var = if let Ok(ident) = parse2::<Ident>(context_type.to_token_stream()) {
+        to_snake_case_ident(&ident)
+    } else {
+        Ident::new("__context__", Span::call_site())
+    };
+
+    let local_assoc_types: Vec<Ident> = item_impl
+        .items
+        .iter()
+        .filter_map(|item| {
+            if let ImplItem::Type(assoc_type) = item {
+                Some(assoc_type.ident.clone())
+            } else {
+                None
+            }
+        })
+        .collect();
+
+    let raw_out_impl = replace_self_type(
+        item_impl.to_token_stream(),
+        context_type.to_token_stream(),
+        &local_assoc_types,
+    );
+
+    let mut out_impl: ItemImpl = parse2(raw_out_impl)?;
+    out_impl.self_ty = Box::new(provider_type.clone());
+
+    let mut provider_trait_path: SimpleType = consumer_trait_path.clone();
+
+    match &mut provider_trait_path.generics {
+        Some(generics) => {
+            generics
+                .args
+                .insert(0, parse2(context_type.to_token_stream())?);
+        }
+        None => {
+            provider_trait_path.generics = Some(parse2(quote! { < #context_type > })?);
+        }
+    }
+
+    out_impl.trait_ = Some((
+        None,
+        parse2(provider_trait_path.to_token_stream())?,
+        For(Span::call_site()),
+    ));
+
+    for item in out_impl.items.iter_mut() {
+        if let ImplItem::Fn(item_fn) = item
+            && let Some(arg) = item_fn.sig.inputs.first_mut()
+            && let FnArg::Receiver(receiver) = arg
+        {
+            *arg = replace_self_receiver(receiver, &context_var, context_type.to_token_stream());
+
+            let replaced_block = replace_self_var(item_fn.block.to_token_stream(), &context_var);
+            item_fn.block = parse2(replaced_block)?;
+        }
+    }
+
+    Ok(out_impl)
+}
+
+fn replace_self_var(stream: TokenStream, replaced_ident: &Ident) -> TokenStream {
+    let self_ident = format_ident!("self");
+
+    let mut result_stream: Vec<TokenTree> = Vec::new();
+
+    let token_iter = stream.into_iter();
+
+    for tree in token_iter {
+        match tree {
+            TokenTree::Ident(ident) => {
+                if ident == self_ident {
+                    result_stream.push(TokenTree::Ident(replaced_ident.clone()));
+                } else {
+                    result_stream.push(TokenTree::Ident(ident));
+                }
+            }
+            TokenTree::Group(group) => {
+                let replaced_stream = replace_self_var(group.stream(), replaced_ident);
+                let replaced_group = Group::new(group.delimiter(), replaced_stream);
+
+                result_stream.push(TokenTree::Group(replaced_group));
+            }
+            TokenTree::Punct(punct) => {
+                result_stream.push(TokenTree::Punct(punct));
+            }
+            TokenTree::Literal(lit) => result_stream.push(TokenTree::Literal(lit)),
+        }
+    }
+
+    result_stream.into_iter().collect()
+}