Refactor and move delegate_and_check_components! macro implementation to cgp-macro-core (#240)

* Slightly simplify delegate_and_check_components

* Draft new delegate_and_check_components types

* Allow attributes in delegate keys

* Fix peek in DelegateKey

* Refactor CheckParamsAttribute and remove delegate and check constructs

* Implement ToCheckEntries for SingleDelegateKey

* Implement KeyWithCheckParams

* Implement ToKeysWithCheckParams for SingleDelegateKey

* Implement CheckParamsAttribute::merge

* Implement ToKeysWithCheckParams for MultiDelegateKey

* Implement ToKeysWithCheckParams for DelegateEntries

* Implement check_trait_ident

* Implement ItemDelegateAndCheckComponents

* Use ItemDelegateAndCheckComponents

* Remove obsolete constructs

* Add ValidateAttributes

* Add more attributes validation

* AI-revise code

* AI revision

Author: soareschen

crates/macros/cgp-macro-core/src/types/check_components/entries.rs

@@ -4,6 +4,7 @@ use syn::token::Comma;
 
 use crate::types::check_components::{CheckEntry, EvaluatedCheckEntry};
 
+#[derive(Default)]
 pub struct CheckEntries {
     pub entries: Punctuated<CheckEntry, Comma>,
 }

crates/macros/cgp-macro-core/src/types/check_components/table.rs

@@ -17,7 +17,7 @@ pub struct CheckComponentsTable {
     pub impl_generics: ImplGenerics,
     pub trait_name: Ident,
     pub context_type: Type,
-    pub where_clause: WhereClause,
+    pub where_clause: Option<WhereClause>,
     pub check_entries: CheckEntries,
 }
 
@@ -141,21 +141,13 @@ impl Parse for CheckComponentsTable {
         let trait_name = if let Some(check_trait_name) = m_check_trait_name {
             check_trait_name
         } else {
-            let context_type: IdentWithTypeArgs = parse2(context_type.to_token_stream())?;
-
-            Ident::new(
-                &format!("__Check{}", context_type.ident),
-                context_type.span(),
-            )
+            derive_check_trait_ident(&context_type, "__Check")?
         };
 
         let where_clause = if input.peek(Where) {
-            input.parse()?
+            Some(input.parse()?)
         } else {
-            WhereClause {
-                where_token: Where(Span::call_site()),
-                predicates: Punctuated::default(),
-            }
+            None
         };
 
         let content;
@@ -174,6 +166,18 @@ impl Parse for CheckComponentsTable {
     }
 }
 
+/// Derive a check trait identifier from a context type by prepending `prefix`
+/// to the context type's leading identifier, e.g. `__CheckPerson` or
+/// `__CanUsePerson` for the context type `Person`.
+pub fn derive_check_trait_ident(context_type: &Type, prefix: &str) -> syn::Result<Ident> {
+    let context_type: IdentWithTypeArgs = parse2(context_type.to_token_stream())?;
+
+    Ok(Ident::new(
+        &format!("{prefix}{}", context_type.ident),
+        context_type.span(),
+    ))
+}
+
 fn override_span<T>(span: &Span, body: &T) -> syn::Result<T>
 where
     T: Parse + ToTokens,

crates/macros/cgp-macro-core/src/types/delegate_and_check_components/check_params.rs

@@ -0,0 +1,66 @@
+use syn::punctuated::Punctuated;
+use syn::spanned::Spanned;
+use syn::token::Comma;
+use syn::{Attribute, Error, Type};
+
+#[derive(Clone)]
+pub enum CheckParamsAttribute {
+    Default,
+    Skip,
+    Multi(Punctuated<Type, Comma>),
+}
+
+impl CheckParamsAttribute {
+    pub fn merge(&self, other: &Self) -> syn::Result<Self> {
+        let res = match (self, other) {
+            (Self::Default, other) => other.clone(),
+            (other, Self::Default) => other.clone(),
+            (Self::Skip, Self::Skip) => Self::Skip,
+            (Self::Multi(params_a), Self::Multi(params_b)) => Self::Multi(Punctuated::from_iter(
+                params_a.iter().chain(params_b.iter()).cloned(),
+            )),
+            (Self::Skip, Self::Multi(params)) | (Self::Multi(params), Self::Skip) => {
+                return Err(Error::new(
+                    params.span(),
+                    "cannot combine #[skip_check] with #[check_params]",
+                ));
+            }
+        };
+
+        Ok(res)
+    }
+
+    pub fn parse_attributes(attributes: &[Attribute]) -> syn::Result<Self> {
+        if attributes.is_empty() {
+            return Ok(Self::Default);
+        }
+
+        if attributes.len() > 1 {
+            return Err(Error::new(
+                attributes[1].span(),
+                "Expected at most one `#[check_params]` or `#[skip_check]` attribute",
+            ));
+        }
+
+        let attribute = &attributes[0];
+
+        if attribute.path().is_ident("check_params") {
+            let params = attribute.parse_args_with(Punctuated::parse_terminated)?;
+            Ok(CheckParamsAttribute::Multi(params))
+        } else if attribute.path().is_ident("skip_check") {
+            attribute.meta.require_path_only().map_err(|_| {
+                Error::new(
+                    attribute.span(),
+                    "`#[skip_check]` does not take any arguments",
+                )
+            })?;
+
+            Ok(CheckParamsAttribute::Skip)
+        } else {
+            Err(Error::new(
+                attribute.span(),
+                "Expected either `#[skip_check]` or `#[check_params]` attribute for specifying the check generics",
+            ))
+        }
+    }
+}

crates/macros/cgp-macro-core/src/types/delegate_and_check_components/item.rs

@@ -0,0 +1,76 @@
+use syn::parse::{Parse, ParseStream};
+use syn::spanned::Spanned;
+use syn::{Error, Ident};
+
+use crate::types::check_components::{
+    CheckComponentsTable, CheckEntries, derive_check_trait_ident,
+};
+use crate::types::delegate_and_check_components::ToKeysWithCheckParams;
+use crate::types::delegate_component::DelegateTable;
+
+pub struct ItemDelegateAndCheckComponents {
+    pub table: DelegateTable,
+}
+
+impl ItemDelegateAndCheckComponents {
+    pub fn to_check_components(&self) -> syn::Result<CheckComponentsTable> {
+        let trait_name = self.check_trait_ident()?;
+        let check_entries = self.to_check_entries()?;
+
+        let check_table = CheckComponentsTable {
+            check_providers: None,
+            impl_generics: self.table.impl_generics.clone(),
+            trait_name,
+            context_type: self.table.table_type.clone(),
+            where_clause: None,
+            check_entries,
+        };
+
+        Ok(check_table)
+    }
+
+    pub fn to_check_entries(&self) -> syn::Result<CheckEntries> {
+        let keys = self.table.entries.to_keys_with_check_params()?;
+
+        let mut entries = CheckEntries::default();
+
+        for key in keys {
+            entries.entries.extend(key.to_check_entries().entries);
+        }
+
+        Ok(entries)
+    }
+
+    pub fn check_trait_ident(&self) -> syn::Result<Ident> {
+        let attributes = &self.table.attributes;
+
+        if attributes.is_empty() {
+            derive_check_trait_ident(&self.table.table_type, "__CanUse")
+        } else if attributes.len() > 1 {
+            Err(Error::new(
+                attributes[1].span(),
+                "Expected exactly one attribute for the check trait name",
+            ))
+        } else {
+            let attribute = &attributes[0];
+            if !attribute.path().is_ident("check_trait") {
+                return Err(syn::Error::new(
+                    attribute.span(),
+                    "Expected `#[check_trait]` attribute for specifying the check trait name",
+                ));
+            }
+
+            let ident = attribute.parse_args()?;
+
+            Ok(ident)
+        }
+    }
+}
+
+impl Parse for ItemDelegateAndCheckComponents {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let table = input.parse()?;
+
+        Ok(Self { table })
+    }
+}

crates/macros/cgp-macro-core/src/types/delegate_and_check_components/key_with_check_params.rs

@@ -0,0 +1,44 @@
+use syn::Type;
+use syn::punctuated::Punctuated;
+
+use crate::types::check_components::{
+    CheckEntries, CheckEntry, CheckKey, CheckValue, TypeWithGenerics,
+};
+use crate::types::delegate_and_check_components::CheckParamsAttribute;
+
+pub struct KeyWithCheckParams {
+    pub key_type: Type,
+    pub check_params: CheckParamsAttribute,
+}
+
+impl KeyWithCheckParams {
+    pub fn to_check_entries(&self) -> CheckEntries {
+        match &self.check_params {
+            CheckParamsAttribute::Default => {
+                let entry = CheckEntry {
+                    key: CheckKey::Single(self.key_type.clone()),
+                    value: None,
+                };
+
+                CheckEntries {
+                    entries: Punctuated::from_iter([entry]),
+                }
+            }
+            CheckParamsAttribute::Skip => CheckEntries::default(),
+            CheckParamsAttribute::Multi(params) => {
+                let mut entries = CheckEntries::default();
+
+                for param in params {
+                    entries.entries.push(CheckEntry {
+                        key: CheckKey::Single(self.key_type.clone()),
+                        value: Some(CheckValue::Single(Box::new(TypeWithGenerics::from(
+                            param.clone(),
+                        )))),
+                    })
+                }
+
+                entries
+            }
+        }
+    }
+}

crates/macros/cgp-macro-core/src/types/delegate_and_check_components/mod.rs

@@ -0,0 +1,9 @@
+mod check_params;
+mod item;
+mod key_with_check_params;
+mod to_keys_with_check_params;
+
+pub use check_params::*;
+pub use item::*;
+pub use key_with_check_params::*;
+pub use to_keys_with_check_params::*;

crates/macros/cgp-macro-core/src/types/delegate_and_check_components/to_keys_with_check_params.rs

@@ -0,0 +1,96 @@
+use crate::types::delegate_and_check_components::{CheckParamsAttribute, KeyWithCheckParams};
+use crate::types::delegate_component::{
+    DelegateEntries, DelegateKey, DelegateMapping, MultiDelegateKey, SingleDelegateKey,
+    ValidateAttributes,
+};
+
+pub trait ToKeysWithCheckParams {
+    fn to_keys_with_check_params(&self) -> syn::Result<Vec<KeyWithCheckParams>>;
+}
+
+impl ToKeysWithCheckParams for SingleDelegateKey {
+    fn to_keys_with_check_params(&self) -> syn::Result<Vec<KeyWithCheckParams>> {
+        let check_params = CheckParamsAttribute::parse_attributes(&self.attributes)?;
+
+        // Note: any per-key `ImplGenerics` (`self.generics`) are not carried into
+        // the check entry. The generated check impl only sees the table-level
+        // generics, so a key that introduces its own generic parameters would
+        // reference them unbound. Generic keys are therefore not yet supported in
+        // the check half; use `#[skip_check]` for such keys if needed.
+        let key = KeyWithCheckParams {
+            check_params,
+            key_type: self.ty.clone(),
+        };
+
+        Ok(vec![key])
+    }
+}
+
+impl ToKeysWithCheckParams for MultiDelegateKey {
+    fn to_keys_with_check_params(&self) -> syn::Result<Vec<KeyWithCheckParams>> {
+        let check_params = CheckParamsAttribute::parse_attributes(&self.attributes)?;
+
+        let mut out = Vec::new();
+
+        for key in &self.keys {
+            let inner_res = key.to_keys_with_check_params()?;
+            for inner in inner_res {
+                let inner_params = check_params.merge(&inner.check_params)?;
+                out.push(KeyWithCheckParams {
+                    key_type: inner.key_type,
+                    check_params: inner_params,
+                })
+            }
+        }
+
+        Ok(out)
+    }
+}
+
+impl ToKeysWithCheckParams for DelegateKey {
+    fn to_keys_with_check_params(&self) -> syn::Result<Vec<KeyWithCheckParams>> {
+        match self {
+            DelegateKey::Single(key) => key.to_keys_with_check_params(),
+            DelegateKey::Multi(key) => key.to_keys_with_check_params(),
+            DelegateKey::Path(key) => {
+                key.validate_attributes()?;
+                Ok(Vec::new())
+            }
+        }
+    }
+}
+
+impl ToKeysWithCheckParams for DelegateMapping {
+    fn to_keys_with_check_params(&self) -> syn::Result<Vec<KeyWithCheckParams>> {
+        match self {
+            DelegateMapping::Normal(mapping) => mapping.key.to_keys_with_check_params(),
+            DelegateMapping::Direct(mapping) => mapping.key.to_keys_with_check_params(),
+            DelegateMapping::Redirect(mapping) => {
+                // Redirect mappings do not support check params yet, so reject any
+                // attribute on the key rather than silently ignoring it.
+                mapping.key.validate_attributes()?;
+                Ok(Vec::new())
+            }
+        }
+    }
+}
+
+impl ToKeysWithCheckParams for DelegateEntries {
+    fn to_keys_with_check_params(&self) -> syn::Result<Vec<KeyWithCheckParams>> {
+        let mut out = Vec::new();
+
+        // Statement forms (`for`/`namespace`/`open`) are intentionally not checked
+        // for now. They still produce delegate impls via `eval`, but no check
+        // entries are generated for them. Since they cannot carry check params,
+        // reject any attribute on their keys rather than silently ignoring it.
+        for statement in &self.statements {
+            statement.validate_attributes()?;
+        }
+
+        for entry in &self.entries {
+            out.extend(entry.to_keys_with_check_params()?);
+        }
+
+        Ok(out)
+    }
+}

crates/macros/cgp-macro-core/src/types/delegate_component/key/combined.rs

@@ -1,3 +1,4 @@
+use syn::Attribute;
 use syn::parse::{Parse, ParseStream};
 use syn::token::{At, Bracket};
 
@@ -16,12 +17,14 @@ pub enum DelegateKey {
 impl Parse for DelegateKey {
     fn parse(input: ParseStream) -> syn::Result<Self> {
         let fork = input.fork();
+
+        let _attributes = fork.call(Attribute::parse_outer)?;
         let _generics: ImplGenerics = fork.parse()?;
 
         let key = if fork.peek(At) {
             let path = input.parse()?;
             Self::Path(path)
-        } else if input.peek(Bracket) {
+        } else if fork.peek(Bracket) {
             let keys = input.parse()?;
             Self::Multi(keys)
         } else {