feat: implemented deriving for structs of all types

.gitignore

@@ -1 +1,2 @@
-/target
+**/target
+

Cargo.lock

@@ -1,7 +1,54 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
+
+[[package]]
+name = "derive_generic"
+version = "0.1.0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
 
 [[package]]
 name = "generic"
 version = "0.1.0"
+dependencies = [
+ "derive_generic",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.95"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "02b3e5e68a3a1a02aad3ec490a98007cbc13c37cbe84a3cd7b8e406d76e7f778"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.40"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.101"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ce2b7fc941b3a24138a0a7cf8e858bfc6a992e7978a068a5c760deb0ed43caf"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"

Cargo.toml

@@ -4,3 +4,4 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+derive_generic = { path = "derive_generic" }

derive_generic/Cargo.lock

@@ -0,0 +1,47 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "derive_generic"
+version = "0.1.0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.95"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "02b3e5e68a3a1a02aad3ec490a98007cbc13c37cbe84a3cd7b8e406d76e7f778"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.40"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.101"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ce2b7fc941b3a24138a0a7cf8e858bfc6a992e7978a068a5c760deb0ed43caf"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"

derive_generic/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "derive_generic"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1"
+syn = "2.0"
+quote = "1"

derive_generic/src/lib.rs

@@ -0,0 +1,205 @@
+use syn::{parse_macro_input, spanned::Spanned, DeriveInput, Ident};
+use proc_macro::TokenStream;
+use quote::{quote, ToTokens};
+use syn::{Data, Fields, Index, Type};
+
+#[proc_macro]
+pub fn derive_generic_raw(input: TokenStream) -> TokenStream {
+    let ast = parse_macro_input!(input as DeriveInput);
+
+    let data_name = ast.ident;
+
+    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
+
+    let repr = repr_from_data(&ast.data);
+
+    let generalization = general_from_data(&ast.data);
+
+    let specialization = special_from_data(&ast.data);
+
+    quote! {
+        impl #impl_generics generic::Generic for #data_name #ty_generics #where_clause {
+            type Representation = #repr;
+
+            fn generalize(self) -> Self::Representation {
+                #generalization
+            }
+            fn specialize(rep: Self::Representation) -> Self {
+                #specialization
+            }
+        }
+    }.into()
+}
+
+fn special_from_data(data: &Data) -> proc_macro2::TokenStream {
+    match data {
+        Data::Struct(ref r#struct) => {
+            match &r#struct.fields {
+                Fields::Named(ref fields) => {
+                    let bind_names: Vec<_> = fields.named.iter()
+                        .map(|field| field.ident.clone().expect("Named fields must have an identifier."))
+                        .collect();
+
+                    let let_bind = generate_let_binds(bind_names.clone());
+
+                    quote! {
+                        let #let_bind = rep;
+                        Self {
+                            #(#bind_names ,)*
+                        }
+                    }
+                },
+                Fields::Unnamed(ref fields) => {
+                    let bind_names: Vec<_> = fields.unnamed.iter()
+                        .enumerate()
+                        .map(|(i, field)| Ident::new(&format!("field_{i}"), field.span()))
+                        .collect();
+
+                    let let_bind = generate_let_binds(bind_names.clone());
+
+                    quote! {
+                        let #let_bind = rep;
+                        Self( #(#bind_names ,)* )
+                    }
+                },
+                Fields::Unit => quote! {
+                    Self
+                },
+            }
+        },
+        Data::Enum(data_enum) => todo!(),
+        Data::Union(data_union) => todo!(),
+    }
+}
+
+fn generate_let_binds(mut bind_names: Vec<Ident>) -> proc_macro2::TokenStream {
+    match bind_names.len() {
+        0 => quote! {
+            _
+        },
+        _ => {
+            let last = bind_names.pop().unwrap();
+            let last = quote! {
+                generic::Field { value: #last }
+            };
+
+            bind_names.iter().fold(last, |acc, i|
+                quote! {
+                    generic::Product {
+                        left: #i,
+                        right: #acc
+                    }
+                }
+            )
+        }
+    }
+}
+
+fn general_from_data(data: &Data) -> proc_macro2::TokenStream {
+    match data {
+        Data::Struct(ref r#struct) => {
+            match &r#struct.fields {
+                Fields::Named(ref fields) => {
+                    let names: Vec<_> = fields.named.iter()
+                        .map(|field| field.ident.as_ref()
+                            .expect("Named Fields must have an identifier")
+                            .to_token_stream()
+                        )
+                        .collect();
+
+                    match names.len() {
+                        0 => quote! {
+                            let _ = self;
+                            generic::Field { value: () }
+                        },
+                        _ => general_from_names(names)
+                    }
+
+                    
+                },
+                Fields::Unnamed(ref fields) => {
+                    let indices: Vec<_> = fields.unnamed.iter()
+                        .enumerate()
+                        .map(|(i, _)| Index::from(i).to_token_stream())
+                        .collect();
+
+                    match fields.unnamed.len() {
+                        0 => quote! {
+                            let _ = self;
+                            generic::Field { value: () }
+                        },
+                        _ => general_from_names(indices)
+                    }
+                },
+                Fields::Unit => quote! { generic::Field { value: () } },
+            }
+        },
+        Data::Enum(data_enum) => todo!(),
+        Data::Union(data_union) => quote!{},
+    }
+}
+
+fn general_from_names(mut names: Vec<proc_macro2::TokenStream>) -> proc_macro2::TokenStream {
+    let last = names.pop().expect("Impossible");
+    let expr = quote! { generic::Field { value: self.#last } };
+
+    names.iter().fold(expr, |e, i| 
+        quote! { 
+            generic::Product {
+                left: self.#i,
+                right: #e
+            }
+        }
+    )
+}
+
+#[proc_macro_derive(Generic)]
+pub fn derive_generic(input: TokenStream) -> TokenStream {
+    derive_generic_raw(input)
+}
+
+fn product_from_types(mut types: Vec<&Type>) -> proc_macro2::TokenStream {
+    let last = types.pop().unwrap();
+    let last = quote! { generic::Field<#last> };
+
+    types.iter().fold(last, |e, i|
+        quote! {
+            generic::Product<#i, #e>
+        }.into_token_stream()
+    )
+}
+
+fn repr_from_data(data: &Data) -> proc_macro2::TokenStream {
+    match data {
+        Data::Struct(ref r#struct) => {
+            match &r#struct.fields {
+                Fields::Named(ref fields) => {
+                    let v: Vec<_> = fields.named
+                        .iter()
+                        .map(|f| &f.ty)
+                        .collect();
+
+                    match v.len() {
+                        0 => quote! { generic::Field<()> },
+                        _ => product_from_types(v)
+                    }
+                },
+                Fields::Unnamed(ref fields) => {
+                    let v: Vec<_> = fields.unnamed
+                        .iter()
+                        .map(|f| &f.ty)
+                        .collect();
+
+                    match v.len() {
+                        0 => quote! { generic::Field<()> },
+                        _ => product_from_types(v)
+                    }
+                },
+                Fields::Unit => quote! { generic::Field<()> },
+            }
+        },
+        Data::Enum(data_enum) => todo!(),
+        Data::Union(_) => quote! { compile_error!("Cannot derive Generics for union types!") },
+    }
+}
+

src/example.rs

@@ -1,28 +1,18 @@
-use crate::generic::{Field, Sum, Generic};
+use crate::generic;
+use derive_generic::Generic;
 
+#[derive(Generic)]
+struct IntPairTuple (i16, i32);
 
-struct IntPair {
+#[derive(Generic)]
+struct IntPairStruct {
     a: i32,
-    b: i32
+    b: i16,
 }
 
-impl Generic for IntPair {
-    type Representation = Sum<Field<i32>, Field<i32>>;
-    fn generalize(self) -> Self::Representation {
-        Sum { 
-            left: Field { value: self.a },
-            right: Field { value: self.b }
-        }
-    }
-    fn specialize(rep: Self::Representation) -> Self {
-        let Sum {
-            left: Field { value: a },
-            right: Field { value: b },
-        } = rep;
-        IntPair { a, b }
-    }
-}
+#[derive(Generic)]
+struct UnitStruct;
 
-fn convert(x: IntPair) -> (i32, i32) {
-    Generic::specialize(x.generalize())
+#[derive(Generic)]
+struct EmptyStruct {
 }

src/generic.rs

@@ -1,26 +1,63 @@
-pub struct Sum<Con, Rhs> where Con: IsConType, Rhs: IsRepType {
-    pub left: Con,
-    pub right: Rhs,
+use std::ops::Add;
+
+pub enum Sum<Con, Rhs> where Con: IsConType, Rhs: IsRepType {
+    Left(Con),
+    Right(Rhs),
 }
 
 pub struct Product<T, Rhs> where Rhs: IsConType {
-    pub left: Field<T>,
+    pub left: T,
     pub right: Rhs
 }
 
+impl<Field, Rest, RestRhs, FieldRhs> Add<Product<FieldRhs, RestRhs>> for Product<Field, Rest>
+where 
+    Rest: Add<RestRhs> + IsConType,
+    Field: Add<FieldRhs>,
+    RestRhs: IsConType,
+    Rest::Output: IsConType
+{
+    type Output = Product<Field::Output, Rest::Output>;
+
+    fn add(self, other: Product<FieldRhs, RestRhs>) -> Self::Output {
+        Product {
+            left: self.left + other.left,
+            right: self.right + other.right
+        }
+    }
+}
+
+
 pub struct Field<T> {
     pub value: T
 }
 
+impl<R, T: Add<R>> Add<Field<R>> for Field<T> {
+    type Output=Field<T::Output>;
+
+    fn add(self, rhs: Field<R>) -> Self::Output {
+        Field {
+            value: self.value + rhs.value,
+        }
+    }
+}
+
+
 // types used for generic representation
 pub trait IsRepType {}
-impl<Lhs: IsConType, Rhs: IsRepType> IsRepType for Sum<Lhs, Rhs> {}
-impl<T: IsRepType, Rhs: IsConType> IsRepType for Product<T, Rhs> {}
+
+impl<Lhs, Rhs> IsRepType for Sum<Lhs, Rhs>
+    where Lhs: IsConType, Rhs: IsRepType {}
+
+impl<T, Rhs> IsRepType for Product<T, Rhs> 
+    where Rhs: IsConType {}
+
 impl<T> IsRepType for Field<T> {}
 
 // types that represent constructors
 pub trait IsConType {}
-impl<T, Rhs: IsConType> IsConType for Product<T, Rhs> {}
+impl<T, Rhs> IsConType for Product<T, Rhs> 
+    where Rhs: IsConType {}
 impl<T> IsConType for Field<T> {}
 
 
@@ -29,3 +66,4 @@ pub trait Generic {
     fn generalize(self) -> Self::Representation;
     fn specialize(rep: Self::Representation) -> Self;
 }
+

src/instances.rs

@@ -1,19 +1,19 @@
-use crate::generic::{Field, Generic, Sum};
+use crate::generic::{Field, Generic, Product};
 
 impl<A, B> Generic for (A, B) {
-    type Representation = Sum<Field<A>, Field<B>>;
+    type Representation = Product<A, Field<B>>;
 
     fn generalize(self) -> Self::Representation {
         let (l, r) = self;
-        Sum {
-            left: Field { value: l },
+        Product {
+            left: l,
             right: Field { value: r }
         }
     }
 
     fn specialize(rep: Self::Representation) -> Self {
-        let Sum {
-            left: Field { value: a },
+        let Product {
+            left: a,
             right: Field { value: b },
         } = rep;
         (a, b)