Convert fixed size Rust array to fixed size TS tuple

macros/src/types/enum.rs

@@ -50,7 +50,11 @@ pub(crate) fn r#enum_def(s: &ItemEnum) -> syn::Result<DerivedTS> {
     Ok(DerivedTS {
         inline: quote!([#(#formatted_variants),*].join(" | ")),
         decl: quote!(format!("type {}{} = {};", #name, #generic_args, Self::inline())),
-        inline_flattened: None,
+        inline_flattened: Some(
+            quote!(
+                format!("({})", [#(#formatted_variants),*].join(" | "))
+            )
+        ),
         dependencies,
         name,
         export: enum_attr.export,
@@ -130,7 +134,15 @@ fn format_variant(
                     "{{ \"{}\": \"{}\", {} }}",
                     #tag,
                     #name,
-                    #inline_flattened
+                    // At this point inline_flattened looks like
+                    // { /* ...data */ }
+                    // 
+                    // To be flattened, an internally tagged enum must not be
+                    // surrounded by braces, otherwise each variant will look like
+                    // { "tag": "name", { /* ...data */ } }
+                    // when we want it to look like
+                    // { "tag": "name", /* ...data */ }
+                    #inline_flattened.trim_matches(&['{', '}', ' '])
                 )
             },
             None => match &variant.fields {

macros/src/types/generics.rs

@@ -2,7 +2,7 @@ use proc_macro2::TokenStream;
 use quote::{format_ident, quote};
 use syn::{
     GenericArgument, GenericParam, Generics, ItemStruct, PathArguments, Type, TypeArray, TypeGroup,
-    TypeReference, TypeSlice, TypeTuple,
+    TypeReference, TypeSlice, TypeTuple, Expr, ExprLit, Lit,
 };
 
 use crate::{attr::StructAttr, deps::Dependencies};
@@ -62,6 +62,20 @@ pub fn format_type(ty: &Type, dependencies: &mut Dependencies, generics: &Generi
 
     // special treatment for arrays and tuples
     match ty {
+        // When possible, convert a Rust array into a fixed size TS tuple
+        // this is only possible when the length of the array is a numeric literal,
+        // rather than the name of a constant
+        Type::Array(TypeArray {
+            ref elem,
+            len: Expr::Lit(ExprLit { lit: Lit::Int(lit_int), .. }),
+            ..
+        }) => {
+            let inner_ty = elem;
+            let len = lit_int.base10_parse::<usize>().unwrap();
+            let item_ty = (0..len).map(|_| quote!(#inner_ty));
+            let tuple_ty = syn::parse2::<Type>(quote!{ (#(#item_ty),*) }).unwrap();
+            return format_type(&tuple_ty, dependencies, generics)
+        }
         // The field is an array (`[T; n]`) or a slice (`[T]`) so it technically doesn't have a
         // generic argument. Therefore, we handle it explicitly here like a `Vec<T>`
         Type::Array(TypeArray { ref elem, .. }) | Type::Slice(TypeSlice { ref elem, .. }) => {

macros/src/types/named.rs

@@ -17,6 +17,7 @@ pub(crate) fn named(
     generics: &Generics,
 ) -> Result<DerivedTS> {
     let mut formatted_fields = Vec::new();
+    let mut flattened_fields = Vec::new();
     let mut dependencies = Dependencies::default();
     if let Some(tag) = &attr.tag {
         let formatted = format!("{}: \"{}\",", tag, name);
@@ -28,6 +29,7 @@ pub(crate) fn named(
     for field in &fields.named {
         format_field(
             &mut formatted_fields,
+            &mut flattened_fields,
             &mut dependencies,
             field,
             &attr.rename_all,
@@ -36,17 +38,21 @@ pub(crate) fn named(
     }
 
     let fields = quote!(<[String]>::join(&[#(#formatted_fields),*], " "));
+    let flattened = quote!(<[String]>::join(&[#(#flattened_fields),*], " & "));
     let generic_args = format_generics(&mut dependencies, generics);
 
+    let inline = match (formatted_fields.len(), flattened_fields.len()) {
+        (0, 0) => quote!("{  }".to_owned()),
+        (_, 0) => quote!(format!("{{ {} }}", #fields)),
+        (0, 1) => quote!(#flattened.trim_matches(|c| c == '(' || c == ')').to_owned()),
+        (0, _) => quote!(#flattened),
+        (_, _) => quote!(format!("{{ {} }} & {}", #fields, #flattened)),
+    };
+
     Ok(DerivedTS {
-        inline: quote! {
-            format!(
-                "{{ {} }}",
-                #fields,
-            )
-        },
+        inline: quote!(#inline.replace(" } & { ", " ")),
         decl: quote!(format!("type {}{} = {}", #name, #generic_args, Self::inline())),
-        inline_flattened: Some(fields),
+        inline_flattened: Some(quote!(format!("{{ {} }}", #fields))),
         name: name.to_owned(),
         dependencies,
         export: attr.export,
@@ -55,8 +61,18 @@ pub(crate) fn named(
 }
 
 // build an expresion which expands to a string, representing a single field of a struct.
+//
+// formatted_fields will contain all the fields that do not contain the flatten
+// attribute, in the format
+// key: type,
+//
+// flattened_fields will contain all the fields that contain the flatten attribute
+// in their respective formats, which for a named struct is the same as formatted_fields,
+// but for enums is
+// ({ /* variant data */ } | { /* variant data */ })
 fn format_field(
     formatted_fields: &mut Vec<TokenStream>,
+    flattened_fields: &mut Vec<TokenStream>,
     dependencies: &mut Dependencies,
     field: &Field,
     rename_all: &Option<Inflection>,
@@ -88,7 +104,7 @@ fn format_field(
             _ => {}
         }
 
-        formatted_fields.push(quote!(<#ty as ts_rs::TS>::inline_flattened()));
+        flattened_fields.push(quote!(<#ty as ts_rs::TS>::inline_flattened()));
         dependencies.append_from(ty);
         return Ok(());
     }

ts-rs/src/lib.rs

@@ -495,6 +495,30 @@ impl<T: TS> TS for Vec<T> {
         "Array".to_owned()
     }
 
+    fn inline() -> String {
+        format!("Array<{}>", T::inline())
+    }
+
+    fn dependencies() -> Vec<Dependency>
+    where
+        Self: 'static,
+    {
+        [Dependency::from_ty::<T>()].into_iter().flatten().collect()
+    }
+
+    fn transparent() -> bool {
+        true
+    }
+}
+
+impl<T: TS, const N: usize> TS for [T; N] {
+    fn name() -> String {
+        format!(
+            "[{}]",
+            (0..N).map(|_| T::name()).collect::<Box<[_]>>().join(", ")
+        )
+    }
+
     fn name_with_type_args(args: Vec<String>) -> String {
         assert_eq!(
             args.len(),
@@ -506,7 +530,8 @@ impl<T: TS> TS for Vec<T> {
     }
 
     fn inline() -> String {
-        format!("Array<{}>", T::inline())
+        Self::name()
+        // format!("Array<{}>", T::inline())
     }
 
     fn dependencies() -> Vec<Dependency>
@@ -613,7 +638,7 @@ impl_shadow!(as T: impl<'a, T: TS + ?Sized> TS for &T);
 impl_shadow!(as Vec<T>: impl<T: TS, H> TS for HashSet<T, H>);
 impl_shadow!(as Vec<T>: impl<T: TS> TS for BTreeSet<T>);
 impl_shadow!(as HashMap<K, V>: impl<K: TS, V: TS> TS for BTreeMap<K, V>);
-impl_shadow!(as Vec<T>: impl<T: TS, const N: usize> TS for [T; N]);
+// impl_shadow!(as Vec<T>: impl<T: TS, const N: usize> TS for [T; N]);
 impl_shadow!(as Vec<T>: impl<T: TS> TS for [T]);
 
 impl_wrapper!(impl<T: TS + ?Sized> TS for Box<T>);

ts-rs/tests/arrays.rs

@@ -2,24 +2,24 @@ use ts_rs::TS;
 
 #[test]
 fn free() {
-    assert_eq!(<[String; 10]>::inline(), "Array<string>")
+    assert_eq!(<[String; 4]>::inline(), "[string, string, string, string]")
 }
 
 #[test]
 fn interface() {
     #[derive(TS)]
     struct Interface {
         #[allow(dead_code)]
-        a: [i32; 10],
+        a: [i32; 4],
     }
 
-    assert_eq!(Interface::inline(), "{ a: Array<number>, }")
+    assert_eq!(Interface::inline(), "{ a: [number, number, number, number], }")
 }
 
 #[test]
 fn newtype() {
     #[derive(TS)]
-    struct Newtype(#[allow(dead_code)] [i32; 10]);
+    struct Newtype(#[allow(dead_code)] [i32; 4]);
 
-    assert_eq!(Newtype::inline(), "Array<number>")
+    assert_eq!(Newtype::inline(), "[number, number, number, number]")
 }

ts-rs/tests/enum_flattening.rs

@@ -0,0 +1,108 @@
+#[cfg(feature = "serde-compat")]
+use serde::Serialize;
+use ts_rs::TS;
+
+#[test]
+fn externally_tagged() {
+    #[allow(dead_code)]
+    #[cfg_attr(feature = "serde-compat", derive(Serialize, TS))]
+    #[cfg_attr(not(feature = "serde-compat"), derive(TS))]
+    struct Foo {
+        qux: i32,
+        #[cfg_attr(feature = "serde-compat", serde(flatten))]
+        #[cfg_attr(not(feature = "serde-compat"), ts(flatten))]
+        baz: Bar,
+        biz: Option<String>,
+    }
+
+    #[cfg_attr(feature = "serde-compat", derive(Serialize, TS))]
+    #[cfg_attr(not(feature = "serde-compat"), derive(TS))]
+    #[allow(dead_code)]
+    enum Bar {
+        Baz { a: i32, a2: String },
+        Biz { b: bool },
+        Buz { c: String, d: Option<i32> },
+    }
+
+    assert_eq!(
+        Foo::inline(),
+        r#"{ qux: number, biz: string | null, } & ({ "Baz": { a: number, a2: string, } } | { "Biz": { b: boolean, } } | { "Buz": { c: string, d: number | null, } })"#
+    )
+}
+
+#[test]
+#[cfg(feature = "serde-compat")]
+fn adjacently_tagged() {
+    #[derive(Serialize, TS)]
+    struct Foo {
+        one: i32,
+        #[serde(flatten)]
+        baz: Bar,
+        qux: Option<String>,
+    }
+
+    #[derive(Serialize, TS)]
+    #[allow(dead_code)]
+    #[serde(tag = "type", content = "stuff")]
+    enum Bar {
+        Baz { a: i32, a2: String },
+        Biz { b: bool },
+        Buz { c: String, d: Option<i32> },
+    }
+
+    assert_eq!(
+        Foo::inline(),
+        r#"{ one: number, qux: string | null, } & ({ "type": "Baz", "stuff": { a: number, a2: string, } } | { "type": "Biz", "stuff": { b: boolean, } } | { "type": "Buz", "stuff": { c: string, d: number | null, } })"#
+    )
+}
+
+#[test]
+#[cfg(feature = "serde-compat")]
+fn internally_tagged() {
+    #[derive(Serialize, TS)]
+    struct Foo {
+        qux: Option<String>,
+
+        #[serde(flatten)]
+        baz: Bar,
+    }
+
+    #[derive(Serialize, TS)]
+    #[allow(dead_code)]
+    #[serde(tag = "type")]
+    enum Bar {
+        Baz { a: i32, a2: String },
+        Biz { b: bool },
+        Buz { c: String, d: Option<i32> },
+    }
+
+    assert_eq!(
+        Foo::inline(),
+        r#"{ qux: string | null, } & ({ "type": "Baz", a: number, a2: string, } | { "type": "Biz", b: boolean, } | { "type": "Buz", c: string, d: number | null, })"#
+    )
+}
+
+#[test]
+#[cfg(feature = "serde-compat")]
+fn untagged() {
+    #[derive(Serialize, TS)]
+    struct Foo {
+        #[serde(flatten)]
+        baz: Bar,
+    }
+
+    #[derive(Serialize, TS)]
+    #[allow(dead_code)]
+    #[serde(untagged)]
+    enum Bar {
+        Baz { a: i32, a2: String },
+        Biz { b: bool },
+        Buz { c: String },
+    }
+
+    assert_eq!(
+        Foo::inline(),
+        r#"{ a: number, a2: string, } | { b: boolean, } | { c: string, }"#
+    )
+}
+

ts-rs/tests/flatten.rs

@@ -26,6 +26,6 @@ struct C {
 fn test_def() {
     assert_eq!(
         C::inline(),
-        "{ b: { a: number, b: number, c: number, }, d: number, }"
+        "{ b: { c: number, a: number, b: number, }, d: number, }"
     );
 }

ts-rs/tests/generic_fields.rs

@@ -40,7 +40,7 @@ fn named() {
     }
     assert_eq!(
         Struct::inline(),
-        "{ a: Array<string>, b: [Array<string>, Array<string>], c: Array<Array<string>>, }"
+        "{ a: Array<string>, b: [Array<string>, Array<string>], c: [Array<string>, Array<string>, Array<string>], }"
     );
 }
 
@@ -52,7 +52,7 @@ fn named_nested() {
         b: (Vec<Vec<String>>, Vec<Vec<String>>),
         c: [Vec<Vec<String>>; 3],
     }
-    assert_eq!(Struct::inline(), "{ a: Array<Array<string>>, b: [Array<Array<string>>, Array<Array<string>>], c: Array<Array<Array<string>>>, }");
+    assert_eq!(Struct::inline(), "{ a: Array<Array<string>>, b: [Array<Array<string>>, Array<Array<string>>], c: [Array<Array<string>>, Array<Array<string>>, Array<Array<string>>], }");
 }
 
 #[test]
@@ -61,7 +61,7 @@ fn tuple() {
     struct Tuple(Vec<i32>, (Vec<i32>, Vec<i32>), [Vec<i32>; 3]);
     assert_eq!(
         Tuple::inline(),
-        "[Array<number>, [Array<number>, Array<number>], Array<Array<number>>]"
+        "[Array<number>, [Array<number>, Array<number>], [Array<number>, Array<number>, Array<number>]]"
     );
 }
 
@@ -75,6 +75,6 @@ fn tuple_nested() {
     );
     assert_eq!(
         Tuple::inline(),
-        "[Array<Array<number>>, [Array<Array<number>>, Array<Array<number>>], Array<Array<Array<number>>>]"
+        "[Array<Array<number>>, [Array<Array<number>>, Array<Array<number>>], [Array<Array<number>>, Array<Array<number>>, Array<Array<number>>]]"
     );
 }

ts-rs/tests/generics.rs

@@ -142,7 +142,7 @@ fn generic_struct() {
 
     assert_eq!(
         Struct::<()>::decl(),
-        "type Struct<T> = { a: T, b: [T, T], c: [T, [T, T]], d: Array<T>, e: Array<[T, T]>, f: Array<T>, g: Array<Array<T>>, h: Array<Array<[T, T]>>, }"
+        "type Struct<T> = { a: T, b: [T, T], c: [T, [T, T]], d: [T, T, T], e: [[T, T], [T, T], [T, T]], f: Array<T>, g: Array<Array<T>>, h: Array<[[T, T], [T, T], [T, T]]>, }"
     )
 }