Add substrate subfeature

Cargo.toml

@@ -11,7 +11,7 @@ exclude = [
 
 [workspace.package]
 authors = ["Antonio Yang <yanganto@gmail.com>"]
-version = "0.14.0"
+version = "0.14.1"
 edition = "2021"
 categories = ["development-tools"]
 keywords = ["struct", "patch", "macro", "derive", "overlay"]

README.md

@@ -15,7 +15,7 @@ This crate provides the `Patch`, `Filler`, `Substrate`, `Catalyst` and `Complex`
 
 - If any field in a `Patch` is `Some`, it overwrites the corresponding field when applied. Use `apply_with_log` to receive a callback for each field that is actually changed.
 - If any field in the instance is empty (`None` or an empty collection), `Filler` will try to fill it. It supports `Option`, `Vec`, `VecDeque`, `LinkedList`, `HashMap`, `BTreeMap`, `HashSet`, `BTreeSet`, `BinaryHeap` fields, as well as custom types via `#[filler(extendable)]` and any type via `#[filler(empty_value = ...)]`.
-- With the `catalyst` feature, `Substrate`, `Catalyst` and `Complex` traits with accompanying derive macros help you extend a struct with extra fields from another crate.
+- With the `substrate` feature, the `Substrate` derive macro exposes field information so that other crates can access it. With the `catalyst` feature (which implies `substrate`), `Catalyst` and `Complex` derive macros help you extend a struct with extra fields from another crate.
 
 This crate supports `no_std` — check the [no-std-examples](./no-std-examples).
 
@@ -264,7 +264,8 @@ This crate includes the following optional features:
   - `none_as_default` *(optional)*: `T` needs to implement `Default`. When patching on `None`, it patches on a default instance. Mutually exclusive with `keep_none`.
   - `keep_none` *(optional)*: when patching on `None`, it stays `None`. Mutually exclusive with `none_as_default`.
 - `nesting` *(optional)*: allows a field to use `Patch` derive with the `#[patch(nesting)]` attribute.
-- `catalyst` *(optional)*: enables the `Substrate`, `Catalyst`, and `Complex` derive macros for extending a struct with fields from another crate.
+- `substrate` *(optional)*: enables the `Substrate` derive macro for exposing a struct's field layout so downstream crates can access it via `expose()` or source parsing.
+- `catalyst` *(optional)*: enables the `Catalyst` and `Complex` derive macros for extending a struct with fields from another crate. Implies `substrate`.
 - `unsafe` *(optional)*: uses `ManuallyDrop` + `ptr::read` / `MaybeUninit` + `ptr::write` in the generated `bind`, `decouple`, `__substrate_new`, and `__substrate_unpack` to avoid memory moves. Only meaningful with the `catalyst` feature.
 
 [crates-badge]: https://img.shields.io/crates/v/struct-patch.svg

complex-example/Cargo.toml

@@ -6,11 +6,11 @@ members = [
     "catalyst-src",
 ]
 [workspace.dependencies]
-struct-patch = { path = "../lib", features = ["catalyst"] }
+struct-patch = { path = "../lib" }
 
 [workspace.package]
 authors = ["Antonio Yang <yanganto@gmail.com>"]
-version = "0.14.0"
+version = "0.14.1"
 edition = "2021"
 categories = ["development-tools"]
 keywords = ["struct", "patch", "macro", "derive", "overlay"]

complex-example/catalyst-src/Cargo.toml

@@ -12,7 +12,7 @@ description.workspace = true
 rust-version.workspace = true
 
 [dependencies]
-struct-patch.workspace = true
+struct-patch = { workspace = true, features = ["catalyst"] }
 substrate = { path = "../substrate" }
 serde = { version = "1", features = ["derive"] }
 toml = "1.1.2"

complex-example/catalyst/Cargo.toml

@@ -12,7 +12,7 @@ description.workspace = true
 rust-version.workspace = true
 
 [dependencies]
-struct-patch.workspace = true
+struct-patch = { workspace = true, features = ["catalyst"] }
 substrate = { path = "../substrate" }
 serde = { version = "1", features = ["derive"] }
 toml = "1.1.2"

complex-example/substrate/Cargo.toml

@@ -12,7 +12,7 @@ description.workspace = true
 rust-version.workspace = true
 
 [dependencies]
-struct-patch.workspace = true
+struct-patch = { workspace = true, features = ["substrate"] }
 serde = { version = "1", features = ["derive"] }
 
 [dev-dependencies]

derive/Cargo.toml

@@ -26,7 +26,8 @@ status = []
 op = []
 merge = []
 nesting = []
-catalyst = [ "syn-serde", "dep:cargo_metadata", "syn/full" ]
+substrate = [ "syn-serde", "syn/full" ]
+catalyst = [ "substrate", "dep:cargo_metadata" ]
 unsafe = []
 box = []
 

derive/src/lib.rs

@@ -3,14 +3,14 @@ extern crate proc_macro;
 mod catalyst;
 mod filler;
 mod patch;
-#[cfg(feature = "catalyst")]
+#[cfg(feature = "substrate")]
 mod substrate;
 
 #[cfg(feature = "catalyst")]
 use catalyst::Catalyst;
 use filler::Filler;
 use patch::Patch;
-#[cfg(feature = "catalyst")]
+#[cfg(feature = "substrate")]
 use substrate::Substrate;
 
 use syn::meta::ParseNestedMeta;
@@ -42,7 +42,7 @@ pub fn derive_filler(item: proc_macro::TokenStream) -> proc_macro::TokenStream {
         .into()
 }
 
-#[cfg(feature = "catalyst")]
+#[cfg(feature = "substrate")]
 #[proc_macro_derive(Substrate, attributes(substrate))]
 pub fn derive_substrate(item: proc_macro::TokenStream) -> proc_macro::TokenStream {
     Substrate::from_ast(syn::parse_macro_input!(item as syn::DeriveInput))

lib/Cargo.toml

@@ -12,7 +12,7 @@ readme.workspace = true
 rust-version.workspace = true
 
 [dependencies]
-struct-patch-derive = { version = "=0.14.0", path = "../derive" }
+struct-patch-derive = { version = "=0.14.1", path = "../derive" }
 
 [dev-dependencies]
 serde_json = "1.0"
@@ -43,8 +43,12 @@ nesting = [
 ]
 none_as_default = ["option"]
 keep_none = ["option"]
+substrate = [
+    "struct-patch-derive/substrate"
+]
 catalyst = [
-    "struct-patch-derive/catalyst"
+    "struct-patch-derive/catalyst",
+    "struct-patch-derive/substrate"
 ]
 unsafe = [
     "struct-patch-derive/unsafe"

lib/src/lib.rs

@@ -85,7 +85,7 @@ pub use struct_patch_derive::Catalyst;
 pub use struct_patch_derive::Filler;
 #[doc(hidden)]
 pub use struct_patch_derive::Patch;
-#[cfg(feature = "catalyst")]
+#[cfg(feature = "substrate")]
 #[doc(hidden)]
 pub use struct_patch_derive::Substrate;
 pub mod r#box;

lib/src/traits.rs

@@ -214,7 +214,7 @@ pub trait Merge {
     fn merge(self, other: Self) -> Self;
 }
 
-#[cfg(feature = "catalyst")]
+#[cfg(feature = "substrate")]
 /// A substrate struct that can expose the fields information thereof
 pub trait Substrate {
     fn expose_content() -> &'static str;

no-std-examples/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "no-std-examples"
 authors = ["Antonio Yang <yanganto@gmail.com>"]
-version = "0.14.0"
+version = "0.14.1"
 edition = "2021"
 license = "MIT"