support option and box on no_std

.github/workflows/test.yml

@@ -28,6 +28,7 @@ jobs:
           nix develop .#ci -c cargo run --no-default-features --example time
           nix develop .#ci -c cargo run --no-default-features --example clap
           nix develop .#ci -c cargo run --no-default-features --features=nesting --example nesting
+          nix develop .#ci -c cargo run --no-default-features --features=option --example option
           nix develop .#ci -c cargo test --no-default-features
 
       - name: Test with std features
@@ -66,3 +67,9 @@ jobs:
           nix develop .#ci -c cargo run --features=nesting --example nesting
           nix develop .#ci -c cargo run --features=nesting --example clap
           nix develop .#ci -c cargo test
+
+      - name: Test in no std
+        run: |
+          cd no-std-examples
+          nix develop .#no-std -c cargo run --features=box --bin no-std-box
+          nix develop .#no-std -c cargo run --features=option --bin no-std-option

.gitignore

@@ -3,3 +3,4 @@ Cargo.lock
 .envrc
 .direnv/
 struct-patch/examples
+no-std-examples/target

Cargo.toml

@@ -4,6 +4,7 @@ members = [
     "lib",
     "derive",
 ]
+exclude = [ "no-std-examples" ]
 
 [workspace.package]
 authors = ["Antonio Yang <yanganto@gmail.com>"]

derive/src/lib.rs

@@ -52,4 +52,3 @@ fn get_lit(attr_name: String, meta: &ParseNestedMeta) -> syn::Result<Option<syn:
         ))
     }
 }
-

derive/src/patch.rs

@@ -3,9 +3,8 @@ use proc_macro2::{Ident, Span, TokenStream};
 use quote::{quote, ToTokens};
 use std::str::FromStr;
 use syn::{
-    Lit,
-    meta::ParseNestedMeta, parenthesized, spanned::Spanned, DeriveInput, Error, LitStr, Result,
-    Type,
+    meta::ParseNestedMeta, parenthesized, spanned::Spanned, DeriveInput, Error, Lit, LitStr,
+    Result, Type,
 };
 
 #[cfg(feature = "op")]
@@ -148,13 +147,13 @@ impl Patch {
         #[cfg(not(feature = "nesting"))]
         let original_field_name_empty_values = fields
             .iter()
-            .filter(|f| !f.retyped )
+            .filter(|f| !f.retyped)
             .filter_map(|f| f.empty_value.as_ref())
             .collect::<Vec<_>>();
         #[cfg(feature = "nesting")]
         let original_field_name_empty_values = fields
             .iter()
-            .filter(|f| !f.retyped && !f.nesting )
+            .filter(|f| !f.retyped && !f.nesting)
             .filter_map(|f| f.empty_value.as_ref())
             .collect::<Vec<_>>();
 
@@ -824,11 +823,12 @@ impl Field {
                     EMPTY_VALUE => {
                         // #[patch(empty_value = ...)]
                         if empty_value.is_some() {
-                            return Err(meta
-                                .error("The empty value is already set, we can't defined more than once"));
+                            return Err(meta.error(
+                                "The empty value is already set, we can't defined more than once",
+                            ));
                         }
                         if let Some(lit) = crate::get_lit(path, &meta)? {
-                           empty_value= Some(lit);
+                            empty_value = Some(lit);
                         } else {
                             return Err(meta
                                 .error("empty_value needs a clear value to define what is empty"));

flake.nix

@@ -24,15 +24,28 @@
         '';
         updateDependencyScript = pkgs.writeShellScriptBin "update-dependency" ''
           dr ./Cargo.toml
-          if [ -f "Cargo.toml.old" ]; then
-            rm Cargo.toml.old
+
+          cd no-std-examples
+          dr ./Cargo.toml
+
+          if [[ -f "Cargo.toml.old" || -f "no-std-examples/Cargo.toml.old" ]]; then
+            rm -f Cargo.toml.old
+            rm -f no-std-examples/Cargo.toml.old
             exit 1
           fi
         '';
       in
       with pkgs;
       {
-        devShells = {
+        devShells = let
+          noStdRust = rust-bin.stable.latest.default.override {
+            targets = [
+              "thumbv7m-none-eabi"
+            ];
+            extensions = [ "rust-src" "llvm-tools-preview" ];
+          };
+        in
+        {
           default = mkShell {
             buildInputs = [
               rust-bin.stable.latest.minimal
@@ -52,6 +65,13 @@
               updateDependencyScript
             ];
           };
+
+          no-std = mkShell {
+            buildInputs = [
+              noStdRust 
+              qemu
+            ];
+          };
         };
       }
     );

lib/Cargo.toml

@@ -34,11 +34,13 @@ merge = [
     "struct-patch-derive/merge"
 ]
 
+alloc = []
 std = ["box", "option"]
-box = []
+box = ["alloc"]
 option = []
 nesting = [
     "struct-patch-derive/nesting"
 ]
 none_as_default = ["option"]
 keep_none = ["option"]
+

lib/src/box.rs

@@ -0,0 +1,61 @@
+#![cfg(feature = "box")]
+use crate::Patch;
+
+extern crate alloc;
+use alloc::boxed::Box;
+
+impl<T, P> Patch<Box<P>> for T
+where
+    T: Patch<P>,
+{
+    fn apply(&mut self, patch: Box<P>) {
+        self.apply(*patch);
+    }
+
+    fn into_patch(self) -> Box<P> {
+        Box::new(self.into_patch())
+    }
+
+    fn into_patch_by_diff(self, previous_struct: Self) -> Box<P> {
+        Box::new(self.into_patch_by_diff(previous_struct))
+    }
+
+    fn new_empty_patch() -> Box<P> {
+        Box::new(T::new_empty_patch())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate as struct_patch;
+    use crate::Patch;
+    use alloc::string::String;
+
+    #[test]
+    fn test_patch_box_simple() {
+        #[derive(Patch, Debug, PartialEq)]
+        struct Item {
+            field: u32,
+            other: String,
+        }
+
+        let mut item = Item {
+            field: 1,
+            other: String::from("hello"),
+        };
+        let patch = Box::new(ItemPatch {
+            field: None,
+            other: Some(String::from("bye")),
+        });
+
+        item.apply(patch);
+        assert_eq!(
+            item,
+            Item {
+                field: 1,
+                other: String::from("bye")
+            }
+        );
+    }
+}

lib/src/lib.rs

@@ -73,19 +73,24 @@
 //! item.apply(filler_2);
 //! assert_eq!(item.maybe_field_int, Some(7));
 //! ```
-#![cfg_attr(not(any(test, feature = "box", feature = "option")), no_std)]
+#![no_std]
+
+#[cfg(feature = "alloc")]
+extern crate alloc;
 
 #[doc(hidden)]
 pub use struct_patch_derive::Filler;
 #[doc(hidden)]
 pub use struct_patch_derive::Patch;
-#[cfg(any(feature = "box", feature = "option"))]
-pub mod std;
+pub mod r#box;
+pub mod option;
 pub mod traits;
 pub use traits::*;
 
 #[cfg(test)]
 mod tests {
+    extern crate alloc;
+    use alloc::string::String;
     use serde::Deserialize;
     #[cfg(feature = "merge")]
     use struct_patch::Merge;
@@ -486,7 +491,7 @@ mod tests {
             b: B,
         }
 
-        let patches = vec![
+        let patches = alloc::vec![
             APatch {
                 a: Some(1),
                 b: Some(BPatch {