Support no_std stage 2

Cargo.toml

@@ -10,8 +10,12 @@ license = "MIT OR Apache-2.0"
 repository = "https://github.com/Artem-Romanenia/o2o"
 
 [dependencies]
-o2o-impl = { version = "0.4.9-alpha.1", path = "o2o-impl" }
-o2o-macros = { version = "0.4.9-alpha.1", path = "o2o-macros" }
+o2o-impl = { version = "0.4.9-alpha.1", path = "o2o-impl", optional = true }
+o2o-macros = { version = "0.4.9-alpha.1", path = "o2o-macros", optional = true }
+
+[features]
+default = ["macro"]
+macro = ["dep:o2o-impl", "dep:o2o-macros"]
 
 [workspace]
 members = ["o2o-impl", "o2o-macros", "o2o-tests"]

o2o-impl/src/expand.rs

@@ -22,10 +22,7 @@ pub fn derive(node: &DeriveInput) -> Result<TokenStream> {
             validate(&input)?;
             Ok(data_type_impl(input))
         },
-        _ => Err(Error::new_spanned(
-            node,
-            "#[derive(o2o)] only supports structs and enums.",
-        ))
+        _ => Err(Error::new_spanned(node, "#[derive(o2o)] only supports structs and enums."))
     }
 }
 
@@ -384,7 +381,7 @@ fn struct_init_block<'a>(input: &'a Struct, ctx: &ImplContext) -> TokenStream {
             unique_paths.insert(path);
             make_tuple(path, FieldData::Field(x))
         }).collect::<Vec<(usize, &str, FieldData)>>());
-    
+
     fields.extend(input.attrs.ghosts_attrs.iter()
         .flat_map(|x| &x.attr.ghost_data)
         .filter(|x| unique_paths.insert(x.get_child_path_str(None)))

src/lib.rs

@@ -1,8 +1,6 @@
 #![doc = include_str!("../README.md")]
 
-extern crate o2o_impl;
-extern crate o2o_macros;
+#[cfg(feature = "macro")]
+pub use o2o_macros::*;
 
 pub mod traits;
-
-pub use o2o_macros::*;