1 files changed, 72 insertions, 0 deletions
diff --git a/syrette_macros/src/libs/intertrait_macros/gen_caster.rs b/syrette_macros/src/libs/intertrait_macros/gen_caster.rs
new file mode 100644
index 0000000..9d177ed
--- /dev/null
+++ b/syrette_macros/src/libs/intertrait_macros/gen_caster.rs
@@ -0,0 +1,72 @@
+/**
+ * Originally from Intertrait by CodeChain
+ *
+ * https://github.com/CodeChain-io/intertrait
+ * https://crates.io/crates/intertrait/0.2.2
+ *
+ * Licensed under either of
+ *
+ * Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
+
+ * at your option.
+*/
+use std::str::from_utf8_unchecked;
+
+use proc_macro2::TokenStream;
+use uuid::adapter::Simple;
+use uuid::Uuid;
+
+use quote::format_ident;
+use quote::quote;
+use quote::ToTokens;
+
+pub fn generate_caster(
+    ty: &impl ToTokens,
+    trait_: &impl ToTokens,
+    sync: bool,
+) -> TokenStream
+{
+    let mut fn_buf = [0u8; FN_BUF_LEN];
+    let fn_ident = format_ident!("{}", new_fn_name(&mut fn_buf));
+    let new_caster = if sync {
+        quote! {
+            syrette::libs::intertrait::Caster::<dyn #trait_>::new_sync(
+                |from| from.downcast_ref::<#ty>().unwrap(),
+                |from| from.downcast_mut::<#ty>().unwrap(),
+                |from| from.downcast::<#ty>().unwrap(),
+                |from| from.downcast::<#ty>().unwrap(),
+                |from| from.downcast::<#ty>().unwrap()
+            )
+        }
+    } else {
+        quote! {
+            syrette::libs::intertrait::Caster::<dyn #trait_>::new(
+                |from| from.downcast_ref::<#ty>().unwrap(),
+                |from| from.downcast_mut::<#ty>().unwrap(),
+                |from| from.downcast::<#ty>().unwrap(),
+                |from| from.downcast::<#ty>().unwrap(),
+            )
+        }
+    };
+
+    quote! {
+        #[syrette::libs::linkme::distributed_slice(syrette::libs::intertrait::CASTERS)]
+        #[linkme(crate = syrette::libs::linkme)]
+        fn #fn_ident() -> (::std::any::TypeId, syrette::libs::intertrait::BoxedCaster) {
+            (::std::any::TypeId::of::<#ty>(), Box::new(#new_caster))
+        }
+    }
+}
+
+const FN_PREFIX: &[u8] = b"__";
+const FN_BUF_LEN: usize = FN_PREFIX.len() + Simple::LENGTH;
+
+fn new_fn_name(buf: &mut [u8]) -> &str
+{
+    buf[..FN_PREFIX.len()].copy_from_slice(FN_PREFIX);
+    Uuid::new_v4()
+        .to_simple()
+        .encode_lower(&mut buf[FN_PREFIX.len()..]);
+    unsafe { from_utf8_unchecked(&buf[..FN_BUF_LEN]) }
+}