From 17cd9038b75029e307e6c2e32ee36a2982cfd07c Mon Sep 17 00:00:00 2001
From: overlookmotel <557937+overlookmotel@users.noreply.github.com>
Date: Mon, 16 Sep 2024 04:10:31 +0000
Subject: [PATCH] refactor(ast): move functions to top level in `ast` macro
 (#5793)

Pure refactor. Convert nested functions to top level, to make it easier to read.
---
 crates/oxc_ast_macros/src/ast.rs | 95 ++++++++++++++++----------------
 1 file changed, 48 insertions(+), 47 deletions(-)

diff --git a/crates/oxc_ast_macros/src/ast.rs b/crates/oxc_ast_macros/src/ast.rs
index 5207d67b3..083233f87 100644
--- a/crates/oxc_ast_macros/src/ast.rs
+++ b/crates/oxc_ast_macros/src/ast.rs
@@ -42,54 +42,55 @@ fn enum_repr(enum_: &ItemEnum) -> TokenStream {
 /// If `GetSpan` is not in scope, or it is not the correct `oxc_span::GetSpan`,
 /// this will raise a compilation error.
 fn assert_generated_derives(attrs: &[Attribute]) -> TokenStream {
-    #[inline]
-    fn parse(attr: &Attribute) -> impl Iterator<Item = Ident> {
-        attr.parse_args_with(Punctuated::<Ident, Comma>::parse_terminated)
-        .expect("`#[generate_derive]` only accepts traits as single segment paths. Found an invalid argument.")
-        .into_iter()
-    }
-
-    // TODO: benchmark this to see if a lazy static cell containing `HashMap` would perform better.
-    #[inline]
-    fn abs_trait(
-        ident: &Ident,
-    ) -> (/* absolute type path */ TokenStream, /* possible generics */ TokenStream) {
-        #[cold]
-        fn invalid_derive(ident: &Ident) -> ! {
-            panic!(
-                "Invalid derive trait(generate_derive): {ident}.\n\
-                    Help: If you are trying to implement a new `generate_derive` trait, \
-                    Make sure to add it to the list below."
-            )
-        }
-
-        if ident == "CloneIn" {
-            (quote!(::oxc_allocator::CloneIn), quote!(<'static>))
-        } else if ident == "GetSpan" {
-            (quote!(::oxc_span::GetSpan), TokenStream::default())
-        } else if ident == "GetSpanMut" {
-            (quote!(::oxc_span::GetSpanMut), TokenStream::default())
-        } else if ident == "ContentEq" {
-            (quote!(::oxc_span::cmp::ContentEq), TokenStream::default())
-        } else if ident == "ContentHash" {
-            (quote!(::oxc_span::hash::ContentHash), TokenStream::default())
-        } else {
-            invalid_derive(ident)
-        }
-    }
-
     // NOTE: At this level we don't care if a trait is derived multiple times, It is the
     // responsibility of the `ast_tools` to raise errors for those.
-    let assertion =
-        attrs.iter().filter(|attr| attr.path().is_ident("generate_derive")).flat_map(parse).map(
-            |derive| {
-                let (abs_derive, generics) = abs_trait(&derive);
-                quote! {{
-                    // NOTE: these are wrapped in a scope to avoid the need for unique identifiers.
-                    trait AssertionTrait: #abs_derive #generics {}
-                    impl<T: #derive #generics> AssertionTrait for T {}
-                }}
-            },
-        );
+    let assertion = attrs
+        .iter()
+        .filter(|attr| attr.path().is_ident("generate_derive"))
+        .flat_map(parse_attr)
+        .map(|derive| {
+            let (abs_derive, generics) = abs_trait(&derive);
+            quote! {{
+                // NOTE: these are wrapped in a scope to avoid the need for unique identifiers.
+                trait AssertionTrait: #abs_derive #generics {}
+                impl<T: #derive #generics> AssertionTrait for T {}
+            }}
+        });
     quote!(const _: () = { #(#assertion)* };)
 }
+
+#[inline]
+fn parse_attr(attr: &Attribute) -> impl Iterator<Item = Ident> {
+    attr.parse_args_with(Punctuated::<Ident, Comma>::parse_terminated)
+        .expect("`#[generate_derive]` only accepts traits as single segment paths. Found an invalid argument.")
+        .into_iter()
+}
+
+// TODO: benchmark this to see if a lazy static cell containing `HashMap` would perform better.
+#[inline]
+fn abs_trait(
+    ident: &Ident,
+) -> (/* absolute type path */ TokenStream, /* possible generics */ TokenStream) {
+    if ident == "CloneIn" {
+        (quote!(::oxc_allocator::CloneIn), quote!(<'static>))
+    } else if ident == "GetSpan" {
+        (quote!(::oxc_span::GetSpan), TokenStream::default())
+    } else if ident == "GetSpanMut" {
+        (quote!(::oxc_span::GetSpanMut), TokenStream::default())
+    } else if ident == "ContentEq" {
+        (quote!(::oxc_span::cmp::ContentEq), TokenStream::default())
+    } else if ident == "ContentHash" {
+        (quote!(::oxc_span::hash::ContentHash), TokenStream::default())
+    } else {
+        invalid_derive(ident)
+    }
+}
+
+#[cold]
+fn invalid_derive(ident: &Ident) -> ! {
+    panic!(
+        "Invalid derive trait(generate_derive): {ident}.\n\
+        Help: If you are trying to implement a new `generate_derive` trait, \
+        make sure to add it to the list in `abs_trait` function."
+    )
+}