More cleanup

Signed-off-by: Bob Weinand <bob.weinand@datadoghq.com>

Author: bwoebi

datadog-sidecar-macros/src/lib.rs

@@ -2,110 +2,8 @@
 // SPDX-License-Identifier: Apache-2.0
 
 use proc_macro::TokenStream;
-use quote::{format_ident, quote};
-use syn::FnArg::Typed;
-use syn::__private::Span;
-use syn::parse::{Parse, ParseStream};
-use syn::{parse_macro_input, parse_quote, Arm, Ident, ItemTrait, Pat, TraitItem};
-
-fn snake_to_camel(ident_str: &str) -> String {
-    let mut camel_ty = String::with_capacity(ident_str.len());
-
-    let mut last_char_was_underscore = true;
-    for c in ident_str.chars() {
-        match c {
-            '_' => last_char_was_underscore = true,
-            c if last_char_was_underscore => {
-                camel_ty.extend(c.to_uppercase());
-                last_char_was_underscore = false;
-            }
-            c => camel_ty.extend(c.to_lowercase()),
-        }
-    }
-
-    camel_ty.shrink_to_fit();
-    camel_ty
-}
-
-#[proc_macro_attribute]
-pub fn extract_request_id(_attr: TokenStream, input: TokenStream) -> TokenStream {
-    let mut item: ItemTrait = syn::parse(input).unwrap();
-    let name = &format_ident!("{}Request", item.ident);
-    let mut arms: Vec<Arm> = vec![];
-    let mut backpressure_variants: Vec<Ident> = vec![];
-
-    for inner in item.items.iter_mut() {
-        if let TraitItem::Fn(func) = inner {
-            // Strip #[force_backpressure] and record which methods carry it.
-            let had_force_backpressure = func.attrs.iter().any(|attr| {
-                attr.meta
-                    .path()
-                    .get_ident()
-                    .is_some_and(|i| i == "force_backpressure")
-            });
-            func.attrs.retain(|attr| {
-                attr.meta
-                    .path()
-                    .get_ident()
-                    .is_none_or(|i| i != "force_backpressure")
-            });
-
-            let method = Ident::new(
-                &snake_to_camel(&func.sig.ident.to_string()),
-                Span::mixed_site(),
-            );
-
-            if had_force_backpressure {
-                backpressure_variants.push(method.clone());
-            }
-
-            for any_arg in &func.sig.inputs {
-                if let Typed(arg) = any_arg {
-                    if let Pat::Ident(ident) = &*arg.pat {
-                        let matched_enum_type = match ident.ident.to_string().as_str() {
-                            "session_id" => Some(format_ident!("SessionId")),
-                            "instance_id" => Some(format_ident!("InstanceId")),
-                            _ => None,
-                        };
-                        if let Some(enum_type) = matched_enum_type {
-                            arms.push(parse_quote! {
-                                #name::#method { #ident, .. } => RequestIdentifier::#enum_type(#ident.clone())
-                            });
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    let backpressure_body = if backpressure_variants.is_empty() {
-        quote! { false }
-    } else {
-        quote! { matches!(self, #(#name::#backpressure_variants { .. })|*) }
-    };
-
-    TokenStream::from(quote! {
-        #item
-
-        impl RequestIdentification for tarpc::Request<#name> {
-            fn extract_identifier(&self) -> RequestIdentifier {
-                match &self.message {
-                    #(
-                        #arms,
-                    )*
-                    _ => RequestIdentifier::None,
-                }
-            }
-        }
-
-        impl #name {
-            /// Returns true if this request variant was annotated with `#[force_backpressure]`.
-            pub fn requires_backpressure(&self) -> bool {
-                #backpressure_body
-            }
-        }
-    })
-}
+use quote::quote;
+use syn::{parse_macro_input, parse::{Parse, ParseStream}};
 
 struct EnvOrDefault {
     name: syn::LitStr,