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https://github.com/hexedtech/jni-toolbox.git
synced 2024-12-23 05:44:52 +01:00
feat: throw exception, allow specifying custom ones
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2 changed files with 216 additions and 0 deletions
19
macro/Cargo.toml
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19
macro/Cargo.toml
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@ -0,0 +1,19 @@
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[package]
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name = "jni-toolbox-macro"
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description = "proc macro to automate making JNI extern functions"
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repository = "https://github.com/hexedtech/jni-toolbox"
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authors = [
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"alemi <me@alemi.dev>"
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]
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license = "GPL-3.0-only"
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version = "0.1.0"
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edition = "2021"
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[lib]
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proc-macro = true
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path = "macro.rs"
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[dependencies]
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syn = {version = "2.0", features = ["full"]}
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quote = "1.0"
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proc-macro2 = "1.0"
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197
macro/macro.rs
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197
macro/macro.rs
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@ -0,0 +1,197 @@
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#[proc_macro_attribute]
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pub fn jni(
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attrs: proc_macro::TokenStream,
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input: proc_macro::TokenStream,
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) -> proc_macro::TokenStream {
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generate_jni_wrapper(
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syn::parse_macro_input!(attrs),
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syn::parse_macro_input!(input),
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)
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.unwrap()
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.into()
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}
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use proc_macro2::{Span, TokenStream, TokenTree};
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use quote::TokenStreamExt;
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use syn::{FnArg, Item, ReturnType, Type};
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fn generate_jni_wrapper(attrs: TokenStream, input: TokenStream) -> Result<TokenStream, syn::Error> {
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let mut out = TokenStream::new();
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let Item::Fn(fn_item) = syn::parse2(input.clone())? else {
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return Err(syn::Error::new(Span::call_site(), "#[jni] is only supported on functions"));
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};
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let mut what_next = WhatNext::Nothing;
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let mut package = None;
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let mut clazz = None;
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let mut exception = None;
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for attr in attrs {
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match what_next {
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WhatNext::Nothing => {
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if let TokenTree::Ident(ref i) = attr {
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match i.to_string().as_ref() {
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"package" => what_next = WhatNext::Package,
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"class" => what_next = WhatNext::Class,
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"exception" => what_next = WhatNext::Exception,
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_ => return Err(syn::Error::new(Span::call_site(), "unexpected attribute on macro: {attr}")),
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}
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}
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},
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WhatNext::Class => {
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if let TokenTree::Literal(i) = attr {
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let raw = i.to_string().replace('"', "");
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clazz = Some(syn::Ident::new(&raw, Span::call_site()));
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what_next = WhatNext::Nothing;
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}
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},
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WhatNext::Package => {
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if let TokenTree::Literal(i) = attr {
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let raw = i.to_string().replace('"', "").replace(".", "_");
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package = Some(syn::Ident::new(&raw, Span::call_site()));
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what_next = WhatNext::Nothing;
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}
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},
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WhatNext::Exception => {
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if let TokenTree::Literal(i) = attr {
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let raw = i.to_string().replace('"', "").replace(".", "_");
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exception = Some(i);
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what_next = WhatNext::Nothing;
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}
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}
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}
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}
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let Some(package) = package else { return Err(syn::Error::new(Span::call_site(), "missing attribute 'package'")) };
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let Some(clazz) = clazz else { return Err(syn::Error::new(Span::call_site(), "missing attribute 'class'")) };
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let (could_error, ret_type) = match fn_item.sig.output {
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syn::ReturnType::Default => (false, fn_item.sig.output),
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syn::ReturnType::Type(_tok, ty) => match *ty {
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syn::Type::Path(ref path) => {
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let Some(last) = path.path.segments.last() else {
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return Err(syn::Error::new(Span::call_site(), "empty Result type is not valid"));
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};
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// TODO this is terrible, macro returns a function and we call it?? there must be a
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// better way!!!
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let mut out = (
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false,
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ReturnType::Type(syn::Token), Box::new(Type::Path(path.clone())))
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);
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if last.ident == "Result" {
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match &last.arguments {
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syn::PathArguments::None => return Err(syn::Error::new(Span::call_site(), "Result without generics is not valid")),
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syn::PathArguments::Parenthesized(_) => return Err(syn::Error::new(Span::call_site(), "Parenthesized Result is not valid")),
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syn::PathArguments::AngleBracketed(ref generics) => for generic in generics.args.iter() {
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match generic {
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syn::GenericArgument::Lifetime(_) => continue,
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syn::GenericArgument::Type(ty) => {
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out = (true, ReturnType::Type(syn::Token), Box::new(ty.clone())));
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break;
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},
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_ => return Err(syn::Error::new(Span::call_site(), "unexpected type in Result")),
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}
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}
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}
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}
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out
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},
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_ => return Err(syn::Error::new(Span::call_site(), "unsupported return type")),
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},
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};
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let mut incoming = TokenStream::new();
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let mut forwarding = TokenStream::new();
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for arg in fn_item.sig.inputs {
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let FnArg::Typed(ty) = arg else {
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return Err(syn::Error::new(Span::call_site(), "#[jni] macro doesn't work on methods"));
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};
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incoming.append_all(quote::quote!( #ty , ));
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let pat = ty.pat;
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forwarding.append_all(quote::quote!( #pat , ));
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}
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let name = fn_item.sig.ident.to_string();
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let name_jni = name.replace("_", "_1");
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let fn_name_inner = syn::Ident::new(&name, Span::call_site());
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let fn_name = syn::Ident::new(&format!("Java_{package}_{clazz}_{name_jni}"), Span::call_site());
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let Some(env_ident) = forwarding.clone().into_iter().next() else {
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return Err(syn::Error::new(Span::call_site(), "missing JNIEnv argument"));
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};
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let wrapped = if could_error {
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if let Some(exception) = exception {
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// V----------------------------------V
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quote::quote! {
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#[no_mangle]
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pub extern "system" fn #fn_name<'local>(#incoming) #ret_type {
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use jni_toolbox::JniToolboxError;
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match #fn_name_inner(#forwarding) {
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Ok(ret) => ret,
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Err(e) => match #env_ident.throw_new(#exception, format!("{e:?}")) {
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Ok(_) => return 0,
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Err(e) => panic!("error throwing java exception: {e}"),
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}
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}
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}
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}
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// ^----------------------------------^
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} else {
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// V----------------------------------V
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quote::quote! {
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#[no_mangle]
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pub extern "system" fn #fn_name<'local>(#incoming) #ret_type {
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use jni_toolbox::JniToolboxError;
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match #fn_name_inner(#forwarding) {
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Err(e) => match #env_ident.find_class(e.jclass()) {
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Err(e) => panic!("error throwing Java exception -- failed resolving error class: {e}"),
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Ok(class) => match #env_ident.new_string(format!("{e:?}")) {
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Err(e) => panic!("error throwing Java exception -- failed creating error string: {e}"),
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Ok(msg) => match #env_ident.new_object(class, "(Ljava/lang/String;)V", &[jni::objects::JValueGen::Object(&msg)]) {
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Err(e) => panic!("error throwing Java exception -- failed creating object: {e}"),
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Ok(obj) => match #env_ident.throw(obj) {
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Err(e) => panic!("error throwing Java exception -- failed throwing: {e}"),
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Ok(_) => return 0,
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},
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},
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},
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}
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Ok(ret) => ret,
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}
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}
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}
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// ^----------------------------------^
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}
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} else {
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// V----------------------------------V
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quote::quote! {
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#[no_mangle]
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pub extern "system" fn #fn_name<'local>(#incoming) #ret_type {
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#fn_name_inner(#forwarding)
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}
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}
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// ^----------------------------------^
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};
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out.append_all(input);
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out.append_all(wrapped);
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Ok(out)
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}
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enum WhatNext {
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Nothing,
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Package,
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Class,
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Exception,
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}
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