hexedtech/jni-toolbox
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chore: made a jni-toolbox wrapper crate

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əlemi 2024-09-21 17:52:20 +02:00
parent 5e560d2f3d
commit c044fff422
Signed by: alemi
GPG key ID: A4895B84D311642C
3 changed files with 18 additions and 165 deletions
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9
Cargo.lock generated
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@ -3,7 +3,14 @@
version = 3
[[package]]
name = "jni-macro"
name = "jni-toolbox"
version = "0.1.0"
dependencies = [
"jni-toolbox-macro",
]
[[package]]
name = "jni-toolbox-macro"
version = "0.1.0"
dependencies = [
"proc-macro2",

14
Cargo.toml
View file

@ -1,6 +1,9 @@
[workspace]
members = ["macro"]
[package]
name = "jni-macro"
description = "proc macro to automate making JNI extern functions"
name = "jni-toolbox"
description = "tools to make writing JNI native functions less tiresome"
repository = "https://github.com/hexedtech/jni-macro"
authors = [
"alemi <me@alemi.dev>"
@ -9,10 +12,5 @@ license = "GPL-3.0-only"
version = "0.1.0"
edition = "2021"
[lib]
proc-macro = true
[dependencies]
syn = {version = "2.0", features = ["full"]}
quote = "1.0"
proc-macro2 = "1.0"
jni-toolbox-macro = { path = "./macro" }

160
src/lib.rs
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@ -1,157 +1,5 @@
#[proc_macro_attribute]
pub fn jni(
attrs: proc_macro::TokenStream,
input: proc_macro::TokenStream,
) -> proc_macro::TokenStream {
generate_jni_wrapper(
syn::parse_macro_input!(attrs),
syn::parse_macro_input!(input),
)
.unwrap()
.into()
}
use proc_macro2::{Span, TokenStream, TokenTree};
use quote::TokenStreamExt;
use syn::{FnArg, Item, ReturnType, Type};
fn generate_jni_wrapper(attrs: TokenStream, input: TokenStream) -> Result<TokenStream, syn::Error> {
let mut out = TokenStream::new();
let Item::Fn(fn_item) = syn::parse2(input.clone())? else {
return Err(syn::Error::new(Span::call_site(), "#[jni] is only supported on functions"));
};
let mut what_next = WhatNext::Nothing;
let mut package = None;
let mut clazz = None;
for attr in attrs {
match what_next {
WhatNext::Nothing => {
if let TokenTree::Ident(ref i) = attr {
match i.to_string().as_ref() {
"package" => what_next = WhatNext::Package,
"class" => what_next = WhatNext::Class,
_ => return Err(syn::Error::new(Span::call_site(), "unexpected attribute on macro: {attr}")),
}
}
},
WhatNext::Class => {
if let TokenTree::Literal(i) = attr {
let raw = i.to_string().replace('"', "");
clazz = Some(syn::Ident::new(&raw, Span::call_site()));
what_next = WhatNext::Nothing;
}
},
WhatNext::Package => {
if let TokenTree::Literal(i) = attr {
let raw = i.to_string().replace('"', "").replace(".", "_");
package = Some(syn::Ident::new(&raw, Span::call_site()));
what_next = WhatNext::Nothing;
}
},
}
}
let Some(package) = package else { return Err(syn::Error::new(Span::call_site(), "missing attribute 'package'")) };
let Some(clazz) = clazz else { return Err(syn::Error::new(Span::call_site(), "missing attribute 'class'")) };
let (could_error, ret_type) = match fn_item.sig.output {
syn::ReturnType::Default => (false, fn_item.sig.output),
syn::ReturnType::Type(_tok, ty) => match *ty {
syn::Type::Path(ref path) => {
let Some(last) = path.path.segments.last() else {
return Err(syn::Error::new(Span::call_site(), "empty Result type is not valid"));
};
// TODO this is terrible, macro returns a function and we call it?? there must be a
// better way!!!
let mut out = (
false,
ReturnType::Type(syn::Token![->](Span::call_site()), Box::new(Type::Path(path.clone())))
);
if last.ident == "Result" {
match &last.arguments {
syn::PathArguments::None => return Err(syn::Error::new(Span::call_site(), "Result without generics is not valid")),
syn::PathArguments::Parenthesized(_) => return Err(syn::Error::new(Span::call_site(), "Parenthesized Result is not valid")),
syn::PathArguments::AngleBracketed(ref generics) => for generic in generics.args.iter() {
match generic {
syn::GenericArgument::Lifetime(_) => continue,
syn::GenericArgument::Type(ty) => {
out = (true, ReturnType::Type(syn::Token![->](Span::call_site()), Box::new(ty.clone())));
break;
},
_ => return Err(syn::Error::new(Span::call_site(), "unexpected type in Result")),
}
}
}
}
out
},
_ => return Err(syn::Error::new(Span::call_site(), "unsupported return type")),
},
};
let mut incoming = TokenStream::new();
let mut forwarding = TokenStream::new();
for arg in fn_item.sig.inputs {
let FnArg::Typed(ty) = arg else {
return Err(syn::Error::new(Span::call_site(), "#[jni] macro doesn't work on methods"));
};
incoming.append_all(quote::quote!( #ty , ));
let pat = ty.pat;
forwarding.append_all(quote::quote!( #pat , ));
}
let name = fn_item.sig.ident.to_string();
let name_jni = name.replace("_", "_1");
let fn_name_inner = syn::Ident::new(&name, Span::call_site());
let fn_name = syn::Ident::new(&format!("Java_{package}_{clazz}_{name_jni}"), Span::call_site());
let Some(env_ident) = forwarding.clone().into_iter().next() else {
return Err(syn::Error::new(Span::call_site(), "missing JNIEnv argument"));
};
let wrapped = if could_error {
quote::quote! {
#[no_mangle]
pub extern "system" fn #fn_name<'local>(#incoming) #ret_type {
match #fn_name_inner(#forwarding) {
Ok(x) => x,
Err(e) => {
#env_ident
.throw_new("java/lang/RuntimeException", format!("{e:?}"))
.expect("failed throwing Java exception from native call");
return 0;
}
}
}
}
} else {
quote::quote! {
#[no_mangle]
pub extern "system" fn #fn_name<'local>(#incoming) #ret_type {
#fn_name_inner(#forwarding)
}
}
};
out.append_all(input);
out.append_all(wrapped);
Ok(out)
}
enum WhatNext {
Nothing,
Package,
Class,
pub use jni_toolbox_macro::jni;
pub trait JniToolboxError: std::error::Error {
fn jclass(&self) -> String;
}