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use proc_macro::TokenStream;
use quote::{quote, ToTokens};
use syn::{
parse, parse_macro_input, parse_str, punctuated::Punctuated, token::Comma,
AttributeArgs, FnArg, GenericArgument, ImplItem, ItemImpl, Meta, NestedMeta, Path,
PathArguments, Type, TypePath,
};
mod libs;
use libs::intertrait_macros::{
args::{Casts, Flag, Targets},
gen_caster::generate_caster,
};
const NO_INTERFACE_ARG_ERR_MESSAGE: &str =
"Expected a argument specifying a interface trait";
const INVALID_ARG_ERR_MESSAGE: &str = "Invalid argument passed";
const INVALID_ITEM_TYPE_ERR_MESSAGE: &str =
"The attached to item is not a trait implementation";
const IMPL_NO_NEW_METHOD_ERR_MESSAGE: &str =
"The attached to trait implementation is missing a new method";
const IMPL_NEW_METHOD_SELF_PARAM_ERR_MESSAGE: &str =
"The new method of the attached to trait implementation cannot have a self parameter";
const IMPL_NEW_METHOD_BOX_PARAMS_ERR_MESSAGE: &str =
"All parameters of the new method of the attached to trait implementation must be std::boxed::Box";
fn path_to_string(path: &Path) -> String
{
return path
.segments
.pairs()
.fold(String::new(), |mut acc, segment_pair| {
let segment_ident = &segment_pair.value().ident;
acc.push_str(segment_ident.to_string().as_str());
let opt_colon_two = segment_pair.punct();
match opt_colon_two {
Some(colon_two) => {
acc.push_str(colon_two.to_token_stream().to_string().as_str())
}
None => {}
}
acc
});
}
fn get_fn_args_has_self(fn_args: &Punctuated<FnArg, Comma>) -> bool
{
return fn_args.iter().any(|arg| match arg {
FnArg::Receiver(_) => true,
&_ => false,
});
}
fn get_fn_arg_type_paths(fn_args: &Punctuated<FnArg, Comma>) -> Vec<TypePath>
{
return fn_args.iter().fold(Vec::<TypePath>::new(), |mut acc, arg| {
match arg {
FnArg::Typed(typed_fn_arg) => match typed_fn_arg.ty.as_ref() {
Type::Path(arg_type_path) => acc.push(arg_type_path.clone()),
&_ => {}
},
FnArg::Receiver(_receiver_fn_arg) => {}
}
acc
});
}
fn get_dependency_types(item_impl: &ItemImpl) -> Vec<Type>
{
let impl_items = &item_impl.items;
let opt_new_method_impl_item = impl_items.iter().find(|item| match item {
ImplItem::Method(method_item) => method_item.sig.ident == "new",
&_ => false,
});
let new_method_impl_item = match opt_new_method_impl_item {
Some(item) => match item {
ImplItem::Method(method_item) => method_item,
&_ => panic!("{}", IMPL_NO_NEW_METHOD_ERR_MESSAGE),
},
None => panic!("{}", IMPL_NO_NEW_METHOD_ERR_MESSAGE),
};
let new_method_inputs = &new_method_impl_item.sig.inputs;
if get_fn_args_has_self(new_method_inputs) {
panic!("{}", IMPL_NEW_METHOD_SELF_PARAM_ERR_MESSAGE)
}
let new_method_arg_type_paths = get_fn_arg_type_paths(new_method_inputs);
return new_method_arg_type_paths.iter().fold(
Vec::<Type>::new(),
|mut acc, arg_type_path| {
let arg_type_path_string = path_to_string(&arg_type_path.path);
if arg_type_path_string != "Box"
&& arg_type_path_string != "std::boxed::Box"
&& arg_type_path_string != "boxed::Box"
{
panic!("{}", IMPL_NEW_METHOD_BOX_PARAMS_ERR_MESSAGE);
}
// Assume the type path has a last segment.
// The Box check wouldn't pass if it didn't
let last_path_segment = arg_type_path.path.segments.last().unwrap();
match &last_path_segment.arguments {
PathArguments::AngleBracketed(angle_bracketed_generic_args) => {
let generic_args = &angle_bracketed_generic_args.args;
let opt_first_generic_arg = generic_args.first();
// Assume a first generic argument exists because Box requires one
let first_generic_arg = opt_first_generic_arg.as_ref().unwrap();
match first_generic_arg {
GenericArgument::Type(first_generic_arg_type) => {
acc.push(first_generic_arg_type.clone());
}
&_ => {}
}
}
&_ => {}
}
acc
},
);
}
#[proc_macro_attribute]
pub fn injectable(args_stream: TokenStream, impl_stream: TokenStream) -> TokenStream
{
let args = parse_macro_input!(args_stream as AttributeArgs);
if args.is_empty() {
panic!("{}", NO_INTERFACE_ARG_ERR_MESSAGE);
}
if args.len() > 1 {
panic!("Only a single argument is expected");
}
let interface_path = match &args[0] {
NestedMeta::Meta(arg_meta) => match arg_meta {
Meta::Path(path_arg) => path_arg,
&_ => panic!("{}", INVALID_ARG_ERR_MESSAGE),
},
&_ => panic!("{}", INVALID_ARG_ERR_MESSAGE),
};
let item_impl: ItemImpl = match parse(impl_stream) {
Ok(impl_parsed) => impl_parsed,
Err(_) => {
panic!("{}", INVALID_ITEM_TYPE_ERR_MESSAGE)
}
};
let self_type = item_impl.self_ty.as_ref();
let self_type_path = match self_type {
Type::Path(path_self_type) => path_self_type.path.clone(),
&_ => parse_str("invalid_type").unwrap(),
};
let dependency_types = get_dependency_types(&item_impl);
quote! {
#item_impl
impl syrette::injectable::Injectable for #self_type_path {
fn resolve(
di_container: &syrette::DIContainer
) -> error_stack::Result<Box<Self>, syrette::injectable::ResolveError>
{
use error_stack::ResultExt;
return Ok(Box::new(Self::new(
#(di_container.get::<#dependency_types>()
.change_context(syrette::injectable::ResolveError)
.attach_printable(format!(
"Unable to resolve a dependency of {}",
std::any::type_name::<#self_type_path>()
))?,
)*
)));
}
}
syrette::castable_to!(#self_type_path => #interface_path);
}
.into()
}
#[proc_macro]
pub fn castable_to(input: TokenStream) -> TokenStream
{
let Casts {
ty,
targets: Targets { flags, paths },
} = parse_macro_input!(input);
paths
.iter()
.map(|t| generate_caster(&ty, t, flags.contains(&Flag::Sync)))
.collect::<proc_macro2::TokenStream>()
.into()
}
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