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use std::error::Error;
use proc_macro2::Ident;
use syn::{parse2, FnArg, GenericArgument, LitStr, PathArguments, Type};
use crate::named_attr_input::NamedAttrInput;
use crate::util::syn_path::syn_path_to_string;
pub struct Dependency
{
pub interface: Type,
pub ptr: Ident,
pub name: Option<LitStr>,
}
impl Dependency
{
pub fn build(new_method_arg: &FnArg) -> Result<Self, Box<dyn Error>>
{
let typed_new_method_arg = match new_method_arg {
FnArg::Typed(typed_arg) => Ok(typed_arg),
FnArg::Receiver(_) => Err("Unexpected self argument in 'new' method"),
}?;
let ptr_type_path = match typed_new_method_arg.ty.as_ref() {
Type::Path(arg_type_path) => Ok(arg_type_path),
Type::Reference(ref_type_path) => match ref_type_path.elem.as_ref() {
Type::Path(arg_type_path) => Ok(arg_type_path),
&_ => Err("Unexpected reference to non-path type"),
},
&_ => Err("Expected a path or a reference type"),
}?;
let ptr_path_segment = ptr_type_path.path.segments.last().map_or_else(
|| Err("Expected pointer type path to have a last segment"),
Ok,
)?;
let ptr = ptr_path_segment.ident.clone();
let ptr_path_generic_args = &match &ptr_path_segment.arguments {
PathArguments::AngleBracketed(generic_args) => Ok(generic_args),
&_ => Err("Expected pointer type to have a generic type argument"),
}?
.args;
let interface = if let Some(GenericArgument::Type(interface)) =
ptr_path_generic_args.first()
{
Ok(interface.clone())
} else {
Err("Expected pointer type to have a generic type argument")
}?;
let arg_attrs = &typed_new_method_arg.attrs;
let opt_named_attr = arg_attrs.iter().find(|attr| {
attr.path.get_ident().map_or_else(
|| false,
|attr_ident| attr_ident.to_string().as_str() == "named",
) || syn_path_to_string(&attr.path) == "syrette::named"
});
let opt_named_attr_tokens = opt_named_attr.map(|attr| &attr.tokens);
let opt_named_attr_input =
if let Some(named_attr_tokens) = opt_named_attr_tokens {
Some(parse2::<NamedAttrInput>(named_attr_tokens.clone()).map_err(
|err| format!("Invalid input for 'named' attribute. {}", err),
)?)
} else {
None
};
Ok(Self {
interface,
ptr,
name: opt_named_attr_input.map(|named_attr_input| named_attr_input.name),
})
}
}
|
