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use proc_macro2::Ident;
use syn::{parse::Parse, LitStr};
use crate::common::args::{IdentArg, StrArg};
pub(crate) struct RegisterMacroArgs {
pub(crate) name: Option<LitStr>,
pub(crate) target: Ident,
}
#[derive(Default)]
struct RegisterMacroArgsBuilder {
name: Option<LitStr>,
target: Option<Ident>,
}
impl RegisterMacroArgsBuilder {
fn build(self, input: &syn::parse::ParseStream) -> syn::Result<RegisterMacroArgs> {
if let Some(target) = self.target {
Ok(RegisterMacroArgs {
name: self.name,
target,
})
} else {
Err(input.error("missing `target` argument"))
}
}
}
impl Parse for RegisterMacroArgs {
fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
let mut builder = RegisterMacroArgsBuilder::default();
while !input.is_empty() {
let lookahead = input.lookahead1();
if lookahead.peek(kw::name) {
if builder.name.is_some() {
return Err(input.error("expected only a single `name` argument"));
}
let name = input.parse::<StrArg<kw::name>>()?.value;
builder.name = Some(name);
} else if lookahead.peek(kw::target) {
if builder.target.is_some() {
return Err(input.error("expected only a single `target` argument"));
}
let target = input.parse::<IdentArg<kw::target>>()?.value;
builder.target = Some(target);
} else {
let _ = input.parse::<proc_macro2::TokenTree>();
}
}
builder.build(&input)
}
}
mod kw {
syn::custom_keyword!(name);
syn::custom_keyword!(target);
}
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