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extern crate proc_macro;
use proc_macro::TokenStream;
use proc_macro2::{Ident, Span};
use quote::quote;
use syn::{self, parse_macro_input, ItemFn};
#[cfg(feature = "debug")]
macro_rules! proc_dbg {
($x:expr) => {
dbg!($x)
};
}
#[cfg(not(feature = "debug"))]
macro_rules! proc_dbg {
($x:expr) => {};
}
struct Tokens {
expr: syn::Expr,
}
impl syn::parse::Parse for Tokens {
fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
Ok(Tokens {
expr: input.parse()?,
})
}
}
#[proc_macro]
pub fn main(stream: TokenStream) -> TokenStream {
let Tokens { expr } = syn::parse_macro_input!(stream as Tokens);
proc_dbg!(&expr);
const ARG_PANIC_TEXT: &str =
"expected ident lexical path (or a literal string version) to 'uumain()' as argument";
let mut expr = match expr {
syn::Expr::Lit(expr_lit) => match expr_lit.lit {
syn::Lit::Str(ref lit_str) => lit_str.parse::<syn::ExprPath>().unwrap(),
_ => panic!("{}", ARG_PANIC_TEXT),
},
syn::Expr::Path(expr_path) => expr_path,
_ => panic!("{}", ARG_PANIC_TEXT),
};
proc_dbg!(&expr);
if expr.path.segments.len() < 2 {
expr = syn::parse_quote!( #expr::uumain );
};
proc_dbg!(&expr);
let f = quote::quote! { #expr(uucore::args_os()) };
proc_dbg!(&f);
let result = quote::quote! {
fn main() {
use std::io::Write;
uucore::panic::mute_sigpipe_panic();
let code = #f;
std::io::stdout().flush().expect("could not flush stdout");
std::process::exit(code);
}
};
TokenStream::from(result)
}
#[proc_macro_attribute]
pub fn gen_uumain(_args: TokenStream, stream: TokenStream) -> TokenStream {
let mut ast = parse_macro_input!(stream as ItemFn);
ast.sig.ident = Ident::new("uumain_result", Span::call_site());
let new = quote!(
pub fn uumain(args: impl uucore::Args) -> i32 {
#ast
let result = uumain_result(args);
match result {
Ok(()) => uucore::error::get_exit_code(),
Err(e) => {
let s = format!("{}", e);
if s != "" {
show_error!("{}", s);
}
if e.usage() {
eprintln!("Try '{} --help' for more information.", executable!());
}
e.code()
}
}
}
);
TokenStream::from(new)
}