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extern crate proc_macro;
use core::iter;
use core::str::FromStr;
use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
#[proc_macro]
pub fn array_const_fn_init(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let mut iter = input.into_iter();
let func_name = match iter.next() {
Some(proc_macro::TokenTree::Ident(i)) => i.to_string(),
Some(other) => panic!("Expected function name, found {}", other),
None => panic!("Unexpected end of macro input"),
};
match iter.next() {
Some(proc_macro::TokenTree::Punct(ref p)) if p.as_char() == ';' => {}
Some(other) => panic!("Expected ';', found {}", other),
None => panic!("Unexpected end of macro input"),
};
let array_size: usize = match iter.next() {
Some(proc_macro::TokenTree::Literal(ref p)) => {
usize::from_str(&p.to_string()).expect("Expected <usize>")
}
Some(other) => panic!("Expected <usize>, found {}", other),
None => panic!("Unexpected end of macro input"),
};
match iter.next() {
None => {}
Some(_) => panic!("Unexpected trailing tokens in macro"),
}
let mut ts = TokenStream::new();
let span: Span = Span::call_site();
ts.extend({
let mut g = Group::new(Delimiter::Bracket, {
let mut ts = TokenStream::new();
(0..array_size).for_each(|i| {
ts.extend(iter::once(TokenTree::from(Ident::new(&func_name, span))));
ts.extend({
let mut g = Group::new(Delimiter::Parenthesis, {
let mut ts = TokenStream::new();
let _span: Span = span;
ts.extend(iter::once(TokenTree::from(Literal::usize_suffixed(i))));
ts
});
g.set_span(span);
Some(TokenTree::from(g))
});
ts.extend(iter::once(TokenTree::from(Punct::new(',', Spacing::Alone))));
});
ts
});
g.set_span(span);
Some(TokenTree::from(g))
});
ts
}