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rustc: remove the explicit count from the lang_item macro. #11657

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merged 1 commit into from
Jan 20, 2014
Merged

rustc: remove the explicit count from the lang_item macro. #11657

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22 changes: 17 additions & 5 deletions src/librustc/middle/lang_items.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -33,12 +33,27 @@ use std::hashmap::HashMap;
use std::iter::Enumerate;
use std::vec;


// Get the last "argument" (has to be done recursively to avoid phoney local ambiguity error)
macro_rules! last {
( $first:expr, $( $remainder:expr, )+ ) => ( last!( $( $remainder, )+ ) );
( $first:expr, ) => ( $first )
}

// The actual lang items defined come at the end of this file in one handy table.
// So you probably just want to nip down to the end.
macro_rules! lets_do_this {
// secondary rule to allow us to use `$num` as both an expression
// and a pattern.
(
$( $num:tt, $variant:ident, $name:expr, $method:ident; )*
) => {
lets_do_this!(count = 1 + last!($($num,)*),
$($num, $variant, $name, $method; )*)
};

(
There are $num_lang_items:expr lang items.
$( $num:pat, $variant:ident, $name:expr, $method:ident; )*
count = $num_lang_items:expr, $( $num:pat, $variant:ident, $name:expr, $method:ident; )*
) => {

pub enum LangItem {
Expand Down Expand Up @@ -207,8 +222,6 @@ pub fn collect_language_items(crate: &ast::Crate,
}

lets_do_this! {
There are 40 lang items.

// ID, Variant name, Name, Method name;
0, FreezeTraitLangItem, "freeze", freeze_trait;
1, SendTraitLangItem, "send", send_trait;
Expand Down Expand Up @@ -261,4 +274,3 @@ lets_do_this! {
38, ExchangeHeapLangItem, "exchange_heap", exchange_heap;
39, GcLangItem, "gc", gc;
}