| use syntax::ext::base::{self, ExtCtxt}; |
| use syntax::symbol::kw; |
| use syntax_pos::Span; |
| use syntax::tokenstream::{TokenTree, TokenStream}; |
| |
| pub fn expand_trace_macros(cx: &mut ExtCtxt<'_>, |
| sp: Span, |
| tt: TokenStream) |
| -> Box<dyn base::MacResult + 'static> { |
| let mut cursor = tt.into_trees(); |
| let mut err = false; |
| let value = match &cursor.next() { |
| Some(TokenTree::Token(token)) if token.is_keyword(kw::True) => true, |
| Some(TokenTree::Token(token)) if token.is_keyword(kw::False) => false, |
| _ => { |
| err = true; |
| false |
| }, |
| }; |
| err |= cursor.next().is_some(); |
| if err { |
| cx.span_err(sp, "trace_macros! accepts only `true` or `false`") |
| } else { |
| cx.set_trace_macros(value); |
| } |
| |
| base::DummyResult::any_valid(sp) |
| } |