src/libsyntax_ext/log_syntax.rs

   1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use syntax::ext::base;
  12 use syntax::feature_gate;
  13 use syntax::print;
  14 use syntax::tokenstream;
  15 use syntax_pos;
  16
  17 pub fn expand_syntax_ext<'cx>(cx: &'cx mut base::ExtCtxt,
  18                               sp: syntax_pos::Span,
  19                               tts: &[tokenstream::TokenTree])
  20                               -> Box<base::MacResult + 'cx> {
  21     if !cx.ecfg.enable_log_syntax() {
  22         feature_gate::emit_feature_err(&cx.parse_sess,
  23                                        "log_syntax",
  24                                        sp,
  25                                        feature_gate::GateIssue::Language,
  26                                        feature_gate::EXPLAIN_LOG_SYNTAX);
  27         return base::DummyResult::any(sp);
  28     }
  29
  30     println!("{}", print::pprust::tts_to_string(tts));
  31
  32     // any so that `log_syntax` can be invoked as an expression and item.
  33     base::DummyResult::any(sp)
  34 }