1 // Copyright 2012-2013 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 ast;
12 use attr;
13 use codemap::Span;
14 use diagnostic;
15 use visit;
16 use visit::Visitor;
17
18 struct MacroRegistrarContext {
19 registrars: Vec<(ast::NodeId, Span)> ,
20 }
21
22 impl Visitor<()> for MacroRegistrarContext {
23 fn visit_item(&mut self, item: &ast::Item, _: ()) {
24 match item.node {
25 ast::ItemFn(..) => {
26 if attr::contains_name(item.attrs.as_slice(),
27 "macro_registrar") {
28 self.registrars.push((item.id, item.span));
29 }
30 }
31 _ => {}
32 }
33
34 visit::walk_item(self, item, ());
35 }
36 }
37
38 pub fn find_macro_registrar(diagnostic: &diagnostic::SpanHandler,
39 krate: &ast::Crate) -> Option<ast::NodeId> {
40 let mut ctx = MacroRegistrarContext { registrars: Vec::new() };
41 visit::walk_crate(&mut ctx, krate, ());
42
43 match ctx.registrars.len() {
44 0 => None,
45 1 => {
46 let (node_id, _) = ctx.registrars.pop().unwrap();
47 Some(node_id)
48 },
49 _ => {
50 diagnostic.handler().err("multiple macro registration functions found");
51 for &(_, span) in ctx.registrars.iter() {
52 diagnostic.span_note(span, "one is here");
53 }
54 diagnostic.handler().abort_if_errors();
55 unreachable!();
56 }
57 }
58 }