src/librustc_plugin/build.rs

   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 //! Used by `rustc` when compiling a plugin crate.
  12
  13 use syntax::ast;
  14 use syntax::attr;
  15 use syntax::codemap::Span;
  16 use syntax::diagnostic;
  17 use rustc_front::intravisit::Visitor;
  18 use rustc_front::hir;
  19
  20 struct RegistrarFinder {
  21     registrars: Vec<(ast::NodeId, Span)> ,
  22 }
  23
  24 impl<'v> Visitor<'v> for RegistrarFinder {
  25     fn visit_item(&mut self, item: &hir::Item) {
  26         if let hir::ItemFn(..) = item.node {
  27             if attr::contains_name(&item.attrs,
  28                                    "plugin_registrar") {
  29                 self.registrars.push((item.id, item.span));
  30             }
  31         }
  32     }
  33 }
  34
  35 /// Find the function marked with `#[plugin_registrar]`, if any.
  36 pub fn find_plugin_registrar(diagnostic: &diagnostic::SpanHandler,
  37                              krate: &hir::Crate)
  38                              -> Option<ast::NodeId> {
  39     let mut finder = RegistrarFinder { registrars: Vec::new() };
  40     krate.visit_all_items(&mut finder);
  41
  42     match finder.registrars.len() {
  43         0 => None,
  44         1 => {
  45             let (node_id, _) = finder.registrars.pop().unwrap();
  46             Some(node_id)
  47         },
  48         _ => {
  49             diagnostic.handler().err("multiple plugin registration functions found");
  50             for &(_, span) in &finder.registrars {
  51                 diagnostic.span_note(span, "one is here");
  52             }
  53             diagnostic.handler().abort_if_errors();
  54             unreachable!();
  55         }
  56     }
  57 }