src/libsyntax/ext/deriving/bounds.rs

   1 // Copyright 2014 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::{MetaItem, MetaWord, Item};
  12 use codemap::Span;
  13 use ext::base::ExtCtxt;
  14 use ext::deriving::generic::*;
  15 use ext::deriving::generic::ty::*;
  16 use ptr::P;
  17
  18 pub fn expand_deriving_bound<F>(cx: &mut ExtCtxt,
  19                                 span: Span,
  20                                 mitem: &MetaItem,
  21                                 item: &Item,
  22                                 push: F) where
  23     F: FnOnce(P<Item>),
  24 {
  25     let name = match mitem.node {
  26         MetaWord(ref tname) => {
  27             match tname.get() {
  28                 "Copy" => "Copy",
  29                 "Send" | "Sync" => {
  30                     return cx.span_err(span,
  31                                        format!("{} is an unsafe trait and it \
  32                                                 should be implemented explicitly",
  33                                                *tname).as_slice())
  34                 }
  35                 ref tname => {
  36                     cx.span_bug(span,
  37                                 format!("expected built-in trait name but \
  38                                          found {}", *tname).as_slice())
  39                 }
  40             }
  41         },
  42         _ => {
  43             return cx.span_err(span, "unexpected value in deriving, expected \
  44                                       a trait")
  45         }
  46     };
  47
  48     let trait_def = TraitDef {
  49         span: span,
  50         attributes: Vec::new(),
  51         path: Path::new(vec!("std", "marker", name)),
  52         additional_bounds: Vec::new(),
  53         generics: LifetimeBounds::empty(),
  54         methods: Vec::new(),
  55         associated_types: Vec::new(),
  56     };
  57
  58     trait_def.expand(cx, mitem, item, push)
  59 }