1 // Copyright 2015 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.
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.
13 #![feature(plugin_registrar)]
14 #![feature(box_syntax)]
15 #![feature(rustc_private)]
21 use syntax::codemap::Span;
22 use syntax::ext::base::{MultiDecorator, ExtCtxt, Annotatable};
23 use syntax::ext::build::AstBuilder;
24 use syntax::ext::deriving::generic::{cs_fold, TraitDef, MethodDef, combine_substructure};
25 use syntax::ext::deriving::generic::ty::{Literal, LifetimeBounds, Path, borrowed_explicit_self};
26 use syntax::parse::token;
28 use rustc::plugin::Registry;
31 pub fn plugin_registrar(reg: &mut Registry) {
32 reg.register_syntax_extension(
33 token::intern("derive_TotalSum"),
34 MultiDecorator(box expand));
37 fn expand(cx: &mut ExtCtxt,
39 mitem: &ast::MetaItem,
41 push: &mut FnMut(Annotatable)) {
42 let trait_def = TraitDef {
45 path: Path::new(vec!["TotalSum"]),
46 additional_bounds: vec![],
47 generics: LifetimeBounds::empty(),
48 associated_types: vec![],
53 generics: LifetimeBounds::empty(),
54 explicit_self: borrowed_explicit_self(),
56 ret_ty: Literal(Path::new_local("isize")),
59 combine_substructure: combine_substructure(box |cx, span, substr| {
60 let zero = cx.expr_isize(span, 0);
62 |cx, span, subexpr, field, _| {
63 cx.expr_binary(span, ast::BiAdd, subexpr,
64 cx.expr_method_call(span, field,
65 token::str_to_ident("total_sum"), vec![]))
68 box |cx, span, _, _| { cx.span_bug(span, "wtf??"); },
75 trait_def.expand(cx, mitem, item, push)