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::attr::AttrMetaMethods;
22 use syntax::codemap::Span;
23 use syntax::ext::base::{MultiDecorator, ExtCtxt, Annotatable};
24 use syntax::ext::build::AstBuilder;
25 use syntax::ext::deriving::generic::{cs_fold, TraitDef, MethodDef, combine_substructure};
26 use syntax::ext::deriving::generic::{Substructure, Struct, EnumMatching};
27 use syntax::ext::deriving::generic::ty::{Literal, LifetimeBounds, Path, borrowed_explicit_self};
28 use syntax::parse::token;
30 use rustc::plugin::Registry;
33 pub fn plugin_registrar(reg: &mut Registry) {
34 reg.register_syntax_extension(
35 token::intern("derive_TotalSum"),
36 MultiDecorator(box expand));
39 fn expand(cx: &mut ExtCtxt,
41 mitem: &ast::MetaItem,
43 push: &mut FnMut(Annotatable)) {
44 let trait_def = TraitDef {
47 path: Path::new(vec!["TotalSum"]),
48 additional_bounds: vec![],
49 generics: LifetimeBounds::empty(),
50 associated_types: vec![],
55 generics: LifetimeBounds::empty(),
56 explicit_self: borrowed_explicit_self(),
58 ret_ty: Literal(Path::new_local("isize")),
61 combine_substructure: combine_substructure(Box::new(totalsum_substructure)),
66 trait_def.expand(cx, mitem, item, push)
69 // Mostly copied from syntax::ext::deriving::hash
70 /// Defines how the implementation for `trace()` is to be generated
71 fn totalsum_substructure(cx: &mut ExtCtxt, trait_span: Span,
72 substr: &Substructure) -> P<ast::Expr> {
73 let fields = match *substr.fields {
74 Struct(ref fs) | EnumMatching(_, _, ref fs) => fs,
75 _ => cx.span_bug(trait_span, "impossible substructure")
78 fields.iter().fold(cx.expr_isize(trait_span, 0), |acc, ref item| {
79 if item.attrs.iter().find(|a| a.check_name("ignore")).is_some() {
82 cx.expr_binary(item.span, ast::BiAdd, acc,
83 cx.expr_method_call(item.span,