src/test/auxiliary/custom_derive_plugin_attr.rs

   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.
   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 // force-host
  12
  13 #![feature(plugin_registrar)]
  14 #![feature(box_syntax)]
  15 #![feature(rustc_private)]
  16
  17 extern crate syntax;
  18 extern crate rustc;
  19 extern crate rustc_plugin;
  20
  21 use syntax::ast;
  22 use syntax::attr::AttrMetaMethods;
  23 use syntax::codemap::Span;
  24 use syntax::ext::base::{MultiDecorator, ExtCtxt, Annotatable};
  25 use syntax::ext::build::AstBuilder;
  26 use syntax::ext::deriving::generic::{cs_fold, TraitDef, MethodDef, combine_substructure};
  27 use syntax::ext::deriving::generic::{Substructure, Struct, EnumMatching};
  28 use syntax::ext::deriving::generic::ty::{Literal, LifetimeBounds, Path, borrowed_explicit_self};
  29 use syntax::parse::token;
  30 use syntax::ptr::P;
  31 use rustc_plugin::Registry;
  32
  33 #[plugin_registrar]
  34 pub fn plugin_registrar(reg: &mut Registry) {
  35     reg.register_syntax_extension(
  36         token::intern("derive_TotalSum"),
  37         MultiDecorator(box expand));
  38 }
  39
  40 fn expand(cx: &mut ExtCtxt,
  41           span: Span,
  42           mitem: &ast::MetaItem,
  43           item: &Annotatable,
  44           push: &mut FnMut(Annotatable)) {
  45     let trait_def = TraitDef {
  46         span: span,
  47         attributes: vec![],
  48         path: Path::new(vec!["TotalSum"]),
  49         additional_bounds: vec![],
  50         generics: LifetimeBounds::empty(),
  51         associated_types: vec![],
  52         is_unsafe: false,
  53         methods: vec![
  54             MethodDef {
  55                 name: "total_sum",
  56                 generics: LifetimeBounds::empty(),
  57                 explicit_self: borrowed_explicit_self(),
  58                 args: vec![],
  59                 ret_ty: Literal(Path::new_local("isize")),
  60                 attributes: vec![],
  61                 is_unsafe: false,
  62                 combine_substructure: combine_substructure(Box::new(totalsum_substructure)),
  63             },
  64         ],
  65     };
  66
  67     trait_def.expand(cx, mitem, item, push)
  68 }
  69
  70 // Mostly copied from syntax::ext::deriving::hash
  71 /// Defines how the implementation for `trace()` is to be generated
  72 fn totalsum_substructure(cx: &mut ExtCtxt, trait_span: Span,
  73                          substr: &Substructure) -> P<ast::Expr> {
  74     let fields = match *substr.fields {
  75         Struct(ref fs) | EnumMatching(_, _, ref fs) => fs,
  76         _ => cx.span_bug(trait_span, "impossible substructure")
  77     };
  78
  79     fields.iter().fold(cx.expr_isize(trait_span, 0), |acc, ref item| {
  80         if item.attrs.iter().find(|a| a.check_name("ignore")).is_some() {
  81             acc
  82         } else {
  83             cx.expr_binary(item.span, ast::BiAdd, acc,
  84                            cx.expr_method_call(item.span,
  85                                                item.self_.clone(),
  86                                                substr.method_ident,
  87                                                Vec::new()))
  88         }
  89     })
  90 }