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