src/test/auxiliary/custom_derive_plugin.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::codemap::Span;
  22 use syntax::ext::base::{Decorator, 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;
  27 use syntax::ptr::P;
  28 use rustc::plugin::Registry;
  29
  30 #[plugin_registrar]
  31 pub fn plugin_registrar(reg: &mut Registry) {
  32     reg.register_syntax_extension(
  33         token::intern("derive_TotalSum"),
  34         Decorator(box expand));
  35 }
  36
  37 fn expand(cx: &mut ExtCtxt,
  38           span: Span,
  39           mitem: &ast::MetaItem,
  40           item: &ast::Item,
  41           push: &mut FnMut(P<ast::Item>)) {
  42     let trait_def = TraitDef {
  43         span: span,
  44         attributes: vec![],
  45         path: Path::new(vec!["TotalSum"]),
  46         additional_bounds: vec![],
  47         generics: LifetimeBounds::empty(),
  48         associated_types: vec![],
  49         methods: vec![
  50             MethodDef {
  51                 name: "total_sum",
  52                 generics: LifetimeBounds::empty(),
  53                 explicit_self: borrowed_explicit_self(),
  54                 args: vec![],
  55                 ret_ty: Literal(Path::new_local("isize")),
  56                 attributes: vec![],
  57                 combine_substructure: combine_substructure(box |cx, span, substr| {
  58                     let zero = cx.expr_isize(span, 0);
  59                     cs_fold(false,
  60                             |cx, span, subexpr, field, _| {
  61                                 cx.expr_binary(span, ast::BiAdd, subexpr,
  62                                     cx.expr_method_call(span, field,
  63                                         token::str_to_ident("total_sum"), vec![]))
  64                             },
  65                             zero,
  66                             box |cx, span, _, _| { cx.span_bug(span, "wtf??"); },
  67                             cx, span, substr)
  68                 }),
  69             },
  70         ],
  71     };
  72
  73     trait_def.expand(cx,
  74                      mitem,
  75                      Annotatable::Item(P(item.clone())),
  76                      &mut |i| {
  77                         match i {
  78                             Annotatable::Item(i) => push(i),
  79                             _ => panic!("Not an item")
  80                         }
  81                      })
  82 }