src/libsyntax/ext/deriving/cmp/eq.rs

   1 // Copyright 2013 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 use ast::{MetaItem, Expr};
  12 use codemap::Span;
  13 use ext::base::{ExtCtxt, Annotatable};
  14 use ext::build::AstBuilder;
  15 use ext::deriving::generic::*;
  16 use ext::deriving::generic::ty::*;
  17 use parse::token::InternedString;
  18 use ptr::P;
  19
  20 pub fn expand_deriving_eq(cx: &mut ExtCtxt,
  21                           span: Span,
  22                           mitem: &MetaItem,
  23                           item: &Annotatable,
  24                           push: &mut FnMut(Annotatable))
  25 {
  26     fn cs_total_eq_assert(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
  27         cs_same_method(
  28             |cx, span, exprs| {
  29                 // create `a.<method>(); b.<method>(); c.<method>(); ...`
  30                 // (where method is `assert_receiver_is_total_eq`)
  31                 let stmts = exprs.into_iter().map(|e| cx.stmt_expr(e)).collect();
  32                 let block = cx.block(span, stmts, None);
  33                 cx.expr_block(block)
  34             },
  35             Box::new(|cx, sp, _, _| {
  36                 cx.span_bug(sp, "non matching enums in derive(Eq)?") }),
  37             cx,
  38             span,
  39             substr
  40         )
  41     }
  42
  43     let inline = cx.meta_word(span, InternedString::new("inline"));
  44     let hidden = cx.meta_word(span, InternedString::new("hidden"));
  45     let doc = cx.meta_list(span, InternedString::new("doc"), vec!(hidden));
  46     let attrs = vec!(cx.attribute(span, inline),
  47                      cx.attribute(span, doc));
  48     let trait_def = TraitDef {
  49         span: span,
  50         attributes: Vec::new(),
  51         path: path_std!(cx, core::cmp::Eq),
  52         additional_bounds: Vec::new(),
  53         generics: LifetimeBounds::empty(),
  54         methods: vec!(
  55             MethodDef {
  56                 name: "assert_receiver_is_total_eq",
  57                 generics: LifetimeBounds::empty(),
  58                 explicit_self: borrowed_explicit_self(),
  59                 args: vec!(),
  60                 ret_ty: nil_ty(),
  61                 attributes: attrs,
  62                 is_unsafe: false,
  63                 combine_substructure: combine_substructure(Box::new(|a, b, c| {
  64                     cs_total_eq_assert(a, b, c)
  65                 }))
  66             }
  67         ),
  68         associated_types: Vec::new(),
  69     };
  70     trait_def.expand(cx, mitem, item, push)
  71 }