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 deriving::generic::*;
  12 use deriving::generic::ty::*;
  13
  14 use syntax::ast::{MetaItem, Expr};
  15 use syntax::ext::base::{ExtCtxt, Annotatable};
  16 use syntax::ext::build::AstBuilder;
  17 use syntax::parse::token::InternedString;
  18 use syntax::ptr::P;
  19 use syntax_pos::Span;
  20
  21 pub fn expand_deriving_eq(cx: &mut ExtCtxt,
  22                           span: Span,
  23                           mitem: &MetaItem,
  24                           item: &Annotatable,
  25                           push: &mut FnMut(Annotatable))
  26 {
  27     fn cs_total_eq_assert(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
  28         cs_same_method(
  29             |cx, span, exprs| {
  30                 // create `a.<method>(); b.<method>(); c.<method>(); ...`
  31                 // (where method is `assert_receiver_is_total_eq`)
  32                 let stmts = exprs.into_iter().map(|e| cx.stmt_expr(e)).collect();
  33                 let block = cx.block(span, stmts);
  34                 cx.expr_block(block)
  35             },
  36             Box::new(|cx, sp, _, _| {
  37                 cx.span_bug(sp, "non matching enums in derive(Eq)?") }),
  38             cx,
  39             span,
  40             substr
  41         )
  42     }
  43
  44     let inline = cx.meta_word(span, InternedString::new("inline"));
  45     let hidden = cx.meta_word(span, InternedString::new("hidden"));
  46     let doc = cx.meta_list(span, InternedString::new("doc"), vec!(hidden));
  47     let attrs = vec!(cx.attribute(span, inline),
  48                      cx.attribute(span, doc));
  49     let trait_def = TraitDef {
  50         span: span,
  51         attributes: Vec::new(),
  52         path: path_std!(cx, core::cmp::Eq),
  53         additional_bounds: Vec::new(),
  54         generics: LifetimeBounds::empty(),
  55         is_unsafe: false,
  56         methods: vec!(
  57             MethodDef {
  58                 name: "assert_receiver_is_total_eq",
  59                 generics: LifetimeBounds::empty(),
  60                 explicit_self: borrowed_explicit_self(),
  61                 args: vec!(),
  62                 ret_ty: nil_ty(),
  63                 attributes: attrs,
  64                 is_unsafe: false,
  65                 unify_fieldless_variants: true,
  66                 combine_substructure: combine_substructure(Box::new(|a, b, c| {
  67                     cs_total_eq_assert(a, b, c)
  68                 }))
  69             }
  70         ),
  71         associated_types: Vec::new(),
  72     };
  73     trait_def.expand(cx, mitem, item, push)
  74 }