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, Item, Expr, self};
  12 use codemap::Span;
  13 use ext::base::ExtCtxt;
  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<F>(cx: &mut ExtCtxt,
  21                              span: Span,
  22                              mitem: &MetaItem,
  23                              item: &Item,
  24                              push: F) where
  25     F: FnOnce(P<Item>),
  26 {
  27     // structures are equal if all fields are equal, and non equal, if
  28     // any fields are not equal or if the enum variants are different
  29     fn cs_eq(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
  30         cs_fold(
  31             true,  // use foldl
  32             |cx, span, subexpr, self_f, other_fs| {
  33                 let other_f = match other_fs {
  34                     [ref o_f] => o_f,
  35                     _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialEq)`")
  36                 };
  37
  38                 let eq = cx.expr_binary(span, ast::BiEq, self_f, other_f.clone());
  39
  40                 cx.expr_binary(span, ast::BiAnd, subexpr, eq)
  41             },
  42             cx.expr_bool(span, true),
  43             box |cx, span, _, _| cx.expr_bool(span, false),
  44             cx, span, substr)
  45     }
  46     fn cs_ne(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
  47         cs_fold(
  48             true,  // use foldl
  49             |cx, span, subexpr, self_f, other_fs| {
  50                 let other_f = match other_fs {
  51                     [ref o_f] => o_f,
  52                     _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialEq)`")
  53                 };
  54
  55                 let eq = cx.expr_binary(span, ast::BiNe, self_f, other_f.clone());
  56
  57                 cx.expr_binary(span, ast::BiOr, subexpr, eq)
  58             },
  59             cx.expr_bool(span, false),
  60             box |cx, span, _, _| cx.expr_bool(span, true),
  61             cx, span, substr)
  62     }
  63
  64     macro_rules! md {
  65         ($name:expr, $f:ident) => { {
  66             let inline = cx.meta_word(span, InternedString::new("inline"));
  67             let attrs = vec!(cx.attribute(span, inline));
  68             MethodDef {
  69                 name: $name,
  70                 generics: LifetimeBounds::empty(),
  71                 explicit_self: borrowed_explicit_self(),
  72                 args: vec!(borrowed_self()),
  73                 ret_ty: Literal(path!(bool)),
  74                 attributes: attrs,
  75                 combine_substructure: combine_substructure(box |a, b, c| {
  76                     $f(a, b, c)
  77                 })
  78             }
  79         } }
  80     }
  81
  82     let trait_def = TraitDef {
  83         span: span,
  84         attributes: Vec::new(),
  85         path: path_std!(cx, core::cmp::PartialEq),
  86         additional_bounds: Vec::new(),
  87         generics: LifetimeBounds::empty(),
  88         methods: vec!(
  89             md!("eq", cs_eq),
  90             md!("ne", cs_ne)
  91         ),
  92         associated_types: Vec::new(),
  93     };
  94     trait_def.expand(cx, mitem, item, push)
  95 }