src/libsyntax/ext/deriving/cmp/partial_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, self};
  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_partial_eq(cx: &mut ExtCtxt,
  21                                   span: Span,
  22                                   mitem: &MetaItem,
  23                                   item: &Annotatable,
  24                                   push: &mut FnMut(Annotatable))
  25 {
  26     // structures are equal if all fields are equal, and non equal, if
  27     // any fields are not equal or if the enum variants are different
  28     fn cs_eq(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
  29         cs_fold(
  30             true,  // use foldl
  31             |cx, span, subexpr, self_f, other_fs| {
  32                 let other_f = match (other_fs.len(), other_fs.get(0)) {
  33                     (1, Some(o_f)) => o_f,
  34                     _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialEq)`")
  35                 };
  36
  37                 let eq = cx.expr_binary(span, ast::BiEq, self_f, other_f.clone());
  38
  39                 cx.expr_binary(span, ast::BiAnd, subexpr, eq)
  40             },
  41             cx.expr_bool(span, true),
  42             Box::new(|cx, span, _, _| cx.expr_bool(span, false)),
  43             cx, span, substr)
  44     }
  45     fn cs_ne(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
  46         cs_fold(
  47             true,  // use foldl
  48             |cx, span, subexpr, self_f, other_fs| {
  49                 let other_f = match (other_fs.len(), other_fs.get(0)) {
  50                     (1, Some(o_f)) => o_f,
  51                     _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialEq)`")
  52                 };
  53
  54                 let eq = cx.expr_binary(span, ast::BiNe, self_f, other_f.clone());
  55
  56                 cx.expr_binary(span, ast::BiOr, subexpr, eq)
  57             },
  58             cx.expr_bool(span, false),
  59             Box::new(|cx, span, _, _| cx.expr_bool(span, true)),
  60             cx, span, substr)
  61     }
  62
  63     macro_rules! md {
  64         ($name:expr, $f:ident) => { {
  65             let inline = cx.meta_word(span, InternedString::new("inline"));
  66             let attrs = vec!(cx.attribute(span, inline));
  67             MethodDef {
  68                 name: $name,
  69                 generics: LifetimeBounds::empty(),
  70                 explicit_self: borrowed_explicit_self(),
  71                 args: vec!(borrowed_self()),
  72                 ret_ty: Literal(path_local!(bool)),
  73                 attributes: attrs,
  74                 is_unsafe: false,
  75                 combine_substructure: combine_substructure(Box::new(|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 }