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;
12 use ast::{MetaItem, Item, Expr};
13 use codemap::Span;
14 use ext::base::ExtCtxt;
15 use ext::build::AstBuilder;
16 use ext::deriving::generic::*;
17 use parse::token::InternedString;
18
19 pub fn expand_deriving_ord(cx: &mut ExtCtxt,
20 span: Span,
21 mitem: @MetaItem,
22 item: @Item,
23 push: |@Item|) {
24 macro_rules! md (
25 ($name:expr, $op:expr, $equal:expr) => { {
26 let inline = cx.meta_word(span, InternedString::new("inline"));
27 let attrs = vec!(cx.attribute(span, inline));
28 MethodDef {
29 name: $name,
30 generics: LifetimeBounds::empty(),
31 explicit_self: borrowed_explicit_self(),
32 args: vec!(borrowed_self()),
33 ret_ty: Literal(Path::new(vec!("bool"))),
34 attributes: attrs,
35 const_nonmatching: false,
36 combine_substructure: combine_substructure(|cx, span, substr| {
37 cs_op($op, $equal, cx, span, substr)
38 })
39 }
40 } }
41 );
42
43 let trait_def = TraitDef {
44 span: span,
45 attributes: Vec::new(),
46 path: Path::new(vec!("std", "cmp", "Ord")),
47 additional_bounds: Vec::new(),
48 generics: LifetimeBounds::empty(),
49 methods: vec!(
50 md!("lt", true, false),
51 md!("le", true, true),
52 md!("gt", false, false),
53 md!("ge", false, true)
54 )
55 };
56 trait_def.expand(cx, mitem, item, push)
57 }
58
59 /// Strict inequality.
60 fn cs_op(less: bool, equal: bool, cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> @Expr {
61 let op = if less {ast::BiLt} else {ast::BiGt};
62 cs_fold(
63 false, // need foldr,
64 |cx, span, subexpr, self_f, other_fs| {
65 /*
66 build up a series of chain ||'s and &&'s from the inside
67 out (hence foldr) to get lexical ordering, i.e. for op ==
68 `ast::lt`
69
70 ```
71 self.f1 < other.f1 || (!(other.f1 < self.f1) &&
72 (self.f2 < other.f2 || (!(other.f2 < self.f2) &&
73 (false)
74 ))
75 )
76 ```
77
78 The optimiser should remove the redundancy. We explicitly
79 get use the binops to avoid auto-deref derefencing too many
80 layers of pointers, if the type includes pointers.
81 */
82 let other_f = match other_fs {
83 [o_f] => o_f,
84 _ => cx.span_bug(span, "not exactly 2 arguments in `deriving(Ord)`")
85 };
86
87 let cmp = cx.expr_binary(span, op, self_f, other_f);
88
89 let not_cmp = cx.expr_unary(span, ast::UnNot,
90 cx.expr_binary(span, op, other_f, self_f));
91
92 let and = cx.expr_binary(span, ast::BiAnd, not_cmp, subexpr);
93 cx.expr_binary(span, ast::BiOr, cmp, and)
94 },
95 cx.expr_bool(span, equal),
96 |cx, span, args, _| {
97 // nonmatching enums, order by the order the variants are
98 // written
99 match args {
100 [(self_var, _, _),
101 (other_var, _, _)] =>
102 cx.expr_bool(span,
103 if less {
104 self_var < other_var
105 } else {
106 self_var > other_var
107 }),
108 _ => cx.span_bug(span, "not exactly 2 arguments in `deriving(Ord)`")
109 }
110 },
111 cx, span, substr)
112 }
libsyntax/ext/deriving/cmp/ord.rs:59:23-59:23 -fn- definition:
/// Strict inequality.
fn cs_op(less: bool, equal: bool, cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> @Expr {
let op = if less {ast::BiLt} else {ast::BiGt};
references:- 436: combine_substructure: combine_substructure(|cx, span, substr| {
37: cs_op($op, $equal, cx, span, substr)
38: })