1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
|
// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use ast::{MetaItem, Item, Expr};
use codemap::Span;
use ext::base::ExtCtxt;
use ext::build::AstBuilder;
use ext::deriving::generic::*;
use parse::token::InternedString;
pub fn expand_deriving_zero(cx: &mut ExtCtxt,
span: Span,
mitem: @MetaItem,
item: @Item,
push: |@Item|) {
let inline = cx.meta_word(span, InternedString::new("inline"));
let attrs = vec!(cx.attribute(span, inline));
let trait_def = TraitDef {
span: span,
attributes: Vec::new(),
path: Path::new(vec!("std", "num", "Zero")),
additional_bounds: Vec::new(),
generics: LifetimeBounds::empty(),
methods: vec!(
MethodDef {
name: "zero",
generics: LifetimeBounds::empty(),
explicit_self: None,
args: Vec::new(),
ret_ty: Self,
attributes: attrs.clone(),
const_nonmatching: false,
combine_substructure: zero_substructure
},
MethodDef {
name: "is_zero",
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
args: Vec::new(),
ret_ty: Literal(Path::new(vec!("bool"))),
attributes: attrs,
const_nonmatching: false,
combine_substructure: |cx, span, substr| {
cs_and(|cx, span, _, _| cx.span_bug(span,
"Non-matching enum \
variant in \
deriving(Zero)"),
cx, span, substr)
}
}
)
};
trait_def.expand(cx, mitem, item, push)
}
fn zero_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> @Expr {
let zero_ident = vec!(
cx.ident_of("std"),
cx.ident_of("num"),
cx.ident_of("Zero"),
cx.ident_of("zero")
);
let zero_call = |span| cx.expr_call_global(span, zero_ident.clone(), Vec::new());
return match *substr.fields {
StaticStruct(_, ref summary) => {
match *summary {
Unnamed(ref fields) => {
if fields.is_empty() {
cx.expr_ident(trait_span, substr.type_ident)
} else {
let exprs = fields.iter().map(|sp| zero_call(*sp)).collect();
cx.expr_call_ident(trait_span, substr.type_ident, exprs)
}
}
Named(ref fields) => {
let zero_fields = fields.iter().map(|&(ident, span)| {
cx.field_imm(span, ident, zero_call(span))
}).collect();
cx.expr_struct_ident(trait_span, substr.type_ident, zero_fields)
}
}
}
StaticEnum(..) => {
cx.span_err(trait_span, "`Zero` cannot be derived for enums, only structs");
// let compilation continue
cx.expr_uint(trait_span, 0)
}
_ => cx.bug("Non-static method in `deriving(Zero)`")
};
}
|
