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
99
100
101
102
103
104
105
106
|
// 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;
use ast::{meta_item, item, expr};
use codemap::span;
use ext::base::ExtCtxt;
use ext::build::AstBuilder;
use ext::deriving::generic::*;
pub fn expand_deriving_to_str(cx: @ExtCtxt,
span: span,
mitem: @meta_item,
in_items: ~[@item])
-> ~[@item] {
let trait_def = TraitDef {
path: Path::new(~["std", "to_str", "ToStr"]),
additional_bounds: ~[],
generics: LifetimeBounds::empty(),
methods: ~[
MethodDef {
name: "to_str",
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
args: ~[],
ret_ty: Ptr(~Literal(Path::new_local("str")), Send),
const_nonmatching: false,
combine_substructure: to_str_substructure
}
]
};
trait_def.expand(cx, span, mitem, in_items)
}
// It used to be the case that this deriving implementation invoked
// std::sys::log_str, but this isn't sufficient because it doesn't invoke the
// to_str() method on each field. Hence we mirror the logic of the log_str()
// method, but with tweaks to call to_str() on sub-fields.
fn to_str_substructure(cx: @ExtCtxt, span: span,
substr: &Substructure) -> @expr {
let to_str = cx.ident_of("to_str");
let doit = |start: &str, end: @str, name: ast::ident,
fields: &[(Option<ast::ident>, @expr, ~[@expr])]| {
if fields.len() == 0 {
cx.expr_str_uniq(span, cx.str_of(name))
} else {
let buf = cx.ident_of("buf");
let start = cx.str_of(name) + start;
let init = cx.expr_str_uniq(span, start.to_managed());
let mut stmts = ~[cx.stmt_let(span, true, buf, init)];
let push_str = cx.ident_of("push_str");
let push = |s: @expr| {
let ebuf = cx.expr_ident(span, buf);
let call = cx.expr_method_call(span, ebuf, push_str, ~[s]);
stmts.push(cx.stmt_expr(call));
};
for fields.iter().enumerate().advance |(i, &(name, e, _))| {
if i > 0 {
push(cx.expr_str(span, @", "));
}
match name {
None => {}
Some(id) => {
let name = cx.str_of(id) + ": ";
push(cx.expr_str(span, name.to_managed()));
}
}
push(cx.expr_method_call(span, e, to_str, ~[]));
}
push(cx.expr_str(span, end));
cx.expr_blk(cx.blk(span, stmts, Some(cx.expr_ident(span, buf))))
}
};
return match *substr.fields {
Struct(ref fields) => {
if fields.len() == 0 || fields[0].n0_ref().is_none() {
doit("(", @")", substr.type_ident, *fields)
} else {
doit("{", @"}", substr.type_ident, *fields)
}
}
EnumMatching(_, variant, ref fields) => {
match variant.node.kind {
ast::tuple_variant_kind(*) =>
doit("(", @")", variant.node.name, *fields),
ast::struct_variant_kind(*) =>
doit("{", @"}", variant.node.name, *fields),
}
}
_ => cx.bug("expected Struct or EnumMatching in deriving(ToStr)")
};
}
|
