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
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
// arg_util.rs
// *************************************************************************
// * Copyright (C) 2019 Daniel Mueller (deso@posteo.net) *
// * *
// * This program is free software: you can redistribute it and/or modify *
// * it under the terms of the GNU General Public License as published by *
// * the Free Software Foundation, either version 3 of the License, or *
// * (at your option) any later version. *
// * *
// * This program is distributed in the hope that it will be useful, *
// * but WITHOUT ANY WARRANTY; without even the implied warranty of *
// * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
// * GNU General Public License for more details. *
// * *
// * You should have received a copy of the GNU General Public License *
// * along with this program. If not, see <http://www.gnu.org/licenses/>. *
// *************************************************************************
macro_rules! count {
($head:ident) => { 1 };
($head:ident, $($tail:ident),*) => {
1 + count!($($tail),*)
}
}
macro_rules! Command {
( $name:ident, [ $( $var:ident => ($str:expr, $exec:expr), ) *] ) => {
#[derive(Debug, PartialEq)]
pub enum $name {
$(
$var,
)*
}
enum_int! {$name, [
$( $var => $str, )*
]}
#[allow(unused_qualifications)]
impl $name {
fn execute(
self,
ctx: &mut crate::args::ExecCtx<'_>,
args: ::std::vec::Vec<::std::string::String>,
) -> crate::Result<()> {
match self {
$(
$name::$var => $exec(ctx, args),
)*
}
}
}
};
}
/// A macro for generating an enum with a set of simple (i.e., no
/// parameters) variants and their textual representations.
// TODO: Right now we hard code the derives we create. We may want to
// make this set configurable.
macro_rules! Enum {
( $name:ident, [ $( $var:ident => $str:expr, ) *] ) => {
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum $name {
$(
$var,
)*
}
enum_int! {$name, [
$( $var => $str, )*
]}
};
}
macro_rules! enum_int {
( $name:ident, [ $( $var:ident => $str:expr, ) *] ) => {
impl $name {
#[allow(unused)]
pub fn all(&self) -> [$name; count!($($var),*) ] {
$name::all_variants()
}
pub fn all_variants() -> [$name; count!($($var),*) ] {
[
$(
$name::$var,
)*
]
}
}
impl ::std::convert::AsRef<str> for $name {
fn as_ref(&self) -> &'static str {
match *self {
$(
$name::$var => $str,
)*
}
}
}
impl ::std::fmt::Display for $name {
fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
write!(f, "{}", self.as_ref())
}
}
impl ::std::str::FromStr for $name {
type Err = ::std::string::String;
fn from_str(s: &str) -> ::std::result::Result<Self, Self::Err> {
match s {
$(
$str => Ok($name::$var),
)*
_ => Err(
format!(
"expected one of {}",
$name::all_variants()
.iter()
.map(::std::convert::AsRef::as_ref)
.collect::<::std::vec::Vec<_>>()
.join(", "),
)
)
}
}
}
};
}
/// A macro for formatting the variants of an enum (as created by the
/// Enum!{} macro) ready to be used in a help text. The supplied `fmt`
/// needs to contain the named parameter `{variants}`, which will be
/// replaced with a generated version of the enum's variants.
macro_rules! fmt_enum {
( $enm:ident ) => {{
fmt_enum!($enm.all())
}};
( $all:expr ) => {{
$all
.iter()
.map(::std::convert::AsRef::as_ref)
.collect::<::std::vec::Vec<_>>()
.join("|")
}};
}
/// A macro for generating the help text for a command/subcommand. The
/// argument is the variable representing the command (which in turn is
/// an enum).
/// Note that the name of this variable is embedded into the help text!
macro_rules! cmd_help {
( $cmd:ident ) => {
format!(
concat!("The ", stringify!($cmd), " to execute ({})"),
fmt_enum!($cmd)
)
};
}
#[cfg(test)]
mod tests {
Enum! {Command, [
Var1 => "var1",
Var2 => "2",
Var3 => "crazy",
]}
#[test]
fn all_variants() {
assert_eq!(
Command::all_variants(),
[Command::Var1, Command::Var2, Command::Var3]
)
}
#[test]
fn text_representations() {
assert_eq!(Command::Var1.as_ref(), "var1");
assert_eq!(Command::Var2.as_ref(), "2");
assert_eq!(Command::Var3.as_ref(), "crazy");
}
}
|
