uucore 0.4.0

uutils ~ 'core' uutils code library (cross-platform)
Documentation 
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

// This file is part of the uutils coreutils package.
//
// For the full copyright and license information, please view the LICENSE
// file that was distributed with this source code.

//! Implement GNU-style update functionality.
//!
//! - pre-defined [`clap`-Arguments][1] for inclusion in utilities that
//!   implement updates
//! - determination of the [update mode][2]
//!
//! Update-functionality is implemented by the following utilities:
//!
//! - `cp`
//! - `mv`
//!
//!
//! [1]: arguments
//! [2]: `determine_update_mode()`
//!
//!
//! # Usage example
//!
//! ```
//! #[macro_use]
//! extern crate uucore;
//!
//! use clap::{Command, Arg, ArgMatches};
//! use uucore::update_control::{self, UpdateMode};
//!
//! fn main() {
//!     let matches = Command::new("command")
//!         .arg(update_control::arguments::update())
//!         .arg(update_control::arguments::update_no_args())
//!         .get_matches_from(vec![
//!             "command", "--update=older"
//!         ]);
//!
//!     let update_mode = update_control::determine_update_mode(&matches);
//!
//!     // handle cases
//!     if update_mode == UpdateMode::IfOlder {
//!         // do
//!     } else {
//!         unreachable!()
//!     }
//! }
//! ```
use clap::ArgMatches;

/// Available update mode
#[derive(Clone, Debug, Eq, PartialEq, Default)]
pub enum UpdateMode {
    /// --update=`all`, ``
    #[default]
    All,
    /// --update=`none`
    None,

    /// --update=`older`
    /// -u
    IfOlder,
    NoneFail,
}

pub mod arguments {
    //! Pre-defined arguments for update functionality.
    use crate::parser::shortcut_value_parser::ShortcutValueParser;
    use clap::ArgAction;

    /// `--update` argument
    pub static OPT_UPDATE: &str = "update";
    /// `-u` argument
    pub static OPT_UPDATE_NO_ARG: &str = "u";

    /// `--update` argument, defaults to `older` if no values are provided
    pub fn update() -> clap::Arg {
        clap::Arg::new(OPT_UPDATE)
            .long("update")
            .help("move only when the SOURCE file is newer than the destination file or when the destination file is missing")
            .value_parser(ShortcutValueParser::new(["none", "all", "older","none-fail"]))
            .num_args(0..=1)
            .default_missing_value("older")
            .require_equals(true)
            .overrides_with("update")
            .action(clap::ArgAction::Set)
    }

    /// `-u` argument
    pub fn update_no_args() -> clap::Arg {
        clap::Arg::new(OPT_UPDATE_NO_ARG)
            .short('u')
            .help("like --update but does not accept an argument")
            .action(ArgAction::SetTrue)
    }
}

/// Determine the "mode" for the update operation to perform, if any.
///
/// Parses the backup options and converts them to an instance of
/// `UpdateMode` for further processing.
///
/// Takes [`clap::ArgMatches`] as argument which **must** contain the options
/// from [`arguments::update()`] or [`arguments::update_no_args()`]. Otherwise
/// the `ReplaceAll` mode is returned unconditionally.
///
/// # Examples
///
/// Here's how one would integrate the update mode determination into an
/// application.
///
/// ```
/// #[macro_use]
/// extern crate uucore;
/// use uucore::update_control::{self, UpdateMode};
/// use clap::{Command, Arg, ArgMatches};
///
/// fn main() {
///     let matches = Command::new("command")
///         .arg(update_control::arguments::update())
///         .arg(update_control::arguments::update_no_args())
///         .get_matches_from(vec![
///             "command", "--update=all"
///         ]);
///
///     let update_mode = update_control::determine_update_mode(&matches);
///     assert_eq!(update_mode, UpdateMode::All)
/// }
pub fn determine_update_mode(matches: &ArgMatches) -> UpdateMode {
    if let Some(mode) = matches.get_one::<String>(arguments::OPT_UPDATE) {
        match mode.as_str() {
            "all" => UpdateMode::All,
            "none" => UpdateMode::None,
            "older" => UpdateMode::IfOlder,
            "none-fail" => UpdateMode::NoneFail,
            _ => unreachable!("other args restricted by clap"),
        }
    } else if matches.get_flag(arguments::OPT_UPDATE_NO_ARG) {
        // short form of this option is equivalent to using --update=older
        UpdateMode::IfOlder
    } else {
        // no option was present
        UpdateMode::All
    }
}