      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
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237
    238
    239
    240
    241
    242
    243
    244
    245
    246
    247
    248
    249
    250
    251
    252
    253
    254
    255
    256
    257
    258
    259
    260
    261
    262
    263
    264
    265
    266
    267
    268
    269
    270
    271
    272
    273
    274
    275
    276
    277
    278
    279
    280
    281
    282
    283
    284
    285
    286
    287
    288
    289
    290
    291
    292
    293
    294
    295
    296
    297
    298
    299
    300
    301
    302
    303
    304
    305
    306
    307
    308
    309
    310
    311
    312
    313
    314
    315
    316
    317
    318
    319
    320
    321
    322
    323
    324
    325
    326
    327
    328
    329
    330
    331
    332
    333
    334
    335
    336
    337
    338
    339
    340
    341
    342
    343
    344
    345
    346
    347
    348
    349
    350
    351
    352
    353
    354
    355
    356
    357
    358
    359
    360
    361
    362
    363
    364
    365
    366
    367
    368
    369
    370
    371
    372
    373
    374
    375
    376
    377
    378
    379
    380
    381
    382
    383
    384
    385
    386
    387
    388
    389
    390
    391
    392
    393
    394
    395
    396
    397
    398
    399
    400
    401
    402
    403
    404
    405
    406
    407
    408
    409
    410
    411
    412
    413
    414
    415
    416
    417
    418
    419
    420
    421
    422
    423
    424
    425
    426
    427
    428
    429
    430
    431
    432
    433
    434
    435
    436
    437
    438
    439
    440
    441
    442
    443
    444
    445
    446
    447
    448
    449
    450
    451
    452
    453
    454
    455
    456
    457
    458
    459
    460
    461
    462
    463
    464
    465
    466
    467
    468
    469
    470
    471
    472
    473
    474
    475
    476
    477
    478
    479
    480
    481
    482
    483
    484
    485
    486
    487
    488
    489
    490
    491
    492
    493
    494
    495
    496
    497
    498
    499
    500
    501
    502
    503
    504
    505
    506
    507
    508
    509
    510
    511
    512
    513
    514
    515
    516
    517
    518
    519
    520
    521
    522
    523
    524
    525
    526
    527
    528
    529
    530
    531
    532
    533
    534
    535
    536
    537
    538
    539
    540
    541
    542
    543
    544
    545
    546
    547
    548
    549
    550
    551
    552
    553
    554
    555
    556
    557
    558
    559
    560
    561
    562
    563
    564
    565
    566
    567
    568
    569
    570
    571
    572
    573
    574
    575
    576
    577

    use std::ffi::{OsString, OsStr};
    use std::collections::HashMap;
    use std::iter::Map;
    use std::slice;
    use std::borrow::Cow;

    use vec_map;

    use args::SubCommand;
    use args::MatchedArg;
    use INVALID_UTF8;

    /// Used to get information about the arguments that where supplied to the program at runtime by
    /// the user. New instances of this struct are obtained by using the `App::get_matches` family of
    /// methods.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// # use clap::{App, Arg};
    /// let matches = App::new("MyApp")
    ///     .arg(Arg::with_name("out")
    ///         .long("output")
    ///         .required(true)
    ///         .takes_value(true))
    ///     .arg(Arg::with_name("debug")
    ///         .short("d")
    ///         .multiple(true))
    ///     .arg(Arg::with_name("cfg")
    ///         .short("c")
    ///         .takes_value(true))
    ///     .get_matches(); // builds the instance of ArgMatches
    ///
    /// // to get information about the "cfg" argument we created, such as the value supplied we use
    /// // various ArgMatches methods, such as ArgMatches::value_of
    /// if let Some(c) = matches.value_of("cfg") {
    ///     println!("Value for -c: {}", c);
    /// }
    ///
    /// // The ArgMatches::value_of method returns an Option because the user may not have supplied
    /// // that argument at runtime. But if we specified that the argument was "required" as we did
    /// // with the "out" argument, we can safely unwrap because `clap` verifies that was actually
    /// // used at runtime.
    /// println!("Value for --output: {}", matches.value_of("out").unwrap());
    ///
    /// // You can check the presence of an argument
    /// if matches.is_present("out") {
    ///     // Another way to check if an argument was present, or if it occurred multiple times is to
    ///     // use occurrences_of() which returns 0 if an argument isn't found at runtime, or the
    ///     // number of times that it occurred, if it was. To allow an argument to appear more than
    ///     // once, you must use the .multiple(true) method, otherwise it will only return 1 or 0.
    ///     if matches.occurrences_of("debug") > 2 {
    ///         println!("Debug mode is REALLY on, don't be crazy");
    ///     } else {
    ///         println!("Debug mode kind of on");
    ///     }
    /// }
    /// ```
    #[derive(Debug, Clone)]
    pub struct ArgMatches<'a> {
        #[doc(hidden)]
        pub args: HashMap<&'a str, MatchedArg>,
        #[doc(hidden)]
        pub subcommand: Option<Box<SubCommand<'a>>>,
        #[doc(hidden)]
        pub usage: Option<String>,
    }

    impl<'a> Default for ArgMatches<'a> {
        fn default() -> Self {
            ArgMatches {
                args: HashMap::new(),
                subcommand: None,
                usage: None,
            }
        }
    }

    impl<'a> ArgMatches<'a> {
        #[doc(hidden)]
        pub fn new() -> Self { ArgMatches { ..Default::default() } }

        /// Gets the value of a specific option or positional argument (i.e. an argument that takes
        /// an additional value at runtime). If the option wasn't present at runtime
        /// it returns `None`.
        ///
        /// *NOTE:* If getting a value for an option or positional argument that allows multiples,
        /// prefer `values_of()` as `value_of()` will only return the *first* value.
        ///
        /// # Panics
        ///
        /// This method will `panic!` if the value contains invalid UTF-8 code points.
        ///
        /// # Examples
        ///
        /// ```rust
        /// # use clap::{App, Arg};
        /// let m = App::new("myapp")
        ///     .arg(Arg::with_name("output")
        ///         .takes_value(true))
        ///     .get_matches_from(vec!["myapp", "something"]);
        ///
        /// assert_eq!(m.value_of("output"), Some("something"));
        /// ```
        pub fn value_of<S: AsRef<str>>(&self, name: S) -> Option<&str> {
            if let Some(ref arg) = self.args.get(name.as_ref()) {
                if let Some(v) = arg.vals.values().nth(0) {
                    return Some(v.to_str().expect(INVALID_UTF8));
                }
            }
            None
        }

        /// Gets the lossy value of a specific argument. If the argument wasn't present at runtime
        /// it returns `None`. A lossy value is one which contains invalid UTF-8 code points, those
        /// invalid points will be replaced with `\u{FFFD}`
        ///
        /// *NOTE:* If getting a value for an option or positional argument that allows multiples,
        /// prefer `values_of_lossy()` as `value_of_lossy()` will only return the *first* value.
        ///
        /// # Examples
        ///
        /// ```ignore
        /// # use clap::{App, Arg};
        /// use std::ffi::OsString;
        /// use std::os::unix::ffi::OsStrExt;
        ///
        /// let m = App::new("utf8")
        ///     .arg(Arg::from_usage("<arg> 'some arg'"))
        ///     .get_matches_from(vec![OsString::from("myprog"),
        ///                             // "Hi {0xe9}!"
        ///                             OsString::from_vec(vec![b'H', b'i', b' ', 0xe9, b'!'])]);
        /// assert_eq!(&*m.value_of_lossy("arg").unwrap(), "Hi \u{FFFD}!");
        /// ```
        pub fn value_of_lossy<S: AsRef<str>>(&'a self, name: S) -> Option<Cow<'a, str>> {
            if let Some(arg) = self.args.get(name.as_ref()) {
                if let Some(v) = arg.vals.values().nth(0) {
                    return Some(v.to_string_lossy());
                }
            }
            None
        }

        /// Gets the OS version of a string value of a specific argument. If the option wasn't present
        /// at runtime it returns `None`. An OS value on Unix-like systems is any series of bytes,
        /// regardless of whether or not they contain valid UTF-8 code points. Since `String`s in Rust
        /// are guaranteed to be valid UTF-8, a valid filename on a Unix system as an argument value may
        /// contain invalid UTF-8 code points.
        ///
        /// *NOTE:* If getting a value for an option or positional argument that allows multiples,
        /// prefer `values_of_os()` as `value_of_os()` will only return the *first* value.
        ///
        /// # Examples
        ///
        /// ```ignore
        /// # use clap::{App, Arg};
        /// use std::ffi::OsString;
        /// use std::os::unix::ffi::OsStrExt;
        ///
        /// let m = App::new("utf8")
        ///     .arg(Arg::from_usage("<arg> 'some arg'"))
        ///     .get_matches_from(vec![OsString::from("myprog"),
        ///                             // "Hi {0xe9}!"
        ///                             OsString::from_vec(vec![b'H', b'i', b' ', 0xe9, b'!'])]);
        /// assert_eq!(&*m.value_of_os("arg").unwrap().as_bytes(), [b'H', b'i', b' ', 0xe9, b'!']);
        /// ```
        pub fn value_of_os<S: AsRef<str>>(&self, name: S) -> Option<&OsStr> {
            self.args.get(name.as_ref()).map_or(None, |arg| arg.vals.values().nth(0).map(|v| v.as_os_str()))
        }

        /// Gets an Iterator of values of a specific argument (i.e. an argument that takes multiple
        /// values at runtime). If the option wasn't present at runtime it returns `None`
        ///
        /// # Panics
        ///
        /// This method will panic if any of the values contain invalid UTF-8 code points.
        ///
        /// # Examples
        ///
        /// ```rust
        /// # use clap::{App, Arg};
        /// let m = App::new("myprog")
        ///     .arg(Arg::with_name("output")
        ///         .multiple(true)
        ///         .short("o")
        ///         .takes_value(true))
        ///     .get_matches_from(vec![
        ///         "myprog", "-o", "val1", "val2", "val3"
        ///     ]);
        /// let vals: Vec<&str> = m.values_of("output").unwrap().collect();
        /// assert_eq!(vals, ["val1", "val2", "val3"]);
        /// ```
        pub fn values_of<S: AsRef<str>>(&'a self, name: S) -> Option<Values<'a>> {
            if let Some(ref arg) = self.args.get(name.as_ref()) {
                fn to_str_slice(o: &OsString) -> &str { o.to_str().expect(INVALID_UTF8) }
                let to_str_slice: fn(&OsString) -> &str = to_str_slice; // coerce to fn pointer
                return Some(Values { iter: arg.vals.values().map(to_str_slice) });
            }
            None
        }

        /// Gets the lossy values of a specific argument If the option wasn't present at runtime
        /// it returns `None`. A lossy value is one which contains invalid UTF-8 code points, those
        /// invalid points will be replaced with `\u{FFFD}`
        ///
        /// # Examples
        ///
        /// ```ignore
        /// # use clap::{App, Arg};
        /// use std::ffi::OsString;
        /// use std::os::unix::ffi::OsStrExt;
        ///
        /// let m = App::new("utf8")
        ///     .arg(Arg::from_usage("<arg> 'some arg'"))
        ///     .get_matches_from(vec![OsString::from("myprog"),
        ///                             // "Hi {0xe9}!"
        ///                             OsString::from_vec(vec![b'H', b'i', b' ', 0xe9, b'!'])]);
        /// let itr = m.values_of_lossy("arg").unwrap();
        /// assert_eq!(&*itr.next().unwrap(), "Hi");
        /// assert_eq!(&*itr.next().unwrap(), "\u{FFFD}!");
        /// assert_eq!(itr.next(), None);
        /// ```
        pub fn values_of_lossy<S: AsRef<str>>(&'a self, name: S) -> Option<Vec<String>> {
            if let Some(ref arg) = self.args.get(name.as_ref()) {
                return Some(arg.vals.values()
                               .map(|v| v.to_string_lossy().into_owned())
                               .collect());
            }
            None
        }

        /// Gets the OS version of a string value of a specific argument If the option wasn't present
        /// at runtime it returns `None`. An OS value on Unix-like systems is any series of bytes,
        /// regardless of whether or not they contain valid UTF-8 code points. Since `String`s in Rust
        /// are guaranteed to be valid UTF-8, a valid filename as an argument value on Linux (for
        /// example) may contain invalid UTF-8 code points.
        ///
        /// # Examples
        ///
        /// ```ignore
        /// # use clap::{App, Arg};
        /// use std::ffi::OsString;
        /// use std::os::unix::ffi::OsStrExt;
        ///
        /// let m = App::new("utf8")
        ///     .arg(Arg::from_usage("<arg> 'some arg'"))
        ///     .get_matches_from(vec![OsString::from("myprog"),
        ///                                 // "Hi"
        ///                                 OsString::from_vec(vec![b'H', b'i']),
        ///                                 // "{0xe9}!"
        ///                                 OsString::from_vec(vec![0xe9, b'!'])]);
        ///
        /// let itr = m.values_of_os("arg").unwrap();
        /// assert_eq!(itr.next(), Some(&*OsString::from("Hi")));
        /// assert_eq!(itr.next(), Some(&*OsString::from_vec(vec![0xe9, b'!'])));
        /// assert_eq!(itr.next(), None);
        /// ```
        pub fn values_of_os<S: AsRef<str>>(&'a self, name: S) -> Option<OsValues<'a>> {
            fn to_str_slice(o: &OsString) -> &OsStr { &*o }
            let to_str_slice: fn(&'a OsString) -> &'a OsStr = to_str_slice; // coerce to fn pointer
            if let Some(ref arg) = self.args.get(name.as_ref()) {
                return Some(OsValues { iter: arg.vals.values().map(to_str_slice) });
            }
            None
        }

        /// Returns `true` if an argument was present at runtime, otherwise `false`.
        ///
        /// # Examples
        ///
        /// ```rust
        /// # use clap::{App, Arg};
        /// let m = App::new("myprog")
        ///     .arg(Arg::with_name("debug")
        ///         .short("d"))
        ///     .get_matches_from(vec![
        ///         "myprog", "-d"
        ///     ]);
        ///
        /// assert!(m.is_present("debug"));
        /// ```
        pub fn is_present<S: AsRef<str>>(&self, name: S) -> bool {
            if let Some(ref sc) = self.subcommand {
                if sc.name == name.as_ref() {
                    return true;
                }
            }
            self.args.contains_key(name.as_ref())
        }

        /// Returns the number of times an argument was used at runtime. If an argument isn't present
        /// it will return `0`.
        ///
        /// **NOTE:** This returns the number of times the argument was used, *not* the number of
        /// values. For example, `-o val1 val2 val3 -o val4` would return `2`.
        ///
        /// # Examples
        ///
        /// ```rust
        /// # use clap::{App, Arg};
        /// let m = App::new("myprog")
        ///     .arg(Arg::with_name("debug")
        ///         .short("d")
        ///         .multiple(true))
        ///     .get_matches_from(vec![
        ///         "myprog", "-d", "-d", "-d"
        ///     ]);
        ///
        /// assert_eq!(m.occurrences_of("debug"), 3);
        /// ```
        ///
        /// This next example shows that counts actual uses of the argument, not just `-`'s
        ///
        /// ```rust
        /// # use clap::{App, Arg};
        /// let m = App::new("myprog")
        ///     .arg(Arg::with_name("debug")
        ///         .short("d")
        ///         .multiple(true))
        ///     .arg(Arg::with_name("flag")
        ///         .short("f"))
        ///     .get_matches_from(vec![
        ///         "myprog", "-ddfd"
        ///     ]);
        ///
        /// assert_eq!(m.occurrences_of("debug"), 3);
        /// assert_eq!(m.occurrences_of("flag"), 1);
        /// ```
        pub fn occurrences_of<S: AsRef<str>>(&self, name: S) -> u64 {
            self.args.get(name.as_ref()).map_or(0, |a| a.occurs)
        }

        /// Because subcommands are essentially "sub-apps" they have their own `ArgMatches` as well.
        /// This method returns the `ArgMatches` for a particular subcommand or None if the subcommand
        /// wasn't present at runtime.
        ///
        /// # Examples
        ///
        /// ```rust
        /// # use clap::{App, Arg, SubCommand};
        /// let app_m = App::new("myprog")
        ///     .arg(Arg::with_name("debug")
        ///         .short("d"))
        ///     .subcommand(SubCommand::with_name("test")
        ///         .arg(Arg::with_name("opt")
        ///             .long("option")
        ///             .takes_value(true)))
        ///     .get_matches_from(vec![
        ///         "myprog", "-d", "test", "--option", "val"
        ///     ]);
        ///
        /// // Both parent commands, and child subcommands can have arguments present at the same times
        /// assert!(app_m.is_present("debug"));
        ///
        /// // Get the subcommand's ArgMatches instance
        /// if let Some(sub_m) = app_m.subcommand_matches("test") {
        ///     // Use the struct like normal
        ///     assert_eq!(sub_m.value_of("opt"), Some("val"));
        /// }
        /// ```
        pub fn subcommand_matches<S: AsRef<str>>(&self, name: S) -> Option<&ArgMatches<'a>> {
            if let Some(ref s) = self.subcommand {
                if s.name == name.as_ref() { return Some(&s.matches) }
            }
            None
        }

        /// Because subcommands are essentially "sub-apps" they have their own `ArgMatches` as well.
        /// But simply getting the sub-`ArgMatches` doesn't help much if we don't also know which
        /// subcommand was actually used. This method returns the name of the subcommand that was used
        /// at runtime, or `None` if one wasn't.
        ///
        /// *NOTE*: Subcommands form a hierarchy, where multiple subcommands can be used at runtime,
        /// but only a single subcommand from any group of sibling commands may used at once.
        ///
        /// An ASCII art depiction may help explain this better...Using a fictional version of `git` as
        /// the demo subject. Imagine the following are all subcommands of `git` (note, the author is
        /// aware these aren't actually all subcommands in the real `git` interface, but it makes
        /// explaination easier)
        ///
        /// ```notrust
        ///              Top Level App (git)                         TOP
        ///                              |
        ///       -----------------------------------------
        ///      /             |                \          \
        ///   clone          push              add       commit      LEVEL 1
        ///     |           /    \            /    \       |
        ///    url      origin   remote    ref    name   message     LEVEL 2
        ///             /                  /\
        ///          path            remote  local                   LEVEL 3
        /// ```
        ///
        /// Given the above fictional subcommand hierarchy, valid runtime uses would be (not an all
        /// inclusive list, and not including argument options per command for brevity and clarity):
        ///
        /// ```ignore
        /// $ git clone url
        /// $ git push origin path
        /// $ git add ref local
        /// $ git commit message
        /// ```
        ///
        /// Notice only one command per "level" may be used. You could not, for example, do `$ git
        /// clone url push origin path`
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg, SubCommand};
        ///  let app_m = App::new("git")
        ///      .subcommand(SubCommand::with_name("clone"))
        ///      .subcommand(SubCommand::with_name("push"))
        ///      .subcommand(SubCommand::with_name("commit"))
        ///      .get_matches();
        ///
        /// match app_m.subcommand_name() {
        ///     Some("clone")  => {}, // clone was used
        ///     Some("push")   => {}, // push was used
        ///     Some("commit") => {}, // commit was used
        ///     _              => {}, // Either no subcommand or one not tested for...
        /// }
        /// ```
        pub fn subcommand_name(&self) -> Option<&str> {
            self.subcommand.as_ref().map(|sc| &sc.name[..])
        }

        /// This brings together `ArgMatches::subcommand_matches` and `ArgMatches::subcommand_name` by
        /// returning a tuple with both pieces of information.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg, SubCommand};
        ///  let app_m = App::new("git")
        ///      .subcommand(SubCommand::with_name("clone"))
        ///      .subcommand(SubCommand::with_name("push"))
        ///      .subcommand(SubCommand::with_name("commit"))
        ///      .get_matches();
        ///
        /// match app_m.subcommand() {
        ///     ("clone",  Some(sub_m)) => {}, // clone was used
        ///     ("push",   Some(sub_m)) => {}, // push was used
        ///     ("commit", Some(sub_m)) => {}, // commit was used
        ///     _                       => {}, // Either no subcommand or one not tested for...
        /// }
        /// ```
        ///
        /// Another useful scenario is when you want to support third party, or external, subcommands.
        /// In these cases you can't know the subcommand name ahead of time, so use a variable instead
        /// with pattern matching!
        ///
        /// ```rust
        /// # use clap::{App, AppSettings};
        /// // Assume there is an external subcommand named "subcmd"
        /// let app_m = App::new("myprog")
        ///     .setting(AppSettings::AllowExternalSubcommands)
        ///     .get_matches_from(vec![
        ///         "myprog", "subcmd", "--option", "value", "-fff", "--flag"
        ///     ]);
        ///
        /// // All trailing arguments will be stored under the subcommand's sub-matches using a value
        /// // of the runtime subcommand name (in this case "subcmd")
        /// match app_m.subcommand() {
        ///     (external, Some(sub_m)) => {
        ///          let ext_args: Vec<&str> = sub_m.values_of(external).unwrap().collect();
        ///          assert_eq!(ext_args, ["--option", "value", "-fff", "--flag"]);
        ///     },
        ///     _ => {},
        /// }
        /// ```
        pub fn subcommand(&self) -> (&str, Option<&ArgMatches<'a>>) {
            self.subcommand.as_ref().map_or(("", None), |sc| (&sc.name[..], Some(&sc.matches)))
        }

        /// Returns a string slice of the usage statement for the `App` (or `SubCommand`)
        ///
        /// # Examples
        ///
        /// ```no_run
        /// # use clap::{App, Arg, SubCommand};
        /// let app_m = App::new("myprog")
        ///     .subcommand(SubCommand::with_name("test"))
        ///     .get_matches();
        ///
        /// println!("{}", app_m.usage());
        /// ```
        pub fn usage(&self) -> &str {
            self.usage.as_ref().map_or("", |u| &u[..])
        }
    }

    // The following were taken and adapated from vec_map source
    // repo: https://github.com/contain-rs/vec-map
    // commit: be5e1fa3c26e351761b33010ddbdaf5f05dbcc33
    // license: MIT - Copyright (c) 2015 The Rust Project Developers

    #[derive(Clone)]
    #[allow(missing_debug_implementations)]
    pub struct Values<'a> {
        iter: Map<vec_map::Values<'a, OsString>, fn(&'a OsString) -> &'a str>
    }

    impl<'a> Iterator for Values<'a> {
        type Item = &'a str;

        fn next(&mut self) -> Option<&'a str> { self.iter.next() }
        fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
    }

    impl<'a> DoubleEndedIterator for Values<'a> {
        fn next_back(&mut self) -> Option<&'a str> { self.iter.next_back() }
    }

    /// An iterator over the key-value pairs of a map.
    #[derive(Clone)]
    pub struct Iter<'a, V:'a> {
        front: usize,
        back: usize,
        iter: slice::Iter<'a, Option<V>>
    }

    impl<'a, V> Iterator for Iter<'a, V> {
        type Item = &'a V;

        #[inline]
        fn next(&mut self) -> Option<&'a V> {
            while self.front < self.back {
                if let Some(elem) = self.iter.next() {
                    if let Some(x) = elem.as_ref() {
                        self.front += 1;
                        return Some(x);
                    }
                }
                self.front += 1;
            }
            None
        }

        #[inline]
        fn size_hint(&self) -> (usize, Option<usize>) {
            (0, Some(self.back - self.front))
        }
    }

    impl<'a, V> DoubleEndedIterator for Iter<'a, V> {
        #[inline]
        fn next_back(&mut self) -> Option<&'a V> {
            while self.front < self.back {
                if let Some(elem) = self.iter.next_back() {
                    if let Some(x) = elem.as_ref() {
                        self.back -= 1;
                        return Some(x);
                    }
                }
                self.back -= 1;
            }
            None
        }
    }

    #[derive(Clone)]
    #[allow(missing_debug_implementations)]
    pub struct OsValues<'a> {
        iter: Map<vec_map::Values<'a, OsString>, fn(&'a OsString) -> &'a OsStr>
    }

    impl<'a> Iterator for OsValues<'a> {
        type Item = &'a OsStr;

        fn next(&mut self) -> Option<&'a OsStr> { self.iter.next() }
        fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
    }

    impl<'a> DoubleEndedIterator for OsValues<'a> {
        fn next_back(&mut self) -> Option<&'a OsStr> { self.iter.next_back() }
    }

# Help

## Keyboard Shortcuts

?
  Show this help dialog
S
  Focus the search field
⇤
  Move up in search results
⇥
  Move down in search results
⏎
  Go to active search result

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)