feat(flag_aliases): Ability to alias flags

Added same alias funtionality for flags, now you can do:
```
Arg::with_name("flg")
    .long("flag")
    .short("f")
    .alias("not_visible_flag")
    .visible_alias("awesome_v_flag")
```

Signed-off-by: Salim Afiune <afiune@chef.io>

src/app/parser.rs

@@ -1250,7 +1250,16 @@ impl<'a, 'b> Parser<'a, 'b>
             return Ok(ret);
         } else if let Some(flag) = self.flags
             .iter()
-            .find(|v| v.long.is_some() && &*v.long.unwrap() == arg) {
+            .find(|v|
+                (v.long.is_some() &&
+                 &*v.long.unwrap() == arg) ||
+                (v.aliases.is_some() &&
+                 v.aliases
+                    .as_ref()
+                    .unwrap()
+                    .iter()
+                    .any(|&(n, _)| n == &*arg))
+            ) {
             debugln!("Found valid flag '{}'", flag.to_string());
             // Only flags could be help or version, and we need to check the raw long
             // so this is the first point to check

src/args/arg.rs

@@ -452,6 +452,7 @@ impl<'a, 'b> Arg<'a, 'b> {
     /// # use clap::{App, Arg};
     /// let m = App::new("myprog")
     ///             .arg(Arg::with_name("test")
+    ///                     .long("test")
     ///                     .aliases(&["do-stuff", "do-tests", "tests"])
     ///                     .help("the file to add")
     ///                     .required(false))
@@ -506,6 +507,7 @@ impl<'a, 'b> Arg<'a, 'b> {
     /// # use clap::{App, Arg};
     /// let m = App::new("myprog")
     ///             .arg(Arg::with_name("test")
+    ///                 .long("test")
     ///                 .visible_aliases(&["something", "awesome", "cool"]))
     ///        .get_matches_from(vec!["myprog", "--awesome"]);
     /// assert!(m.is_present("test"));

src/args/arg_builder/flag.rs

@@ -17,6 +17,7 @@ use args::settings::{ArgFlags, ArgSettings};
 pub struct FlagBuilder<'n, 'e> {
     pub name: &'n str,
     pub long: Option<&'e str>,
+    pub aliases: Option<Vec<(&'e str, bool)>>,
     pub help: Option<&'e str>,
     pub blacklist: Option<Vec<&'e str>>,
     pub requires: Option<Vec<&'e str>>,
@@ -31,6 +32,7 @@ impl<'n, 'e> Default for FlagBuilder<'n, 'e> {
         FlagBuilder {
             name: "",
             long: None,
+            aliases: None,
             help: None,
             blacklist: None,
             requires: None,
@@ -68,6 +70,7 @@ impl<'a, 'b, 'z> From<&'z Arg<'a, 'b>> for FlagBuilder<'a, 'b> {
             name: a.name,
             short: a.short,
             long: a.long,
+            aliases: a.aliases.clone(),
             help: a.help,
             blacklist: a.blacklist.clone(),
             overrides: a.overrides.clone(),
@@ -81,10 +84,27 @@ impl<'a, 'b, 'z> From<&'z Arg<'a, 'b>> for FlagBuilder<'a, 'b> {
 impl<'n, 'e> Display for FlagBuilder<'n, 'e> {
     fn fmt(&self, f: &mut Formatter) -> Result {
         if let Some(l) = self.long {
-            write!(f, "--{}", l)
+            try!(write!(f, "--{}", l));
         } else {
-            write!(f, "-{}", self.short.unwrap())
+            try!(write!(f, "-{}", self.short.unwrap()));
         }
+
+        // Write aliases such as [aliases: alias, new-alias]
+        if let Some(ref vec) = self.aliases {
+            try!(write!(f, " [aliases: "));
+            let mut it = vec.iter().peekable();
+            while let Some(&(val, b)) = it.next() {
+                if b {
+                    try!(write!(f, "{}", val));
+                    if it.peek().is_some() {
+                        try!(write!(f, ", "));
+                    }
+                }
+            }
+            try!(write!(f, "]"));
+        }
+
+        Ok(())
     }
 }
 
@@ -94,6 +114,7 @@ impl<'n, 'e> Clone for FlagBuilder<'n, 'e> {
             name: self.name,
             short: self.short,
             long: self.long,
+            aliases: self.aliases.clone(),
             help: self.help,
             blacklist: self.blacklist.clone(),
             overrides: self.overrides.clone(),
@@ -169,7 +190,19 @@ impl<'n, 'e> AnyArg<'n, 'e> for FlagBuilder<'n, 'e> {
         self.long.is_some()
     }
     fn aliases(&self) -> Option<Vec<&'e str>> {
-        None
+        if let Some(ref aliases) = self.aliases {
+            let vis_aliases: Vec<_> =
+                aliases.iter()
+                    .filter_map(|&(n, v)| if v { Some(n) } else { None })
+                    .collect();
+            if vis_aliases.is_empty() {
+                None
+            } else {
+                Some(vis_aliases)
+            }
+        } else {
+            None
+        }
     }
 }
 
@@ -197,4 +230,26 @@ mod test {
 
         assert_eq!(&*format!("{}", f2), "-f");
     }
+
+    #[test]
+    fn flagbuilder_display_single_alias() {
+        let mut f = FlagBuilder::new("flg");
+        f.long = Some("flag");
+        f.aliases = Some(vec![("als", true)]);
+
+        assert_eq!(&*format!("{}", f), "--flag [aliases: als]");
+    }
+
+    #[test]
+    fn flagbuilder_display_multiple_aliases() {
+        let mut f = FlagBuilder::new("flg");
+        f.short = Some('f');
+        f.aliases = Some(vec![
+                         ("alias_not_visible", false),
+                         ("f2", true),
+                         ("f3", true),
+                         ("f4", true)
+                    ]);
+        assert_eq!(&*format!("{}", f), "-f [aliases: f2, f3, f4]");
+    }
 }

src/args/arg_builder/option.rs

@@ -344,6 +344,7 @@ mod test {
         assert_eq!(&*format!("{}", o), "--option <opt> [aliases: als]");
     }
 
+    #[test]
     fn optbuilder_display_multiple_aliases() {
         let mut o = OptBuilder::new("opt");
         o.long = Some("option");

tests/arg_aliases.rs

@@ -9,22 +9,30 @@ static SC_VISIBLE_ALIAS_HELP: &'static str = "test
 Some help
 
 USAGE:
-    test [OPTIONS]
+    test [FLAGS] [OPTIONS]
+
+FLAGS:
+    -f, --flag                                  
+            flag with aliases [aliases: v_flg, flag2, flg3]
 
 OPTIONS:
-        --opt <opt>     [aliases: visible]";
+    -o, --opt <opt>
+    help for option with alias [aliases: visible]";
 
 static SC_INVISIBLE_ALIAS_HELP: &'static str = "test 
 Some help
 
 USAGE:
-    test [OPTIONS]
+    test [FLAGS] [OPTIONS]
+
+FLAGS:
+    -f, --flag                flag with aliases
 
 OPTIONS:
-        --opt <opt>    ";
+    -o, --opt <opt>    help for option with alias";
 
 #[test]
-fn single_alias_of_option_long() {
+fn single_alias_of_option() {
     let a = App::new("single_alias")
         .arg(Arg::with_name("alias")
             .long("alias")
@@ -41,7 +49,7 @@ fn single_alias_of_option_long() {
 }
 
 #[test]
-fn multiple_aliases_of_option_long() {
+fn multiple_aliases_of_option() {
     let a = App::new("multiple_aliases")
         .arg(Arg::with_name("aliases")
             .long("aliases")
@@ -86,6 +94,49 @@ fn multiple_aliases_of_option_long() {
     assert_eq!(als3.value_of("aliases").unwrap(), "value");
 }
 
+#[test]
+fn single_alias_of_flag() {
+    let a = App::new("test")
+                .arg(Arg::with_name("flag")
+                    .long("flag")
+                    .alias("alias"))
+                .get_matches_from_safe(vec!["", "--alias"]);
+    assert!(a.is_ok());
+    let a = a.unwrap();
+    assert!(a.is_present("flag"));
+}
+
+#[test]
+fn multiple_aliases_of_flag() {
+    let a = App::new("test")
+                .arg(Arg::with_name("flag")
+                    .long("flag")
+                    .aliases(&["invisible",
+                        "set", "of",
+                        "cool", "aliases"]));
+
+    let flag = a.clone().get_matches_from_safe(vec!["", "--flag"]);
+    assert!(flag.is_ok());
+    let flag = flag.unwrap();
+
+    let inv = a.clone().get_matches_from_safe(vec!["", "--invisible"]);
+    assert!(inv.is_ok());
+    let inv = inv.unwrap();
+
+    let cool = a.clone().get_matches_from_safe(vec!["", "--cool"]);
+    assert!(cool.is_ok());
+    let cool = cool.unwrap();
+
+    let als = a.clone().get_matches_from_safe(vec!["", "--aliases"]);
+    assert!(als.is_ok());
+    let als = als.unwrap();
+
+    assert!(flag.is_present("flag"));
+    assert!(inv.is_present("flag"));
+    assert!(cool.is_present("flag"));
+    assert!(als.is_present("flag"));
+}
+
 #[test]
 fn alias_on_a_subcommand_option() {
     let m = App::new("test")
@@ -112,36 +163,40 @@ fn alias_on_a_subcommand_option() {
 #[test]
 fn invisible_arg_aliases_help_output() {
     let app = App::new("clap-test")
+        .author("Salim Afiune")
         .subcommand(SubCommand::with_name("test")
             .about("Some help")
             .arg(Arg::with_name("opt")
                 .long("opt")
+                .short("o")
+                .help("help for option with alias")
                 .takes_value(true)
-                .aliases(&["invisible", "als1", "more"])));
+                .aliases(&["invisible", "als1", "more"]))
+            .arg(Arg::with_name("flg")
+                .long("flag")
+                .short("f")
+                .help("flag with aliases")
+                .aliases(&["invisible", "flg1", "anyway"])));
     test::check_subcommand_help(app, "test", SC_INVISIBLE_ALIAS_HELP);
 }
 
 #[test]
 fn visible_arg_aliases_help_output() {
     let app = App::new("clap-test")
+        .author("Salim Afiune")
         .subcommand(SubCommand::with_name("test")
             .about("Some help")
             .arg(Arg::with_name("opt")
                 .long("opt")
+                .short("o")
+                .help("help for option with alias")
                 .takes_value(true)
                 .alias("invisible")
-                .visible_alias("visible")));
+                .visible_alias("visible"))
+            .arg(Arg::with_name("flg")
+                .long("flag")
+                .short("f")
+                .help("flag with aliases")
+                .visible_aliases(&["v_flg", "flag2", "flg3"])));
     test::check_subcommand_help(app, "test", SC_VISIBLE_ALIAS_HELP);
 }
-
-#[test]
-fn visible_arg_flag_aliases() {
-    let a = App::new("test")
-                .arg(Arg::with_name("opt")
-                    .long("opt")
-                    .aliases(&["invisible", "set", "of", "aliases"]))
-                .get_matches_from_safe(vec!["", "--aliases"]);
-    assert!(a.is_ok());
-    let a = a.unwrap();
-    assert!(a.is_present("opt"));
-}