Merge pull request #5647 from epage/infer

feat(complete): Infer shell for dynamic completions

clap_complete/src/dynamic/shells/shell.rs

@@ -10,14 +10,77 @@ use clap::ValueEnum;
 pub enum Shell {
     /// Bourne Again `SHell` (bash)
     Bash,
+    /// Elvish shell
+    Elvish,
     /// Friendly Interactive `SHell` (fish)
     Fish,
-    /// Z shell (zsh)
-    Zsh,
-    /// Elf `SHell` (elvish)
-    Elvish,
-    /// Powerful `SHell` (powershel)
+    /// `PowerShell`
     Powershell,
+    /// Z `SHell` (zsh)
+    Zsh,
+}
+
+impl Shell {
+    /// Parse a shell from a path to the executable for the shell
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use clap_complete::shells::Shell;
+    ///
+    /// assert_eq!(Shell::from_shell_path("/bin/bash"), Some(Shell::Bash));
+    /// assert_eq!(Shell::from_shell_path("/usr/bin/zsh"), Some(Shell::Zsh));
+    /// assert_eq!(Shell::from_shell_path("/opt/my_custom_shell"), None);
+    /// ```
+    pub fn from_shell_path(path: impl AsRef<std::path::Path>) -> Option<Shell> {
+        parse_shell_from_path(path.as_ref())
+    }
+
+    /// Determine the user's current shell from the environment
+    ///
+    /// This will read the SHELL environment variable and try to determine which shell is in use
+    /// from that.
+    ///
+    /// If SHELL is not set, then on windows, it will default to powershell, and on
+    /// other operating systems it will return `None`.
+    ///
+    /// If SHELL is set, but contains a value that doesn't correspond to one of the supported shell
+    /// types, then return `None`.
+    ///
+    /// # Example:
+    ///
+    /// ```no_run
+    /// # use clap::Command;
+    /// use clap_complete::{generate, shells::Shell};
+    /// # fn build_cli() -> Command {
+    /// #     Command::new("compl")
+    /// # }
+    /// let shell = Shell::from_env();
+    /// println!("{shell:?}");
+    /// ```
+    pub fn from_env() -> Option<Shell> {
+        if let Some(env_shell) = std::env::var_os("SHELL") {
+            Shell::from_shell_path(env_shell)
+        } else if cfg!(windows) {
+            Some(Shell::Powershell)
+        } else {
+            None
+        }
+    }
+}
+
+// use a separate function to avoid having to monomorphize the entire function due
+// to from_shell_path being generic
+fn parse_shell_from_path(path: &std::path::Path) -> Option<Shell> {
+    let name = path.file_stem()?.to_str()?;
+    match name {
+        "bash" => Some(Shell::Bash),
+        "elvish" => Some(Shell::Elvish),
+        "fish" => Some(Shell::Fish),
+        "powershell" | "powershell_ise" => Some(Shell::Powershell),
+        "zsh" => Some(Shell::Zsh),
+        _ => None,
+    }
 }
 
 impl Display for Shell {
@@ -47,20 +110,20 @@ impl ValueEnum for Shell {
     fn value_variants<'a>() -> &'a [Self] {
         &[
             Shell::Bash,
-            Shell::Fish,
-            Shell::Zsh,
             Shell::Elvish,
+            Shell::Fish,
             Shell::Powershell,
+            Shell::Zsh,
         ]
     }
 
     fn to_possible_value(&self) -> Option<PossibleValue> {
         Some(match self {
             Shell::Bash => PossibleValue::new("bash"),
-            Shell::Fish => PossibleValue::new("fish"),
-            Shell::Zsh => PossibleValue::new("zsh"),
             Shell::Elvish => PossibleValue::new("elvish"),
+            Shell::Fish => PossibleValue::new("fish"),
             Shell::Powershell => PossibleValue::new("powershell"),
+            Shell::Zsh => PossibleValue::new("zsh"),
         })
     }
 }
@@ -69,10 +132,10 @@ impl Shell {
     fn completer(&self) -> &dyn crate::dynamic::shells::ShellCompleter {
         match self {
             Self::Bash => &super::Bash,
-            Self::Fish => &super::Fish,
-            Self::Zsh => &super::Zsh,
             Self::Elvish => &super::Elvish,
+            Self::Fish => &super::Fish,
             Self::Powershell => &super::Powershell,
+            Self::Zsh => &super::Zsh,
         }
     }
 }

clap_complete/tests/snapshots/home/static/exhaustive/bash/.bashrc

@@ -245,7 +245,7 @@ _exhaustive() {
             fi
             case "${prev}" in
                 --shell)
-                    COMPREPLY=($(compgen -W "bash fish zsh elvish powershell" -- "${cur}"))
+                    COMPREPLY=($(compgen -W "bash elvish fish powershell zsh" -- "${cur}"))
                     return 0
                     ;;
                 --register)

clap_complete/tests/snapshots/home/static/exhaustive/fish/fish/completions/exhaustive.fish

@@ -136,7 +136,7 @@ complete -c exhaustive -n "__fish_exhaustive_using_subcommand hint" -l email -r
 complete -c exhaustive -n "__fish_exhaustive_using_subcommand hint" -l global -d 'everywhere'
 complete -c exhaustive -n "__fish_exhaustive_using_subcommand hint" -s h -l help -d 'Print help'
 complete -c exhaustive -n "__fish_exhaustive_using_subcommand hint" -s V -l version -d 'Print version'
-complete -c exhaustive -n "__fish_exhaustive_using_subcommand complete" -l shell -d 'Specify shell to complete for' -r -f -a "{bash\t'',fish\t'',zsh\t'',elvish\t'',powershell\t''}"
+complete -c exhaustive -n "__fish_exhaustive_using_subcommand complete" -l shell -d 'Specify shell to complete for' -r -f -a "{bash\t'',elvish\t'',fish\t'',powershell\t'',zsh\t''}"
 complete -c exhaustive -n "__fish_exhaustive_using_subcommand complete" -l register -d 'Path to write completion-registration to' -r -F
 complete -c exhaustive -n "__fish_exhaustive_using_subcommand complete" -l global -d 'everywhere'
 complete -c exhaustive -n "__fish_exhaustive_using_subcommand complete" -s h -l help -d 'Print help (see more with \'--help\')'

clap_complete/tests/snapshots/home/static/exhaustive/zsh/zsh/_exhaustive

@@ -325,7 +325,7 @@ _arguments "${_arguments_options[@]}" : \
 ;;
 (complete)
 _arguments "${_arguments_options[@]}" : \
-'--shell=[Specify shell to complete for]:SHELL:(bash fish zsh elvish powershell)' \
+'--shell=[Specify shell to complete for]:SHELL:(bash elvish fish powershell zsh)' \
 '--register=[Path to write completion-registration to]:REGISTER:_files' \
 '--global[everywhere]' \
 '-h[Print help (see more with '\''--help'\'')]' \