feat: Added xonsh shell support

doc/user-guide/src/installation/index.md

@@ -100,3 +100,5 @@ For `zsh`, you must then add the following line in your `~/.zshrc` before
 ```zsh
 fpath+=~/.zfunc
 ```
+
+In Xonsh you can reuse Fish completion by installing [xontrib-fish-completer](https://github.com/xonsh/xontrib-fish-completer).

src/cli/help.rs

@@ -261,6 +261,10 @@ pub(crate) fn completions_help() -> String {
   This installs the completion script. You may have to log out and
   log back in to your shell session for the changes to take effect.
 
+  {SUBHEADER}Xonsh:{SUBHEADER:#}
+
+  In Xonsh you can reuse Fish completion by installing `xontrib-fish-completer`.
+
   {SUBHEADER}Zsh:{SUBHEADER:#}
 
   ZSH completions are commonly stored in any directory listed in

src/cli/self_update.rs

@@ -457,6 +457,7 @@ This is usually done by running one of the following (note the leading DOT):
     source $"{cargo_home_nushell}/env.nu"  # For nushell
     source "{cargo_home}/env.tcsh"  # For tcsh
     . "{cargo_home}/env.ps1"        # For pwsh
+    source "{cargo_home}/env.xsh"   # For xonsh
 "#
     };
 }

src/cli/self_update/env.xsh

@@ -0,0 +1 @@
+$PATH.append(_cargo_bin) if (_cargo_bin := '{cargo_bin}') not in $PATH else None

src/cli/self_update/shell.rs

@@ -69,6 +69,7 @@ fn enumerate_shells() -> Vec<Shell> {
         Box::new(Nu),
         Box::new(Tcsh),
         Box::new(Pwsh),
+        Box::new(Xonsh),
     ]
 }
 
@@ -445,6 +446,61 @@ impl UnixShell for Pwsh {
     }
 }
 
+struct Xonsh;
+
+impl UnixShell for Xonsh {
+    fn does_exist(&self, process: &Process) -> bool {
+        process.var("XONSHRC").is_ok() || utils::find_cmd(&["xonsh"], process).is_some()
+    }
+
+    fn rcfiles(&self, process: &Process) -> Vec<PathBuf> {
+        let mut paths = vec![];
+
+        if let Ok(p) = process.var("XDG_CONFIG_HOME") {
+            let mut p = PathBuf::from(p);
+            p.extend(["xonsh", "rc.xsh"]);
+            paths.push(p);
+        }
+
+        if let Some(mut p) = process.home_dir() {
+            p.extend([".config", "xonsh", "rc.xsh"]);
+            paths.push(p);
+        }
+
+        if let Some(home) = process.home_dir() {
+            paths.push(home.join(".xonshrc"));
+        }
+
+        paths
+    }
+
+    fn update_rcs(&self, process: &Process) -> Vec<PathBuf> {
+        // The first rcfile in XDG_CONFIG_HOME takes precedence.
+        match self.rcfiles(process).into_iter().next() {
+            Some(path) => vec![path],
+            None => vec![],
+        }
+    }
+
+    fn env_script(&self) -> ShellScript {
+        ShellScript {
+            name: "env.xsh",
+            content: include_str!("env.xsh"),
+        }
+    }
+
+    fn source_string(&self, process: &Process) -> Result<String> {
+        Ok(format!(
+            r#"source "{}/env.xsh""#,
+            self.cargo_home_str(process)?
+        ))
+    }
+
+    fn cargo_home_str(&self, process: &Process) -> Result<Cow<'static, str>> {
+        cargo_home_str_with_home("$HOME", process)
+    }
+}
+
 pub(crate) fn legacy_paths(process: &Process) -> impl Iterator<Item = PathBuf> + '_ {
     let zprofiles = Zsh::zdotdir(process)
         .into_iter()