feat: Add support for the ion shell (#704)

src/init/mod.rs

@@ -109,6 +109,10 @@ fi"#,
             );
             Some(script)
         }
+        Some("ion") => {
+            let script = format!("eval $({} init ion --print-full-init)", starship);
+            Some(script)
+        }
         None => {
             println!(
                 "Invalid shell name provided: {}\\n\
@@ -122,7 +126,7 @@ fi"#,
         Some(shell_basename) => {
             println!(
                 "printf \"\\n{0} is not yet supported by starship.\\n\
-                 For the time being, we support bash, zsh, and fish.\\n\
+                 For the time being, we support bash, zsh, fish, and ion.\\n\
                  Please open an issue in the starship repo if you would like to \
                  see support for {0}:\\nhttps://github.com/starship/starship/issues/new\"\\n\\n",
                 shell_basename
@@ -146,6 +150,7 @@ pub fn init_main(shell_name: &str) -> io::Result<()> {
         "zsh" => Some(ZSH_INIT),
         "fish" => Some(FISH_INIT),
         "powershell" => Some(PWSH_INIT),
+        "ion" => Some(ION_INIT),
         _ => {
             println!(
                 "printf \"Shell name detection failed on phase two init.\\n\
@@ -186,3 +191,5 @@ const ZSH_INIT: &str = include_str!("starship.zsh");
 const FISH_INIT: &str = include_str!("starship.fish");
 
 const PWSH_INIT: &str = include_str!("starship.ps1");
+
+const ION_INIT: &str = include_str!("starship.ion");

src/init/starship.ion

@@ -0,0 +1,15 @@
+# The PROMPT function is called whenever a prompt needs to be drawn. Docs: https://doc.redox-os.org/ion-manual/html/misc/06-prompt_fn.html
+fn PROMPT
+    # Save the status immediately, since the status is also updated after variable assignment, etc.
+    let STARSHIP_ION_STATUS = $?
+    # Save the ION_CMD_DURATION before running any other commands, but after the status since the
+    # duration is not updated during variable assignment
+    let STARSHIP_ION_CMD_DURATION = $ION_CMD_DURATION
+
+    # The STARSHIP between the colons will be replaced with the actual path to the starship executable.
+    # The jobs command outputs to stderr, therefore we need to pipe stderr to `wc -l`.
+    ::STARSHIP:: prompt --status $STARSHIP_ION_STATUS --jobs $(jobs ^| wc -l) --cmd-duration $STARSHIP_ION_CMD_DURATION
+end
+
+# Export the correct name of the shell
+export STARSHIP_SHELL="ion"

src/main.rs

@@ -34,7 +34,7 @@ fn main() {
     let shell_arg = Arg::with_name("shell")
         .value_name("SHELL")
         .help(
-            "The name of the currently running shell\nCurrently supported options: bash, zsh, fish, powershell",
+            "The name of the currently running shell\nCurrently supported options: bash, zsh, fish, powershell, ion",
         )
         .required(true);