add trim_whitespace command

helix-term/src/commands/typed.rs

@@ -1515,6 +1515,28 @@ fn run_shell_command(
     Ok(())
 }
 
+fn trim_whitespace(
+    cx: &mut compositor::Context,
+    _: &[Cow<str>],
+    _: PromptEvent,
+) -> anyhow::Result<()> {
+    let mut pos = 0;
+    let (view, doc) = current!(cx.editor);
+    let transaction = Transaction::change(
+        doc.text(),
+        doc.text().lines().filter_map(|line| {
+            let start = pos
+                + movement::backwards_skip_while(line, line.len_chars(), |x| x.is_whitespace())?;
+            let end = pos + line.len_chars();
+            pos += line.len_chars();
+            Some((start, end, None))
+        }),
+    );
+    doc.apply(&transaction, view.id);
+    doc.append_changes_to_history(view.id);
+    Ok(())
+}
+
 pub const TYPABLE_COMMAND_LIST: &[TypableCommand] = &[
         TypableCommand {
             name: "quit",
@@ -1995,6 +2017,13 @@ pub const TYPABLE_COMMAND_LIST: &[TypableCommand] = &[
             fun: run_shell_command,
             completer: Some(completers::directory),
         },
+        TypableCommand {
+            name: "trim_whitespace",
+            aliases: &["trim"],
+            doc: "Trim whitespace at the end of all lines.",
+            fun: trim_whitespace,
+            completer: None,
+        },
     ];
 
 pub static TYPABLE_COMMAND_MAP: Lazy<HashMap<&'static str, &'static TypableCommand>> =