add missing file

crates/shell/src/helper.rs

@@ -0,0 +1,43 @@
+use rustyline::{
+    highlight::Highlighter, validate::MatchingBracketValidator, Completer, Helper, Hinter,
+    Validator,
+};
+
+use crate::completion;
+
+use std::borrow::Cow::Borrowed;
+
+#[derive(Helper, Completer, Hinter, Validator)]
+pub(crate) struct ShellPromptHelper {
+    #[rustyline(Completer)]
+    completer: completion::ShellCompleter,
+
+    #[rustyline(Validator)]
+    validator: MatchingBracketValidator,
+
+    pub colored_prompt: String,
+}
+
+impl Default for ShellPromptHelper {
+    fn default() -> Self {
+        Self {
+            completer: completion::ShellCompleter,
+            validator: MatchingBracketValidator::new(),
+            colored_prompt: String::new(),
+        }
+    }
+}
+
+impl Highlighter for ShellPromptHelper {
+    fn highlight_prompt<'b, 's: 'b, 'p: 'b>(
+        &'s self,
+        prompt: &'p str,
+        default: bool,
+    ) -> std::borrow::Cow<'b, str> {
+        if default {
+            Borrowed(&self.colored_prompt)
+        } else {
+            Borrowed(prompt)
+        }
+    }
+}