repl: support customizable multiline subprompt

Add a  option to the REPL to allow custom prompts
for multiline input, replacing the default

Author: pckrishnadas88

lib/internal/readline/interface.js

@@ -172,6 +172,7 @@ function InterfaceConstructor(input, output, completer, terminal) {
   let crlfDelay;
   let prompt = '> ';
   let signal;
+  const userMultilinePrompt = input?.multilinePrompt ?? '| ';
 
   if (input?.input) {
     // An options object was given
@@ -228,7 +229,6 @@ function InterfaceConstructor(input, output, completer, terminal) {
   }
 
   const self = this;
-
   this.line = '';
   this[kIsMultiline] = false;
   this[kSubstringSearch] = null;
@@ -237,7 +237,9 @@ function InterfaceConstructor(input, output, completer, terminal) {
   this[kUndoStack] = [];
   this[kRedoStack] = [];
   this[kPreviousCursorCols] = -1;
-  this[kMultilinePrompt] ||= { description: '| ' };
+  this[kMultilinePrompt] = {
+    description: userMultilinePrompt,
+  };
 
   // The kill ring is a global list of blocks of text that were previously
   // killed (deleted). If its size exceeds kMaxLengthOfKillRing, the oldest
@@ -412,23 +414,6 @@ class Interface extends InterfaceConstructor {
     });
   }
 
-  /**
-   * Sets the multiline prompt.
-   * @param {string} prompt
-   * @returns {void}
-   */
-  setMultilinePrompt(prompt) {
-    this[kMultilinePrompt].description = prompt;
-  }
-
-  /**
-   * Returns the current multiline prompt.
-   * @returns {string}
-   */
-  getMultilinePrompt() {
-    return this[kMultilinePrompt].description;
-  }
-
   [kSetRawMode](mode) {
     const wasInRawMode = this.input.isRaw;
 

lib/internal/repl.js

@@ -22,7 +22,6 @@ function createRepl(env, opts, cb) {
     ignoreUndefined: false,
     useGlobal: true,
     breakEvalOnSigint: true,
-    multilinePrompt: opts?.multilinePrompt ?? '| ',
     ...opts,
   };
 

lib/repl.js

@@ -800,10 +800,22 @@ class REPLServer extends Interface {
 
     self.clearBufferedCommand();
 
-    function completer(text, cb) {
-      ReflectApply(complete, self,
-                   [text, self.editorMode ? self.completeOnEditorMode(cb) : cb]);
-    }
+  function completer(text, cb) {
+    ReflectApply(complete, self,
+                 [text, self.editorMode ? self.completeOnEditorMode(cb) : cb]);
+  }
+
+  // All the parameters in the object are defining the "input" param of the
+  // InterfaceConstructor.
+  ReflectApply(Interface, this, [{
+    input: options.input,
+    output: options.output,
+    completer: options.completer || completer,
+    terminal: options.terminal,
+    historySize: options.historySize,
+    prompt,
+    multilinePrompt: options.multilinePrompt,
+  }]);
 
     self.resetContext();
 
@@ -1192,7 +1204,7 @@ class REPLServer extends Interface {
   displayPrompt(preserveCursor) {
     let prompt = this._initialPrompt;
     if (this[kBufferedCommandSymbol].length) {
-    this[kMultilinePrompt].description = '| ';
+    // this[kMultilinePrompt].description = '| ';
       prompt = this[kMultilinePrompt].description;
     }
 

test/parallel/test-repl-multiline-prompt.js

@@ -22,12 +22,10 @@ function runPromptTest(promptStr, { useColors }) {
     input: inputStream,
     output: outputStream,
     terminal: true,
-    useColors
+    useColors,
+    multilinePrompt: promptStr,
   });
 
-  // Set the custom multiline prompt
-  r.setMultilinePrompt(promptStr);
-
   r.on('exit', common.mustCall(() => {
     const lines = output.split('\n');