feat: add multiline editing in the REPL

PR-URL: #2347
Closes: #2060
Co-authored-by: Athan Reines <kgryte@gmail.com>
Reviewed-by: Athan Reines <kgryte@gmail.com> 
Signed-off-by: Snehil Shah <snehilshah.989@gmail.com>

Author: Snehil-Shah

lib/node_modules/@stdlib/repl/lib/completer_preview.js

@@ -246,34 +246,37 @@ setNonEnumerableReadOnly( PreviewCompleter.prototype, 'onKeypress', function onK
 * @type {Function}
 * @param {string} data - input data
 * @param {(Object|void)} key - key object
-* @returns {void}
+* @returns {boolean} boolean indicating whether the preview was auto-completed
 */
 setNonEnumerableReadOnly( PreviewCompleter.prototype, 'beforeKeypress', function beforeKeypress( data, key ) {
 	if ( !this._enabled ) {
-		return;
+		return false;
 	}
 	if ( !key || this._preview === '' ) {
-		return;
+		return false;
 	}
 	// Avoid clashing with existing TAB completion behavior...
 	if ( key.name === 'tab' ) {
-		return this.clear();
+		this.clear();
+		return false;
 	}
 	// Handle the case where the user is not at the end of the line...
 	if ( this._rli.cursor !== this._rli.line.length ) {
 		// If a user is in the middle of a line and presses ENTER, clear the preview string, as the preview was not accepted prior to executing the expression...
 		if ( key.name === 'return' || key.name === 'enter' ) {
 			debug( 'Received an ENTER keypress event while in the middle of the line.' );
-			return this.clear();
+			this.clear();
 		}
-		return;
+		return false;
 	}
 	// When the user is at the end of the line, auto-complete the line with the completion preview when a user presses RETURN or the RIGHT arrow key (note: pressing ENTER will result in both completion AND execution)...
 	if ( key.name === 'return' || key.name === 'enter' || key.name === 'right' ) {
 		debug( 'Completion preview accepted. Performing auto-completion...' );
 		this._rli.write( this._preview );
 		this._preview = '';
+		return true;
 	}
+	return false;
 });
 
 

lib/node_modules/@stdlib/repl/lib/main.js

@@ -61,8 +61,8 @@ var commands = require( './commands.js' );
 var displayPrompt = require( './display_prompt.js' );
 var inputPrompt = require( './input_prompt.js' );
 var OutputStream = require( './output_stream.js' );
-var processLine = require( './process_line.js' );
 var completerFactory = require( './completer.js' );
+var MultilineHandler = require( './multiline_handler.js' );
 var PreviewCompleter = require( './completer_preview.js' );
 var AutoCloser = require( './auto_close_pairs.js' );
 var SyntaxHighlighter = require( './syntax_highlighter.js' );
@@ -237,11 +237,6 @@ function REPL( options ) {
 	// Define the current workspace:
 	setNonEnumerable( this, '_currentWorkspace', 'base' );
 
-	// Initialize an internal status object for multi-line mode:
-	setNonEnumerable( this, '_multiline', {} );
-	setNonEnumerable( this._multiline, 'active', false );
-	setNonEnumerable( this._multiline, 'mode', 'incomplete_expression' );
-
 	// Initialize an internal flag indicating whether the REPL has been closed:
 	setNonEnumerable( this, '_closed', false );
 
@@ -273,6 +268,9 @@ function REPL( options ) {
 		'completer': this._completer
 	}));
 
+	// Initialize a multi-line handler:
+	setNonEnumerableReadOnly( this, '_multilineHandler', new MultilineHandler( this, this._rli._ttyWrite ) );
+
 	// Create a new auto-closer:
 	setNonEnumerableReadOnly( this, '_autoCloser', new AutoCloser( this._rli, this._settings.autoClosePairs, this._settings.autoDeletePairs ) );
 
@@ -337,12 +335,20 @@ function REPL( options ) {
 	* @param {(Object|void)} key - key object
 	*/
 	function beforeKeypress( data, key ) {
+		var completed;
+
 		if ( self._ostream.isPaging ) {
 			self._ostream.beforeKeypress( data, key );
 			return;
 		}
 		self._autoCloser.beforeKeypress( data, key );
-		self._previewCompleter.beforeKeypress( data, key );
+		completed = self._previewCompleter.beforeKeypress( data, key );
+
+		// If completion was auto-completed, don't trigger multi-line keybindings to avoid double operations...
+		if ( !completed ) {
+			self._multilineHandler.beforeKeypress( data, key );
+			return;
+		}
 		self._ttyWrite.call( self._rli, data, key );
 	}
 
@@ -366,6 +372,7 @@ function REPL( options ) {
 		if ( autoClosed ) {
 			self._previewCompleter.clear();
 		}
+		self._multilineHandler.onKeypress( data, key );
 		self._syntaxHighlighter.onKeypress();
 		self._previewCompleter.onKeypress( data, key );
 	}
@@ -379,7 +386,7 @@ function REPL( options ) {
 	function onLine( line ) {
 		self._SIGINT = false; // reset flag
 		if ( self._closed === false ) {
-			processLine( self, line );
+			self._multilineHandler.processLine( line );
 		}
 	}
 
@@ -1261,7 +1268,7 @@ setNonEnumerableReadOnly( REPL.prototype, 'clearCommand', function onClearComman
 		throw new Error( 'invalid operation. Cannot clear the command buffer of a REPL which has already closed.' );
 	}
 	// Clear any command which has been buffered but not yet executed:
-	this._cmd.length = 0;
+	this._multilineHandler.resetInput();
 
 	return this;
 });