feat: add multiline editing in the REPL

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

@@ -228,7 +228,7 @@
 		return;
 	}
 	// Check for existing content beyond the cursor which could "collide" with a preview completion...
 	if ( /[^a-zA-Z0-9_$]/.test( this._rli.line.substring( this._rli.cursor ) ) ) { // FIXME: this is not robust (see https://mathiasbynens.be/notes/javascript-identifiers)
 		return;
 	}
 	try {
@@ -246,34 +246,37 @@
 * @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 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 @@
 	// 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 @@
 		'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 ) );
 
@@ -286,7 +284,7 @@
 	setNonEnumerableReadOnly( this, '_ttyWrite', this._rli._ttyWrite );
 
 	// Overwrite the private `ttyWrite` method to allow processing input before a "keypress" event is triggered:
 	this._rli._ttyWrite = beforeKeypress; // WARNING: overwriting a private property
 
 	// Add event listeners:
 	this._rli.on( 'close', onClose );
@@ -306,9 +304,9 @@
 	// Write a welcome message:
 	this._wstream.write( opts.welcome );
 
 	// TODO: check whether to synchronously initialize a REPL history file
 
 	// TODO: check whether to synchronously initialize a REPL log file
 
 	// Add any provided user-defined themes...
 	if ( opts.themes ) {
@@ -337,12 +335,20 @@
 	* @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 @@
 		if ( autoClosed ) {
 			self._previewCompleter.clear();
 		}
+		self._multilineHandler.onKeypress( data, key );
 		self._syntaxHighlighter.onKeypress();
 		self._previewCompleter.onKeypress( data, key );
 	}
@@ -379,7 +386,7 @@
 	function onLine( line ) {
 		self._SIGINT = false; // reset flag
 		if ( self._closed === false ) {
-			processLine( self, line );
+			self._multilineHandler.processLine( line );
 		}
 	}
 
@@ -469,9 +476,9 @@
 		// Update the internal command history buffer: [..., <id>, <cmd>, <success>, ...]
 		self._history.push( self._count, cmd, success );
 
 		// TODO: if successful and if necessary, (asynchronously?) write the command to a history file (question: do we only want to write successful commands to the history file? maybe we need to option for limiting to successful commands?)
 
 		// TODO: if necessary, (asynchronously?) write the command and result to a log file (JSON serialization?)
 	}
 }
 
@@ -695,7 +702,7 @@
 
 	// Before creating a new execution context in a non-sandboxed environment, remove current workspace variables in order to allow garbage collection and avoid memory leaks (e.g., variables/functions declared during a REPL session which might remain bound to the environment `global` after clearing a REPL):
 	if ( this._sandbox === false ) {
 		// WARNING: in a non-sandboxed environment, if a global variable is externally introduced during a REPL session (i.e., introduced via a mechanism outside of the REPL environment), we will delete that global variable, which means the following logic may introduce unintended side-effects for this particular edge case (e.g., application code may expect the presence of the subsequently deleted global variable). While not ideal, (a) user applications should not be introducing globals to begin with and (b) the probability of a user running a REPL session, a user clearing that REPL session, AND a global variable being introduced between starting a REPL and clearing the REPL should be negligible.
 		tmp = this._context.vars();
 		for ( i = 0; i < tmp.length; i++ ) {
 			if ( isConfigurableProperty( this._context, tmp[ i ] ) ) {
@@ -1261,7 +1268,7 @@
 		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;
 });
@@ -1299,9 +1306,9 @@
 	// Clear the command queue:
 	this._queue.clear();
 
 	// TODO: ensure REPL history is saved (flushed) to file before closing the REPL (see https://github.com/nodejs/node/blob/b21e7c7bcf23a2715951e4cd96180e4dbf1dcd4d/lib/repl.js#L805)
 
 	// TODO: ensure REPL log is saved (flushed) to file before closing the REPL
 
 	nextTick( onTick );
 
@@ -1324,7 +1331,7 @@
 
 		// If this is a non-sandboxed REPL, remove global variables/properties which were introduced during context creation and by a user during a REPL session...
 		if ( self._sandbox === false ) {
 			// WARNING: in a non-sandboxed environment, if a global variable is externally introduced during a REPL session (i.e., introduced via a mechanism outside of the REPL environment), we will delete that global variable, which means the following logic may introduce unintended side-effects for this particular edge case (e.g., application code may expect the presence of the subsequently deleted global variable). While not ideal, (a) user applications should not be introducing globals to begin with and (b) the probability of a user running a REPL session, a user closing that REPL session, AND a global variable being introduced between starting a REPL and closing the REPL should be negligible.
 			tmp = self._context.vars(); // current workspace variables
 			for ( i = 0; i < tmp.length; i++ ) {
 				if ( isConfigurableProperty( self._context, tmp[ i ] ) ) {