fix: adapt REPL welcome message to terminal width

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

@@ -23,7 +23,6 @@
 var stdin = require( '@stdlib/streams/node/stdin' );
 var stdout = require( '@stdlib/streams/node/stdout' );
 var DEFAULT_KEYBINDINGS = require( './default_keybindings.js' );
-var WELCOME = require( './welcome_text.js' );
 
 
 // MAIN //
@@ -64,8 +63,8 @@ function defaults() {
 		// Flag indicating whether to run a REPL in a sandboxed context:
 		'sandbox': true,
 
-		// Welcome message:
-		'welcome': WELCOME,
+		// Welcome message (null means generate dynamically based on terminal width):
+		'welcome': null,
 
 		// File path specifying where to save REPL command history:
 		'save': '',

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

@@ -74,6 +74,7 @@
 var ALIAS_OVERRIDES = require( './alias_overrides.js' );
 var SETTINGS = require( './settings.js' );
 var SETTINGS_VALIDATORS = require( './settings_validators.js' );
+var welcomeText = require( './welcome_text.js' );
 
 
 // VARIABLES //
@@ -311,7 +312,7 @@
 	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 );
@@ -329,11 +330,11 @@
 	this._istream.on( 'keypress', onKeypress );
 
 	// Write a welcome message:
-	this._wstream.write( opts.welcome );
+	this._wstream.write( ( opts.welcome === null ) ? welcomeText( this._wstream.columns || 80 ) : 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 ) {
@@ -531,9 +532,9 @@
 		// 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?)
 	}
 }
 
@@ -800,7 +801,7 @@
 
 	// 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 ] ) ) {
@@ -1223,7 +1224,7 @@
 	debug( 'Loading filepath: %s', fpath );
 
 	// Attempt to synchronously read the file:
 	file = readFileSync( fpath, 'utf8' );
 	if ( file instanceof Error ) {
 		debug( 'Error: %s', file.message );
 		clbk( file );
@@ -1478,9 +1479,9 @@
 	// 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 );
 

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

@@ -18,35 +18,229 @@
 
 'use strict';
 
-// MAIN //
+// VARIABLES //
+
+// Minimum terminal width (in columns) for rendering the logo and info text side-by-side. Below this threshold, the welcome message switches to a stacked layout. NOTE: this value corresponds to the width of the widest side-by-side line; if the logo, info text, or command descriptions are modified, re-verify that this threshold still exceeds the widest rendered line.
+var SIDE_BY_SIDE_MIN_WIDTH = 70;
+
+// Minimum number of spaces separating the command column from the description column in the side-by-side help layout:
+var HELP_GAP = 4;
+
+// Indentation preceding each command in the help section:
+var HELP_INDENT = '    ';
+
+// Indentation preceding each description in the stacked (narrow) help layout:
+var HELP_DESC_INDENT = '        ';
+
+// Indentation preceding each line of info text in the stacked (narrow) layout:
+var INFO_INDENT = '  ';
 
-var MSG = [
+// Gutter placed on each side of the vertical bar separating the logo from the info text in the side-by-side layout:
+var LOGO_GUTTER = '  ';
+
+// Vertical bar separating the logo from the info text in the side-by-side layout:
+var LOGO_BAR = '|';
+
+var LOGO = [
 	'     _      _ _ _ _',
-	' ___| |_ __| | (_) |__    |  A better REPL for JavaScript and Node.js.',
-	'/ __| __/ _` | | | \'_ \\   |',
-	'\\__ \\ || (_| | | | |_) |  |  For more info, see the source repository:',
-	'|___/\\__\\__,_|_|_|_.__/   |  https://github.com/stdlib-js/stdlib',
-	'',
+	' ___| |_ __| | (_) |__',
+	'/ __| __/ _` | | | \'_ \\',
+	'\\__ \\ || (_| | | | |_) |',
+	'|___/\\__\\__,_|_|_|_.__/'
+];
 
-	// TODO: include platform, copyright, version (see Julia, R, and Python for inspiration)
-	'',
-	'    help()                  Print help text.',
-	'    help(alias)             Print help text for a specified alias.',
-	'    help(alias.<key>)       Print help text for a specified property.',
-	'',
-	'    example(alias)          Run examples for a specified alias.',
-	'    example(alias.<key>)    Run examples for a specified property.',
+// Info text rendered beside the logo. In the side-by-side layout, the first logo line has no counterpart, so these lines align to the logo lines beginning with the second (hence `LOGO.length` must equal `INFO_LINES.length+1`):
+var INFO_LINES = [
+	'A better REPL for JavaScript and Node.js.',
 	'',
-	'    reset()                 Reset the REPL.',
-	'    quit()                  Exit the REPL.',
-	'',
-	'    license()               Print license information.',
-	'    copyright()             Print copyright information.',
-	'',
-	''
-].join( '\n' );
+	'For more info, see the source repository:',
+	'https://github.com/stdlib-js/stdlib'
+];
+
+var COMMANDS = [
+	{
+		'cmd': 'help()',
+		'desc': 'Print help text.'
+	},
+	{
+		'cmd': 'help(alias)',
+		'desc': 'Print help text for a specified alias.'
+	},
+	{
+		'cmd': 'help(alias.<key>)',
+		'desc': 'Print help text for a specified property.'
+	},
+	{
+		'cmd': '',
+		'desc': ''
+	},
+	{
+		'cmd': 'example(alias)',
+		'desc': 'Run examples for a specified alias.'
+	},
+	{
+		'cmd': 'example(alias.<key>)',
+		'desc': 'Run examples for a specified property.'
+	},
+	{
+		'cmd': '',
+		'desc': ''
+	},
+	{
+		'cmd': 'reset()',
+		'desc': 'Reset the REPL.'
+	},
+	{
+		'cmd': 'quit()',
+		'desc': 'Exit the REPL.'
+	},
+	{
+		'cmd': '',
+		'desc': ''
+	},
+	{
+		'cmd': 'license()',
+		'desc': 'Print license information.'
+	},
+	{
+		'cmd': 'copyright()',
+		'desc': 'Print copyright information.'
+	}
+];
+
+
+// FUNCTIONS //
+
+/**
+* Returns a string consisting of a character repeated a specified number of times.
+*
+* @private
+* @param {string} ch - character to repeat
+* @param {NonNegativeInteger} n - number of repetitions
+* @returns {string} repeated string
+*
+* @example
+* var str = repeat( '-', 3 );
+* // returns '---'
+*/
+function repeat( ch, n ) {
+	var out;
+	var i;
+
+	out = '';
+	for ( i = 0; i < n; i++ ) {
+		out += ch;
+	}
+	return out;
+}
+
+/**
+* Right-pads a string with spaces up to a minimum length.
+*
+* ## Notes
+*
+* -   If the input string is already at least the desired length, the string is returned unchanged.
+*
+* @private
+* @param {string} str - input string
+* @param {NonNegativeInteger} len - minimum output length
+* @returns {string} padded string
+*
+* @example
+* var str = rightPad( 'abc', 5 );
+* // returns 'abc  '
+*/
+function rightPad( str, len ) {
+	if ( str.length >= len ) {
+		return str;
+	}
+	return str + repeat( ' ', len-str.length );
+}
+
+
+// MAIN //
+
+/**
+* Returns the welcome message formatted for the given terminal width.
+*
+* @private
+* @param {PositiveInteger} columns - terminal width in columns
+* @returns {string} formatted welcome message
+*/
+function welcomeText( columns ) {
+	var cmdWidth;
+	var isWide;
+	var logoW;
+	var lines;
+	var line;
+	var text;
+	var i;
+
+	isWide = ( columns >= SIDE_BY_SIDE_MIN_WIDTH );
+
+	// Resolve the width of the widest logo line (used to align the separator in both layouts):
+	logoW = 0;
+	for ( i = 0; i < LOGO.length; i++ ) {
+		if ( LOGO[ i ].length > logoW ) {
+			logoW = LOGO[ i ].length;
+		}
+	}
+	lines = [];
+	if ( isWide ) {
+		// Side-by-side layout: render the first logo line on its own, then pair each subsequent logo line with a line of info text separated by a vertical bar...
+		lines.push( LOGO[ 0 ] );
+		for ( i = 1; i < LOGO.length; i++ ) {
+			line = rightPad( LOGO[ i ], logoW ) + LOGO_GUTTER + LOGO_BAR;
+			text = INFO_LINES[ i-1 ];
+			if ( text ) {
+				line += LOGO_GUTTER + text;
+			}
+			lines.push( line );
+		}
+	} else {
+		// Stacked layout for narrow terminals: render the logo, a separator, and then the info text on successive lines...
+		for ( i = 0; i < LOGO.length; i++ ) {
+			lines.push( LOGO[ i ] );
+		}
+		lines.push( '' );
+		lines.push( repeat( '-', logoW ) );
+		lines.push( '' );
+		for ( i = 0; i < INFO_LINES.length; i++ ) {
+			lines.push( INFO_INDENT + INFO_LINES[ i ] );
+		}
+	}
+
+	// Append the help text section:
+	lines.push( '' );
+
+	// In the side-by-side layout, resolve the command column width from the longest command so that descriptions remain aligned and separated by at least `HELP_GAP` spaces:
+	cmdWidth = 0;
+	if ( isWide ) {
+		for ( i = 0; i < COMMANDS.length; i++ ) {
+			if ( COMMANDS[ i ].cmd.length > cmdWidth ) {
+				cmdWidth = COMMANDS[ i ].cmd.length;
+			}
+		}
+		cmdWidth += HELP_GAP;
+	}
+	for ( i = 0; i < COMMANDS.length; i++ ) {
+		if ( COMMANDS[ i ].cmd === '' ) {
+			lines.push( '' );
+		} else if ( isWide ) {
+			lines.push( HELP_INDENT + rightPad( COMMANDS[ i ].cmd, cmdWidth ) + COMMANDS[ i ].desc );
+		} else {
+			// Stack the command and its description on separate lines:
+			lines.push( HELP_INDENT + COMMANDS[ i ].cmd );
+			lines.push( HELP_DESC_INDENT + COMMANDS[ i ].desc );
+		}
+	}
+	lines.push( '' );
+	lines.push( '' );
+
+	return lines.join( '\n' );
+}
 
 
 // EXPORTS //
 
-module.exports = MSG;
+module.exports = welcomeText;