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/**
* @license Apache-2.0
*
* Copyright (c) 2019 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* eslint-disable no-underscore-dangle */
'use strict';
// MODULES //
var logger = require( 'debug' );
var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
// VARIABLES //
var debug = logger( 'repl:command:load' );
// MAIN //
/**
* Returns a callback to be invoked upon calling the `load` command.
*
* @private
* @param {REPL} repl - REPL instance
* @returns {Function} callback
*/
function command( repl ) {
return onCommand;
/**
* Loads and evaluates a JavaScript file line-by-line.
*
* @private
* @param {string} fpath - file path
* @returns {void}
*/
function onCommand( fpath ) {
var err;
if ( !isString( fpath ) ) {
err = new TypeError( 'invalid argument. Must provide a string. Value: `'+fpath+'`.' );
debug( 'Error: %s', err.message );
repl._ostream.write( 'Error: '+err.message+'\n' );
return;
}
repl.once( 'drain', onDrain );
/**
* Callback invoked upon a 'drain' event.
*
* @private
*/
function onDrain() {
debug( 'Loading a file...' );
repl.load( fpath, clbk );
}
/**
* Callback invoked upon loading a file.
*
* @private
* @param {Error} [error] - error object
*/
function clbk( error ) {
var pos;
if ( error ) {
// NOTE: we can assume that the error pertains to actually reading the file (e.g., loading from disk) and NOT the line-by-line evaluation, where error handling should be handled separately...
debug( 'Error: %s', error.message );
// Infer the current cursor column position based on the length of the command prompt string:
pos = repl._prompt().length; // FIXME: how to address multi-column characters?
// FIXME: handle non-TTY output streams!
/*
* Print the error message on the previous line and generate the expected display prompt and cursor position.
*
* [ANSI escape sequences][1]:
*
* - `\u001b`: ESC, the escape character
* - `[1A`: move cursor up one line
* - `[nD`: move cursor back (to the left) `n` columns (cells)
* - `[0J`: clear the screen beginning from the current cursor position to the end of the screen
*
* [1]: https://en.wikipedia.org/wiki/ANSI_escape_code
*/
repl._ostream.write( '\u001b[1A\u001b['+pos+'DError: '+error.message+'\u001b[0J\n' );
// Show a new display prompt:
repl._displayPrompt();
return;
}
debug( 'Successfully loaded file.' );
}
}
}
// EXPORTS //
module.exports = command;
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