lib/utils.js - compiler-explorer - Rivoreo Source Code Repositories

 // Copyright (c) 2016, Compiler Explorer Authors
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are met:
 //
 //     * Redistributions of source code must retain the above copyright notice,
 //       this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above copyright
 //       notice, this list of conditions and the following disclaimer in the
 //       documentation and/or other materials provided with the distribution.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 // POSSIBILITY OF SUCH DAMAGE.

 import crypto from 'crypto';
 import path from 'path';
 import { fileURLToPath } from 'url';

 import fs from 'fs-extra';
 import quote from 'shell-quote';
 import _ from 'underscore';

 const tabsRe = /\t/g;
 const lineRe = /\r?\n/;

 /***
  *
  * @param {string} text
  * @returns {string[]}
  */
 export function splitLines(text) {
     if (!text) return [];
     const result = text.split(lineRe);
     if (result.length > 0 && result[result.length - 1] === '')
         return result.slice(0, -1);
     return result;
 }

 /***
  * @callback eachLineFunc
  * @param {string} line
  * @returns {*}
  */

 /***
  *
  * @param {string} text
  * @param {eachLineFunc} func
  * @param {*} [context]
  */
 export function eachLine(text, func, context) {
     return _.each(splitLines(text), func, context);
 }

 /***
  *
  * @param {string} line
  * @returns {string}
  */
 export function expandTabs(line) {
     let extraChars = 0;
     return line.replace(tabsRe, function (match, offset) {
         const total = offset + extraChars;
         const spacesNeeded = (total + 8) & 7;
         extraChars += spacesNeeded - 1;
         return '        '.substr(spacesNeeded);
     });
 }

 /***
  * @typedef {Object} lineTag
  * @property {string} text
  * @property {number} line
  * @property {number} text
  */

 /***
  * @typedef {Object} lineObj
  * @property {string} text
  * @property {lineTag} [tag]
  * @inner
  */

 const ansiColoursRe = /\x1B\[[\d;]*[Km]/g;

 function _parseOutputLine(line, inputFilename, pathPrefix) {
     line = line.split('<stdin>').join('<source>');
     if (pathPrefix) line = line.replace(pathPrefix, '');
     if (inputFilename) {
         line = line.split(inputFilename).join('<source>');

         if (inputFilename.indexOf('./') === 0) {
             line = line.split('/home/ubuntu/' + inputFilename.substr(2)).join('<source>');
             line = line.split('/home/ce/' + inputFilename.substr(2)).join('<source>');
         }
     }
     return line;
 }

 /***
  *
  * @param lines
  * @param inputFilename
  * @param pathPrefix
  * @returns {lineObj[]}
  */
 export function parseOutput(lines, inputFilename, pathPrefix) {
     const re = /^\s*<source>[(:](\d+)(:?,?(\d+):?)?[):]*\s*(.*)/;
     const result = [];
     eachLine(lines, line => {
         line = _parseOutputLine(line, inputFilename, pathPrefix);
         if (line !== null) {
             const lineObj = {text: line};
             const match = line.replace(ansiColoursRe, '').match(re);
             if (match) {
                 lineObj.tag = {
                     line: parseInt(match[1]),
                     column: parseInt(match[3] || '0'),
                     text: match[4].trim(),
                 };
             }
             result.push(lineObj);
         }
     });
     return result;
 }

 /***
  *
  * @param lines
  * @param inputFilename
  * @param pathPrefix
  * @returns {lineObj[]}
  */
 export function parseRustOutput(lines, inputFilename, pathPrefix) {
     const re = /^ --> <source>[(:](\d+)(:?,?(\d+):?)?[):]*\s*(.*)/;
     const result = [];
     eachLine(lines, line => {
         line = _parseOutputLine(line, inputFilename, pathPrefix);
         if (line !== null) {
             const lineObj = {text: line};
             const match = line.replace(ansiColoursRe, '').match(re);

             if (match) {
                 const line = parseInt(match[1]);
                 const column = parseInt(match[3] || '0');

                 const previous = result.pop();
                 previous.tag = {
                     line,
                     column,
                     text: previous.text.replace(ansiColoursRe, ''),
                 };
                 result.push(previous);

                 lineObj.tag = {
                     line,
                     column,
                     text: '', // Left empty so that it does not show up in the editor
                 };
             }
             result.push(lineObj);
         }
     });
     return result;
 }

 /***
  *
  * @param {string} name
  * @param {number} len
  * @returns {string}
  */
 export function padRight(name, len) {
     while (name.length < len) name = name + ' ';
     return name;
 }

 /***
  *
  * @param {string} name
  * @returns {string}
  */
 export function trimRight(name) {
     let l = name.length;
     while (l > 0 && name[l - 1] === ' ') l -= 1;
     return name.substr(0, l);
 }

 /***
  * Anonymizes given IP.
  * For IPv4, it removes the last octet
  * For IPv6, it removes the last three hextets
  *
  * @param {string} ip - IP string, of either type (localhost|IPv4|IPv6)
  * @returns {string} Anonymized IP
  */
 export function anonymizeIp(ip) {
     if (ip.includes('localhost')) {
         return ip;
     } else if (ip.includes(':')) {
         // IPv6
         return ip.replace(/(?::[\dA-Fa-f]{0,4}){3}$/, ':0:0:0');
     } else {
         // IPv4
         return ip.replace(/\.\d{1,3}$/, '.0');
     }
 }

 /***
  *
  * @param {*} object
  * @returns {string}
  */
 function objectToHashableString(object) {
     // See https://stackoverflow.com/questions/899574/which-is-best-to-use-typeof-or-instanceof/6625960#6625960
     return (typeof (object) === 'string') ? object : JSON.stringify(object);
 }

 const DefaultHash = 'Compiler Explorer Default Version 1';

 /***
  * Gets the hash (as a binary buffer) of the given object
  *
  * Limitation: object shall not have circular references
  * @param {*} object - Object to get hash from
  * @param {string} [HashVersion=DefaultHash] - Hash "version" key
  * @returns {Buffer} - Hash of object
  */
 export function getBinaryHash(object, HashVersion = DefaultHash) {
     return crypto.createHmac('sha256', HashVersion)
         .update(objectToHashableString(object))
         .digest();
 }

 /***
  * Gets the hash (as a hex string) of the given object
  *
  * Limitation: object shall not have circular references
  * @param {*} object - Object to get hash from
  * @param {string} [HashVersion=DefaultHash] - Hash "version" key
  * @returns {string} - Hash of object
  */
 export function getHash(object, HashVersion = DefaultHash) {
     return crypto.createHmac('sha256', HashVersion)
         .update(objectToHashableString(object))
         .digest('hex');
 }

 /***
  * @typedef {Object} glEditorMainContent
  * @property {string} source - Editor content
  * @property {string} language - Editor syntax language
  * @inner
  */

 /***
  * @typedef {Object} glCompilerMainContent
  * @property {string} compiler - Compiler id
  * @inner
  */

 /***
  * @typedef {Object} glContents
  * @property {glEditorMainContent[]} editors
  * @property {glCompilerMainContent[]} compilers
  * @inner
  */

 /***
  * Gets every (source, lang) & (compilerId) available
  * @param {Array} content - GoldenLayout config topmost content field
  * @returns {glContents}
  */
 export function glGetMainContents(content) {
     let contents = {editors: [], compilers: []};
     _.each(content, element => {
         if (element.type === 'component') {
             if (element.componentName === 'codeEditor') {
                 contents.editors.push({source: element.componentState.source, language: element.componentState.lang});
             } else if (element.componentName === 'compiler') {
                 contents.compilers.push({compiler: element.componentState.compiler});
             }
         } else {
             const subComponents = glGetMainContents(element.content);
             contents.editors = contents.editors.concat(subComponents.editors);
             contents.compilers = contents.compilers.concat(subComponents.compilers);
         }
     });
     return contents;
 }

 /***
  *
  * @param {string} line
  * @param {boolean} [atStart=true]
  * @returns {string}
  */
 export function squashHorizontalWhitespace(line, atStart) {
     if (atStart === undefined) atStart = true;
     if (line.trim().length === 0) {
         return '';
     }
     const splat = line.split(/\s+/);
     if (splat[0] === '' && atStart) {
         // An indented line: preserve a two-space indent (max)
         const intent = line[1] !== ' ' ? ' ' : '  ';
         return intent + splat.slice(1).join(' ');
     }
     return splat.join(' ');
 }

 /***
  *
  * @param {string} prop
  * @returns {boolean|number|string}
  */
 export function toProperty(prop) {
     if (prop === 'true' || prop === 'yes') return true;
     if (prop === 'false' || prop === 'no') return false;
     if (/^-?(0|[1-9]\d*)$/.test(prop)) return parseInt(prop);
     if (/^-?\d*\.\d+$/.test(prop)) return parseFloat(prop);
     return prop;
 }

 /***
  * This function replaces all the "oldValues" in line with "newValue". It handles overlapping string replacement cases,
  * and is careful to return the exact same line object if there's no matches. This turns out to be super important for
  * performance.
  * @param {string} line
  * @param {string} oldValue
  * @param {string} newValue
  * @returns {string}
  */
 export function replaceAll(line, oldValue, newValue) {
     if (oldValue.length === 0) return line;
     let startPoint = 0;
     for (; ;) {
         const index = line.indexOf(oldValue, startPoint);
         if (index === -1) break;
         line = line.substr(0, index) + newValue + line.substr(index + oldValue.length);
         startPoint = index + newValue.length;
     }
     return line;
 }

 // Initially based on http://philzimmermann.com/docs/human-oriented-base-32-encoding.txt
 const BASE32_ALPHABET = '13456789EGKMPTWYabcdefhjnoqrsvxz';

 /***
  *  A Base32 encoding implementation valid for our needs.
  *  Of importance, note that there's no padding
  * @param {Buffer} buffer
  * @returns {string}
  */
 export function base32Encode(buffer) {
     let output = '';
     // This can grow up to 12 bits
     let digest = 0;
     // How many bits are we actually using from digest
     let bits = 0;

     function encodeNewWord() {
         // Get first 5 bits
         const word = digest & 0b11111;
         const character = BASE32_ALPHABET[word];
         output += character;
         bits -= 5;
         // Shift out the newly processed word
         digest = (digest >>> 5);
     }

     for (const byte of buffer) {
         // Append current byte to digest
         digest = (byte << bits) | digest;
         bits += 8;

         // Add characters until we run out of bits
         while (bits >= 5) {
             encodeNewWord();
         }
     }
     // Do we need a last pass?
     if (bits !== 0) {
         encodeNewWord();
     }

     return output;
 }

 export function splitArguments(options) {
     return _.chain(quote.parse(options || '')
         .map(x => typeof (x) === 'string' ? x : x.pattern))
         .compact()
         .value();
 }

 /***
  * Absolute path to the root of the application
  */
 export const APP_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');

 export function resolvePathFromAppRoot(...args) {
     return path.resolve(APP_ROOT, ...args);
 }

 export async function fileExists(filename) {
     try {
         const stat = await fs.stat(filename);
         return stat.isFile();
     } catch {
         return false;
     }
 }
	// Copyright (c) 2016, Compiler Explorer Authors
	// All rights reserved.
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are met:
	//
	// * Redistributions of source code must retain the above copyright notice,
	// this list of conditions and the following disclaimer.
	// * Redistributions in binary form must reproduce the above copyright
	// notice, this list of conditions and the following disclaimer in the
	// documentation and/or other materials provided with the distribution.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
	// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	// POSSIBILITY OF SUCH DAMAGE.

	import crypto from 'crypto';
	import path from 'path';
	import { fileURLToPath } from 'url';

	import fs from 'fs-extra';
	import quote from 'shell-quote';
	import _ from 'underscore';

	const tabsRe = /\t/g;
	const lineRe = /\r?\n/;

	/***
	*
	* @param {string} text
	* @returns {string[]}
	*/
	export function splitLines(text) {
	if (!text) return [];
	const result = text.split(lineRe);
	if (result.length > 0 && result[result.length - 1] === '')
	return result.slice(0, -1);
	return result;
	}

	/***
	* @callback eachLineFunc
	* @param {string} line
	* @returns {*}
	*/

	/***
	*
	* @param {string} text
	* @param {eachLineFunc} func
	* @param {*} [context]
	*/
	export function eachLine(text, func, context) {
	return _.each(splitLines(text), func, context);
	}

	/***
	*
	* @param {string} line
	* @returns {string}
	*/
	export function expandTabs(line) {
	let extraChars = 0;
	return line.replace(tabsRe, function (match, offset) {
	const total = offset + extraChars;
	const spacesNeeded = (total + 8) & 7;
	extraChars += spacesNeeded - 1;
	return ' '.substr(spacesNeeded);
	});
	}

	/***
	* @typedef {Object} lineTag
	* @property {string} text
	* @property {number} line
	* @property {number} text
	*/

	/***
	* @typedef {Object} lineObj
	* @property {string} text
	* @property {lineTag} [tag]
	* @inner
	*/

	const ansiColoursRe = /\x1B\[[\d;]*[Km]/g;

	function _parseOutputLine(line, inputFilename, pathPrefix) {
	line = line.split('<stdin>').join('<source>');
	if (pathPrefix) line = line.replace(pathPrefix, '');
	if (inputFilename) {
	line = line.split(inputFilename).join('<source>');

	if (inputFilename.indexOf('./') === 0) {
	line = line.split('/home/ubuntu/' + inputFilename.substr(2)).join('<source>');
	line = line.split('/home/ce/' + inputFilename.substr(2)).join('<source>');
	}
	}
	return line;
	}

	/***
	*
	* @param lines
	* @param inputFilename
	* @param pathPrefix
	* @returns {lineObj[]}
	*/
	export function parseOutput(lines, inputFilename, pathPrefix) {
	const re = /^\s<source>[(:](\d+)(:?,?(\d+):?)?[):]\s(.)/;
	const result = [];
	eachLine(lines, line => {
	line = _parseOutputLine(line, inputFilename, pathPrefix);
	if (line !== null) {
	const lineObj = {text: line};
	const match = line.replace(ansiColoursRe, '').match(re);
	if (match) {
	lineObj.tag = {
	line: parseInt(match[1]),
	column: parseInt(match[3] \|\| '0'),
	text: match[4].trim(),
	};
	}
	result.push(lineObj);
	}
	});
	return result;
	}

	/***
	*
	* @param lines
	* @param inputFilename
	* @param pathPrefix
	* @returns {lineObj[]}
	*/
	export function parseRustOutput(lines, inputFilename, pathPrefix) {
	const re = /^ --> <source>[(:](\d+)(:?,?(\d+):?)?[):]\s(.*)/;
	const result = [];
	eachLine(lines, line => {
	line = _parseOutputLine(line, inputFilename, pathPrefix);
	if (line !== null) {
	const lineObj = {text: line};
	const match = line.replace(ansiColoursRe, '').match(re);

	if (match) {
	const line = parseInt(match[1]);
	const column = parseInt(match[3] \|\| '0');

	const previous = result.pop();
	previous.tag = {
	line,
	column,
	text: previous.text.replace(ansiColoursRe, ''),
	};
	result.push(previous);

	lineObj.tag = {
	line,
	column,
	text: '', // Left empty so that it does not show up in the editor
	};
	}
	result.push(lineObj);
	}
	});
	return result;
	}

	/***
	*
	* @param {string} name
	* @param {number} len
	* @returns {string}
	*/
	export function padRight(name, len) {
	while (name.length < len) name = name + ' ';
	return name;
	}

	/***
	*
	* @param {string} name
	* @returns {string}
	*/
	export function trimRight(name) {
	let l = name.length;
	while (l > 0 && name[l - 1] === ' ') l -= 1;
	return name.substr(0, l);
	}

	/***
	* Anonymizes given IP.
	* For IPv4, it removes the last octet
	* For IPv6, it removes the last three hextets
	*
	* @param {string} ip - IP string, of either type (localhost\|IPv4\|IPv6)
	* @returns {string} Anonymized IP
	*/
	export function anonymizeIp(ip) {
	if (ip.includes('localhost')) {
	return ip;
	} else if (ip.includes(':')) {
	// IPv6
	return ip.replace(/(?::[\dA-Fa-f]{0,4}){3}$/, ':0:0:0');
	} else {
	// IPv4
	return ip.replace(/\.\d{1,3}$/, '.0');
	}
	}

	/***
	*
	* @param {*} object
	* @returns {string}
	*/
	function objectToHashableString(object) {
	// See https://stackoverflow.com/questions/899574/which-is-best-to-use-typeof-or-instanceof/6625960#6625960
	return (typeof (object) === 'string') ? object : JSON.stringify(object);
	}

	const DefaultHash = 'Compiler Explorer Default Version 1';

	/***
	* Gets the hash (as a binary buffer) of the given object
	*
	* Limitation: object shall not have circular references
	* @param {*} object - Object to get hash from
	* @param {string} [HashVersion=DefaultHash] - Hash "version" key
	* @returns {Buffer} - Hash of object
	*/
	export function getBinaryHash(object, HashVersion = DefaultHash) {
	return crypto.createHmac('sha256', HashVersion)
	.update(objectToHashableString(object))
	.digest();
	}

	/***
	* Gets the hash (as a hex string) of the given object
	*
	* Limitation: object shall not have circular references
	* @param {*} object - Object to get hash from
	* @param {string} [HashVersion=DefaultHash] - Hash "version" key
	* @returns {string} - Hash of object
	*/
	export function getHash(object, HashVersion = DefaultHash) {
	return crypto.createHmac('sha256', HashVersion)
	.update(objectToHashableString(object))
	.digest('hex');
	}

	/***
	* @typedef {Object} glEditorMainContent
	* @property {string} source - Editor content
	* @property {string} language - Editor syntax language
	* @inner
	*/

	/***
	* @typedef {Object} glCompilerMainContent
	* @property {string} compiler - Compiler id
	* @inner
	*/

	/***
	* @typedef {Object} glContents
	* @property {glEditorMainContent[]} editors
	* @property {glCompilerMainContent[]} compilers
	* @inner
	*/

	/***
	* Gets every (source, lang) & (compilerId) available
	* @param {Array} content - GoldenLayout config topmost content field
	* @returns {glContents}
	*/
	export function glGetMainContents(content) {
	let contents = {editors: [], compilers: []};
	_.each(content, element => {
	if (element.type === 'component') {
	if (element.componentName === 'codeEditor') {
	contents.editors.push({source: element.componentState.source, language: element.componentState.lang});
	} else if (element.componentName === 'compiler') {
	contents.compilers.push({compiler: element.componentState.compiler});
	}
	} else {
	const subComponents = glGetMainContents(element.content);
	contents.editors = contents.editors.concat(subComponents.editors);
	contents.compilers = contents.compilers.concat(subComponents.compilers);
	}
	});
	return contents;
	}

	/***
	*
	* @param {string} line
	* @param {boolean} [atStart=true]
	* @returns {string}
	*/
	export function squashHorizontalWhitespace(line, atStart) {
	if (atStart === undefined) atStart = true;
	if (line.trim().length === 0) {
	return '';
	}
	const splat = line.split(/\s+/);
	if (splat[0] === '' && atStart) {
	// An indented line: preserve a two-space indent (max)
	const intent = line[1] !== ' ' ? ' ' : ' ';
	return intent + splat.slice(1).join(' ');
	}
	return splat.join(' ');
	}

	/***
	*
	* @param {string} prop
	* @returns {boolean\|number\|string}
	*/
	export function toProperty(prop) {
	if (prop === 'true' \|\| prop === 'yes') return true;
	if (prop === 'false' \|\| prop === 'no') return false;
	if (/^-?(0\|[1-9]\d*)$/.test(prop)) return parseInt(prop);
	if (/^-?\d*\.\d+$/.test(prop)) return parseFloat(prop);
	return prop;
	}

	/***
	* This function replaces all the "oldValues" in line with "newValue". It handles overlapping string replacement cases,
	* and is careful to return the exact same line object if there's no matches. This turns out to be super important for
	* performance.
	* @param {string} line
	* @param {string} oldValue
	* @param {string} newValue
	* @returns {string}
	*/
	export function replaceAll(line, oldValue, newValue) {
	if (oldValue.length === 0) return line;
	let startPoint = 0;
	for (; ;) {
	const index = line.indexOf(oldValue, startPoint);
	if (index === -1) break;
	line = line.substr(0, index) + newValue + line.substr(index + oldValue.length);
	startPoint = index + newValue.length;
	}
	return line;
	}

	// Initially based on http://philzimmermann.com/docs/human-oriented-base-32-encoding.txt
	const BASE32_ALPHABET = '13456789EGKMPTWYabcdefhjnoqrsvxz';

	/***
	* A Base32 encoding implementation valid for our needs.
	* Of importance, note that there's no padding
	* @param {Buffer} buffer
	* @returns {string}
	*/
	export function base32Encode(buffer) {
	let output = '';
	// This can grow up to 12 bits
	let digest = 0;
	// How many bits are we actually using from digest
	let bits = 0;

	function encodeNewWord() {
	// Get first 5 bits
	const word = digest & 0b11111;
	const character = BASE32_ALPHABET[word];
	output += character;
	bits -= 5;
	// Shift out the newly processed word
	digest = (digest >>> 5);
	}

	for (const byte of buffer) {
	// Append current byte to digest
	digest = (byte << bits) \| digest;
	bits += 8;

	// Add characters until we run out of bits
	while (bits >= 5) {
	encodeNewWord();
	}
	}
	// Do we need a last pass?
	if (bits !== 0) {
	encodeNewWord();
	}

	return output;
	}

	export function splitArguments(options) {
	return _.chain(quote.parse(options \|\| '')
	.map(x => typeof (x) === 'string' ? x : x.pattern))
	.compact()
	.value();
	}

	/***
	* Absolute path to the root of the application
	*/
	export const APP_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');

	export function resolvePathFromAppRoot(...args) {
	return path.resolve(APP_ROOT, ...args);
	}

	export async function fileExists(filename) {
	try {
	const stat = await fs.stat(filename);
	return stat.isFile();
	} catch {
	return false;
	}
	}