90 lines
3.7 KiB
JavaScript
90 lines
3.7 KiB
JavaScript
export class ArgError extends Error {}
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export class ArgParser {
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/**
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* Create a unix-like argument parser to extract flags from the argument list. Can also create help messages.
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* @param name {string} - Script name
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* @param desc {string} - Help text desciption
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* @param examples {string[]} - Help text examples
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* @param argList {name: string, desc: string, flags: string[], type: string, default: any}[] - Array of CLI arguments
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*/
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constructor(name, desc, examples, argList) {
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this.name = name ?? 'example.js';
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this.description = desc ?? 'Example description';
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this.examples = examples || [`${argList.find(arg => !!arg.flags) ? '[OPTIONS] ' : ''}${argList.filter(arg => !arg.flags).map(arg => (arg.optional ? `[${arg.name.toUpperCase()}]` : arg.name.toUpperCase()) + (arg.extras ? '...' : '')).join(' ')}`];
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this.examples.push('--help');
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this.argList = argList || [];
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this.argList.push({name: 'help', desc: 'Display this help message', flags: ['-h', '--help'], type: 'bool'});
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}
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/**
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* Parse an array into an arguments dictionary using the configuration.
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* @param args {string[]} - Array of arguments to be parsed
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* @returns {object} - Dictionary of arguments with defaults applied
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*/
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parse(args) {
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// Parse arguments
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const queue = [...args], extra = [];
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const parsed = this.argList.reduce((acc, arg) => ({...acc, [arg.name]: arg.default ?? (arg.type == 'bool' ? false : null)}), {});
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// Flags
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while(queue.length) {
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let parse = queue.splice(0, 1)[0];
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if(parse[0] == '-') {
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// Check combined flags
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if(parse[1] != '-' && parse.length > 2) {
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parse = `-${parse[1]}`;
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queue = parse.substring(1).split('').map(a => `-${a}`).concat(queue);
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}
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// Find & add flag
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const split = parse.split('=');
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const arg = this.argList.find(arg => arg.flags && arg.flags.includes(split[0] || parse));
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if(arg == null) throw new ArgError(`Option unknown: ${parse}`);
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if(arg.name == 'help') throw new ArgError('Help');
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const value = arg.type == 'bool' ? true : split[1] || queue.splice(queue.findIndex(q => q[0] != '-'), 1)[0];
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if(value == null) throw new ArgError(`Option missing value: ${arg.name}`);
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parsed[arg.name] = value;
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} else {
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// Save for required parsing
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extra.push(parse);
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}
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}
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// Arguments
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this.argList.filter(arg => !arg.flags && !arg.extras).forEach(arg => {
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if(!arg.optional && !extra.length) throw new ArgError(`Argument missing: ${arg.name.toUpperCase()}`);
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const value = extra.splice(0, 1)[0];
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if(value != null) parsed[arg.name] = value;
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});
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// Extras
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const extraKey = this.argList.find(arg => arg.extras)?.name || 'extra';
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parsed[extraKey] = extra;
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return parsed;
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}
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/**
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* Create help message from the provided description, examples & argument list.
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* @param message {string} - Message to display, defaults to the description
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* @returns {string} - Help message
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*/
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help(msg) {
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// Description
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let message = '\n\n' + (msg && msg.toLowerCase() != 'help' ? msg : this.description);
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// Usage
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if(this.examples.length) message += '\n\nUsage:\t' + this.examples.map(ex => `run ${this.name} ${ex}`).join('\n\t');
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// Arguments
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const req = this.argList.filter(a => !a.flags);
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if(req.length) message += '\n\n\t' + req.map(arg => {
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const padding = 3 - ~~(arg.name.length / 8);
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return `${arg.name.toUpperCase()}${Array(padding).fill('\t').join('')} ${arg.desc}`;
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}).join('\n\t');
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// Flags
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const opts = this.argList.filter(a => a.flags);
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if(opts.length) message += '\n\nOptions:\n\t' + opts.map(a => {
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const flgs = a.flags.join(' ');
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const padding = 3 - ~~(flgs.length / 8);
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return `${flgs}${Array(padding).fill('\t').join('')} ${a.desc}`;
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}).join('\n\t');
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// Print final message
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return `${message}\n\n`;
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}
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}
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