131 lines
3.5 KiB
JavaScript
131 lines
3.5 KiB
JavaScript
const flagSymbol = Symbol('arg flag');
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function arg(opts, {argv = process.argv.slice(2), permissive = false, stopAtPositional = false} = {}) {
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if (!opts) {
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throw new Error('Argument specification object is required');
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}
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const result = {_: []};
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const aliases = {};
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const handlers = {};
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for (const key of Object.keys(opts)) {
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if (!key) {
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throw new TypeError('Argument key cannot be an empty string');
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}
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if (key[0] !== '-') {
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throw new TypeError(`Argument key must start with '-' but found: '${key}'`);
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}
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if (key.length === 1) {
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throw new TypeError(`Argument key must have a name; singular '-' keys are not allowed: ${key}`);
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}
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if (typeof opts[key] === 'string') {
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aliases[key] = opts[key];
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continue;
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}
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let type = opts[key];
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let isFlag = false;
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if (Array.isArray(type) && type.length === 1 && typeof type[0] === 'function') {
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const [fn] = type;
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type = (value, name, prev = []) => {
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prev.push(fn(value, name, prev[prev.length - 1]));
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return prev;
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};
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isFlag = fn === Boolean || fn[flagSymbol] === true;
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} else if (typeof type === 'function') {
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isFlag = type === Boolean || type[flagSymbol] === true;
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} else {
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throw new TypeError(`Type missing or not a function or valid array type: ${key}`);
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}
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if (key[1] !== '-' && key.length > 2) {
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throw new TypeError(`Short argument keys (with a single hyphen) must have only one character: ${key}`);
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}
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handlers[key] = [type, isFlag];
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}
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for (let i = 0, len = argv.length; i < len; i++) {
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const wholeArg = argv[i];
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if (stopAtPositional && result._.length > 0) {
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result._ = result._.concat(argv.slice(i));
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break;
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}
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if (wholeArg === '--') {
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result._ = result._.concat(argv.slice(i + 1));
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break;
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}
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if (wholeArg.length > 1 && wholeArg[0] === '-') {
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/* eslint-disable operator-linebreak */
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const separatedArguments = (wholeArg[1] === '-' || wholeArg.length === 2)
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? [wholeArg]
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: wholeArg.slice(1).split('').map(a => `-${a}`);
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/* eslint-enable operator-linebreak */
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for (let j = 0; j < separatedArguments.length; j++) {
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const arg = separatedArguments[j];
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const [originalArgName, argStr] = arg[1] === '-' ? arg.split(/=(.*)/, 2) : [arg, undefined];
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let argName = originalArgName;
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while (argName in aliases) {
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argName = aliases[argName];
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}
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if (!(argName in handlers)) {
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if (permissive) {
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result._.push(arg);
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continue;
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} else {
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const err = new Error(`Unknown or unexpected option: ${originalArgName}`);
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err.code = 'ARG_UNKNOWN_OPTION';
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throw err;
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}
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}
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const [type, isFlag] = handlers[argName];
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if (!isFlag && ((j + 1) < separatedArguments.length)) {
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throw new TypeError(`Option requires argument (but was followed by another short argument): ${originalArgName}`);
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}
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if (isFlag) {
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result[argName] = type(true, argName, result[argName]);
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} else if (argStr === undefined) {
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if (argv.length < i + 2 || (argv[i + 1].length > 1 && argv[i + 1][0] === '-')) {
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const extended = originalArgName === argName ? '' : ` (alias for ${argName})`;
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throw new Error(`Option requires argument: ${originalArgName}${extended}`);
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}
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result[argName] = type(argv[i + 1], argName, result[argName]);
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++i;
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} else {
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result[argName] = type(argStr, argName, result[argName]);
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}
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}
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} else {
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result._.push(wholeArg);
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}
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}
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return result;
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}
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arg.flag = fn => {
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fn[flagSymbol] = true;
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return fn;
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};
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// Utility types
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arg.COUNT = arg.flag((v, name, existingCount) => (existingCount || 0) + 1);
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module.exports = arg;
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