44 lines
2 KiB
TypeScript
44 lines
2 KiB
TypeScript
import initState from './initState';
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import IOption from './IOption';
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import parseArgument from './parseArgument';
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import runPreParseHook from './runPreParseHook';
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/**
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* Checks the command line arguments against the given specification, and returns the arguments as a JavaScript object, as well as a failure function that prints the usage instructions before terminating.
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* If an error is found, outputs an error message and terminates with a non-zero exit code.
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* @param spec A specification of what arguments are expected.
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* @param preParseHook Optionally, a function to modify the command line arguments before parsing them.
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*/
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export default function parseArguments(
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spec: { [key: string]: IOption },
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preParseHook?: (args: string[]) => (string[] | undefined),
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): { fail: (errorMessage: string) => never, args: { [key: string]: string } } {
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//Initialize state
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const { outputArgs, shortToLongLookup, requiredOptions, fail } = initState(spec);
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try {
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const args = runPreParseHook({ args: process.argv.slice(2), preParseHook });
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//Iterate through all command line arguments. When we have read both name and value, verify the argument for correctness.
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//Show error if a name has no value afterwards, or a value has no name in front of it.
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const lastOption = args.reduce(parseArgument.bind(null, { spec, outputArgs, requiredOptions, shortToLongLookup }));
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// argumentName must be cleared to '' after the value is read, so if it is not an empty string, the value was missing
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if (lastOption !== '') {
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throw new Error(`Option "${lastOption}" was not followed by a value.`);
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}
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//check if any entry in requiredArguments was not set
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for (const optName in requiredOptions) {
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if (spec.hasOwnProperty(optName) && requiredOptions[optName] === false) {
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throw new Error(`Missing option "${optName}" even though it is required.`);
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}
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}
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} catch (error) {
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fail((error as Error).message);
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}
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return {
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fail,
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args: outputArgs,
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};
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}
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