@ayonli/jsext/esm/try.js

A JavaScript extension package for building strong and modern applications.

import { isAsyncGenerator, isGenerator } from './external/check-iterable/index.js';
import { ThenableAsyncGenerator } from './external/thenable-generator/index.js';

/**
 * Calls a function safely and return errors when captured.
 *
 * NOTE: Since v1.5.0, this module will convert the error to an instance of
 * `Error` if it's not one already.
 *
 * NOTE: This module, inspired by Golang, is not well-designed, take a look at
 * the [result](https://jsr.io/@ayonli/jsext/doc/result/~) module for a better
 * alternative.
 * @module
 */
// @ts-ignore
function _try(fn, ...args) {
    if (typeof fn === "function") {
        try {
            return _try(fn.apply(void 0, args));
        }
        catch (err) {
            err = err instanceof Error ? err : new Error(String(err));
            return [err, undefined];
        }
    }
    let returns = fn;
    // Implementation details should be ordered from complex to simple.
    if (returns instanceof ThenableAsyncGenerator) {
        // special case for `ThenableAsyncGenerator`
        return Promise.resolve(returns)
            .then((value) => [null, value])
            .catch((err) => {
            err = err instanceof Error ? err : new Error(String(err));
            return [err, undefined];
        });
    }
    else if (isAsyncGenerator(returns)) {
        // @ts-ignore
        return (async function* () {
            let input;
            let result;
            // Use `while` loop instead of `for...of...` in order to
            // retrieve the return value of a generator function.
            while (true) {
                try {
                    const { done, value } = await returns.next(input);
                    if (done) {
                        result = value;
                        break;
                    }
                    else {
                        // Receive any potential input value that passed
                        // to the outer `next()` call, and pass them to
                        // `res.next()` in the next call.
                        input = yield Promise.resolve([null, value]);
                    }
                }
                catch (err) {
                    // If any error occurs, yield that error as resolved
                    // and break the loop immediately, indicating the
                    // process is forced broken.
                    err = err instanceof Error ? err : new Error(String(err));
                    yield Promise.resolve([err, undefined]);
                    break;
                }
            }
            return [null, result];
        })();
    }
    else if (isGenerator(returns)) {
        return (function* () {
            let input;
            let result;
            while (true) {
                try {
                    const { done, value } = returns.next(input);
                    if (done) {
                        result = value;
                        break;
                    }
                    else {
                        input = yield [null, value];
                    }
                }
                catch (err) {
                    err = err instanceof Error ? err : new Error(String(err));
                    yield [err, undefined];
                    break;
                }
            }
            return [null, result];
        })();
    }
    else if (typeof (returns === null || returns === void 0 ? void 0 : returns.then) === "function") {
        return Promise.resolve(returns)
            .then((value) => [null, value])
            .catch((err) => {
            err = err instanceof Error ? err : new Error(String(err));
            return [err, undefined];
        });
    }
    else {
        return [null, returns];
    }
}

export { _try as default };
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