option-t/esm/maybe/operators/map_or.js

A toolkit of Nullable/Option/Result type implementation in ECMAScript. Their APIs are inspired by Rust's `Option<T>` and `Result<T, E>`.

import { expectNotNullOrUndefined } from '../core/maybe.js';
import { ERR_MSG_TRANSFORMER_MUST_NOT_RETURN_NO_VAL_FOR_MAYBE, ERR_MSG_DEFAULT_VALUE_MUST_NOT_BE_NO_VAL_FOR_MAYBE, } from '../internal/error_message.js';
/**
 *  Return the result of _transformer_ with using _input_ as an argument for it if _input_ is not `null` and `undefined`.
 *  Otherwise, return _defaultValue_.
 *
 *  Basically, this operation is a combination `map()` and `unwrapOr()`.
 *
 *  * `U` must not be `Maybe<*>`.
 *      * If the result of _transformer_ is `null` or `undefined`, this throw an `Error`.
 *      * If the result of _defaultValue_ is `null` or `undefined`, this throw an `Error`.
 *  * If you'd like to accept `Maybe<*>` as `U`, use a combination `andThen()` and `or()`.
 */
export function mapOrForMaybe(input, defaultValue, transformer) {
    let result;
    let msg = '';
    if (input !== undefined && input !== null) {
        result = transformer(input);
        msg = ERR_MSG_TRANSFORMER_MUST_NOT_RETURN_NO_VAL_FOR_MAYBE;
    }
    else {
        result = defaultValue;
        msg = ERR_MSG_DEFAULT_VALUE_MUST_NOT_BE_NO_VAL_FOR_MAYBE;
    }
    const passed = expectNotNullOrUndefined(result, msg);
    return passed;
}