harperdb/components/OptionsWatcher.d.ts

HarperDB is a distributed database, caching service, streaming broker, and application development platform focused on performance and ease of use.

import { EventEmitter } from 'events';
export interface Config {
    [key: string]: ConfigValue;
}
export type ConfigValue = undefined | null | string | number | boolean | Array<ConfigValue> | Config;
export type OptionsWatcherEventMap = {
    ready: [config?: ConfigValue];
    change: [key: string[], value: ConfigValue, config: ConfigValue];
    remove: [];
    error: [error: unknown];
    close: [];
};
export declare class OptionsWatcherConfigFileError extends Error {
    constructor(configFilePath: string, error: unknown);
}
export declare class UninitializedOptionsWatcherError extends Error {
    constructor();
}
export declare class InvariantUninitializedOptionsWatcherError extends Error {
    constructor();
}
export declare class InvalidValueTypeError extends Error {
    constructor(keys: string[], value: unknown);
}
export declare class KeyDoesNotExistError extends Error {
    constructor(keys: string[], key: string);
}
export declare class CannotSetPropertyError extends Error {
    constructor(keys: string[]);
}
/**
 * Watches a YAML configuration file for changes and provides methods to access the configuration.
 *
 * @emits ready - When the configuration file is initially loaded and values are available
 * @emits change - When any value in the configuration changes (with key, new value, and full config)
 * @emits remove - When the configuration file is removed or the extension is removed from the config
 * @emits error - When an error occurs reading or parsing the file
 * @emits close - When the watcher is closed
 */
export declare class OptionsWatcher extends EventEmitter<OptionsWatcherEventMap> {
    #private;
    ready: Promise<any[]>;
    constructor(name: string, filePath: string, logger?: any);
    /**
     * Closes the underlying file watcher, emits the `close` event, and removes any listeners on the OptionsWatcher instance
     */
    close(): this;
    /**
     * Get a value from the configuration using an array of strings representing the key.
     *
     * For example, if the configuration is:
     * ```yaml
     * foo:
     *  bar:
     *   baz: 42
     * ```
     * Then `get(['foo','bar','baz'])` will return `42`.
     *
     * If the key does not exist, `undefined` will be returned.
     * @param key an array of strings representing the key.
     * @returns
     */
    get(key: string[]): ConfigValue | undefined;
    /**
     * Get the entire configuration object.
     *
     * @returns A deep clone of the entire configuration object.
     */
    getAll(): ConfigValue | undefined;
    /**
     * Get the entire root configuration object from the config file.
     */
    getRoot(): Config | undefined;
}