declare class CrossEnvConfig {
    private static _overrides;
    /**
     * This is a key/value object of config values that can be used to look up values.
     * Set with attachConfigRegistry
     */
    private static _registry?;
    /**
     * A function that can be used to dynamically look up config values.
     * Set with attachConfigFactory
     */
    private static _factory?;
    /**
     * A map of aliases that can be used to look up config values.
     *
     * @private
     */
    private static readonly _aliases;
    /**
     * Get a config value from either the environment or any registry overrides
     * @param prop
     */
    static get(prop: string): string | undefined;
    /**
     * Set a value explicitly
     *
     * @param key
     * @param value
     */
    static set(key: string, value: string): Map<string, string>;
    /**
     * Alias a key to another key if helpful. This is useful if you have different naming
     * constructs for different environments.
     *
     * @param from
     * @param to
     */
    static alias(from: string, to: string): Map<string, string>;
    /**
     * Helpful if you've decided to store settings in another object and want to
     * make that available here. For example in client-side implementations you may reserve
     * a window.FLATFILE_CONFIG object to store settings.
     *
     * @param obj
     */
    static attachConfigRegistry(obj: any): void;
    /**
     * Use this to provide an override getter for config values. This is useful
     * if you need to dynamically look up values. Overrides will still take precedence.
     *
     * @param cb
     */
    static attachConfigFactory(cb?: (key: string) => string): void;
    static reset(): void;
    /**
     * Internal function for traversing the possible environment sources for a value
     *
     * @param prop
     * @private
     */
    private static safeEnvLookup;
    /**
     * Internal function for checking for stored variables in a browser-like environment
     *
     * @param prop
     * @private
     */
    private static checkForBrowserVariables;
}

export { CrossEnvConfig };