type TNever = {
    /**
     * This property exists to stop TNever also including other types.
     * At time of writing, it seems to affect all that we use: `T[]`, `boolean`, `string` and `number`.
     */
    neverType: string;
};
/** An object used to facilitate activity input validation. */
export declare namespace validation {
    const never: TNever;
    /**
     * Coerces an array out of a value.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     */
    function array<T>(inputName: string, value: T | T[] | undefined | null): T[] | undefined;
    /**
     * Coerces an array out of a value.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue The value to use if `value` is `undefined` or `null`. When this is `validation.never` the function will throw an `ActivityInputError` instead.
     */
    function array<T>(inputName: string, value: T | T[] | undefined | null, defaultValue: undefined): T[] | undefined;
    /**
     * Coerces an array out of a value.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue The value to use if `value` is `undefined` or `null`. When this is `validation.never` the function will throw an `ActivityInputError` instead.
     */
    function array<T>(inputName: string, value: T | T[] | undefined | null, defaultValue: T | T[] | TNever): T[];
    function isBoolean(value: boolean | TNever): value is boolean;
    /**
     * Checks if the given value is a boolean. If not a default value is returned instead.
     * When `defaultValue` is `validation.never`, an error is thrown instead.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue The value to use if `value` is `undefined` or `null`. When this is `validation.never` the function will throw an `ActivityInputError` instead.
     * @returns `value` if it is a boolean, `defaultValue` if it is a boolean. Otherwise an ActivityInputError is thrown.
     */
    function boolean(inputName: string, value: any): boolean | undefined;
    /**
     * Checks if the given value is a boolean. If not a default value is returned instead.
     * When `defaultValue` is `validation.never`, an error is thrown instead.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue The value to use if `value` is `undefined` or `null`. When this is `validation.never` the function will throw an `ActivityInputError` instead.
     * @returns `value` if it is a boolean, `defaultValue` if it is a boolean. Otherwise an ActivityInputError is thrown.
     */
    function boolean(inputName: string, value: any, defaultValue: undefined): boolean | undefined;
    /**
     * Checks if the given value is a boolean. If not a default value is returned instead.
     * When `defaultValue` is `validation.never`, an error is thrown instead.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue The value to use if `value` is `undefined` or `null`. When this is `validation.never` the function will throw an `ActivityInputError` instead.
     * @returns `value` if it is a boolean, `defaultValue` if it is a boolean. Otherwise an ActivityInputError is thrown.
     */
    function boolean(inputName: string, value: any, defaultValue: boolean | TNever): boolean;
    /**
     * Checks if the given value is defined and throws an error if not.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @returns The supplied value, if it is defined.
     * @throws An `ActivityInputError` if `value` is `undefined` or `null`.
     */
    function exists<T>(inputName: string, value: T | undefined): T;
    /**
     * Checks if the given value is defined and throws an error if not.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue The default value to use when `value` is not defined. If `validation.never`, an error is thrown instead.
     * @returns The supplied value, if it is defined. Otherwise, `defaultValue` if it is not `validation.never`.
     * @throws An `ActivityInputError` if `value` is `undefined` or `null` and `defaultValue` is `validation.never`.
     */
    function exists<T>(inputName: string, value: T | undefined, defaultValue: T | TNever): T;
    function id(inputName: string, value: any): string | number | undefined;
    function id(inputName: string, value: any, defaultValue: undefined): string | number | undefined;
    function id(inputName: string, value: any, defaultValue: string | number | TNever): string | number;
    /**
     * Checks if the given value is a number or a type that can be converted into one.
     * If so, the numeric value is returned.
     * If not, `undefined` is returned.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     */
    function number(inputName: string, value: number): number;
    /**
     * Checks if the given value is a number or a type that can be converted into one.
     * If so, the numeric value is returned.
     * If not, `undefined` is returned.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     */
    function number(inputName: string, value: number | undefined): number | undefined;
    /**
     * Checks if the given value is a number or a type that can be converted into one.
     * If so, the numeric value is returned.
     * If not, `undefined` is returned.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     */
    function number(inputName: string, value: any): number | undefined;
    /**
     * Checks if the given value is a number or a type that can be converted into one.
     * If so, the numeric value is returned.
     * If not, `undefined` is returned.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue A value to return if `value` could not be converted to a number.
     */
    function number(inputName: string, value: any, defaultValue: undefined): number | undefined;
    /**
     * Checks if the given value is a number or a type that can be converted into one.
     * If so, the numeric value is returned.
     * If not, `undefined` is returned.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue A value to return if `value` could not be converted to a number. If `validation.never`, an `ActivityInputError` is thrown instead.
     */
    function number(inputName: string, value: any, defaultValue: number | TNever): number;
    /**
     * Checks if the given value is a string.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     */
    function string(inputName: string, value: string): string;
    /**
     * Checks if the given value is a string.
     * If so, the value is returned. If not, undefined is returned.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     */
    function string(inputName: string, value: any): string | undefined;
    /**
     * Checks if the given value is a string.
     * If so, the value is returned. If not, the default value is returned.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue The value to return if `value` is not a string.
     */
    function string(inputName: string, value: any, defaultValue: undefined): string | undefined;
    /**
     * Checks if the given value is a string.
     * If so, the value is returned. If not, the default value is returned
     * unless the default value is `validation.never`, in which case an `ActivityInputError` is thrown.
     * @param inputName The name of the input being checked.
     * @param value The value of the input.
     * @param defaultValue The value to return if `value` is not a string.
     */
    function string(inputName: string, value: any, defaultValue: string | TNever): string;
    /**
     * Checks if an input object contains a url or an esri layer with a url.
     * @param inputs The inputs to an activity.
     * @returns The supplied layer, or a new FeatureLayer using the supplied url.
     */
    function layer(inputs: {
        layer?: __esri.Layer | __esri.SubtypeSublayer;
        url?: string;
    }): __esri.Layer | __esri.SubtypeSublayer;
    /** Checks if an input object contains a url or an esri layer with a url. */
    function urlOrLayer(inputs: {
        layer?: __esri.Layer | __esri.SubtypeSublayer;
        url?: string;
    }): string;
}
export {};