import { Expression } from "../expression/expression";
import { Optional } from "../../optional/optional";
export declare type ExpressionOrString = string | Expression;
export declare type SyncExpressionChain = ExpressionOrString[];
export declare type AsyncExpressionChain = [true, ExpressionOrString[]];
export declare type ExpressionChain = string | SyncExpressionChain | AsyncExpressionChain;
export declare type NullableExpressionChain = Optional<ExpressionChain>;
export interface ExpressionChainDict {
    [key: string]: ExpressionChain | undefined;
}
/**
 * Returns true if the given ExpressionChain is a pure string
 * @param {NullableExpressionChain} expressionChain
 * @returns {expressionChain is string}
 */
export declare function isPureStringExpressionChain(expressionChain: NullableExpressionChain): expressionChain is string;
/**
 * Returns true if the given ExpressionChain is asynchronous
 * @param {NullableExpressionChain} expressionChain
 * @returns {expressionChain is AsyncExpressionChain}
 */
export declare function isAsyncExpressionChain(expressionChain: NullableExpressionChain): expressionChain is AsyncExpressionChain;
/**
 * Returns true if the given ExpressionChain is synchronous
 * @param {NullableExpressionChain} expressionChain
 * @returns {expressionChain is SyncExpressionChain}
 */
export declare function isSyncExpressionChain(expressionChain: NullableExpressionChain): expressionChain is SyncExpressionChain;
/**
 * Returns true if the given ExpressionChain is a string or synchronous
 * @param {NullableExpressionChain} expressionChain
 * @returns {expressionChain is string|SyncExpressionChain}
 */
export declare function isStringOrSyncExpressionChain(expressionChain: NullableExpressionChain): expressionChain is string | SyncExpressionChain;
/**
 * Takes Expressions or strings for an ExpressionChain
 * @param {ExpressionChain} expressionChain
 * @returns {ExpressionOrString[]}
 */
export declare function takeExpressionsOrStrings(expressionChain: ExpressionChain): ExpressionOrString[];
/**
 * Returns true if the given ExpressionChain contains at least one Expression
 * @param {ExpressionChain} expressionChain
 * @returns {boolean}
 */
export declare function expressionChainContainsExpression(expressionChain: ExpressionChain): boolean;
/**
 * Returns true if the given item is a ExpressionChain
 * @param {NullableExpressionChain} item
 * @returns {boolean}
 */
export declare function isExpressionChain(item: NullableExpressionChain | ExpressionChainDict): item is ExpressionChain;