import type { ECConfig } from '../types.js';
/**
 * A single partial config contribution that can participate in a merge.
 */
type ConfigLayer = Partial<ECConfig> | undefined;
/**
 * Merges multiple config layers into a single ECConfig.
 *
 * Nested plain objects are deep-merged recursively. Arrays are always
 * replaced by the rightmost (latest) value that provides them. Undefined
 * or null layers are silently ignored, allowing conditional config layers
 * to be passed without pre-filtering.
 *
 * This is the primary low-level helper used inside ConfigModifier functions
 * and builder operations. When no layers are provided, returns an empty object.
 *
 * @param layers Variable number of config layers to merge, applied left-to-right.
 * @returns The fully merged chart configuration.
 *
 * @example
 * ```ts
 * // Basic merge
 * const myModifier: ConfigModifier = (config) =>
 *   mergeConfigs(config, { xAxis: { name: 'Days' } });
 *
 * // With conditional layers
 * const config = mergeConfigs(
 *   baseConfig,
 *   shouldAddTitle ? { title: { text: 'My Chart' } } : undefined,
 *   { yAxis: { name: 'Values' } }
 * );
 * ```
 */
export declare const mergeConfigs: (...layers: ConfigLayer[]) => ECConfig;
/**
 * The signature of a function that modifies a chart configuration.
 *
 * @example
 * ```ts
 * const myModifier: ConfigModifier = (config) =>
 *   mergeConfigs(config, { xAxis: { name: 'Days' } });
 * ```
 */
export type ConfigModifier = (config: ECConfig) => ECConfig;
/**
 * Composes multiple modifiers into a single `ConfigModifier`.
 * Modifiers are applied left-to-right, so later Modifiers override earlier ones.
 *
 * Each modifier is evaluated against the accumulated, merged config so composed
 * patch-style modifiers can depend on updates from earlier ones.
 *
 * @param modifiers The modifiers to apply in sequence.
 * @returns A single `ConfigModifier` representing the full composition.
 *
 * @example
 * ```ts
 * const combined = compose(axesShowSplitLines(), axesHideYLabels());
 * ```
 */
export declare const compose: (...modifiers: ConfigModifier[]) => ConfigModifier;
export {};