import { Context } from '../context';
import { ContextBindingController } from '../ContextBindingController';
import { ContextConsumerController } from '../ContextConsumerController';
/**
 * Binds CSS variables to a context.
 */
export declare class ContextCssVarsController extends ContextBindingController<string> {
    protected _transformers: Map<string, (varName: string, value: any) => any>;
    /**
     * Binds a context to a CSS variable on the current `ref` element. By binds we mean as the
     * context value changes it will update the given CSS custom property on the current `ref`
     * element.
     *
     * @param context The context to bind to.
     * @param varName The name of the CSS custom property to bind the context to. This is will
     * result in `--${varName}`.
     * @param transformer An optional transformer to transform the context value before it is
     * stringified and applied as the CSS custom property value. Returning `null` or `undefined`
     * will remove the custom property.
     */
    bind<T>(context: Context<T>, varName: string, transformer?: (value: T) => any): this;
    protected _handleBindToContext(): void;
    protected _handleBindingUpdate(consumer: ContextConsumerController<any>, varName: string): void;
    protected _handleUnbindFromContext(_: ContextConsumerController<any>, varName: string): void;
    /**
     * Override to transform CSS variable names.
     */
    protected _transformVarName(varName: string): string;
    /**
     * Override to transform context values to be used as CSS property values. Returning `null`
     * or `undefined` will remove the CSS property. This is provided as the default transformer when
     * one isn't provided in the `bind()` method call..
     */
    protected _transformVarValue(varName: string, value: unknown): any;
}