/**
 * The Rust line breaker, compiled to WebAssembly (#779). It chooses the
 * breaks the TypeScript one chooses, the same arithmetic in the same order,
 * two to three times faster, so which of the two answers a paragraph never
 * changes a layout: the module is compiled on the first paragraph where
 * that can be done at once (a worker, Node, Bun), and in the background
 * where it cannot (a page's main thread, where a browser compiles a module
 * this size only asynchronously); until it is ready, and wherever
 * WebAssembly is missing or refused, the TypeScript breaker answers.
 */
import { type Breaker } from './abi.js';
/**
 * Compiles the WebAssembly line breaker, in the background. Resolves true
 * when it answers from then on, false where WebAssembly is unavailable.
 * The engine starts it on its own; a host may call it early so that the
 * first layout of a page already uses it.
 */
export declare function initLineBreaker(): Promise<boolean>;
/** The WebAssembly breaker when it can answer now, else null (and the
 *  module compiles in the background when it cannot be compiled at once). */
export declare function readyWasmBreaker(): Breaker | null;
/**
 * Whether paragraphs are broken by the WebAssembly line breaker when it is
 * available (the default) or always by the TypeScript one. The two choose
 * the same breaks: this is for measuring and testing them.
 */
export declare function useWasmLineBreaker(on: boolean): void;
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