@humanspeak/svelte-markdown/dist/utils/incremental-parser.d.ts

Markdown and HTML renderer for Svelte 5 — built for rendering streaming AI agent output from Claude Code, ChatGPT, and agentic workflows. XSS-safe defaults, streaming-aware sanitization, token caching, TypeScript types, and Svelte 5 runes.

/**
 * Incremental Markdown Parser for Streaming
 *
 * Optimizes streaming scenarios (LLM token-by-token updates) by performing
 * a full re-parse but diffing the result against the previous token array.
 * Only changed/appended tokens are returned as updates, allowing Svelte to
 * skip re-rendering unchanged components.
 *
 * @module incremental-parser
 */
import type { SvelteMarkdownOptions } from '../types.js';
import type { Token } from './markdown-parser.js';
/**
 * Result of an incremental parse update.
 */
export interface IncrementalUpdateResult {
    /** The full new token array */
    tokens: Token[];
    /** Index of the first token that differs from the previous parse */
    divergeAt: number;
}
/**
 * Streaming-optimized parser that performs full re-parses but diffs results
 * against the previous token array to minimize DOM updates.
 *
 * For append-only streaming (typical LLM use case), most tokens are identical
 * between updates. By comparing `raw` strings, we identify which tokens changed
 * so Svelte can skip re-rendering unchanged components.
 *
 * @example
 * ```typescript
 * const parser = new IncrementalParser({ gfm: true })
 *
 * // First update — all tokens are "new"
 * const r1 = parser.update('# Hello')
 * // r1.divergeAt === 0
 *
 * // Second update — heading unchanged, paragraph appended
 * const r2 = parser.update('# Hello\n\nWorld')
 * // r2.divergeAt === 1 (heading at index 0 unchanged)
 * ```
 */
export declare class IncrementalParser {
    /** Previous parse result for diffing */
    private prevTokens;
    /** Previous full source string for append-only tail reparsing */
    private prevSource;
    /** Parser options passed to the Marked lexer */
    private options;
    /** Whether caller-supplied parser hooks make tail-window reparsing unsafe */
    private tailWindowDisabled;
    /** True iff any token in `prevTokens` is an HTML opening (closed or
     *  unclosed) whose `.raw` is shorter than its actual source span. The
     *  tail-window's sum-of-raws offset arithmetic only works when token
     *  raws sum to the source length; this flag detects when that
     *  invariant is broken so we fall through to a full re-parse. Cached
     *  to keep `getTailWindowBoundary` O(1) on the hot path. */
    private prevHasHtmlSpanMismatch;
    /**
     * Creates a new incremental parser instance.
     *
     * @param options - Svelte markdown parser options forwarded to Marked's Lexer
     */
    constructor(options: SvelteMarkdownOptions);
    private getTailWindowBoundary;
    /**
     * True for an HTML opening tag whose `.raw` is shorter than its
     * actual source span. After token-cleanup, a non-self-closing html
     * opening token's `.raw` is only the opening tag itself (e.g.
     * `<div>`); its children and closing tag (if any) live on
     * `.tokens`. The tail-window's `reparseOffset = sum(raws)` math is
     * unsound any time such a token sits in `prevTokens`, regardless
     * of whether the close has arrived yet.
     */
    private hasHtmlSpanMismatch;
    private isStableAtSourceEnd;
    private hasAppendSensitiveReferenceSyntax;
    private canUseTailWindow;
    private parseSource;
    /**
     * Parses the full source and diffs against the previous result.
     *
     * @param source - The full accumulated markdown source string
     * @returns The new tokens and the index where they diverge from the previous parse
     */
    update: (source: string) => IncrementalUpdateResult;
}