/**
 * Utilities for manipulating the external-workbook prefix in formula strings.
 *
 * Excel formula strings containing external workbook references have the
 * shape `[<workbook>]Sheet!Ref` where `<workbook>` is either
 *
 *   - a 1-based numeric index  — `[1]Sheet1!A1`  (the canonical on-disk form
 *     stored inside `<f>` elements of worksheet XML), or
 *   - a filename / relative path — `[测试.xlsx]Sheet1!A1`  (what Excel
 *     displays in the formula bar; not part of the OOXML storage contract,
 *     but produced by hand-written formulas and some older tools).
 *
 * When writing, excelts always emits the numeric form — indices map
 * positionally into the workbook's `<externalReferences>` list. When a
 * formula arrives with the filename form, the writer assigns (or reuses) an
 * ExternalLinkModel with that filename as its `target` and rewrites the
 * formula to the numeric form. This matches how Excel itself stores formulas
 * and makes them round-trippable.
 *
 * The quoted variant `'[file.xlsx]Sheet with space'!A1` is handled too — Excel
 * wraps the `[name]Sheet` segment in single quotes when the sheet name needs
 * quoting. The matching logic here recognises both the unquoted and quoted
 * forms, rewriting inside the quotes when needed.
 *
 * Edge cases we explicitly *do not* treat as external refs:
 *   - `[@Column]`, `[#Headers]`, `[Column Name]` — table structured refs
 *     (no `]Sheet!` tail). The regex requires the `]<sheet>!` follow-up,
 *     which structured refs never have.
 *   - Array literals `{1,2;3,4}` use `{}`, not `[]`.
 *   - String literals `"[Book]Sheet!A1"` — handled by scanning only outside
 *     string literal regions.
 */
/**
 * A single match of an external reference inside a formula string. The
 * writer uses `workbook` to find/create an ExternalLinkModel and `sheet`
 * for reporting / sheet-name upsert. `replacement` is the substring that
 * should replace `match` in the final formula (with the workbook token
 * rewritten to a numeric index).
 */
export interface ExternalRefMatch {
    /** Full matched prefix including trailing `!`, e.g. `[测试.xlsx]Sheet1!`. */
    match: string;
    /** The workbook token inside `[]` — either numeric or a filename/path. */
    workbook: string;
    /** Whether the workbook token was already a numeric index. */
    numeric: boolean;
    /** The 1-based numeric index parsed from the workbook token, if numeric. */
    index: number | null;
    /** The sheet name (unquoted). */
    sheet: string;
    /** Whether the match came from the quoted variant `'[..]..'!`. */
    quoted: boolean;
    /** Start offset in the source formula. */
    start: number;
    /** End offset (exclusive) in the source formula. */
    end: number;
}
/**
 * Scan a formula string for all external-workbook references. String
 * literals (inside `"..."`) are skipped so that a string value like
 * `"[Book]Sheet!A1"` is not misidentified as a ref.
 *
 * The returned matches are in source order. If a formula contains no
 * external refs, the array is empty.
 */
export declare function findExternalRefs(formula: string): ExternalRefMatch[];
/**
 * Replace every external-workbook token in `formula` using the supplied
 * resolver. The resolver is called once per match and returns the numeric
 * index to substitute; returning `null` leaves the match unchanged (useful
 * when the caller cannot resolve a particular filename).
 *
 * Returns the rewritten formula. Offsets inside the original formula are
 * adjusted correctly even when multiple rewrites change the total length.
 */
export declare function rewriteExternalRefs(formula: string, resolve: (match: ExternalRefMatch) => number | null): string;