/**
 * @copyright Sister Software
 * @license AGPL-3.0
 * @author Teffen Ellis, et al.
 *
 * Reading a delimited file's header line, and refusing one that stops naming a column an adapter
 * indexes.
 *
 * A fetch module checks the file it just wrote against the columns its adapter reads by name,
 * because a renamed column reaches the adapter as an empty string on every row rather than as an
 * error. The check belongs here rather than in each publisher's module: every caller needs the same
 * two steps, and each one that wrote them again would also be a second answer to how the file is
 * parsed.
 */
import type { PathBuilderLike } from "path-ts";
/**
 * The header line's column names.
 *
 * Read through `CSVSpliterator`, which is the reader the adapters use, rather than through
 * a split of a fetch module's own: which columns a publisher quotes is a property of
 * the edition, and a second reader would be a second answer to that question.
 * `columnScan: "rows"` keeps the first row from decoding the whole file,
 * which the default `"auto"` does even for one row.
 *
 * @param path The written file.
 * @param columnDelimiter The publisher's delimiter, which defaults to a comma.
 * @throws When the file holds no row at all, so an empty or truncated file reports itself
 * rather than reading as a file with no columns.
 */
export declare function readDelimitedHeader(path: PathBuilderLike, columnDelimiter?: string): Promise<readonly string[]>;
/**
 * Refuse a header that does not name every column a caller reads.
 *
 * @param columns The header {@linkcode readDelimitedHeader} returned.
 * @param required The columns the adapter indexes by name.
 * @param context What is being checked, which opens the message.
 * @throws Naming the columns that are absent, so a renamed column is a reported failure
 * rather than an empty string on every row the adapter emits.
 */
export declare function assertHeaderColumns(columns: readonly string[], required: readonly string[], context: string): void;
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