/**
 * @copyright Sister Software
 * @license AGPL-3.0
 * @author Teffen Ellis, et al.
 *
 *   Typed wrapper around `@dsnp/parquetjs`'s `ParquetReader` that narrows the row-iterator generic to
 *   a user-supplied record type and adds `AsyncDisposable` support so `await using` cleans up the
 *   envelope reader without an explicit `close()`.
 */
import { ParquetReader as BaseParquetReader } from "@dsnp/parquetjs";
import type { BufferReaderOptions } from "@dsnp/parquetjs/dist/lib/bufferReader.js";
import { ParquetEnvelopeReader } from "@dsnp/parquetjs/dist/lib/reader.js";
import type { ParquetSchema, ParquetRecordLike } from "./schema.ts";
/**
 * A typed Parquet reader, wrapping the base Parquet reader.
 */
export declare class ParquetReader<T extends ParquetRecordLike> extends BaseParquetReader implements AsyncDisposable {
    schema: ParquetSchema<T>;
    static openFile<T extends ParquetRecordLike>(filePath: string | URL, options?: BufferReaderOptions): Promise<ParquetReader<T>>;
    static openBuffer<T extends ParquetRecordLike>(buffer: Buffer, options?: BufferReaderOptions): Promise<ParquetReader<T>>;
    static openEnvelopeReader<T extends ParquetRecordLike>(envelopeReader: ParquetEnvelopeReader, opts?: BufferReaderOptions): Promise<ParquetReader<T>>;
    [Symbol.asyncIterator](): AsyncGenerator<T, void, unknown>;
    /**
     * Iterate a subset of the columns, narrowed to the keys asked for.
     *
     * Parquet is columnar, so a projection is read avoided rather than read-then-discarded: on a 14-column corpus shard,
     * two columns cost 93 ms against 253 ms for the whole row. The default iterator reads every column, which is what a
     * caller wanting the whole record should use.
     */
    project<K extends keyof T>(...columns: K[]): AsyncGenerator<Pick<T, K>, void, unknown>;
    [Symbol.asyncDispose](): Promise<void>;
    dispose(): Promise<void>;
}
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