/**
 * TransformPipeline — Composable row transformation engine.
 *
 * Allows chaining multiple transform functions into a pipeline.
 * Each transform is applied in order. If any transform returns null,
 * the row is filtered out and subsequent transforms are skipped.
 *
 * @example
 * ```typescript
 * const pipeline = new TransformPipeline()
 *   .pipe((row) => row.status === 'inactive' ? null : row)  // filter
 *   .pipe((row) => ({ ...row, age: parseInt(row.age, 10) })) // type coerce
 *   .pipe(async (row) => {                                    // async enrich
 *     const geo = await geocode(row.address);
 *     return { ...row, lat: geo.lat, lng: geo.lng };
 *   });
 *
 * for await (const batch of csvSuperPro('data.csv', {
 *   licenseKey: key,
 *   transform: pipeline.toFn(),
 * })) {
 *   await db.insert(batch.rows);
 * }
 * ```
 */
import type { CsvRow, TransformFn, BatchResult } from '../types/index.js';
export declare class TransformPipeline {
    private readonly steps;
    /**
     * Add a transform step to the pipeline.
     * Returns `this` for method chaining.
     *
     * @param fn  Transform function: row → modified row | null (filtered)
     */
    pipe(fn: TransformFn): this;
    /**
     * Export the pipeline as a single TransformFn.
     * This is what you pass to `csvSuperPro({ transform: pipeline.toFn() })`.
     */
    toFn(): TransformFn;
    /**
     * Apply the pipeline to an entire batch.
     * Rows transformed to null are removed from the result.
     *
     * @returns New BatchResult with transformed rows.
     */
    applyToBatch(batch: BatchResult): Promise<BatchResult>;
    /**
     * Apply the pipeline to an array of rows (without BatchResult wrapping).
     */
    applyToRows(rows: CsvRow[]): Promise<CsvRow[]>;
    /** Number of transform steps in the pipeline. */
    get size(): number;
    /** Check if the pipeline has any transforms. */
    get isEmpty(): boolean;
    /**
     * Add a filter step that removes rows where `predicate` returns false.
     */
    filter(predicate: (row: CsvRow) => boolean | Promise<boolean>): this;
    /**
     * Add a field selection step (keep only specified columns).
     *
     * @example `.select(['name', 'email', 'age'])`
     */
    select(columns: string[]): this;
    /**
     * Add a field rename step.
     *
     * @example `.rename({ 'old_name': 'newName', 'email_addr': 'email' })`
     */
    rename(mapping: Record<string, string>): this;
    /**
     * Add a field transformation step for specific columns.
     *
     * @example `.mapField('age', (v) => String(parseInt(v, 10)))`
     */
    mapField(column: string, fn: (value: string) => string | Promise<string>): this;
    /**
     * Add a field trimming step (removes leading/trailing whitespace from all values).
     */
    trim(): this;
}
//# sourceMappingURL=transform-pipeline.d.ts.map