CSV parser

1import {
2  createCsvNormalizer,
3  padRowsToColumnCount,
4  type CsvNormalizer,
5} from "./csv-normalizer";
6import { createCsvParser } from "./csv-parser";
7 
8export {
9  DEFAULT_CSV_DIALECT,
10  extensionOfDelimitedName,
11  inferCsvDialect,
12  isTabDelimited,
13  normalizeCsvDelimiter,
14  resolveCsvDialect,
15  type CsvDialect,
16  type CsvDialectDescriptor,
17} from "./csv-dialect";
18export {
19  createCsvNormalizer,
20  padRowsToColumnCount,
21  type CsvNormalizer,
22  type CsvNormalizerOptions,
23  type CsvTable,
24  type CsvTableEvent,
25} from "./csv-normalizer";
26export {
27  createCsvParser,
28  type CsvParser,
29  type CsvParserOptions,
30} from "./csv-parser";
31 
32export interface ParsedCsv {
33  columns: string[];
34  rows: string[][];
35}
36 
37export interface ParseCsvOptions {
38  /** Field delimiter. Defaults to ",". */
39  delimiter?: string;
40  /** Treat the first record as a header row. Defaults to true. */
41  hasHeader?: boolean;
42}
43 
44export function parseCsv(
45  input: string,
46  options: ParseCsvOptions = {},
47): ParsedCsv {
48  const parser = createCsvParser({ delimiter: options.delimiter });
49  const normalizer = createCsvNormalizer({ hasHeader: options.hasHeader });
50  const rows: string[][] = [];
51  let columns: string[] = [];
52 
53  handleCsvRecords(parser.push(input), normalizer, rows, (nextColumns) => {
54    columns = nextColumns;
55    padRowsToColumnCount(rows, columns.length);
56  });
57  handleCsvRecords(parser.flush(), normalizer, rows, (nextColumns) => {
58    columns = nextColumns;
59    padRowsToColumnCount(rows, columns.length);
60  });
61 
62  return { columns, rows };
63}
64 
65function handleCsvRecords(
66  records: string[][],
67  normalizer: CsvNormalizer,
68  rows: string[][],
69  onColumns: (columns: string[]) => void,
70) {
71  for (const record of records) {
72    for (const event of normalizer.accept(record)) {
73      if (event.type === "columns") {
74        onColumns(event.columns);
75      } else {
76        rows.push(event.row);
77      }
78    }
79  }
80}
81 
82/** Pad a record to a fixed width. */
83export function fitRow(row: string[], width: number): string[] {
84  if (row.length === width) return row;
85  if (row.length < width)
86    return [...row, ...Array(width - row.length).fill("")];
87  return row;
88}
89 
90export interface CsvStreamHandlers {
91  onColumns: (columns: string[]) => void;
92  onRows: (rows: string[][]) => void;
93  onDone?: () => void;
94  onError?: (error: unknown) => void;
95}
96 
97export interface CsvStreamOptions extends ParseCsvOptions {
98  /** Rows per batch handed to `onRows`. Defaults to 2000. */
99  batchSize?: number;
100// … truncated