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std/encoding/csv.ts

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// Ported from Go:// https://github.com/golang/go/blob/go1.12.5/src/encoding/csv/// Copyright 2011 The Go Authors. All rights reserved. BSD license.// https://github.com/golang/go/blob/master/LICENSE// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
import { BufReader } from "../io/bufio.ts";import { TextProtoReader } from "../textproto/mod.ts";import { StringReader } from "../io/readers.ts";import { assert } from "../testing/asserts.ts";
const INVALID_RUNE = ["\r", "\n", '"'];
export const ERR_BARE_QUOTE = 'bare " in non-quoted-field';export const ERR_QUOTE = 'extraneous or missing " in quoted-field';export const ERR_INVALID_DELIM = "Invalid Delimiter";export const ERR_FIELD_COUNT = "wrong number of fields";
export class ParseError extends Error { StartLine: number; Line: number; constructor(start: number, line: number, message: string) { super(message); this.StartLine = start; this.Line = line; }}
/** * @property comma - Character which separates values. Default: ',' * @property comment - Character to start a comment. Default: '#' * @property trimLeadingSpace - Flag to trim the leading space of the value. * Default: 'false' * @property lazyQuotes - Allow unquoted quote in a quoted field or non double * quoted quotes in quoted field Default: 'false' * @property fieldsPerRecord - Enabling the check of fields for each row. * If == 0, first row is used as referal for the number of fields. */export interface ReadOptions { comma?: string; comment?: string; trimLeadingSpace?: boolean; lazyQuotes?: boolean; fieldsPerRecord?: number;}
function chkOptions(opt: ReadOptions): void { if (!opt.comma) { opt.comma = ","; } if (!opt.trimLeadingSpace) { opt.trimLeadingSpace = false; } if ( INVALID_RUNE.includes(opt.comma) || (typeof opt.comment === "string" && INVALID_RUNE.includes(opt.comment)) || opt.comma === opt.comment ) { throw new Error(ERR_INVALID_DELIM); }}
async function readRecord( Startline: number, reader: BufReader, opt: ReadOptions = { comma: ",", trimLeadingSpace: false }): Promise<string[] | Deno.EOF> { const tp = new TextProtoReader(reader); const lineIndex = Startline; let line = await readLine(tp);
if (line === Deno.EOF) return Deno.EOF; if (line.length === 0) { return []; } // line starting with comment character is ignored if (opt.comment && line[0] === opt.comment) { return []; }
assert(opt.comma != null);
let quoteError: string | null = null; const quote = '"'; const quoteLen = quote.length; const commaLen = opt.comma.length; let recordBuffer = ""; const fieldIndexes = [] as number[]; parseField: for (;;) { if (opt.trimLeadingSpace) { line = line.trimLeft(); }
if (line.length === 0 || !line.startsWith(quote)) { // Non-quoted string field const i = line.indexOf(opt.comma); let field = line; if (i >= 0) { field = field.substring(0, i); } // Check to make sure a quote does not appear in field. if (!opt.lazyQuotes) { const j = field.indexOf(quote); if (j >= 0) { quoteError = ERR_BARE_QUOTE; break parseField; } } recordBuffer += field; fieldIndexes.push(recordBuffer.length); if (i >= 0) { line = line.substring(i + commaLen); continue parseField; } break parseField; } else { // Quoted string field line = line.substring(quoteLen); for (;;) { const i = line.indexOf(quote); if (i >= 0) { // Hit next quote. recordBuffer += line.substring(0, i); line = line.substring(i + quoteLen); if (line.startsWith(quote)) { // `""` sequence (append quote). recordBuffer += quote; line = line.substring(quoteLen); } else if (line.startsWith(opt.comma)) { // `","` sequence (end of field). line = line.substring(commaLen); fieldIndexes.push(recordBuffer.length); continue parseField; } else if (0 === line.length) { // `"\n` sequence (end of line). fieldIndexes.push(recordBuffer.length); break parseField; } else if (opt.lazyQuotes) { // `"` sequence (bare quote). recordBuffer += quote; } else { // `"*` sequence (invalid non-escaped quote). quoteError = ERR_QUOTE; break parseField; } } else if (line.length > 0 || !(await isEOF(tp))) { // Hit end of line (copy all data so far). recordBuffer += line; const r = await readLine(tp); if (r === Deno.EOF) { if (!opt.lazyQuotes) { quoteError = ERR_QUOTE; break parseField; } fieldIndexes.push(recordBuffer.length); break parseField; } recordBuffer += "\n"; // preserve line feed (This is because TextProtoReader removes it.) line = r; } else { // Abrupt end of file (EOF on error). if (!opt.lazyQuotes) { quoteError = ERR_QUOTE; break parseField; } fieldIndexes.push(recordBuffer.length); break parseField; } } } } if (quoteError) { throw new ParseError(Startline, lineIndex, quoteError); } const result = [] as string[]; let preIdx = 0; for (const i of fieldIndexes) { result.push(recordBuffer.slice(preIdx, i)); preIdx = i; } return result;}
async function isEOF(tp: TextProtoReader): Promise<boolean> { return (await tp.r.peek(0)) === Deno.EOF;}
async function readLine(tp: TextProtoReader): Promise<string | Deno.EOF> { let line: string; const r = await tp.readLine(); if (r === Deno.EOF) return Deno.EOF; line = r;
// For backwards compatibility, drop trailing \r before EOF. if ((await isEOF(tp)) && line.length > 0 && line[line.length - 1] === "\r") { line = line.substring(0, line.length - 1); }
// Normalize \r\n to \n on all input lines. if ( line.length >= 2 && line[line.length - 2] === "\r" && line[line.length - 1] === "\n" ) { line = line.substring(0, line.length - 2); line = line + "\n"; }
return line;}
export async function readMatrix( reader: BufReader, opt: ReadOptions = { comma: ",", trimLeadingSpace: false, lazyQuotes: false, }): Promise<string[][]> { const result: string[][] = []; let _nbFields: number | undefined; let lineResult: string[]; let first = true; let lineIndex = 0; chkOptions(opt);
for (;;) { const r = await readRecord(lineIndex, reader, opt); if (r === Deno.EOF) break; lineResult = r; lineIndex++; // If fieldsPerRecord is 0, Read sets it to // the number of fields in the first record if (first) { first = false; if (opt.fieldsPerRecord !== undefined) { if (opt.fieldsPerRecord === 0) { _nbFields = lineResult.length; } else { _nbFields = opt.fieldsPerRecord; } } }
if (lineResult.length > 0) { if (_nbFields && _nbFields !== lineResult.length) { throw new ParseError(lineIndex, lineIndex, ERR_FIELD_COUNT); } result.push(lineResult); } } return result;}
/** * HeaderOptions provides the column definition * and the parse function for each entry of the * column. */export interface HeaderOptions { name: string; parse?: (input: string) => unknown;}
export interface ParseOptions extends ReadOptions { header: boolean | string[] | HeaderOptions[]; parse?: (input: unknown) => unknown;}
/** * Csv parse helper to manipulate data. * Provides an auto/custom mapper for columns and parse function * for columns and rows. * @param input Input to parse. Can be a string or BufReader. * @param opt options of the parser. * @param [opt.header=false] HeaderOptions * @param [opt.parse=null] Parse function for rows. * Example: * const r = await parseFile('a,b,c\ne,f,g\n', { * header: ["this", "is", "sparta"], * parse: (e: Record<string, unknown>) => { * return { super: e.this, street: e.is, fighter: e.sparta }; * } * }); * // output * [ * { super: "a", street: "b", fighter: "c" }, * { super: "e", street: "f", fighter: "g" } * ] */export async function parse( input: string | BufReader, opt: ParseOptions = { header: false, }): Promise<unknown[]> { let r: string[][]; if (input instanceof BufReader) { r = await readMatrix(input, opt); } else { r = await readMatrix(new BufReader(new StringReader(input)), opt); } if (opt.header) { let headers: HeaderOptions[] = []; let i = 0; if (Array.isArray(opt.header)) { if (typeof opt.header[0] !== "string") { headers = opt.header as HeaderOptions[]; } else { const h = opt.header as string[]; headers = h.map( (e): HeaderOptions => { return { name: e, }; } ); } } else { const head = r.shift(); assert(head != null); headers = head.map( (e): HeaderOptions => { return { name: e, }; } ); i++; } return r.map((e): unknown => { if (e.length !== headers.length) { throw `Error number of fields line:${i}`; } i++; const out: Record<string, unknown> = {}; for (let j = 0; j < e.length; j++) { const h = headers[j]; if (h.parse) { out[h.name] = h.parse(e[j]); } else { out[h.name] = e[j]; } } if (opt.parse) { return opt.parse(out); } return out; }); } if (opt.parse) { return r.map((e: string[]): unknown => { assert(opt.parse, "opt.parse must be set"); return opt.parse(e); }); } return r;}