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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* A Class to parse CSV files
*/
const QUOTATION_MARK = '"';
const LINE_BREAKS = ["\r", "\n"];
const EOL = {};
class ParsingFailedException extends Error {
constructor(message) {
super(message ? message : `Stopped parsing because of wrong csv format`);
}
}
export class CSV {
/**
* Parses a csv formated string into rows split into [headerLine, parsedLines].
* The csv string format has to follow RFC 4180, otherwise the parsing process is stopped and a ParsingFailedException is thrown, e.g.:
* (wrong format => right format):
* 'abc"def' => 'abc""def'
* abc,def => "abc,def"
*
* @param {string} text
* @param {string} delimiter a comma for CSV files and a tab for TSV files
* @returns {Array[]} headerLine: column names (first line of text), parsedLines: Array of Login Objects with column name as properties and login data as values.
*/
static parse(text, delimiter) {
let headerline = [];
let parsedLines = [];
for (let row of this.mapValuesToRows(this.readCSV(text, delimiter))) {
if (!headerline.length) {
headerline = row;
} else {
let login = {};
row.forEach((attr, i) => (login[headerline[i]] = attr));
parsedLines.push(login);
}
}
return [headerline, parsedLines];
}
static *readCSV(text, delimiter) {
function maySkipMultipleLineBreaks() {
while (LINE_BREAKS.includes(text[current])) {
current++;
}
}
function readUntilSingleQuote() {
const start = ++current;
while (current < text.length) {
if (text[current] === QUOTATION_MARK) {
if (text[current + 1] !== QUOTATION_MARK) {
const result = text.slice(start, current).replaceAll('""', '"');
current++;
return result;
}
current++;
}
current++;
}
throw new ParsingFailedException();
}
function readUntilDelimiterOrNewLine() {
const start = current;
while (current < text.length) {
if (text[current] === delimiter) {
const result = text.slice(start, current);
current++;
return result;
} else if (LINE_BREAKS.includes(text[current])) {
const result = text.slice(start, current);
return result;
}
current++;
}
return text.slice(start);
}
let current = 0;
maySkipMultipleLineBreaks();
while (current < text.length) {
if (LINE_BREAKS.includes(text[current])) {
maySkipMultipleLineBreaks();
yield EOL;
}
let quotedValue = "";
let value = "";
if (text[current] === QUOTATION_MARK) {
quotedValue = readUntilSingleQuote();
}
value = readUntilDelimiterOrNewLine();
if (quotedValue && value) {
throw new ParsingFailedException();
}
yield quotedValue ? quotedValue : value;
}
}
static *mapValuesToRows(values) {
let row = [];
for (const value of values) {
if (value === EOL) {
yield row;
row = [];
} else {
row.push(value);
}
}
if (!(row.length === 1 && row[0] === "") && row.length) {
yield row;
}
}
}
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