File size: 2,672 Bytes
48183e3 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 | import fs from "node:fs"
// Minimal RFC4180-ish CSV parser: handles quoted fields, embedded commas,
// embedded quotes ("" escaping), and embedded newlines inside quotes.
// Strips a leading UTF-8 BOM. Good enough for the well-formed spreadsheet
// exports this project produces -- not a general-purpose CSV library.
export function parseCsv(text) {
const body = text.charCodeAt(0) === 0xfeff ? text.slice(1) : text
const rows = []
let row = []
let field = ""
let inQuotes = false
for (let i = 0; i < body.length; i++) {
const c = body[i]
if (inQuotes) {
if (c === '"') {
if (body[i + 1] === '"') {
field += '"'
i++
} else {
inQuotes = false
}
} else {
field += c
}
continue
}
if (c === '"') {
inQuotes = true
} else if (c === ",") {
row.push(field)
field = ""
} else if (c === "\n" || c === "\r") {
if (c === "\r" && body[i + 1] === "\n") i++
row.push(field)
rows.push(row)
row = []
field = ""
} else {
field += c
}
}
if (field.length > 0 || row.length > 0) {
row.push(field)
rows.push(row)
}
return rows.filter((r) => !(r.length === 1 && r[0] === ""))
}
function csvEscape(value) {
const s = value == null ? "" : String(value)
if (/[",\n\r]/.test(s)) {
return `"${s.replace(/"/g, '""')}"`
}
return s
}
// `leadingNotes` (optional): human-readable note rows written before the
// header, one full-width row per note (note text in the first column,
// blanks elsewhere) -- the same convention the data/ SAMPLE files used for
// "Illustrative only" banners. Purely for a human reader; a file written
// this way should not be re-parsed as CSV data by another script, since
// readCsvObjects would treat the first note row as the header.
export function writeCsv(path, header, rows, { leadingNotes = [] } = {}) {
const lines = []
for (const note of leadingNotes) {
lines.push([note, ...Array(header.length - 1).fill("")].map(csvEscape).join(","))
}
lines.push(header.map(csvEscape).join(","))
for (const row of rows) {
lines.push(header.map((col) => csvEscape(row[col])).join(","))
}
fs.writeFileSync(path, "" + lines.join("\r\n") + "\r\n", "utf8")
}
export function readCsvObjects(path) {
const text = fs.readFileSync(path, "utf8")
const rows = parseCsv(text)
if (rows.length === 0) return { header: [], records: [] }
const [header, ...rest] = rows
const records = rest.map((r) => {
const obj = {}
header.forEach((col, i) => {
obj[col] = r[i] ?? ""
})
return obj
})
return { header, records }
}
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