File handling CSV Tabular data

CSV File Handling

The klyn.io.csv package provides an RFC-4180 style reader and writer. It handles quoted fields, delimiters, embedded newlines, doubled quotes, and common dialect options.

Imports

import klyn.collections
import klyn.io
import klyn.io.csv

Reading Rows

CSVReader materializes rows as ArrayList<String> values. It can read a file name, a Path, or any TextReader.

import klyn.collections
import klyn.io
import klyn.io.csv

reader = CSVReader("contacts.csv", delimiter=';')
reader.skip(1)  # Skip header row.

for row as ArrayList<String> in reader:
    name = row[0]
    email = row[1]
    print(name + " <" + email + ">")

Writing Rows

CSVWriter can buffer output in memory or write directly to a file or text writer. Use try with file-backed writers so the file is closed deterministically.

import klyn.io.csv

try writer = CSVWriter("contacts.csv", delimiter=';'):
    writer.writeRow(["name", "email"])
    writer.writeRow(["Ada Lovelace", "ada@example.test"])
    writer.writeRow(["Grace Hopper", "grace@example.test"])

For diagnostics or tests, create a buffered writer and call toString().

writer = CSVWriter(',', '"', Char(0), true, "\n")
writer.writeRow(["name", "note"])
writer.writeRow(["Ada, A.", "uses \"quotes\""])
print(writer.toString())

Dialects

The reader and writer expose the usual CSV knobs: delimiter, quote character, escape character, double-quote escaping, initial-space handling, line terminator, and quoting mode.

Option	Typical use
`delimiter`	Use `';'` for semicolon-separated files.
`skipInitialSpace`	Ignore spaces immediately after delimiters.
`quoting`	`minimal`, `all`, or `none` for writer output.
`strict`	Raise `CSVException` on malformed quoted fields.