gugglegum/clv-rw

Reader and writer for text files with constant length values

2.0.0 2026-05-22 19:33 UTC

Requires

• php: >=8.3
• ext-mbstring: *

Requires (Dev)

• phpunit/phpunit: ^11.0

MIT

• Paul Melekhov

• text
• parser
• writer
• table
• reader
• fixed length
• cells
• columns
• fixed size
• constant size
• constant length

README

CLV is a text-table format with fixed-width cells and no delimiter character. Each row is a text line separated by LF or CRLF (\n or \r\n). Each cell has a predefined character width, and missing characters are padded with spaces by default.

This format is mostly useful when integrating with older systems. For new services, CSV or JSON is usually a better choice. The main limitation is that values cannot be longer than their configured column width unless you explicitly enable trimming.

The library can work with both files and streams, so it can read from STDIN, write to STDOUT, or work with temporary streams such as php://temp.

Column widths are measured in UTF-8 characters, not bytes.

Requirements

• PHP 8.3 or newer
• ext-mbstring

Installation

composer require gugglegum/clv-rw

Reading

use gugglegum\ClvRw\Column;
use gugglegum\ClvRw\ColumnsSet;
use gugglegum\ClvRw\Reader;

$columns = new ColumnsSet([
    Column::create('Code', 4),
    Column::create('Name', 10),
]);

$reader = (new Reader())->open('input.clv', $columns);

foreach ($reader as $row) {
    echo $row['Code'], ': ', $row['Name'], PHP_EOL;
}

$reader->close();

Writing

use gugglegum\ClvRw\Column;
use gugglegum\ClvRw\ColumnsSet;
use gugglegum\ClvRw\Writer;

$columns = new ColumnsSet([
    Column::create('Code', 4),
    Column::create('Name', 10),
]);

$writer = (new Writer())->open('output.clv', $columns);
$writer->writeRow(['Code' => 'A1', 'Name' => 'Widget']);
$writer->close();

Writer::open() opens the target file in write mode and truncates existing contents. Use Writer::assign() if you need to write to an already opened stream, for example STDOUT or php://temp.

By default, values that exceed their column width throw an exception. You can trim them instead:

$writer->setTrimTooLongValues(true);

Examples

See the example/ directory:

php example/reader.php
php example/reader.php | php example/writer.php

Line Endings

The reader handles LF and CRLF line endings. Classic Mac CR-only files should be normalized before reading. PHP's auto_detect_line_endings option is deprecated, so it is better not to rely on it for new code.

Exceptions

Package errors are thrown as gugglegum\ClvRw\Exception, which extends PHP's RuntimeException.