Transcoder

Introduction

This is a wrapper around PHP’s mb_convert_encoding and iconv functions. This library adds:

• fallback from mb to iconv for encodings it does not support
• conversion of warnings to proper exceptions.

Installation

The recommended way to install the Transcoder library is through Composer:

$ composer require fossar/transcoder

This command requires you to have Composer installed globally, as explained in the installation chapter of the Composer documentation.

Usage

Basics

Create the right transcoder for your platform and translate a string to ISO-8859-1 encoding:

use Ddeboer\Transcoder\Transcoder;

$transcoder = Transcoder::create();
$result = $transcoder->transcode('España', 'iso-8859-1');

You can also manually instantiate a transcoder of your liking:

use Ddeboer\Transcoder\MbTranscoder;

$transcoder = new MbTranscoder();

Or:

use Ddeboer\Transcoder\IconvTranscoder;

$transcoder = new IconvTranscoder();

Source encoding

The second argument accepts source encoding and can actually be omitted or passed null.

$transcoder->transcode('España');

In that case, however, the behaviour is backend-specific:

• IconvTranscoder will use the encoding of the current locale of the process.
• MbTranscoder will try to detect encoding from a list based on the value of mbstring.language setting. By default, this tries ASCII, followed by UTF-8. The number of supported languages is limited though and the encoding tables often overlap so the detection might be unreliable.

As you can see, this is mostly useless for western languages. You will get much more reliable results when you specify the source encoding explicitly.

Target encoding

Specify a default target encoding as the first argument to create():

use Ddeboer\Transcoder\Transcoder;

$isoTranscoder = Transcoder::create('iso-8859-1');

Alternatively, specify a target encoding as the third argument in a transcode() call:

use Ddeboer\Transcoder\Transcoder;

$transcoder->transcode('España', 'iso-8859-1', 'UTF-8');

Error handling

PHP’s mv_convert_encoding and iconv are inconvenient to use because they generate notices and warnings instead of proper exceptions. This library fixes that:

use Ddeboer\Transcoder\Exception\UndetectableEncodingException;
use Ddeboer\Transcoder\Exception\UnsupportedEncodingException;
use Ddeboer\Transcoder\Exception\IllegalCharacterException;

$input = 'España';

try {
    $transcoder->transcode($input, 'utf-8', 'not-a-real-encoding');
} catch (UnsupportedEncodingException $e) {
    // ‘not-a-real-encoding’ is an unsupported encoding
}

try {
    $transcoder->transcode('Illegal quotes: ‘ ’', 'utf-8', 'iso-8859-1');
} catch (IllegalCharacterException $e) {
    // Curly quotes ‘ ’ are illegal in ISO-8859-1
}

try {
    $transcoder->transcode($input);
} catch (UndetectableEncodingException $e) {
    // Failed to automatically detect $input’s encoding (mb) or not a valid string in current locale locale (iconv)
}

Transcoder fallback

In general, mb_convert_encoding is faster than iconv. However, as iconv supports more encodings than mb_convert_encoding, it makes sense to combine the two.

So, the Transcoder returned from create():

• uses mb_convert_encoding if the mbstring PHP extension is installed;
• if not, it uses iconv instead if the iconv extension is installed;
• if both the mbstring and iconv extension are available, the Transcoder will first try mb_convert_encoding and fall back to iconv.