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Aura.Intl

The Aura.Intl package provides internationalization (I18N) tools, specifically package-oriented per-locale message translation.

Getting Started

You can instantiate TranslatorLocator object from TranslatorLocatorFactory as below

<?php
use Aura\Intl\TranslatorLocatorFactory;

$factory = new TranslatorLocatorFactory();
$translators = $factory->newInstance();
?>

Alternatively, we can add the Aura.Intl package /path/to/Aura.Intl/src to our autoloader and build a translator locator manually:

<?php
use Aura\Intl\PackageLocator;
use Aura\Intl\FormatterLocator;
use Aura\Intl\TranslatorFactory;
use Aura\Intl\TranslatorLocator;

return new TranslatorLocator(
    new PackageLocator,
    new FormatterLocator([
        'basic' => function () { return new \Aura\Intl\BasicFormatter; },
        'intl'  => function () { return new \Aura\Intl\IntlFormatter; },
    ]),
    new TranslatorFactory,
    'en_US'
);
?>

Setting Localized Messages For A Package

We can set localized messages for a package through the PackageLocator object from the translator locator. We create a new Package with messages and place it into the locator as a callable. The messages take the form of a message key and and message string.

<?php
use Aura\Intl\Package;

// get the package locator
$packages = $translators->getPackages();

// place into the locator for Vendor.Package
$packages->set('Vendor.Package', 'en_US', function() {
    // create a US English message set
    $package = new Package;
    $package->setMessages([
        'FOO' => 'The text for "foo."',
        'BAR' => 'The text for "bar."',
    ]);
    return $package;
});

// place into the locator for a Vendor.Package
$packages->set('Vendor.Package', 'pt_BR', function() {
    // a Brazilian Portuguese message set
    $package = new Package;
    $package->setMessages([
        'FOO' => 'O texto de "foo".',
        'BAR' => 'O texto de "bar".',
    ]);
    return $package;
});
?>

Setting The Default Locale

We can set the default locale for translations using the setLocale() method:

<?php
$translators->setLocale('pt_BR');
?>

Getting A Localized Message

Now that the translator locator has messages and a default locale, we can get an individual package translator. The package translator is suitable for injection into another class, or for standalone use.

<?php
// recall that the default locale is pt_BR
$translator = $translators->get('Vendor.Package');
echo $translator->translate('FOO'); // 'O texto de "foo".'
?>

You can get a translator for a non-default locale as well:

<?php
$translator = $translators->get('Vendor.Package', 'en_US');
echo $translator->translate('FOO'); // 'The text for "foo."'
?>

Replacing Message Tokens With Values

We often need to use dynamic values in translated messages. First, the message string needs to have a token placeholder for the dynamic value:

<?php
// get the packages out of the translator locator
$packages = $translators->getPackages();

$packages->set('Vendor.Dynamic', 'en_US', function() {

    // US English messages
    $package = new Package;
    $package->setMessages([
        'PAGE' => 'Page {page} of {pages} pages.',
    ]);
    return $package;
});

$packages->set('Vendor.Dynamic', 'pt_BR', function() {
    // Brazilian Portuguese messages
    $package = new Package;
    $package->setMessages([
        'PAGE' => 'Página {page} de {pages} páginas.',
    ]);
    return $package;
});
?>

Then, when we translate the message, we provide an array of tokens and replacement values. These will be interpolated into the message string.

<?php
// recall that the default locale is pt_BR
$translator = $translators->get('Vendor.Dynamic');
echo $translator->translate('PAGE', [
    'page' => 1,
    'pages' => 1,
]); // 'Página 1 de 1 páginas.'
?>

Pluralized Messages

Usually, we need to use different messages when a value is singular or plural. The BasicFormatter is not capable of presenting different messages based on different token values. The IntlFormatter is capable, but the PHP intl extension must be loaded to take advantage of it, and we must specify the 'intl' formatter for the package in the catalog.

When using the IntlFormatter, we can build our message strings to present singular or plural messages, as in the following example:

<?php
// get the packages out of the translator locator
$packages = $translators->getCatalog();

// get the Vendor.Dynamic package en_US locale and set
// US English messages with pluralization. note the use
// of # instead of {pages} herein; using the placeholder
// "inside itself" with the Intl formatter causes trouble.
$package->setMessages([
    'PAGE' => '{pages,plural,'
            . '=0{No pages.}'
            . '=1{One page only.}'
            . 'other{Page {page} of # pages.}'
            . '}'
]);

// use the 'intl' formatter for this package and locale
$package->setFormatter('intl');

// now that we have added the pluralizable messages,
// get the US English translator for the package
$translator = $translators->get('Vendor.Dynamic', 'en_US');

// zero translation
echo $translator->translate('PAGE', [
    'page' => 0,
    'pages' => 0,
]); // 'No pages.'

// singular translation
echo $translator->translate('PAGE', [
    'page' => 1,
    'pages' => 1,
]); // 'One page only.'

// plural translation
echo $translator->translate('PAGE', [
    'page' => 3,
    'pages' => 10,
]); // 'Page 3 of 10 pages.'
?>

Note that you can use other tokens within a pluralized token string to build more complex messages. For more information, see the following:

http://icu-project.org/apiref/icu4j/com/ibm/icu/text/MessageFormat.html

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