<?php 
namespace Aws\Endpoint; 
 
use Aws\Exception\UnresolvedEndpointException; 
 
/** 
 * Endpoint providers. 
 * 
 * An endpoint provider is a function that accepts a hash of endpoint options, 
 * including but not limited to "service" and "region" key value pairs. The 
 * endpoint provider function returns a hash of endpoint data, which MUST 
 * include an "endpoint" key value pair that represents the resolved endpoint 
 * or NULL if an endpoint cannot be determined. 
 * 
 * You can wrap your calls to an endpoint provider with the 
 * {@see EndpointProvider::resolve} function to ensure that an endpoint hash is 
 * created. If an endpoint hash is not created, then the resolve() function 
 * will throw an {@see Aws\Exception\UnresolvedEndpointException}. 
 * 
 *     use Aws\Endpoint\EndpointProvider; 
 *     $provider = EndpointProvider::defaultProvider(); 
 *     // Returns an array or NULL. 
 *     $endpoint = $provider(['service' => 'ec2', 'region' => 'us-west-2']); 
 *     // Returns an endpoint array or throws. 
 *     $endpoint = EndpointProvider::resolve($provider, [ 
 *         'service' => 'ec2', 
 *         'region'  => 'us-west-2' 
 *     ]); 
 * 
 * You can compose multiple providers into a single provider using 
 * {@see Aws\or_chain}. This function accepts providers as arguments and 
 * returns a new function that will invoke each provider until a non-null value 
 * is returned. 
 * 
 *     $a = function (array $args) { 
 *         if ($args['region'] === 'my-test-region') { 
 *             return ['endpoint' => 'http://localhost:123/api']; 
 *         } 
 *     }; 
 *     $b = EndpointProvider::defaultProvider(); 
 *     $c = \Aws\or_chain($a, $b); 
 *     $config = ['service' => 'ec2', 'region' => 'my-test-region']; 
 *     $res = $c($config);  // $a handles this. 
 *     $config['region'] = 'us-west-2'; 
 *     $res = $c($config); // $b handles this. 
 */ 
class EndpointProvider 
{ 
    /** 
     * Resolves and endpoint provider and ensures a non-null return value. 
     * 
     * @param callable $provider Provider function to invoke. 
     * @param array    $args     Endpoint arguments to pass to the provider. 
     * 
     * @return array 
     * @throws UnresolvedEndpointException 
     */ 
    public static function resolve(callable $provider, array $args = []) 
    { 
        $result = $provider($args); 
        if (is_array($result)) { 
            return $result; 
        } 
 
        throw new UnresolvedEndpointException( 
            'Unable to resolve an endpoint using the provider arguments: ' 
            . json_encode($args) . '. Note: you can provide an "endpoint" ' 
            . 'option to a client constructor to bypass invoking an endpoint ' 
            . 'provider.'); 
    } 
 
    /** 
     * Creates and returns the default SDK endpoint provider. 
     * 
     * @return callable 
     */ 
    public static function defaultProvider() 
    { 
        $data = \Aws\load_compiled_json(__DIR__ . '/../data/endpoints.json'); 
 
        return new PatternEndpointProvider($data['endpoints']); 
    } 
 
    /** 
     * Creates and returns an endpoint provider that uses patterns from an 
     * array. 
     * 
     * @param array $patterns Endpoint patterns 
     * 
     * @return callable 
     */ 
    public static function patterns(array $patterns) 
    { 
        return new PatternEndpointProvider($patterns); 
    } 
} 
 
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