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<?php |
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/** |
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* Speculative Loading |
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* |
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* Injects a <script type="speculationrules"> block to enable browser-native |
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* speculative prefetch / prerender of same-origin links. |
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* |
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* @package Upress\EzCache |
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*/ |
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namespace Upress\EzCache; |
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|
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class SpeculativeLoading { |
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|
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private static $instance; |
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private $settings; |
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|
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private function __construct() { |
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$this->settings = Settings::get_settings(); |
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} |
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|
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public static function instance() { |
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if ( ! self::$instance ) { |
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self::$instance = new self(); |
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} |
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return self::$instance; |
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} |
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|
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/** |
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* Register WordPress hooks. |
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*/ |
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public function register() { |
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if ( empty( $this->settings->enable_speculative_loading ) ) { |
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return; |
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} |
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add_action( 'wp_head', [ $this, 'inject_speculation_rules' ], 2 ); |
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} |
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|
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/** |
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* Print the speculationrules script tag. |
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*/ |
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public function inject_speculation_rules() { |
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if ( is_admin() ) { return; } |
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|
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$mode = isset( $this->settings->speculative_mode ) ? $this->settings->speculative_mode : 'moderate'; |
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$rules = $this->build_rules( $mode ); |
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echo '<script type="speculationrules">' . wp_json_encode( $rules ) . '</script>' . "\n"; |
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} |
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|
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/** |
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* Build the speculation rules JSON object. |
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* |
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* @param string $mode conservative | moderate | eager |
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* @return array |
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*/ |
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private function build_rules( $mode ) { |
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switch ( $mode ) { |
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case 'eager': |
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// Prerender all same-origin links eagerly |
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return [ |
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'prerender' => [ |
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[ |
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'where' => [ 'href_matches' => '/*' ], |
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'eagerness' => 'eager', |
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], |
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], |
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]; |
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|
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case 'conservative': |
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// Only prefetch same-origin links user hovers on |
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return [ |
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'prefetch' => [ |
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[ |
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'where' => [ |
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'and' => [ |
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[ 'href_matches' => '/*' ], |
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[ 'not' => [ 'selector_matches' => '.no-prefetch' ] ], |
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], |
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], |
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'eagerness' => 'conservative', |
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], |
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], |
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]; |
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|
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case 'moderate': |
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default: |
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// Prerender likely navigations (moderate eagerness) |
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return [ |
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'prerender' => [ |
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[ |
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'where' => [ |
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'and' => [ |
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[ 'href_matches' => '/*' ], |
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[ 'not' => [ 'selector_matches' => '[rel~=nofollow]' ] ], |
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[ 'not' => [ 'href_matches' => '/wp-admin/*' ] ], |
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[ 'not' => [ 'href_matches' => '/wp-login.php' ] ], |
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], |
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], |
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'eagerness' => 'moderate', |
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], |
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], |
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]; |
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} |
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} |
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} |
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|
