class-feature-flags.php
139 lines
| 1 | <?php |
| 2 | /** |
| 3 | * Lightweight feature flag registry. |
| 4 | * |
| 5 | * @package automattic/jetpack-feature-flags |
| 6 | */ |
| 7 | |
| 8 | namespace Automattic\Jetpack\Feature_Flags; |
| 9 | |
| 10 | /** |
| 11 | * Registers feature flag metadata and resolves flag state. |
| 12 | */ |
| 13 | class Feature_Flags { |
| 14 | |
| 15 | const PACKAGE_VERSION = '0.1.0'; |
| 16 | |
| 17 | /** |
| 18 | * Registered feature flags. |
| 19 | * |
| 20 | * @var array<string, array> |
| 21 | */ |
| 22 | private static $flags = array(); |
| 23 | |
| 24 | /** |
| 25 | * Register a feature flag. |
| 26 | * |
| 27 | * Supported definition keys: |
| 28 | * - default: bool Whether the flag is enabled by default. |
| 29 | * - description: string Human-readable description. |
| 30 | * - owner: string Owning package, plugin, or product area. |
| 31 | * |
| 32 | * Flag names must match /^[a-z0-9][a-z0-9_-]*$/. This is enforced at lint |
| 33 | * time by the `Jetpack.FeatureFlags.FeatureFlagName` PHPCS sniff rather than |
| 34 | * at runtime, so registration stays allocation-free on the hot path. |
| 35 | * |
| 36 | * @param string $name Flag name. |
| 37 | * @param array $definition Flag definition. |
| 38 | * @return void |
| 39 | */ |
| 40 | public static function register( $name, array $definition = array() ) { |
| 41 | $definition = array_merge( self::default_definition( $name ), $definition ); |
| 42 | $definition['default'] = (bool) $definition['default']; |
| 43 | $definition['name'] = $name; |
| 44 | |
| 45 | self::$flags[ $name ] = $definition; |
| 46 | } |
| 47 | |
| 48 | /** |
| 49 | * Return a registered flag definition. |
| 50 | * |
| 51 | * @param string $name Flag name. |
| 52 | * @return array|null Flag definition, or null when the flag is unknown. |
| 53 | */ |
| 54 | public static function get( $name ) { |
| 55 | return self::$flags[ $name ] ?? null; |
| 56 | } |
| 57 | |
| 58 | /** |
| 59 | * Return all registered flag definitions. |
| 60 | * |
| 61 | * @return array<string, array> |
| 62 | */ |
| 63 | public static function all() { |
| 64 | $flags = self::$flags; |
| 65 | ksort( $flags ); |
| 66 | |
| 67 | return $flags; |
| 68 | } |
| 69 | |
| 70 | /** |
| 71 | * Return whether a feature flag is enabled. |
| 72 | * |
| 73 | * Unknown flags default to false but still pass through the global filter. |
| 74 | * |
| 75 | * @param string $name Flag name. |
| 76 | * @return bool Whether the flag is enabled. |
| 77 | */ |
| 78 | public static function is_enabled( $name ) { |
| 79 | $definition = self::get( $name ); |
| 80 | |
| 81 | if ( null === $definition ) { |
| 82 | $definition = self::default_definition( $name ); |
| 83 | } |
| 84 | |
| 85 | $default = (bool) $definition['default']; |
| 86 | |
| 87 | /** |
| 88 | * Filters whether a Jetpack feature flag is enabled. |
| 89 | * |
| 90 | * @since 0.1.0 |
| 91 | * |
| 92 | * @param bool $enabled Whether the flag is enabled. Defaults to the registered default. |
| 93 | * @param string $flag_name Feature flag name. |
| 94 | * @param array $definition Registered feature flag definition. |
| 95 | */ |
| 96 | $enabled = (bool) apply_filters( 'jetpack_feature_flag_enabled', $default, $name, $definition ); |
| 97 | |
| 98 | /** |
| 99 | * Filters whether a specific Jetpack feature flag is enabled. |
| 100 | * |
| 101 | * The dynamic portion of the hook name, `$name`, refers to the feature flag name. |
| 102 | * This mirrors the WordPress `option_{$option}` convention so a single flag can be |
| 103 | * toggled with a `__return_true`/`__return_false` one-liner. |
| 104 | * |
| 105 | * @since 0.1.0 |
| 106 | * |
| 107 | * @param bool $enabled Whether the flag is enabled. |
| 108 | * @param array $definition Registered feature flag definition. |
| 109 | */ |
| 110 | return (bool) apply_filters( "jetpack_feature_flag_enabled_{$name}", $enabled, $definition ); |
| 111 | } |
| 112 | |
| 113 | /** |
| 114 | * Clear registered flags. |
| 115 | * |
| 116 | * Intended for tests. |
| 117 | * |
| 118 | * @return void |
| 119 | */ |
| 120 | public static function reset() { |
| 121 | self::$flags = array(); |
| 122 | } |
| 123 | |
| 124 | /** |
| 125 | * Build the default definition for a flag. |
| 126 | * |
| 127 | * @param string $name Flag name. |
| 128 | * @return array Default flag definition. |
| 129 | */ |
| 130 | private static function default_definition( $name ) { |
| 131 | return array( |
| 132 | 'default' => false, |
| 133 | 'description' => '', |
| 134 | 'owner' => '', |
| 135 | 'name' => $name, |
| 136 | ); |
| 137 | } |
| 138 | } |
| 139 |