includes/Settings/DynamicDefaultValues.php

   1 <?php
   2
   3 namespace MediaWiki\Settings;
   4
   5 use LogicException;
   6 use MediaWiki\Settings\Config\ConfigBuilder;
   7 use MediaWiki\Settings\Config\ConfigSchema;
   8
   9 class DynamicDefaultValues {
  10
  11         private ConfigSchema $configSchema;
  12
  13         /**
  14          * @var array
  15          */
  16         private $declarations;
  17
  18         /**
  19          * @param ConfigSchema $configSchema
  20          */
  21         public function __construct( ConfigSchema $configSchema ) {
  22                 $this->configSchema = $configSchema;
  23                 $this->declarations = $this->configSchema->getDynamicDefaults();
  24         }
  25
  26         /**
  27          * Compute dynamic defaults for settings that have them defined.
  28          *
  29          * @param ConfigBuilder $configBuilder
  30          *
  31          * @return void
  32          */
  33         public function applyDynamicDefaults( ConfigBuilder $configBuilder ): void {
  34                 $alreadyComputed = [];
  35
  36                 foreach ( $this->declarations as $key => $unused ) {
  37                         $this->computeDefaultFor( $key, $configBuilder, $alreadyComputed );
  38                 }
  39         }
  40
  41         /**
  42          * Compute dynamic default for a setting, recursively computing any dependencies.
  43          *
  44          * @param string $key Name of setting
  45          * @param ConfigBuilder $configBuilder
  46          * @param array &$alreadyComputed Map whose keys are the names of settings whose dynamic
  47          *   defaults have already been computed
  48          * @param array $currentlyComputing Ordered map whose keys are the names of settings whose
  49          *   dynamic defaults are currently being computed, for cycle detection.
  50          */
  51         private function computeDefaultFor(
  52                 string $key,
  53                 ConfigBuilder $configBuilder,
  54                 array &$alreadyComputed = [],
  55                 array $currentlyComputing = []
  56         ): void {
  57                 if ( !isset( $this->declarations[ $key ] ) || isset( $alreadyComputed[ $key ] ) ) {
  58                         return;
  59                 }
  60                 if ( isset( $currentlyComputing[ $key ] ) ) {
  61                         throw new LogicException(
  62                                 'Cyclic dependency when computing dynamic default: ' .
  63                                 implode( ' -> ', array_keys( $currentlyComputing ) ) . " -> $key"
  64                         );
  65                 }
  66                 if (
  67                         $configBuilder->get( $key ) !==
  68                         $this->configSchema->getDefaultFor( $key )
  69                 ) {
  70                         // Default was already overridden, nothing more to do
  71                         $alreadyComputed[ $key ] = true;
  72
  73                         return;
  74                 }
  75
  76                 $currentlyComputing[ $key ] = true;
  77
  78                 $callback = $this->declarations[ $key ]['callback'];
  79                 $argNames = $this->declarations[ $key ]['use'] ?? [];
  80                 $args = [];
  81
  82                 foreach ( $argNames as $argName ) {
  83                         $this->computeDefaultFor(
  84                                 $argName,
  85                                 $configBuilder,
  86                                 $alreadyComputed,
  87                                 $currentlyComputing
  88                         );
  89                         $args[] = $configBuilder->get( $argName );
  90                 }
  91
  92                 $configBuilder->set( $key, $callback( ...$args ) );
  93
  94                 $alreadyComputed[ $key ] = true;
  95         }
  96 }