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123 lines
2.5 KiB
123 lines
2.5 KiB
<?php
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declare(strict_types=1);
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namespace App\Util;
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class DependencyGraph
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{
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/** @var DependencyGraphNode[] */
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protected $nodes;
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public function __construct()
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{
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$this->nodes = [];
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}
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public function add(string $name, array $depends_on = []): void
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{
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if (!isset($this->nodes[$name]))
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{
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$node = new DependencyGraphNode($name);
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$this->nodes[$name] = $node;
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$node->DependsOn = $depends_on;
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}
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else
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{
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// Probably unnecessary -- if the same node is added multiple times
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// with different dependencies something's probably way messed up,
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// but... we'll try our best?!
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$this->nodes[$name] = array_unique(array_merge($this->nodes[$name]->DependsOn, $depends_on));
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}
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}
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public function link(): void
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{
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foreach ($this->nodes as $node)
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{
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foreach ($node->DependsOn as $depends_on)
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{
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if (!isset($this->nodes[$depends_on]))
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{
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throw new \Exception('Unmet dependency on node: '.$depends_on);
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}
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if (!in_array($node->Name, $this->nodes[$depends_on]->DependedOnBy))
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{
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$this->nodes[$depends_on]->DependedOnBy[] = $node->Name;
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}
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}
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}
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}
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public function flatten(): array
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{
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$state = [];
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// Find leaf nodes, add each one to our state array.
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foreach ($this->nodes as $node)
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{
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if (sizeof($node->DependedOnBy) == 0)
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{
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$state[] = $node;
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}
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}
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// Then walk through the array and insert each node's dependencies before
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// it recursively.
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$iter = 0;
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for ($i = 0; $i < sizeof($state); $i++)
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{
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if ($state[$i]->Processed)
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{
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continue;
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}
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$state[$i]->Processed = true;
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$depends_on = [];
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foreach ($state[$i]->DependsOn as $depends_on_name)
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{
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$depends_on[] = $this->nodes[$depends_on_name];
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}
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array_splice($state, $i, 0, $depends_on);
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--$i;
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}
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// Remove all but the first appearance of a node.
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// array_unique guarantees that the _first_ element will be retained,
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// so this satisfies what we're trying to do.
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return array_unique(array_map(static function($node) { return $node->Name; }, $state));
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}
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}
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class DependencyGraphNode
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{
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/** @var string */
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public $Name;
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/** @var string */
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public $DependsOn;
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/** @var string */
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public $DependedOnBy;
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/** @var bool */
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public $Processed;
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public function __construct(string $name)
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{
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$this->Name = $name;
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$this->DependsOn = [];
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$this->DependedOnBy = [];
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$this->Processed = false;
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}
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public function dependsOn(string $node): void
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{
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$this->DependsOn[] = $node;
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}
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public function dependedOnBy(string $node): void
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{
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$this->DependedOnBy[] = $node;
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}
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}
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