SDK Form demonstrator introduce field dependency graph

sources/Forms/Dependency/GraphTrait.php

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+<?php
+/*
+ * @copyright   Copyright (C) 2010-2025 Combodo SARL
+ * @license     http://opensource.org/licenses/AGPL-3.0
+ */
+
+namespace Combodo\iTop\Forms\Dependency;
+
+trait GraphTrait
+{
+	private array $aChildren = [];
+	private int $iPosition = 0;
+
+	public function AddChild(DependencyNode $node) {
+		$this->aChildren[] = $node;
+	}
+
+	public function IsLast(): bool
+	{
+		return $this->iPosition === count($this->aChildren) - 1;
+	}
+
+	/*
+	 * Iterator interface
+	 */
+	public function current(): mixed
+	{
+		return $this->aChildren[$this->iPosition];
+	}
+
+	public function next(): void
+	{
+		$this->iPosition++;
+	}
+
+	public function key(): mixed
+	{
+		return $this->iPosition;
+	}
+
+	public function valid(): bool
+	{
+		return isset($this->aChildren[$this->iPosition]);
+	}
+
+	public function rewind(): void
+	{
+		$this->iPosition = 0;
+	}
+}