SDK Form demonstrator introduce field dependency graph

sources/Forms/Dependency/DependencyGraph.php

@@ -0,0 +1,78 @@
+<?php
+/*
+ * @copyright   Copyright (C) 2010-2025 Combodo SARL
+ * @license     http://opensource.org/licenses/AGPL-3.0
+ */
+namespace Combodo\iTop\Forms\Dependency;
+
+class DependencyGraph implements \Iterator
+{
+	use GraphTrait;
+	private array $aFieldNameToPosition = [];
+
+	/**
+	 * @param string $sName
+	 * @param string $sType
+	 * @param array $aDependencies
+	 * @param array $aUserOptions
+	 *
+	 * @return void
+	 * @throws \Combodo\iTop\Forms\Dependency\DependencyException
+	 */
+	public function Add(string $sName, string $sType, array $aDependencies = [], array $aUserOptions = []): void
+	{
+		$oNode = new DependencyNode($sName, $sType, $aUserOptions);
+		// Store field position
+		$this->aFieldNameToPosition[$sName] = count($this->aFieldNameToPosition);
+
+		if (empty($aDependencies)) {
+			$this->AddChild($oNode);
+			return;
+		}
+
+		// Search the last added dependency
+		$oParentNode = null;
+		$iParentPosition = -1;
+		foreach ($aDependencies as $sNodeName) {
+			if ($sNodeName === $sName) {
+				throw new DependencyException("Form field '$sName' cannot reference itself");
+			}
+			if (!isset($this->aFieldNameToPosition[$sNodeName])) {
+				throw new DependencyException("Form field '$sNodeName' is not existing");
+			}
+			if ($this->aFieldNameToPosition[$sNodeName] > $iParentPosition) {
+				$oParentNode = $this->SearchNode($sNodeName);
+				$iParentPosition = $this->aFieldNameToPosition[$sNodeName];
+			}
+		}
+
+		if (is_null($oParentNode)) {
+			throw new DependencyException("Could not find dependency for field '$sName'");
+		}
+
+		// Add to the latest dependency
+		$oParentNode->AddChild($oNode);
+	}
+
+	private function SearchNode(string $sName) : ?DependencyNode
+	{
+		foreach($this as $oChildNode) {
+			$oNode = $oChildNode->SearchNode($sName);
+			if ($oNode instanceof DependencyNode) {
+				return $oNode;
+			}
+		}
+
+		return null;
+	}
+
+	public function __toString(): string
+	{
+		$sResult = "\n";
+		foreach ($this as $oNode) {
+			$sResult .= $oNode->Display();
+		}
+
+		return $sResult;
+	}
+}