Implement isset operation in template If statements

class.templater.php

@@ -530,7 +530,22 @@ class Templater
 		if($identifier == "if")
 		{
 			$statement_parts = explode(" ", $statement, 3);
-			$element->left = $statement_parts[0];
+			
+			$variable = $statement_parts[0];
+			
+			if(strpos($variable, "|") !== false)
+			{
+				$variable_parts = explode("|", $variable, 2);
+				
+				$element->operation = $variable_parts[0];
+				$element->left = $variable_parts[1];
+			}
+			else
+			{
+				$element->left = $variable;
+			}
+			
+			
 			$element->operator = $statement_parts[1];
 			$element->right = $statement_parts[2];
 		}
@@ -648,8 +663,11 @@ class TemplateIfElement extends TemplateSyntaxElement
 	public $left = "";
 	public $right = "";
 	public $operator = "";
+	public $operation = "";
 	
 	public function Evaluate($data)
+	{
+		if(empty($this->operation))
 		{
 			$a = $this->FetchVariable($this->left, $data);
 			$b = $this->right;
@@ -693,6 +711,38 @@ class TemplateIfElement extends TemplateSyntaxElement
 				return parent::Evaluate($data);
 			}
 		}
+		elseif($this->operation == "isset")
+		{
+			try
+			{
+				$this->FetchVariable($this->left, $data);
+				
+				$found = true;
+			}
+			catch (TemplateEvaluationException $e)
+			{
+				$found = false;
+			}
+			
+			if($this->right == "false")
+			{
+				$desired = false;
+			}
+			else
+			{
+				$desired = true;
+			}
+			
+			if($found === $desired)
+			{
+				return parent::Evaluate($data);
+			}
+			else
+			{
+				return "";
+			}
+		}
+	}
 }
 
 class TemplateForEachElement extends TemplateSyntaxElement