Fix custom function calls (merged fixed from VirtueMart's copy)

library/rules_shipping_framework.php

@@ -167,6 +167,10 @@ class RulesShippingFramework {
 		return array ();
 	}
 	
+	function getCustomFunctionDefinitions() {
+		return $this->custom_functions;
+	}
+	
 	/** @tag system-specific
 	 *  @function printWarning()
 	 *    Print a warning in the system-specific way.
@@ -203,22 +207,14 @@ class RulesShippingFramework {
 	 */
 	public function setup() {
 		$custfuncdefs = $this->getCustomFunctions();
-		// Loop through the return values of all plugins:
-		foreach ($custfuncdefs as $custfuncs) {
-			if (empty($custfuncs))
-				continue;
-			if (!is_array($custfuncs)) {
-				$this->warning('OTSHIPMENT_RULES_CUSTOMFUNCTIONS_NOARRAY');
-			}
-			// Now loop through all custom function definitions of this plugin
-			// If a function was registered before, print a warning and use the first definition
-			foreach ($custfuncs as $fname => $func) {
-				if (isset($this->custom_functions[$fname])) {
-					$this->warning('OTSHIPMENT_RULES_CUSTOMFUNCTIONS_ALREADY_DEFINED', $fname);
-				} else {
-					$this->debug("Defining custom function $fname");
-					$this->custom_functions[strtolower($fname)] = $func;
-				}
+		// Now loop through all custom function definitions of this plugin
+		// If a function was registered before, print a warning and use the first definition
+		foreach ($custfuncdefs as $fname => $func) {
+			if (isset($this->custom_functions[$fname]) && $this->custom_functions[$fname]!=$custfuncs[$fname]) {
+				$this->warning('OTSHIPMENT_RULES_CUSTOMFUNCTIONS_ALREADY_DEFINED', $fname);
+			} else {
+				$this->debug("Defining custom function $fname");
+				$this->custom_functions[strtolower($fname)] = $func;
 			}
 		}
 	}
@@ -644,7 +640,7 @@ class ShippingRule {
 		/* In the advanced version, all conditions and costs can be given as a full mathematical expression */
 		/* Both versions create an expression tree, which can be easily evaluated in evaluateTerm */
 		$rulepart = trim($rulepart);
-		if (empty($rulepart)) return;
+		if (!isset($rulepart) || $rulepart==='') return;
 
 		
 		// Special-case the name assignment, where we don't want to interpret the value as an arithmetic expression!
@@ -831,9 +827,10 @@ class ShippingRule {
 		$func = strtolower($function);
 		// Check if we have a custom function definition and use that if so.
 		// This is done first to allow plugins to override even built-in functions!
-		if (isset($this->plugin->custom_functions[$func])) {
+		$customfunctions = $this->framework->getCustomFunctionDefinitions();
+		if (isset($customfunctions[$func])) {
 			$this->framework->debug("Evaluating custom function $function, defined by a plugin");
-			return call_user_func_array($this->plugin->custom_functions[$func], $args, $this);
+			return call_user_func($customfunctions[$func], $args, $this);
 		}
 
 		// Functions with no argument: