Add: GSCompanyMode::IsValid and IsDeity, and precondition enforcement helpers

src/script/api/game_changelog.hpp

@@ -18,6 +18,8 @@
  * This version is not yet released. The following changes are not set in stone yet.
  *
  * API additions:
+ * \li GSCompanyMode::IsValid
+ * \li GSCompanyMode::IsDeity
  * \li GSTown::ROAD_LAYOUT_RANDOM
  * \li GSVehicle::IsPrimaryVehicle
  *

src/script/api/script_companymode.cpp

@@ -26,3 +26,13 @@ ScriptCompanyMode::~ScriptCompanyMode()
 {
 	ScriptObject::SetCompany(this->last_company);
 }
+
+/* static */ bool ScriptCompanyMode::IsValid()
+{
+	return ScriptObject::GetCompany() != OWNER_DEITY;
+}
+
+/* static */ bool ScriptCompanyMode::IsDeity()
+{
+	return ScriptObject::GetCompany() == OWNER_DEITY;
+}

src/script/api/script_companymode.hpp

@@ -47,6 +47,22 @@ public:
 	 *   in when the instance was created.
 	 */
 	~ScriptCompanyMode();
+
+	/**
+	 * Check whether a company mode is valid. In other words, are commands
+	 * being executed under some company.
+	 * @return true When a company mode is valid.
+	 * @post !ScriptCompanyMode::IsDeity().
+	 */
+	static bool IsValid();
+
+	/**
+	 * Check whether the company mode is not active, i.e. whether we are a deity.
+	 * In other words, are commands are not being executed under some company.
+	 * @return true When we are a deity, i.e. company mode is not active.
+	 * @post !ScriptCompanyMode::IsValid().
+	 */
+	static bool IsDeity();
 };
 
 #endif /* SCRIPT_COMPANYMODE_HPP */

src/script/api/script_error.hpp

@@ -11,6 +11,7 @@
 #define SCRIPT_ERROR_HPP
 
 #include "script_object.hpp"
+#include "script_companymode.hpp"
 #include <map>
 
 /**
@@ -47,6 +48,20 @@
 		return returnval; \
 	}
 
+/**
+ * Helper to enforce the precondition that the company mode is valid.
+ * @param returnval The value to return on failure.
+ */
+#define EnforceCompanyModeValid(returnval) \
+	EnforcePrecondition(returnval, ScriptCompanyMode::IsValid())
+
+/**
+ * Helper to enforce the precondition that we are in a deity mode.
+ * @param returnval The value to return on failure.
+ */
+#define EnforceDeityMode(returnval) \
+	EnforcePrecondition(returnval, ScriptCompanyMode::IsDeity())
+
 /**
  * Class that handles all error related functions.
  * @api ai game