extend is_function() with support for public local functions

doc/script_commands.txt

@@ -2040,16 +2040,19 @@ Example:
 
 ---------------------------------------
 
-*is_function("<function name>")
+*is_function("<function name>"{, <npc id>})
+*is_function("<function name>"{, "<npc name>"})
 
-This command checks whether or not a function exists and returns its type.
-Returns false if it cannot be found.
+This command checks whether or not a function exists and returns its type. If a
+NPC name or ID is provided, it will try to find the label or function within
+this NPC instead of the attached NPC. Returns false if it cannot be found.
 
 return values:
 
 	FUNCTION_IS_COMMAND - built-in script command (eg: mes, select, ...)
 	FUNCTION_IS_GLOBAL  - user-defined global function (callable with callfunc)
 	FUNCTION_IS_LOCAL   - user-defined local function
+	FUNCTION_IS_PUBLIC  - user-defined local function marked as public
 	FUNCTION_IS_LABEL   - user-defined label function (callable with callsub)
 
 Example:

npc/dev/test.txt

@@ -148,6 +148,10 @@ function	script	F_TestVarOfAnotherNPC	{
 
 		return set(getarg(0), 1337);
 	}
+
+OnLabel:
+    // to test is_function() with the label of another NPC
+    end;
 }
 
 function	script	HerculesSelfTestHelper	{
@@ -825,6 +829,18 @@ function	script	HerculesSelfTestHelper	{
 	callsub(OnCheck, "public local function var reference test", .@refTest, 1337);
 	callsub(OnCheck, "programatic public local call",            callfunctionofnpc("export test", "RefTest", .@refTest = 1), 1337);
 
+    private function localFunc {}
+    public  function pubLocalFunc {}
+    callsub(OnCheck, "is_function: not found",                                is_function("does-not-exist"), false);
+    callsub(OnCheck, "is_function: built-in script command",                  is_function("callfunc"), FUNCTION_IS_COMMAND);
+    callsub(OnCheck, "is_function: global function",                          is_function("HerculesSelfTestHelper"), FUNCTION_IS_GLOBAL);
+    callsub(OnCheck, "is_function: local NPC function",                       is_function("localFunc"), FUNCTION_IS_LOCAL);
+    callsub(OnCheck, "is_function: public local NPC function",                is_function("pubLocalFunc"), FUNCTION_IS_PUBLIC);
+    callsub(OnCheck, "is_function: local subroutine",                         is_function("OnCheck"), FUNCTION_IS_LABEL);
+    callsub(OnCheck, "is_function: local NPC function of another NPC",        is_function("Private", "export test"), FUNCTION_IS_LOCAL);
+    callsub(OnCheck, "is_function: public local NPC function of another NPC", is_function("Public", "export test"), FUNCTION_IS_PUBLIC);
+    callsub(OnCheck, "is_function: local subroutine of another NPC",          is_function("OnLabel", "export test"), FUNCTION_IS_LABEL);
+
 	if (.errors) {
 		consolemes(CONSOLEMES_DEBUG, "Script engine self-test   [ \033[0;31mFAILED\033[0m ]");
 		consolemes(CONSOLEMES_DEBUG, "**** The test was completed with " + .errors + " errors. ****");

src/map/script.c

@@ -23900,24 +23900,33 @@ static BUILDIN(getcharip)
 	return true;
 }
 
+/** possible types of script commands */
 enum function_type {
+	/** not found */
 	FUNCTION_IS_NONE = 0,
+	/** script buildin */
 	FUNCTION_IS_COMMAND,
+	/** global user-defined function (for use with callfunc) */
 	FUNCTION_IS_GLOBAL,
+	/** user-defined function local to the NPC */
 	FUNCTION_IS_LOCAL,
+	/** user-defined label (for use with callsub) */
 	FUNCTION_IS_LABEL,
+	/** user-defined function local to the NPC, marked as public */
+	FUNCTION_IS_PUBLIC,
 };
 
 /**
- * is_function(<function name>)
- **/
+ * is_function("<function name>"{, <npc id>})
+ * is_function("<function name>"{, "<npc name>"})
+ *
+ * checks the type of a script command
+ */
 static BUILDIN(is_function)
 {
 	const char *str = script_getstr(st, 2);
 	enum function_type type = FUNCTION_IS_NONE;
 
-	// TODO: add support for exported functions (#2142)
-
 	if (strdb_exists(script->userfunc_db, str)) {
 		type = FUNCTION_IS_GLOBAL;
 	} else {
@@ -23943,6 +23952,41 @@ static BUILDIN(is_function)
 				}
 			}
 		}
+
+		if (type == FUNCTION_IS_LOCAL
+			|| (script_hasdata(st, 3) && type != FUNCTION_IS_COMMAND)) {
+			struct npc_data *nd = map->id2nd(st->oid);
+
+			if (script_hasdata(st, 3)) {
+				// at this point we know it's not a global or a buildin, so we
+				// reset since we want to search another NPC
+				type = FUNCTION_IS_NONE;
+
+				if (script_isint(st, 3)) {
+					nd = map->id2nd(script_getnum(st, 3));
+				} else if (script_isstring(st, 3)) {
+					nd = npc->name2id(script_getstr(st, 3));
+				}
+			}
+
+			if (nd != NULL) {
+				// try to find the label
+				for (int i = 0; i < nd->u.scr.label_list_num; ++i) {
+					if (strcmp(nd->u.scr.label_list[i].name, str) == 0) {
+						if ((nd->u.scr.label_list[i].flags & LABEL_IS_USERFUNC) != 0) {
+							if ((nd->u.scr.label_list[i].flags & LABEL_IS_EXTERN) != 0) {
+								type = FUNCTION_IS_PUBLIC;
+							} else {
+								type = FUNCTION_IS_LOCAL;
+							}
+						} else {
+							type = FUNCTION_IS_LABEL;
+						}
+						break;
+					}
+				}
+			}
+		}
 	}
 
 	script_pushint(st, type);
@@ -27555,7 +27599,7 @@ static void script_parse_builtin(void)
 		 **/
 		BUILDIN_DEF(getargcount,""),
 		BUILDIN_DEF(getcharip,"?"),
-		BUILDIN_DEF(is_function,"s"),
+		BUILDIN_DEF(is_function,"s?"),
 		BUILDIN_DEF(freeloop,"i"),
 		BUILDIN_DEF(getrandgroupitem,"ii"),
 		BUILDIN_DEF(cleanmap,"s"),
@@ -28181,6 +28225,7 @@ static void script_hardcoded_constants(void)
 	script->set_constant("FUNCTION_IS_GLOBAL", FUNCTION_IS_GLOBAL, false, false);
 	script->set_constant("FUNCTION_IS_LOCAL", FUNCTION_IS_LOCAL, false, false);
 	script->set_constant("FUNCTION_IS_LABEL", FUNCTION_IS_LABEL, false, false);
+	script->set_constant("FUNCTION_IS_PUBLIC", FUNCTION_IS_PUBLIC, false, false);
 
 	script->constdb_comment("item trade restrictions");
 	script->set_constant("ITR_NONE", ITR_NONE, false, false);