Add JS_GetAnyOpaque() to support polymorphism

To be able to check if the class ID is one of multiple known ones, where
the data has a common structure.

Author: oleavr

quickjs.c

@@ -9582,6 +9582,18 @@ void *JS_GetOpaque2(JSContext *ctx, JSValueConst obj, JSClassID class_id)
     return p;
 }
 
+void *JS_GetAnyOpaque(JSValueConst obj, JSClassID *class_id)
+{
+    JSObject *p;
+    if (JS_VALUE_GET_TAG(obj) != JS_TAG_OBJECT) {
+        *class_id = 0;
+        return NULL;
+    }
+    p = JS_VALUE_GET_OBJ(obj);
+    *class_id = p->class_id;
+    return p->u.opaque;
+}
+
 #define HINT_STRING  0
 #define HINT_NUMBER  1
 #define HINT_NONE    2

quickjs.h

@@ -761,6 +761,7 @@ int JS_DefinePropertyGetSet(JSContext *ctx, JSValueConst this_obj,
 void JS_SetOpaque(JSValue obj, void *opaque);
 void *JS_GetOpaque(JSValueConst obj, JSClassID class_id);
 void *JS_GetOpaque2(JSContext *ctx, JSValueConst obj, JSClassID class_id);
+void *JS_GetAnyOpaque(JSValueConst obj, JSClassID *class_id);
 
 /* 'buf' must be zero terminated i.e. buf[buf_len] = '\0'. */
 JSValue JS_ParseJSON(JSContext *ctx, const char *buf, size_t buf_len,