[[ ScriptHandlers ]] Add ability to query script handler info

livecodeali · livecodeali · commit d652d07c80af · 2017-12-12T17:01:58.000Z
We need to be able to query things like resolved info from the
binding string of a foreign handler from libfoundation. This
patch adds a query callback to the MCHandlerRef callbacks struct
to enable fetching such data.

The only specific info made available in this patch is the objc
selector pointer.
diff --git a/libfoundation/include/foundation.h b/libfoundation/include/foundation.h
@@ -3060,12 +3060,19 @@ MC_DLLEXPORT bool MCRecordIterate(MCRecordRef record, uintptr_t& x_iterator, MCN
 //  HANDLER DEFINITIONS
 //
 
+enum MCHandlerQueryType
+{
+    kMCHandlerQueryTypeNone,
+    kMCHandlerQueryTypeObjcSelector,
+};
+    
 struct MCHandlerCallbacks
 {
     size_t size;
     void (*release)(void *context);
     bool (*invoke)(void *context, MCValueRef *arguments, uindex_t argument_count, MCValueRef& r_value);
 	bool (*describe)(void *context, MCStringRef& r_desc);
+    bool (*query)(void *context, MCHandlerQueryType type, void *r_info);
 };
 
 MC_DLLEXPORT bool MCHandlerCreate(MCTypeInfoRef typeinfo, const MCHandlerCallbacks *callbacks, void *context, MCHandlerRef& r_handler);
diff --git a/libscript/src/script-instance.cpp b/libscript/src/script-instance.cpp
@@ -1558,12 +1558,44 @@ __MCScriptInternalHandlerDescribe(void *p_context,
 	return MCStringFormat(r_description, "%@.%@()", t_module_name, t_handler_name);
 }
 
+static bool
+__MCScriptInternalHandlerQuery(void *p_context,
+                               MCHandlerQueryType p_query,
+                               void *r_info)
+{
+    if (p_query != kMCHandlerQueryTypeObjcSelector)
+    {
+        return false;
+    }
+ 
+    __MCScriptInternalHandlerContext *context =
+        (__MCScriptInternalHandlerContext *)p_context;
+    
+    if (context->definition->kind != kMCScriptDefinitionKindForeignHandler)
+    {
+        return false;
+    }
+    
+    auto t_definition =
+        static_cast<MCScriptForeignHandlerDefinition *>(context->definition);
+    
+    if (t_definition->language != kMCScriptForeignHandlerLanguageObjC)
+    {
+        return false;
+    }
+    
+    *(void **)r_info = t_definition->objc.objc_selector;
+    
+    return true;
+}
+
 static MCHandlerCallbacks __kMCScriptInternalHandlerCallbacks =
 {
 	sizeof(__MCScriptInternalHandlerContext),
 	__MCScriptInternalHandlerRelease,
 	__MCScriptInternalHandlerInvoke,
-	__MCScriptInternalHandlerDescribe
+	__MCScriptInternalHandlerDescribe,
+    __MCScriptInternalHandlerQuery,
 };
 
 static bool
