Add package core:flags

core/flags/rtti.odin

@@ -0,0 +1,43 @@
+package flags
+
+import "base:runtime"
+
+/*
+Handle setting custom data types.
+
+Inputs:
+- data: A raw pointer to the field where the data will go.
+- data_type: Type information on the underlying field.
+- unparsed_value: The unparsed string that the flag is being set to.
+- args_tag: The `args` tag from the struct's field.
+
+Returns:
+- error: An error message, or an empty string if no error occurred.
+- handled: A boolean indicating if the setter handles this type.
+- alloc_error: If an allocation error occurred, return it here.
+*/
+Custom_Type_Setter :: #type proc(
+	data:           rawptr,
+	data_type:      typeid,
+	unparsed_value: string,
+	args_tag:       string,
+) -> (
+	error:       string,
+	handled:     bool,
+	alloc_error: runtime.Allocator_Error,
+)
+
+@(private)
+global_custom_type_setter: Custom_Type_Setter
+
+/*
+Set the global custom type setter.
+
+Note that only one can be active at a time.
+
+Inputs:
+- setter: The type setter. Pass `nil` to disable any previously set setter.
+*/
+register_type_setter :: proc(setter: Custom_Type_Setter) {
+	global_custom_type_setter = setter
+}