Type Alias FuncLookupFunc 

pub type FuncLookupFunc = unsafe extern "C" fn(*mut c_void, *const xmlChar, *const xmlChar) -> *mut c_void;

C callback for function lookup.

SAFETY: Called from C ABI boundaries. The implementation must not panic and must handle null pointers gracefully.

• data — user-supplied data pointer (the func_lookup_data field).
• ns — namespace URI of the function (may be null for no namespace).
• name — local part of the function name.

Returns an opaque pointer to a function implementation, or null if the function is not found. The interpretation of the returned pointer is defined by the caller that registered the callback.