Type Alias clingo_sys::clingo_ground_callback_t
source · pub type clingo_ground_callback_t = Option<unsafe extern "C" fn(location: *const clingo_location_t, name: *const c_char, arguments: *const clingo_symbol_t, arguments_size: usize, data: *mut c_void, symbol_callback: clingo_symbol_callback_t, symbol_callback_data: *mut c_void) -> bool>;Expand description
! Callback function to implement external functions. ! ! If an external function of form @name(parameters) occurs in a logic program, ! then this function is called with its location, name, parameters, and a callback to inject symbols as arguments. ! The callback can be called multiple times; all symbols passed are injected. ! ! If a (non-recoverable) clingo API function fails in this callback, for example, the symbol callback, the callback must return false. ! In case of errors not related to clingo, this function can set error ::clingo_error_unknown and return false to stop grounding with an error. ! ! @param[in] location location from which the external function was called ! @param[in] name name of the called external function ! @param[in] arguments arguments of the called external function ! @param[in] arguments_size number of arguments ! @param[in] data user data of the callback ! @param[in] symbol_callback function to inject symbols ! @param[in] symbol_callback_data user data for the symbol callback ! (must be passed untouched) ! @return whether the call was successful ! @see clingo_control_ground() ! ! The following example implements the external function @f() returning 42. ! ~~~~~~~~~~~~~~~{.c} ! bool ! ground_callback(clingo_location_t const *location, ! char const *name, ! clingo_symbol_t const *arguments, ! size_t arguments_size, ! void *data, ! clingo_symbol_callback_t symbol_callback, ! void *symbol_callback_data) { ! if (strcmp(name, “f”) == 0 && arguments_size == 0) { ! clingo_symbol_t sym; ! clingo_symbol_create_number(42, &sym); ! return symbol_callback(&sym, 1, symbol_callback_data); ! } ! clingo_set_error(clingo_error_runtime, “function not found”); ! return false; ! } ! ~~~~~~~~~~~~~~~
Aliased Type§
enum clingo_ground_callback_t {
None,
Some(unsafe extern "C" fn(_: *const clingo_location, _: *const i8, _: *const u64, _: usize, _: *mut c_void, _: Option<unsafe extern "C" fn(_: *const u64, _: usize, _: *mut c_void) -> bool>, _: *mut c_void) -> bool),
}