Struct clingo_sys::clingo_propagator

#[repr(C)]
pub struct clingo_propagator {
    pub init: Option<unsafe extern "C" fn(init: *mut clingo_propagate_init_t, data: *mut c_void) -> bool>,
    pub propagate: Option<unsafe extern "C" fn(control: *mut clingo_propagate_control_t, changes: *const clingo_literal_t, size: usize, data: *mut c_void) -> bool>,
    pub undo: Option<unsafe extern "C" fn(control: *const clingo_propagate_control_t, changes: *const clingo_literal_t, size: usize, data: *mut c_void) -> bool>,
    pub check: Option<unsafe extern "C" fn(control: *mut clingo_propagate_control_t, data: *mut c_void) -> bool>,
    pub decide: Option<unsafe extern "C" fn(thread_id: clingo_id_t, assignment: *const clingo_assignment_t, fallback: clingo_literal_t, data: *mut c_void, decision: *mut clingo_literal_t) -> bool>,
}

! An instance of this struct has to be registered with a solver to implement a custom propagator. ! ! Not all callbacks have to be implemented and can be set to NULL if not needed. ! @see Propagator

Fields

init: Option<unsafe extern "C" fn(init: *mut clingo_propagate_init_t, data: *mut c_void) -> bool>

! This function is called once before each solving step. ! It is used to map relevant program literals to solver literals, add watches for solver literals, and initialize the data structures used during propagation. ! ! @note This is the last point to access symbolic and theory atoms. ! Once the search has started, they are no longer accessible. ! ! @param[in] init initizialization object ! @param[in] data user data for the callback ! @return whether the call was successful ! @see ::clingo_propagator_init_callback_t

propagate: Option<unsafe extern "C" fn(control: *mut clingo_propagate_control_t, changes: *const clingo_literal_t, size: usize, data: *mut c_void) -> bool>

! Can be used to propagate solver literals given a @link clingo_assignment_t partial assignment@endlink. ! ! Called during propagation with a non-empty array of @link clingo_propagate_init_add_watch() watched solver literals@endlink ! that have been assigned to true since the last call to either propagate, undo, (or the start of the search) - the change set. ! Only watched solver literals are contained in the change set. ! Each literal in the change set is true w.r.t. the current @link clingo_assignment_t assignment@endlink. ! @ref clingo_propagate_control_add_clause() can be used to add clauses. ! If a clause is unit resulting, it can be propagated using @ref clingo_propagate_control_propagate(). ! If the result of either of the two methods is false, the propagate function must return immediately. ! ! The following snippet shows how to use the methods to add clauses and propagate consequences within the callback. ! The important point is to return true (true to indicate there was no error) if the result of either of the methods is false. ! ~~~~~~~~~~~~~~~{.c} ! bool result; ! clingo_literal_t clause[] = { ... }; ! ! // add a clause ! if (!clingo_propagate_control_add_clause(control, clause, clingo_clause_type_learnt, &result) { return false; } ! if (!result) { return true; } ! // propagate its consequences ! if (!clingo_propagate_control_propagate(control, &result) { return false; } ! if (!result) { return true; } ! ! // add further clauses and propagate them ! ... ! ! return true; ! ~~~~~~~~~~~~~~~ ! ! @note ! This function can be called from different solving threads. ! Each thread has its own assignment and id, which can be obtained using @ref clingo_propagate_control_thread_id(). ! ! @param[in] control control object for the target solver ! @param[in] changes the change set ! @param[in] size the size of the change set ! @param[in] data user data for the callback ! @return whether the call was successful ! @see ::clingo_propagator_propagate_callback_t

undo: Option<unsafe extern "C" fn(control: *const clingo_propagate_control_t, changes: *const clingo_literal_t, size: usize, data: *mut c_void) -> bool>

! Called whenever a solver undoes assignments to watched solver literals. ! ! This callback is meant to update assignment dependent state in the propagator. ! ! @note No clauses must be propagated in this callback. ! ! @param[in] control control object for the target solver ! @param[in] changes the change set ! @param[in] size the size of the change set ! @param[in] data user data for the callback ! @return whether the call was successful ! @see ::clingo_propagator_undo_callback_t

check: Option<unsafe extern "C" fn(control: *mut clingo_propagate_control_t, data: *mut c_void) -> bool>

! This function is similar to @ref clingo_propagate_control_propagate() but is called without a change set on propagation fixpoints. ! ! When exactly this function is called, can be configured using the @ref clingo_propagate_init_set_check_mode() function. ! ! @note This function is called even if no watches have been added. ! ! @param[in] control control object for the target solver ! @param[in] data user data for the callback ! @return whether the call was successful ! @see ::clingo_propagator_check_callback_t

decide: Option<unsafe extern "C" fn(thread_id: clingo_id_t, assignment: *const clingo_assignment_t, fallback: clingo_literal_t, data: *mut c_void, decision: *mut clingo_literal_t) -> bool>

! This function allows a propagator to implement domain-specific heuristics. ! ! It is called whenever propagation reaches a fixed point and ! should return a free solver literal that is to be assigned true. ! In case multiple propagators are registered, ! this function can return 0 to let a propagator registered later make a decision. ! If all propagators return 0, then the fallback literal is ! ! @param[in] thread_id the solver's thread id ! @param[in] assignment the assignment of the solver ! @param[in] fallback the literal choosen by the solver's heuristic ! @param[out] decision the literal to make true ! @return whether the call was successful

Trait Implementations

impl Clone for clingo_propagator

fn clone(&self) -> clingo_propagator

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for clingo_propagator

impl Debug for clingo_propagator

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.