/************************************************************************* * * * YAP Prolog * * * * Yap Prolog was developed at NCCUP - Universidade do Porto * * * * Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 * * * ************************************************************************** * * * File: control.yap * * Last rev: 20/08/09 * * mods: * * comments: control predicates available in yap * * * *************************************************************************/ /** * @file control.yap * @author VITOR SANTOS COSTA * @date Thu Nov 19 10:26:35 2015 * * @brief Control Predicates * * */ :- system_module( '$_control', [at_halt/1, b_getval/2, break/0, call/2, call/3, call/4, call/5, call/6, call/7, call/8, call/9, call/10, call/11, call/12, call_cleanup/2, call_cleanup/3, forall/2, garbage_collect/0, garbage_collect_atoms/0, gc/0, grow_heap/1, grow_stack/1, halt/0, halt/1, if/3, ignore/1, nb_getval/2, nogc/0, notrace/1, once/1, prolog_current_frame/1, prolog_initialization/1, setup_call_catcher_cleanup/4, setup_call_cleanup/3, version/0, version/1], ['$run_atom_goal'/1, '$set_toplevel_hook'/1]). :- use_system_module( '$_boot', ['$call'/4, '$disable_debugging'/0, '$do_live'/0, '$enable_debugging'/0, '$system_catch'/4, '$version'/0]). :- use_system_module( '$_debug', ['$init_debugger'/0]). :- use_system_module( '$_errors', ['$do_error'/2]). :- use_system_module( '$_utils', ['$getval_exception'/3]). :- use_system_module( '$coroutining', [freeze_goal/2]). /** @addtogroup YAPControl @ingroup builtins @{ */ /** @pred forall(: _Cond_,: _Action_) * * * For all alternative bindings of _Cond_ _Action_ can be * proven. The example verifies that all arithmetic statements in the list * _L_ are correct. It does not say which is wrong if one proves wrong. * * ~~~~~{.prolog} * ?- forall(member(Result = Formula, [2 = 1 + 1, 4 = 2 * 2]), * Result =:= Formula). * ~~~~~ * * */ forall(Cond, Action) :- \+((Cond, \+(Action))). /** @pred ignore(: _Goal_) * * * Calls _Goal_ as once/1, but succeeds, regardless of whether * `Goal` succeeded or not. Defined as: * * ~~~~~{.prolog} * ignore(Goal) :- * Goal, !. * ignore(_). * ~~~~~ * * */ ignore(Goal) :- (Goal->true;true). /** @pred if(? _G_,? _H_,? _I_) * * Call goal _H_ once per each solution of goal _H_. If goal * _H_ has no solutions, call goal _I_. * * The built-in `if/3` is similar to `->/3`, with the difference * that it will backtrack over the test. Consider the following * small data-base: * * ~~~~~{.prolog} * a(1). b(a). c(x). * a(2). b(b). c(y). * ~~~~~ * * Execution of an `if/3` query will proceed as follows: * * ~~~~~{.prolog} * ?- if(a(X),b(Y),c(Z)). * * X = 1, * Y = a ? ; * * X = 1, * Y = b ? ; * * X = 2, * Y = a ? ; * * X = 2, * Y = b ? ; * * no * ~~~~~ * * The system will backtrack over the two solutions for `a/1` and the * two solutions for `b/1`, generating four solutions. * * Cuts are allowed inside the first goal _G_, but they will only prune * over _G_. * * If you want _G_ to be deterministic you should use if-then-else, as * it is both more efficient and more portable. * */ if(X,Y,Z) :- ( '$$save_by'(CP), '$call'(X,CP,if(X,Y,Z),M), '$execute'(X), '$clean_ifcp'(CP), '$call'(Y,CP,if(X,Y,Z),M) ; '$call'(Z,CP,if(X,Y,Z),M) ). /** @pred call( Closure,...,? Ai,...) is iso * * * Meta-call with extra pattern arguments, where _Closure_ is a closure * that is converted into a goal by appending the _Ai_ additional * arguments. YAP supports up to 10 extra arguments. * */ call(X,A) :- '$execute'(X,A). call(X,A1,A2) :- '$execute'(X,A1,A2). call(X,A1,A2,A3) :- '$execute'(X,A1,A2,A3). call(X,A1,A2,A3,A4) :- '$execute'(X,A1,A2,A3,A4). call(X,A1,A2,A3,A4,A5) :- '$execute'(X,A1,A2,A3,A4,A5). call(X,A1,A2,A3,A4,A5,A6) :- '$execute'(X,A1,A2,A3,A4,A5,A6). call(X,A1,A2,A3,A4,A5,A6,A7) :- '$execute'(X,A1,A2,A3,A4,A5,A6,A7). call(X,A1,A2,A3,A4,A5,A6,A7,A8) :- '$execute'(X,A1,A2,A3,A4,A5,A6,A7,A8). call(X,A1,A2,A3,A4,A5,A6,A7,A8,A9) :- '$execute'(X,A1,A2,A3,A4,A5,A6,A7,A8,A9). call(X,A1,A2,A3,A4,A5,A6,A7,A8,A9,A10) :- '$execute'(X,A1,A2,A3,A4,A5,A6,A7,A8,A9,A10). call(X,A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,A11) :- '$execute'(X,A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,A11). /** @pred call_cleanup(: _Goal_, : _CleanUpGoal_) * * This is similar to call_cleanup/1 but with an additional * _CleanUpGoal_ which gets called after _Goal_ is finished. * */ call_cleanup(Goal, Cleanup) :- '$gated_call'( false , Goal,_Catcher, Cleanup) . call_cleanup(Goal, Catcher, Cleanup) :- '$gated_call'( false , Goal, Catcher, Cleanup) . /** @pred setup_call_cleanup(: _Setup_,: _Goal_, : _CleanUpGoal_) Calls `(Setup, Goal)`. For each sucessful execution of _Setup_, calling _Goal_, the cleanup handler _Cleanup_ is guaranteed to be called exactly once. This will happen after _Goal_ completes, either through failure, deterministic success, commit, or an exception. _Setup_ will contain the goals that need to be protected from asynchronous interrupts such as the ones received from `call_with_time_limit/2` or thread_signal/2. In most uses, _Setup_ will perform temporary side-effects required by _Goal_ that are finally undone by _Cleanup_. */ setup_call_cleanup(Setup,Goal, Cleanup) :- setup_call_catcher_cleanup(Setup, Goal, _Catcher, Cleanup). setup_call_catcher_cleanup(Setup, Goal, Catcher, Cleanup) :- '$setup_call_catcher_cleanup'(Setup), call_cleanup(Goal, Catcher, Cleanup). /** @pred call_with_args(+ Name,...,? Ai,...) Meta-call where _Name_ is the name of the procedure to be called and the _Ai_ are the arguments. The number of arguments varies between 0 and 10. New code should use `call/N` for better portability. If _Name_ is a complex term, then call_with_args/n behaves as call/n: ~~~~~{.prolog} call(p(X1,...,Xm), Y1,...,Yn) :- p(X1,...,Xm,Y1,...,Yn). ~~~~~ */ %%% Some "dirty" predicates % Only efective if yap compiled with -DDEBUG % this predicate shows the code produced by the compiler '$show_code' :- '$debug'(0'f). %' just make emacs happy /** @pred grow_heap(+ _Size_) Increase heap size _Size_ kilobytes. */ grow_heap(X) :- '$grow_heap'(X). /** @pred grow_stack(+ _Size_) Increase stack size _Size_ kilobytes */ grow_stack(X) :- '$grow_stack'(X). % % gc() expects to be called from "call". Make sure it has an % environment to return to. % %garbage_collect :- save(dump), '$gc', save(dump2). /** @pred garbage_collect The goal `garbage_collect` forces a garbage collection. */ garbage_collect :- '$gc'. /** @pred gc The goal `gc` enables garbage collection. The same as `yap_flag(gc,on)`. */ gc :- yap_flag(gc,on). /** @pred nogc The goal `nogc` disables garbage collection. The same as `yap_flag(gc,off)`. */ nogc :- yap_flag(gc,off). /** @pred garbage_collect_atoms The goal `garbage_collect` forces a garbage collection of the atoms in the data-base. Currently, only atoms are recovered. */ garbage_collect_atoms :- '$atom_gc'. '$force_environment_for_gc'. '$good_list_of_character_codes'(V) :- var(V), !. '$good_list_of_character_codes'([]). '$good_list_of_character_codes'([X|L]) :- '$good_character_code'(X), '$good_list_of_character_codes'(L). '$good_character_code'(X) :- var(X), !. '$good_character_code'(X) :- integer(X), X > -2, X < 256. /** @pred prolog_initialization( _G_) Add a goal to be executed on system initialization. This is compatible with SICStus Prolog's initialization/1. */ prolog_initialization(G) :- var(G), !, '$do_error'(instantiation_error,initialization(G)). prolog_initialization(T) :- callable(T), !, '$assert_init'(T). prolog_initialization(T) :- '$do_error'(type_error(callable,T),initialization(T)). '$assert_init'(T) :- recordz('$startup_goal',T,_), fail. '$assert_init'(_). /** @pred version Write YAP's boot message. */ version :- '$version'. /** @pred version(- _Message_) Add a message to be written when yap boots or after aborting. It is not possible to remove messages. */ version(V) :- var(V), !, '$do_error'(instantiation_error,version(V)). version(T) :- atom(T), !, '$assert_version'(T). version(T) :- '$do_error'(type_error(atom,T),version(T)). '$assert_version'(T) :- recordz('$version',T,_), fail. '$assert_version'(_). '$set_toplevel_hook'(_) :- recorded('$toplevel_hooks',_,R), erase(R), fail. '$set_toplevel_hook'(H) :- recorda('$toplevel_hooks',H,_), fail. '$set_toplevel_hook'(_). query_to_answer(G, V, Status, Vs) :- gated_call( true, (G,'$delayed_goals'(G, V, Vs, LGs, _DCP)), Status, '$answer'( Status, LGs, Vs ) ). '$answer'( exit, LGs, Vs) :- !. %, %'$process_answer'(Vs, LGs). '$answer'( answer, LGs, Vs) :- !. %, % '$process_answer'(Vs, LGs, Bindings). '$answer'(!, _, _). '$answer'(fail,_,_). '$answer'(exception(E),_,_,_) :- '$LoopError'(E,error). '$answer'(external_exception(_),_,_). %% @} %% @addtogroup Global_Variables %% @{ /** @pred nb_getval(+ _Name_,- _Value_) * * * The nb_getval/2 predicate is a synonym for b_getval/2, introduced for * compatibility and symmetry. As most scenarios will use a particular * global variable either using non-backtrackable or backtrackable * assignment, using nb_getval/2 can be used to document that the * variable is used non-backtrackable. * */ nb_getval(GlobalVariable, Val) :- '__NB_getval__'(GlobalVariable, Val, Error), (var(Error) -> true ; '$getval_exception'(GlobalVariable, Val, nb_getval(GlobalVariable, Val)) -> nb_getval(GlobalVariable, Val) ; '$do_error'(existence_error(variable, GlobalVariable),nb_getval(GlobalVariable, Val)) ). /** @pred b_getval(+ _Name_, - _Value_) * * * Get the value associated with the global variable _Name_ and unify * it with _Value_. Note that this unification may further * instantiate the value of the global variable. If this is undesirable * the normal precautions (double negation or copy_term/2) must be * taken. The b_getval/2 predicate generates errors if _Name_ is not * an atom or the requested variable does not exist. * * Notice that for compatibility with other systems _Name_ must be already associated with a term: otherwise the system will generate an error. * * */ b_getval(GlobalVariable, Val) :- '__NB_getval__'(GlobalVariable, Val, Error), (var(Error) -> true ; '$getval_exception'(GlobalVariable, Val, b_getval(GlobalVariable, Val)) -> true ; '$do_error'(existence_error(variable, GlobalVariable),b_getval(GlobalVariable, Val)) ). %% @} %% @addtogroup YAPControl %% @{ /* This is the break predicate, it saves the importante data about current streams and debugger state */ '$debug_state'(state(Trace, Debug, State, SPY_GN, GList)) :- '$init_debugger', nb_getval('$trace',Trace), nb_getval('$debug_state',State), current_prolog_flag(debug, Debug), nb_getval('$spy_gn',SPY_GN), b_getval('$spy_glist',GList). '$debug_stop' :- nb_setval('$debug_state', state(creep,0,stop)), b_setval('$trace',off), set_prolog_flag(debug, false), b_setval('$spy_glist',[]), '$disable_debugging'. '$debug_restore'(state(Trace, Debug, State, SPY_GN, GList)) :- b_setval('$spy_glist',GList), b_setval('$spy_gn',SPY_GN), set_prolog_flag(debug, Debug), nb_setval('$debug_state',State), b_setval('$trace',Trace), '$enable_debugging'. /** @pred break Suspends the execution of the current goal and creates a new execution level similar to the top level, displaying the following message: ~~~~~{.prolog} [ Break (level ) ] ~~~~~ telling the depth of the break level just entered. To return to the previous level just type the end-of-file character or call the end_of_file predicate. This predicate is especially useful during debugging. */ break :- '$debug_state'(DState), '$debug_stop', '$break'( true ), current_output(OutStream), current_input(InpStream), current_prolog_flag(break_level, BL ), NBL is BL+1, set_prolog_flag(break_level, NBL ), format(user_error, '% Break (level ~w)~n', [NBL]), live, !, set_value('$live','$true'), '$debug_restore'(DState), set_input(InpStream), set_output(OutStream), set_prolog_flag(break_level, BL ), '$break'( false ). /** * @pred at_halt( G ) * * Hook predicate: _G_ must be called on exit. * * @param _G_: the hook * * @return succeeds with side-effect. */at_halt(G) :- recorda('$halt', G, _), fail. at_halt(_). /** @pred halt is iso Halts Prolog, and exits to the calling application. In YAP, halt/0 returns the exit code `0`. */ halt :- print_message(informational, halt), fail. halt :- halt(0). /** @pred halt(+ _I_) is iso Halts Prolog, and exits to 1the calling application returning the code given by the integer _I_. */ halt(_) :- recorded('$halt', G, _), catch(once(G), Error, user:'$Error'(Error)), fail. halt(X) :- '$sync_mmapped_arrays', set_value('$live','$false'), '$halt'(X). /** * @pred prolog_current_frame(-Env) * * reports a reference to the last execution environment _Env_. * YAP creates an enviroment when a clause contains several sub-goals. * Facts and simple recursion do not need an environment, * * @param Env * * @return */prolog_current_frame(Env) :- Env is '$env'. '$run_atom_goal'(GA) :- '$current_module'(Module), atom_to_term(GA, G, _), catch(once(Module:G), Error,user:'$Error'(Error)). '$add_dot_to_atom_goal'([],[0'.]) :- !. %' '$add_dot_to_atom_goal'([0'.],[0'.]) :- !. '$add_dot_to_atom_goal'([C|Gs0],[C|Gs]) :- '$add_dot_to_atom_goal'(Gs0,Gs). /** @} */