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    1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2007-2016, University of Amsterdam
    7                              VU University Amsterdam
    8    All rights reserved.
    9
   10    Redistribution and use in source and binary forms, with or without
   11    modification, are permitted provided that the following conditions
   12    are met:
   13
   14    1. Redistributions of source code must retain the above copyright
   15       notice, this list of conditions and the following disclaimer.
   16
   17    2. Redistributions in binary form must reproduce the above copyright
   18       notice, this list of conditions and the following disclaimer in
   19       the documentation and/or other materials provided with the
   20       distribution.
   21
   22    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   23    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   24    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   25    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   26    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   27    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   28    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   29    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   30    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   32    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   33    POSSIBILITY OF SUCH DAMAGE.
   34*/
   35
   36:- module(apply_macros,
   37          [ expand_phrase/2,            % :PhraseGoal, -Goal
   38            expand_phrase/4             % :PhraseGoal, +Pos0, -Goal, -Pos
   39          ]).   40:- autoload(library(error),[type_error/2]).   41:- autoload(library(lists),[append/3]).   42
   43
   44/** <module> Goal expansion rules to avoid meta-calling
   45
   46This module defines goal_expansion/2 rules to   deal with commonly used,
   47but fundamentally slow meta-predicates. Notable   maplist/2... defines a
   48useful set of predicates, but its  execution is considerable slower than
   49a traditional Prolog loop. Using this  library calls to maplist/2... are
   50translated into an call  to  a   generated  auxilary  predicate  that is
   51compiled using compile_aux_clauses/1. Currently this module supports:
   52
   53        * maplist/2..
   54        * forall/2
   55        * once/1
   56        * ignore/1
   57        * phrase/2
   58        * phrase/3
   59        * call_dcg/2
   60        * call_dcg/3
   61
   62The idea for this library originates from ECLiPSe and came to SWI-Prolog
   63through YAP.
   64
   65@tbd    Support more predicates
   66@author Jan Wielemaker
   67*/
   68
   69:- dynamic
   70    user:goal_expansion/2.   71:- multifile
   72    user:goal_expansion/2.   73
   74
   75%!  expand_maplist(+Callable, +Lists, -Goal) is det.
   76%
   77%   Macro expansion for maplist/2 and higher arity.
   78
   79expand_maplist(Callable0, Lists, Goal) :-
   80    length(Lists, N),
   81    expand_closure_no_fail(Callable0, N, Callable1),
   82    (   Callable1 = _:_
   83    ->  strip_module(Callable1, M, Callable),
   84        NextGoal = M:NextCall,
   85        QPred = M:Pred
   86    ;   Callable = Callable1,
   87        NextGoal = NextCall,
   88        QPred = Pred
   89    ),
   90    Callable =.. [Pred|Args],
   91    length(Args, Argc),
   92    length(Argv, Argc),
   93    length(Vars, N),
   94    MapArity is N + 1,
   95    format(atom(AuxName), '__aux_maplist/~d_~w+~d', [MapArity, QPred, Argc]),
   96    append(Lists, Args, AuxArgs),
   97    Goal =.. [AuxName|AuxArgs],
   98
   99    AuxArity is N+Argc,
  100    prolog_load_context(module, Module),
  101    functor(NextCall, Pred, AuxArity),
  102    \+ predicate_property(Module:NextGoal, transparent),
  103    (   predicate_property(Module:Goal, defined)
  104    ->  true
  105    ;   empty_lists(N, BaseLists),
  106        length(Anon, Argc),
  107        append(BaseLists, Anon, BaseArgs),
  108        BaseClause =.. [AuxName|BaseArgs],
  109
  110        heads_and_tails(N, NextArgs, Vars, Tails),
  111        append(NextArgs, Argv, AllNextArgs),
  112        NextHead =.. [AuxName|AllNextArgs],
  113        append(Argv, Vars, PredArgs),
  114        NextCall =.. [Pred|PredArgs],
  115        append(Tails, Argv, IttArgs),
  116        NextIterate =.. [AuxName|IttArgs],
  117        NextClause = (NextHead :- NextGoal, NextIterate),
  118        compile_aux_clauses([BaseClause, NextClause])
  119    ).
  120
  121expand_closure_no_fail(Callable0, N, Callable1) :-
  122    '$expand_closure'(Callable0, N, Callable1),
  123    !.
  124expand_closure_no_fail(Callable, _, Callable).
  125
  126empty_lists(0, []) :- !.
  127empty_lists(N, [[]|T]) :-
  128    N2 is N - 1,
  129    empty_lists(N2, T).
  130
  131heads_and_tails(0, [], [], []).
  132heads_and_tails(N, [[H|T]|L1], [H|L2], [T|L3]) :-
  133    N2 is N - 1,
  134    heads_and_tails(N2, L1, L2, L3).
  135
  136
  137%!  expand_apply(+GoalIn:callable, -GoalOut) is semidet.
  138%
  139%   Macro expansion for `apply' predicates.
  140
  141expand_apply(Maplist, Goal) :-
  142    compound(Maplist),
  143    compound_name_arity(Maplist, maplist, N),
  144    N >= 2,
  145    Maplist =.. [maplist, Callable|Lists],
  146    qcall_instantiated(Callable),
  147    !,
  148    expand_maplist(Callable, Lists, Goal).
  149
  150%!  expand_apply(+GoalIn:callable, -GoalOut, +PosIn, -PosOut) is semidet.
  151%
  152%   Translation  of  simple  meta  calls    to   inline  code  while
  153%   maintaining position information. Note that once(Goal) cannot be
  154%   translated  to  `(Goal->true)`  because  this   will  break  the
  155%   compilation of `(once(X) ; Y)`.  A   correct  translation  is to
  156%   `(Goal->true;fail)`.       Abramo       Bagnara        suggested
  157%   `((Goal->true),true)`, which is both faster   and avoids warning
  158%   if style_check(+var_branches) is used.
  159
  160expand_apply(forall(Cond, Action), Pos0, Goal, Pos) :-
  161    Goal = \+((Cond, \+(Action))),
  162    (   nonvar(Pos0),
  163        Pos0 = term_position(_,_,_,_,[PosCond,PosAct])
  164    ->  Pos = term_position(0,0,0,0, % \+
  165                            [ term_position(0,0,0,0, % ,/2
  166                                            [ PosCond,
  167                                              term_position(0,0,0,0, % \+
  168                                                            [PosAct])
  169                                            ])
  170                            ])
  171    ;   true
  172    ).
  173expand_apply(once(Once), Pos0, Goal, Pos) :-
  174    Goal = (Once->true),
  175    (   nonvar(Pos0),
  176        Pos0 = term_position(_,_,_,_,[OncePos]),
  177        compound(OncePos)
  178    ->  Pos = term_position(0,0,0,0,        % ->/2
  179                            [ OncePos,
  180                              F-T           % true
  181                            ]),
  182        arg(2, OncePos, F),         % highlight true/false on ")"
  183        T is F+1
  184    ;   true
  185    ).
  186expand_apply(ignore(Ignore), Pos0, Goal, Pos) :-
  187    Goal = (Ignore->true;true),
  188    (   nonvar(Pos0),
  189        Pos0 = term_position(_,_,_,_,[IgnorePos]),
  190        compound(IgnorePos)
  191    ->  Pos = term_position(0,0,0,0,                        % ;/2
  192                            [ term_position(0,0,0,0,        % ->/2
  193                                            [ IgnorePos,
  194                                              F-T           % true
  195                                            ]),
  196                              F-T                           % true
  197                            ]),
  198        arg(2, IgnorePos, F),       % highlight true/false on ")"
  199        T is F+1
  200    ;   true
  201    ).
  202expand_apply(Phrase, Pos0, Expanded, Pos) :-
  203    expand_phrase(Phrase, Pos0, Expanded, Pos),
  204    !.
  205
  206
  207%!  expand_phrase(+PhraseGoal, -Goal) is semidet.
  208%!  expand_phrase(+PhraseGoal, +Pos0, -Goal, -Pos) is semidet.
  209%
  210%   Provide goal-expansion for  PhraseGoal.   PhraseGoal  is  either
  211%   phrase/2,3  or  call_dcg/2,3.  The  current   version  does  not
  212%   translate control structures, but  only   simple  terminals  and
  213%   non-terminals.
  214%
  215%   For example:
  216%
  217%     ==
  218%     ?- expand_phrase(phrase(("ab", rule)), List), Goal).
  219%     Goal = (List=[97, 98|_G121], rule(_G121, [])).
  220%     ==
  221%
  222%   @throws Re-throws errors from dcg_translate_rule/2
  223
  224expand_phrase(Phrase, Goal) :-
  225    expand_phrase(Phrase, _, Goal, _).
  226
  227expand_phrase(phrase(NT,Xs), Pos0, NTXsNil, Pos) :-
  228    !,
  229    extend_pos(Pos0, 1, Pos1),
  230    expand_phrase(phrase(NT,Xs,[]), Pos1, NTXsNil, Pos).
  231expand_phrase(Goal, Pos0, NewGoal, Pos) :-
  232    dcg_goal(Goal, NT, Xs0, Xs),
  233    nonvar(NT),
  234    nt_pos(Pos0, NTPos),
  235    dcg_extend(NT, NTPos, NewGoal, Pos, Xs0, Xs).
  236
  237dcg_goal(phrase(NT,Xs0,Xs), NT, Xs0, Xs).
  238dcg_goal(call_dcg(NT,Xs0,Xs), NT, Xs0, Xs).
  239
  240%!  dcg_extend(+Callable, +Pos0, -Goal, -Pos, +Xs0, ?Xs) is semidet.
  241
  242dcg_extend(Compound0, Pos0, Compound, Pos, Xs0, Xs) :-
  243    compound(Compound0),
  244    \+ dcg_control(Compound0),
  245    !,
  246    extend_pos(Pos0, 2, Pos),
  247    compound_name_arguments(Compound0, Name, Args0),
  248    append(Args0, [Xs0,Xs], Args),
  249    compound_name_arguments(Compound, Name, Args).
  250dcg_extend(Name, Pos0, Compound, Pos, Xs0, Xs) :-
  251    atom(Name),
  252    \+ dcg_control(Name),
  253    !,
  254    extend_pos(Pos0, 2, Pos),
  255    compound_name_arguments(Compound, Name, [Xs0,Xs]).
  256dcg_extend(Q0, Pos0, M:Q, Pos, Xs0, Xs) :-
  257    compound(Q0), Q0 = M:Q1,
  258    '$expand':f2_pos(Pos0, MPos, APos0, Pos, MPos, APos),
  259    dcg_extend(Q1, APos0, Q, APos, Xs0, Xs).
  260dcg_extend(Terminal, Pos0, Xs0 = DList, Pos, Xs0, Xs) :-
  261    terminal(Terminal, DList, Xs),
  262    !,
  263    t_pos(Pos0, Pos).
  264
  265dcg_control(!).
  266dcg_control([]).
  267dcg_control([_|_]).
  268dcg_control({_}).
  269dcg_control((_,_)).
  270dcg_control((_;_)).
  271dcg_control((_->_)).
  272dcg_control((_*->_)).
  273dcg_control(_:_).
  274
  275terminal(List, DList, Tail) :-
  276    compound(List),
  277    List = [_|_],
  278    !,
  279    '$skip_list'(_, List, T0),
  280    (   var(T0)
  281    ->  DList = List,
  282        Tail = T0
  283    ;   T0 == []
  284    ->  append(List, Tail, DList)
  285    ;   type_error(list, List)
  286    ).
  287terminal(List, DList, Tail) :-
  288    List == [],
  289    !,
  290    DList = Tail.
  291terminal(String, DList, Tail) :-
  292    string(String),
  293    string_codes(String, List),
  294    append(List, Tail, DList).
  295
  296extend_pos(Var, _, Var) :-
  297    var(Var),
  298    !.
  299extend_pos(term_position(F,T,FF,FT,ArgPos0), Extra,
  300           term_position(F,T,FF,FT,ArgPos)) :-
  301    !,
  302    extra_pos(Extra, T, ExtraPos),
  303    append(ArgPos0, ExtraPos, ArgPos).
  304extend_pos(FF-FT, Extra,
  305           term_position(FF,FT,FF,FT,ArgPos)) :-
  306    !,
  307    extra_pos(Extra, FT, ArgPos).
  308
  309extra_pos(1, T, [T-T]).
  310extra_pos(2, T, [T-T,T-T]).
  311
  312nt_pos(PhrasePos, _NTPos) :-
  313    var(PhrasePos),
  314    !.
  315nt_pos(term_position(_,_,_,_,[NTPos|_]), NTPos).
  316
  317t_pos(Pos0, term_position(F,T,F,T,[F-T,F-T])) :-
  318    compound(Pos0),
  319    !,
  320    arg(1, Pos0, F),
  321    arg(2, Pos0, T).
  322t_pos(_, _).
  323
  324
  325%!  qcall_instantiated(@Term) is semidet.
  326%
  327%   True if Term is instantiated sufficiently to call it.
  328%
  329%   @tbd    Shouldn't this be callable straight away?
  330
  331qcall_instantiated(Var) :-
  332    var(Var),
  333    !,
  334    fail.
  335qcall_instantiated(M:C) :-
  336    !,
  337    atom(M),
  338    callable(C).
  339qcall_instantiated(C) :-
  340    callable(C).
  341
  342
  343                 /*******************************
  344                 *            DEBUGGER          *
  345                 *******************************/
  346
  347:- multifile
  348    prolog_clause:unify_goal/5.  349
  350prolog_clause:unify_goal(Maplist, Expanded, _Module, Pos0, Pos) :-
  351    is_maplist(Maplist),
  352    maplist_expansion(Expanded),
  353    Pos0 = term_position(F,T,FF,FT,[_MapPos|ArgsPos]),
  354    Pos  = term_position(F,T,FF,FT,ArgsPos).
  355
  356is_maplist(Goal) :-
  357    compound(Goal),
  358    compound_name_arity(Goal, maplist, A),
  359    A >= 2.
  360
  361maplist_expansion(Expanded) :-
  362    compound(Expanded),
  363    compound_name_arity(Expanded, Name, _),
  364    sub_atom(Name, 0, _, _, '__aux_maplist/').
  365
  366
  367                 /*******************************
  368                 *          XREF/COLOUR         *
  369                 *******************************/
  370
  371:- multifile
  372    prolog_colour:vararg_goal_classification/3.  373
  374prolog_colour:vararg_goal_classification(maplist, Arity, expanded) :-
  375    Arity >= 2.
  376
  377
  378                 /*******************************
  379                 *           ACTIVATE           *
  380                 *******************************/
  381
  382:- multifile
  383    system:goal_expansion/2,
  384    system:goal_expansion/4.  385
  386%       @tbd    Should we only apply if optimization is enabled (-O)?
  387
  388system:goal_expansion(GoalIn, GoalOut) :-
  389    \+ current_prolog_flag(xref, true),
  390    expand_apply(GoalIn, GoalOut).
  391system:goal_expansion(GoalIn, PosIn, GoalOut, PosOut) :-
  392    expand_apply(GoalIn, PosIn, GoalOut, PosOut)