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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,
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   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]).

Goal expansion rules to avoid meta-calling

This module defines goal_expansion/2 rules to deal with commonly used, but fundamentally slow meta-predicates. Notable maplist/2... defines a useful set of predicates, but its execution is considerable slower than a traditional Prolog loop. Using this library calls to maplist/2... are translated into an call to a generated auxilary predicate that is compiled using compile_aux_clauses/1. Currently this module supports:

The idea for this library originates from ECLiPSe and came to SWI-Prolog through YAP.

author
- Jan Wielemaker */
To be done
- Support more predicates
   69:- dynamic
   70    user:goal_expansion/2.   71:- multifile
   72    user:goal_expansion/2.
 expand_maplist(+Callable, +Lists, -Goal) is det
Macro expansion for maplist/2 and higher arity.
   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).
 expand_apply(+GoalIn:callable, -GoalOut) is semidet
Macro expansion for `apply' predicates.
  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).
 expand_apply(+GoalIn:callable, -GoalOut, +PosIn, -PosOut) is semidet
Translation of simple meta calls to inline code while maintaining position information. Note that once(Goal) cannot be translated to (Goal->true) because this will break the compilation of (once(X) ; Y). A correct translation is to (Goal->true;fail). Abramo Bagnara suggested ((Goal->true),true), which is both faster and avoids warning if style_check(+var_branches) is used.
  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    !.
 expand_phrase(+PhraseGoal, -Goal) is semidet
 expand_phrase(+PhraseGoal, +Pos0, -Goal, -Pos) is semidet
Provide goal-expansion for PhraseGoal. PhraseGoal is either phrase/2,3 or call_dcg/2,3. The current version does not translate control structures, but only simple terminals and non-terminals.

For example:

?- expand_phrase(phrase(("ab", rule)), List), Goal).
Goal = (List=[97, 98|_G121], rule(_G121, [])).
throws
- Re-throws errors from dcg_translate_rule/2
  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).
 dcg_extend(+Callable, +Pos0, -Goal, -Pos, +Xs0, ?Xs) is semidet
  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(_, _).
 qcall_instantiated(@Term) is semidet
True if Term is instantiated sufficiently to call it.
To be done
- Shouldn't this be callable straight away?
  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)