/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2007-2016, University of Amsterdam
VU University Amsterdam
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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*/
:- module(apply_macros,
[ expand_phrase/2, % :PhraseGoal, -Goal
expand_phrase/4 % :PhraseGoal, +Pos0, -Goal, -Pos
]).
:- use_module(library(lists)).
/** <module> 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:
* maplist/2..
* forall/2
* once/1
* ignore/1
* phrase/2
* phrase/3
* call_dcg/2
* call_dcg/3
The idea for this library originates from ECLiPSe and came to SWI-Prolog
through YAP.
@tbd Support more predicates
@author Jan Wielemaker
*/
:- dynamic
user:goal_expansion/2.
:- multifile
user:goal_expansion/2.
%! expand_maplist(+Callable, +Lists, -Goal) is det.
%
% Macro expansion for maplist/2 and higher arity.
expand_maplist(Callable0, Lists, Goal) :-
length(Lists, N),
expand_closure_no_fail(Callable0, N, Callable1),
( Callable1 = _:_
-> strip_module(Callable0, M, Callable),
NextGoal = M:NextCall
; Callable = Callable1,
NextGoal = NextCall
),
Callable =.. [Pred|Args],
length(Args, Argc),
length(Argv, Argc),
length(Vars, N),
MapArity is N + 1,
format(atom(AuxName), '__aux_maplist/~d_~w+~d', [MapArity, Pred, Argc]),
append(Lists, Args, AuxArgs),
Goal =.. [AuxName|AuxArgs],
AuxArity is N+Argc,
prolog_load_context(module, Module),
functor(NextCall, Pred, AuxArity),
\+ predicate_property(Module:NextGoal, transparent),
( predicate_property(Module:Goal, defined)
-> true
; empty_lists(N, BaseLists),
length(Anon, Argc),
append(BaseLists, Anon, BaseArgs),
BaseClause =.. [AuxName|BaseArgs],
heads_and_tails(N, NextArgs, Vars, Tails),
append(NextArgs, Argv, AllNextArgs),
NextHead =.. [AuxName|AllNextArgs],
append(Argv, Vars, PredArgs),
NextCall =.. [Pred|PredArgs],
append(Tails, Argv, IttArgs),
NextIterate =.. [AuxName|IttArgs],
NextClause = (NextHead :- NextGoal, NextIterate),
compile_aux_clauses([BaseClause, NextClause])
).
expand_closure_no_fail(Callable0, N, Callable1) :-
'$expand_closure'(Callable0, N, Callable1),
!.
expand_closure_no_fail(Callable, _, Callable).
empty_lists(0, []) :- !.
empty_lists(N, [[]|T]) :-
N2 is N - 1,
empty_lists(N2, T).
heads_and_tails(0, [], [], []).
heads_and_tails(N, [[H|T]|L1], [H|L2], [T|L3]) :-
N2 is N - 1,
heads_and_tails(N2, L1, L2, L3).
%! expand_apply(+GoalIn:callable, -GoalOut) is semidet.
%
% Macro expansion for `apply' predicates.
expand_apply(Maplist, Goal) :-
compound(Maplist),
compound_name_arity(Maplist, maplist, N),
N >= 2,
Maplist =.. [maplist, Callable|Lists],
qcall_instantiated(Callable),
!,
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.
expand_apply(forall(Cond, Action), Pos0, Goal, Pos) :-
Goal = \+((Cond, \+(Action))),
( nonvar(Pos0),
Pos0 = term_position(_,_,_,_,[PosCond,PosAct])
-> Pos = term_position(0,0,0,0, % \+
[ term_position(0,0,0,0, % ,/2
[ PosCond,
term_position(0,0,0,0, % \+
[PosAct])
])
])
; true
).
expand_apply(once(Once), Pos0, Goal, Pos) :-
Goal = (Once->true),
( nonvar(Pos0),
Pos0 = term_position(_,_,_,_,[OncePos]),
compound(OncePos)
-> Pos = term_position(0,0,0,0, % ->/2
[ OncePos,
F-T % true
]),
arg(2, OncePos, F), % highlight true/false on ")"
T is F+1
; true
).
expand_apply(ignore(Ignore), Pos0, Goal, Pos) :-
Goal = (Ignore->true;true),
( nonvar(Pos0),
Pos0 = term_position(_,_,_,_,[IgnorePos]),
compound(IgnorePos)
-> Pos = term_position(0,0,0,0, % ;/2
[ term_position(0,0,0,0, % ->/2
[ IgnorePos,
F-T % true
]),
F-T % true
]),
arg(2, IgnorePos, F), % highlight true/false on ")"
T is F+1
; true
).
expand_apply(Phrase, Pos0, Expanded, Pos) :-
expand_phrase(Phrase, Pos0, Expanded, Pos),
!.
%! 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
expand_phrase(Phrase, Goal) :-
expand_phrase(Phrase, _, Goal, _).
expand_phrase(phrase(NT,Xs), Pos0, NTXsNil, Pos) :-
!,
extend_pos(Pos0, 1, Pos1),
expand_phrase(phrase(NT,Xs,[]), Pos1, NTXsNil, Pos).
expand_phrase(Goal, Pos0, NewGoal, Pos) :-
dcg_goal(Goal, NT, Xs0, Xs),
nonvar(NT),
nt_pos(Pos0, NTPos),
dcg_extend(NT, NTPos, NewGoal, Pos, Xs0, Xs).
dcg_goal(phrase(NT,Xs0,Xs), NT, Xs0, Xs).
dcg_goal(call_dcg(NT,Xs0,Xs), NT, Xs0, Xs).
%! dcg_extend(+Callable, +Pos0, -Goal, -Pos, +Xs0, ?Xs) is semidet.
dcg_extend(Compound0, Pos0, Compound, Pos, Xs0, Xs) :-
compound(Compound0),
\+ dcg_control(Compound0),
!,
extend_pos(Pos0, 2, Pos),
compound_name_arguments(Compound0, Name, Args0),
append(Args0, [Xs0,Xs], Args),
compound_name_arguments(Compound, Name, Args).
dcg_extend(Name, Pos0, Compound, Pos, Xs0, Xs) :-
atom(Name),
\+ dcg_control(Name),
!,
extend_pos(Pos0, 2, Pos),
compound_name_arguments(Compound, Name, [Xs0,Xs]).
dcg_extend(Q0, Pos0, M:Q, Pos, Xs0, Xs) :-
compound(Q0), Q0 = M:Q1,
'$expand':f2_pos(Pos0, MPos, APos0, Pos, MPos, APos),
dcg_extend(Q1, APos0, Q, APos, Xs0, Xs).
dcg_extend(Terminal, Pos0, Xs0 = DList, Pos, Xs0, Xs) :-
terminal(Terminal, DList, Xs),
!,
t_pos(Pos0, Pos).
dcg_control(!).
dcg_control([]).
dcg_control([_|_]).
dcg_control({_}).
dcg_control((_,_)).
dcg_control((_;_)).
dcg_control((_->_)).
dcg_control((_*->_)).
dcg_control(_:_).
terminal(List, DList, Tail) :-
compound(List),
List = [_|_],
!,
'$skip_list'(_, List, T0),
( var(T0)
-> DList = List,
Tail = T0
; T0 == []
-> append(List, Tail, DList)
; type_error(list, List)
).
terminal(List, DList, Tail) :-
List == [],
!,
DList = Tail.
terminal(String, DList, Tail) :-
string(String),
string_codes(String, List),
append(List, Tail, DList).
extend_pos(Var, _, Var) :-
var(Var),
!.
extend_pos(term_position(F,T,FF,FT,ArgPos0), Extra,
term_position(F,T,FF,FT,ArgPos)) :-
!,
extra_pos(Extra, T, ExtraPos),
append(ArgPos0, ExtraPos, ArgPos).
extend_pos(FF-FT, Extra,
term_position(FF,FT,FF,FT,ArgPos)) :-
!,
extra_pos(Extra, FT, ArgPos).
extra_pos(1, T, [T-T]).
extra_pos(2, T, [T-T,T-T]).
nt_pos(PhrasePos, _NTPos) :-
var(PhrasePos),
!.
nt_pos(term_position(_,_,_,_,[NTPos|_]), NTPos).
t_pos(Pos0, term_position(F,T,F,T,[F-T,F-T])) :-
compound(Pos0),
!,
arg(1, Pos0, F),
arg(2, Pos0, T).
t_pos(_, _).
%! qcall_instantiated(@Term) is semidet.
%
% True if Term is instantiated sufficiently to call it.
%
% @tbd Shouldn't this be callable straight away?
qcall_instantiated(Var) :-
var(Var),
!,
fail.
qcall_instantiated(M:C) :-
!,
atom(M),
callable(C).
qcall_instantiated(C) :-
callable(C).
/*******************************
* DEBUGGER *
*******************************/
:- multifile
prolog_clause:unify_goal/5.
prolog_clause:unify_goal(Maplist, Expanded, _Module, Pos0, Pos) :-
is_maplist(Maplist),
maplist_expansion(Expanded),
Pos0 = term_position(F,T,FF,FT,[_MapPos|ArgsPos]),
Pos = term_position(F,T,FF,FT,ArgsPos).
is_maplist(Goal) :-
compound(Goal),
functor(Goal, maplist, A),
A >= 2.
maplist_expansion(Expanded) :-
compound(Expanded),
functor(Expanded, Name, _),
sub_atom(Name, 0, _, _, '__aux_maplist/').
/*******************************
* XREF/COLOUR *
*******************************/
:- multifile
prolog_colour:vararg_goal_classification/3.
prolog_colour:vararg_goal_classification(maplist, Arity, expanded) :-
Arity >= 2.
/*******************************
* ACTIVATE *
*******************************/
:- multifile
system:goal_expansion/2,
system:goal_expansion/4.
% @tbd Should we only apply if optimization is enabled (-O)?
system:goal_expansion(GoalIn, GoalOut) :-
\+ current_prolog_flag(xref, true),
expand_apply(GoalIn, GoalOut).
system:goal_expansion(GoalIn, PosIn, GoalOut, PosOut) :-
expand_apply(GoalIn, PosIn, GoalOut, PosOut).