/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2007-2023, University of Amsterdam
VU University Amsterdam
SWI-Prolog Solutions b.v.
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*/
:- module(apply,
[ include/3, % :Pred, +List, -Ok
exclude/3, % :Pred. +List, -NotOk
partition/4, % :Pred, +List, -Included, -Excluded
partition/5, % :Pred, +List, ?Less, ?Equal, ?Greater
maplist/2, % :Pred, +List
maplist/3, % :Pred, ?List, ?List
maplist/4, % :Pred, ?List, ?List, ?List
maplist/5, % :Pred, ?List, ?List, ?List, ?List
convlist/3, % :Pred, +List, -List
foldl/4, % :Pred, +List, ?V0, ?V
foldl/5, % :Pred, +List1, +List2, ?V0, ?V
foldl/6, % :Pred, +List1, +List2, +List3, ?V0, ?V
foldl/7, % :Pred, +List1, +List2, +List3, +List4,
% ?V0, ?V
scanl/4, % :Pred, +List, ?V0, ?Vs
scanl/5, % :Pred, +List1, +List2, ?V0, ?Vs
scanl/6, % :Pred, +List1, +List2, +List3, ?V0, ?Vs
scanl/7 % :Pred, +List1, +List2, +List3, +List4,
% ?V0, ?Vs
]).
:- autoload(library(error),[must_be/2]).
:- set_prolog_flag(generate_debug_info, false).
/** <module> Apply predicates on a list
This module defines meta-predicates that apply a predicate on all
members of a list.
All predicates support partial application in the Goal argument. This
means that these calls are identical:
```
?- maplist(=, [foo, foo], [X, Y]).
?- maplist(=(foo), [X, Y]).
```
@see apply_macros.pl provides compile-time expansion for part of this
library.
@see http://www.cs.otago.ac.nz/staffpriv/ok/pllib.htm
@see Unit test code in tests/library/test_apply.pl
@tbd Add include/4, include/5, exclude/4, exclude/5
*/
:- meta_predicate
include(1, +, -),
exclude(1, +, -),
partition(1, +, -, -),
partition(2, +, -, -, -),
maplist(1, ?),
maplist(2, ?, ?),
maplist(3, ?, ?, ?),
maplist(4, ?, ?, ?, ?),
convlist(2, +, -),
foldl(3, +, +, -),
foldl(4, +, +, +, -),
foldl(5, +, +, +, +, -),
foldl(6, +, +, +, +, +, -),
scanl(3, +, +, -),
scanl(4, +, +, +, -),
scanl(5, +, +, +, +, -),
scanl(6, +, +, +, +, +, -).
%! include(:Goal, +List1, ?List2) is det.
%
% Filter elements for which Goal succeeds. True if List2 contains
% those elements Xi of List1 for which call(Goal, Xi) succeeds.
%
% @see exclude/3, partition/4, convlist/3.
% @compat Older versions of SWI-Prolog had sublist/3 with the same
% arguments and semantics.
include(Goal, List, Included) :-
include_(List, Goal, Included).
include_([], _, []).
include_([X1|Xs1], P, Included) :-
( call(P, X1)
-> Included = [X1|Included1]
; Included = Included1
),
include_(Xs1, P, Included1).
%! exclude(:Goal, +List1, ?List2) is det.
%
% Filter elements for which Goal fails. True if List2 contains those
% elements Xi of List1 for which call(Goal, Xi) fails.
%
% @see include/3, partition/4
exclude(Goal, List, Included) :-
exclude_(List, Goal, Included).
exclude_([], _, []).
exclude_([X1|Xs1], P, Included) :-
( call(P, X1)
-> Included = Included1
; Included = [X1|Included1]
),
exclude_(Xs1, P, Included1).
%! partition(:Pred, +List, ?Included, ?Excluded) is det.
%
% Filter elements of List according to Pred. True if Included
% contains all elements for which call(Pred, X) succeeds and
% Excluded contains the remaining elements.
%
% @see include/3, exclude/3, partition/5.
partition(Pred, List, Included, Excluded) :-
partition_(List, Pred, Included, Excluded).
partition_([], _, [], []).
partition_([H|T], Pred, Incl, Excl) :-
( call(Pred, H)
-> Incl = [H|I],
partition_(T, Pred, I, Excl)
; Excl = [H|E],
partition_(T, Pred, Incl, E)
).
%! partition(:Pred, +List, ?Less, ?Equal, ?Greater) is semidet.
%
% Filter List according to Pred in three sets. For each element Xi
% of List, its destination is determined by call(Pred, Xi, Place),
% where Place must be unified to one of =|<|=, =|=|= or =|>|=.
% Pred must be deterministic.
%
% @see partition/4
partition(Pred, List, Less, Equal, Greater) :-
partition_(List, Pred, Less, Equal, Greater).
partition_([], _, [], [], []).
partition_([H|T], Pred, L, E, G) :-
call(Pred, H, Diff),
partition_(Diff, H, Pred, T, L, E, G).
partition_(<, H, Pred, T, L, E, G) :-
!,
L = [H|Rest],
partition_(T, Pred, Rest, E, G).
partition_(=, H, Pred, T, L, E, G) :-
!,
E = [H|Rest],
partition_(T, Pred, L, Rest, G).
partition_(>, H, Pred, T, L, E, G) :-
!,
G = [H|Rest],
partition_(T, Pred, L, E, Rest).
partition_(Diff, _, _, _, _, _, _) :-
must_be(oneof([<,=,>]), Diff).
/*******************************
* MAPLIST *
*******************************/
%! maplist(:Goal, ?List1).
%! maplist(:Goal, ?List1, ?List2).
%! maplist(:Goal, ?List1, ?List2, ?List3).
%! maplist(:Goal, ?List1, ?List2, ?List3, ?List4).
%
% True if Goal is successfully applied on all matching elements of the
% list. The maplist family of predicates is defined as:
%
% ```
% maplist(G, [X_11, ..., X_1n],
% [X_21, ..., X_2n],
% ...,
% [X_m1, ..., X_mn]) :-
% call(G, X_11, ..., X_m1),
% call(G, X_12, ..., X_m2),
% ...
% call(G, X_1n, ..., X_mn).
% ```
%
% This family of predicates is deterministic iff Goal is deterministic
% and List1 is a proper list, i.e., a list that ends in `[]`.
maplist(Goal, List) :-
maplist_(List, Goal).
maplist_([], _).
maplist_([Elem|Tail], Goal) :-
call(Goal, Elem),
maplist_(Tail, Goal).
maplist(Goal, List1, List2) :-
maplist_(List1, List2, Goal).
maplist_([], [], _).
maplist_([Elem1|Tail1], [Elem2|Tail2], Goal) :-
call(Goal, Elem1, Elem2),
maplist_(Tail1, Tail2, Goal).
maplist(Goal, List1, List2, List3) :-
maplist_(List1, List2, List3, Goal).
maplist_([], [], [], _).
maplist_([Elem1|Tail1], [Elem2|Tail2], [Elem3|Tail3], Goal) :-
call(Goal, Elem1, Elem2, Elem3),
maplist_(Tail1, Tail2, Tail3, Goal).
maplist(Goal, List1, List2, List3, List4) :-
maplist_(List1, List2, List3, List4, Goal).
maplist_([], [], [], [], _).
maplist_([Elem1|Tail1], [Elem2|Tail2], [Elem3|Tail3], [Elem4|Tail4], Goal) :-
call(Goal, Elem1, Elem2, Elem3, Elem4),
maplist_(Tail1, Tail2, Tail3, Tail4, Goal).
%! convlist(:Goal, +ListIn, -ListOut) is det.
%
% Similar to maplist/3, but elements for which call(Goal, ElemIn, _)
% fails are omitted from ListOut. For example (using library(yall)):
%
% ```
% ?- convlist([X,Y]>>(integer(X), Y is X^2),
% [3, 5, foo, 2], L).
% L = [9, 25, 4].
% ```
%
% @compat Also appears in YAP =|library(maplist)|= and SICStus
% =|library(lists)|=.
convlist(Goal, ListIn, ListOut) :-
convlist_(ListIn, ListOut, Goal).
convlist_([], [], _).
convlist_([H0|T0], ListOut, Goal) :-
( call(Goal, H0, H)
-> ListOut = [H|T],
convlist_(T0, T, Goal)
; convlist_(T0, ListOut, Goal)
).
/*******************************
* FOLDL *
*******************************/
%! foldl(:Goal, +List, +V0, -V).
%! foldl(:Goal, +List1, +List2, +V0, -V).
%! foldl(:Goal, +List1, +List2, +List3, +V0, -V).
%! foldl(:Goal, +List1, +List2, +List3, +List4, +V0, -V).
%
% Fold an ensemble of _m_ (0 <= _m_ <= 4) lists of length _n_
% head-to-tail ("fold-left"), using columns of _m_ list elements as
% arguments for Goal. The `foldl` family of predicates is defined as
% follows, with `V0` an initial value and `V` the final value of the
% folding operation:
%
% ```
% foldl(G, [X_11, ..., X_1n],
% [X_21, ..., X_2n],
% ...,
% [X_m1, ..., X_mn], V0, V) :-
% call(G, X_11, ..., X_m1, V0, V1),
% call(G, X_12, ..., X_m2, V1, V2),
% ...
% call(G, X_1n, ..., X_mn, V<n-1>, V).
% ```
%
% No implementation for a corresponding `foldr` is given. A `foldr`
% implementation would consist in first calling reverse/2 on each of
% the _m_ input lists, then applying the appropriate `foldl`. This is
% actually more efficient than using a properly programmed-out
% recursive algorithm that cannot be tail-call optimized.
foldl(Goal, List, V0, V) :-
foldl_(List, Goal, V0, V).
foldl_([], _, V, V).
foldl_([H|T], Goal, V0, V) :-
call(Goal, H, V0, V1),
foldl_(T, Goal, V1, V).
foldl(Goal, List1, List2, V0, V) :-
foldl_(List1, List2, Goal, V0, V).
foldl_([], [], _, V, V).
foldl_([H1|T1], [H2|T2], Goal, V0, V) :-
call(Goal, H1, H2, V0, V1),
foldl_(T1, T2, Goal, V1, V).
foldl(Goal, List1, List2, List3, V0, V) :-
foldl_(List1, List2, List3, Goal, V0, V).
foldl_([], [], [], _, V, V).
foldl_([H1|T1], [H2|T2], [H3|T3], Goal, V0, V) :-
call(Goal, H1, H2, H3, V0, V1),
foldl_(T1, T2, T3, Goal, V1, V).
foldl(Goal, List1, List2, List3, List4, V0, V) :-
foldl_(List1, List2, List3, List4, Goal, V0, V).
foldl_([], [], [], [], _, V, V).
foldl_([H1|T1], [H2|T2], [H3|T3], [H4|T4], Goal, V0, V) :-
call(Goal, H1, H2, H3, H4, V0, V1),
foldl_(T1, T2, T3, T4, Goal, V1, V).
/*******************************
* SCANL *
*******************************/
%! scanl(:Goal, +List, +V0, -Values).
%! scanl(:Goal, +List1, +List2, +V0, -Values).
%! scanl(:Goal, +List1, +List2, +List3, +V0, -Values).
%! scanl(:Goal, +List1, +List2, +List3, +List4, +V0, -Values).
%
% Scan an ensemble of _m_ (0 <= _m_ <= 4) lists of length _n_
% head-to-tail ("scan-left"), using columns of _m_ list elements as
% arguments for Goal. The `scanl` family of predicates is defined as
% follows, with `V0` an initial value and `V` the final value of the
% scanning operation:
%
% ```
% scanl(G, [X_11, ..., X_1n],
% [X_21, ..., X_2n],
% ...,
% [X_m1, ..., X_mn], V0, [V0, V1, ..., Vn] ) :-
% call(G, X_11, ..., X_m1, V0, V1),
% call(G, X_12, ..., X_m2, V1, V2),
% ...
% call(G, X_1n, ..., X_mn, V<n-1>, Vn).
% ```
%
% `scanl` behaves like a `foldl` that collects the sequence of
% values taken on by the `Vx` accumulator into a list.
scanl(Goal, List, V0, [V0|Values]) :-
scanl_(List, Goal, V0, Values).
scanl_([], _, _, []).
scanl_([H|T], Goal, V, [VH|VT]) :-
call(Goal, H, V, VH),
scanl_(T, Goal, VH, VT).
scanl(Goal, List1, List2, V0, [V0|Values]) :-
scanl_(List1, List2, Goal, V0, Values).
scanl_([], [], _, _, []).
scanl_([H1|T1], [H2|T2], Goal, V, [VH|VT]) :-
call(Goal, H1, H2, V, VH),
scanl_(T1, T2, Goal, VH, VT).
scanl(Goal, List1, List2, List3, V0, [V0|Values]) :-
scanl_(List1, List2, List3, Goal, V0, Values).
scanl_([], [], [], _, _, []).
scanl_([H1|T1], [H2|T2], [H3|T3], Goal, V, [VH|VT]) :-
call(Goal, H1, H2, H3, V, VH),
scanl_(T1, T2, T3, Goal, VH, VT).
scanl(Goal, List1, List2, List3, List4, V0, [V0|Values]) :-
scanl_(List1, List2, List3, List4, Goal, V0, Values).
scanl_([], [], [], [], _, _, []).
scanl_([H1|T1], [H2|T2], [H3|T3], [H4|T4], Goal, V, [VH|VT]) :-
call(Goal, H1, H2, H3, H4, V, VH),
scanl_(T1, T2, T3, T4, Goal, VH, VT).
/*******************************
* SANDBOX *
*******************************/
:- multifile
sandbox:safe_meta_predicate/1.
safe_api(Name/Arity, sandbox:safe_meta_predicate(apply:Name/Arity)).
term_expansion(safe_api, Clauses) :-
module_property(apply, exports(API)),
maplist(safe_api, API, Clauses).
safe_api.