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) 2007-2023, University of Amsterdam 7 VU University Amsterdam 8 SWI-Prolog Solutions b.v. 9 All rights reserved. 10 11 Redistribution and use in source and binary forms, with or without 12 modification, are permitted provided that the following conditions 13 are met: 14 15 1. Redistributions of source code must retain the above copyright 16 notice, this list of conditions and the following disclaimer. 17 18 2. Redistributions in binary form must reproduce the above copyright 19 notice, this list of conditions and the following disclaimer in 20 the documentation and/or other materials provided with the 21 distribution. 22 23 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 26 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 27 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 28 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 29 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 30 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 31 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 33 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 34 POSSIBILITY OF SUCH DAMAGE. 35*/ 36 37:- module(apply, 38 [ include/3, % :Pred, +List, -Ok 39 exclude/3, % :Pred. +List, -NotOk 40 partition/4, % :Pred, +List, -Included, -Excluded 41 partition/5, % :Pred, +List, ?Less, ?Equal, ?Greater 42 maplist/2, % :Pred, +List 43 maplist/3, % :Pred, ?List, ?List 44 maplist/4, % :Pred, ?List, ?List, ?List 45 maplist/5, % :Pred, ?List, ?List, ?List, ?List 46 convlist/3, % :Pred, +List, -List 47 foldl/4, % :Pred, +List, ?V0, ?V 48 foldl/5, % :Pred, +List1, +List2, ?V0, ?V 49 foldl/6, % :Pred, +List1, +List2, +List3, ?V0, ?V 50 foldl/7, % :Pred, +List1, +List2, +List3, +List4, 51 % ?V0, ?V 52 scanl/4, % :Pred, +List, ?V0, ?Vs 53 scanl/5, % :Pred, +List1, +List2, ?V0, ?Vs 54 scanl/6, % :Pred, +List1, +List2, +List3, ?V0, ?Vs 55 scanl/7 % :Pred, +List1, +List2, +List3, +List4, 56 % ?V0, ?Vs 57 ]). 58:- autoload(library(error),[must_be/2]). 59:- set_prolog_flag(generate_debug_info, false). 60 61/** <module> Apply predicates on a list 62 63This module defines meta-predicates that apply a predicate on all 64members of a list. 65 66All predicates support partial application in the Goal argument. This 67means that these calls are identical: 68 69``` 70?- maplist(=, [foo, foo], [X, Y]). 71?- maplist(=(foo), [X, Y]). 72``` 73 74@see apply_macros.pl provides compile-time expansion for part of this 75 library. 76@see http://www.cs.otago.ac.nz/staffpriv/ok/pllib.htm 77@see Unit test code in tests/library/test_apply.pl 78@tbd Add include/4, include/5, exclude/4, exclude/5 79*/ 80 81:- meta_predicate 82 include(1, +, -), 83 exclude(1, +, -), 84 partition(1, +, -, -), 85 partition(2, +, -, -, -), 86 maplist(1, ?), 87 maplist(2, ?, ?), 88 maplist(3, ?, ?, ?), 89 maplist(4, ?, ?, ?, ?), 90 convlist(2, +, -), 91 foldl(3, +, +, -), 92 foldl(4, +, +, +, -), 93 foldl(5, +, +, +, +, -), 94 foldl(6, +, +, +, +, +, -), 95 scanl(3, +, +, -), 96 scanl(4, +, +, +, -), 97 scanl(5, +, +, +, +, -), 98 scanl(6, +, +, +, +, +, -). 99 100 101%! include(:Goal, +List1, ?List2) is det. 102% 103% Filter elements for which Goal succeeds. True if List2 contains 104% those elements Xi of List1 for which call(Goal, Xi) succeeds. 105% 106% @see exclude/3, partition/4, convlist/3. 107% @compat Older versions of SWI-Prolog had sublist/3 with the same 108% arguments and semantics. 109 110include(_, [], []). 111include(Goal, [X1|Xs1], Included) :- 112 ( call(Goal, X1) 113 -> Included = [X1|Included1] 114 ; Included = Included1 115 ), 116 include(Goal, Xs1, Included1). 117 118 119%! exclude(:Goal, +List1, ?List2) is det. 120% 121% Filter elements for which Goal fails. True if List2 contains those 122% elements Xi of List1 for which call(Goal, Xi) fails. 123% 124% @see include/3, partition/4 125 126exclude(_, [], []). 127exclude(Goal, [X1|Xs1], Included) :- 128 ( call(Goal, X1) 129 -> Included = Included1 130 ; Included = [X1|Included1] 131 ), 132 exclude(Goal, Xs1, Included1). 133 134 135%! partition(:Pred, +List, ?Included, ?Excluded) is det. 136% 137% Filter elements of List according to Pred. True if Included 138% contains all elements for which call(Pred, X) succeeds and 139% Excluded contains the remaining elements. 140% 141% @see include/3, exclude/3, partition/5. 142 143partition(_, [], [], []). 144partition(Pred, [H|T], Incl, Excl) :- 145 ( call(Pred, H) 146 -> Incl = [H|I], 147 partition(Pred, T, I, Excl) 148 ; Excl = [H|E], 149 partition(Pred, T, Incl, E) 150 ). 151 152 153%! partition(:Pred, +List, ?Less, ?Equal, ?Greater) is semidet. 154% 155% Filter List according to Pred in three sets. For each element Xi 156% of List, its destination is determined by call(Pred, Xi, Place), 157% where Place must be unified to one of =|<|=, =|=|= or =|>|=. 158% Pred must be deterministic. 159% 160% @see partition/4 161 162partition(_, [], [], [], []). 163partition(Pred, [H|T], L, E, G) :- 164 call(Pred, H, Diff), 165 partition_(Diff, H, Pred, T, L, E, G). 166 167partition_(<, H, Pred, T, L, E, G) :- 168 !, 169 L = [H|Rest], 170 partition(Pred, T, Rest, E, G). 171partition_(=, H, Pred, T, L, E, G) :- 172 !, 173 E = [H|Rest], 174 partition(Pred, T, L, Rest, G). 175partition_(>, H, Pred, T, L, E, G) :- 176 !, 177 G = [H|Rest], 178 partition(Pred, T, L, E, Rest). 179partition_(Diff, _, _, _, _, _, _) :- 180 must_be(oneof([<,=,>]), Diff). 181 182 183 /******************************* 184 * MAPLIST * 185 *******************************/ 186 187%! maplist(:Goal, ?List1). 188%! maplist(:Goal, ?List1, ?List2). 189%! maplist(:Goal, ?List1, ?List2, ?List3). 190%! maplist(:Goal, ?List1, ?List2, ?List3, ?List4). 191% 192% True if Goal is successfully applied on all matching elements of the 193% list. The maplist family of predicates is defined as: 194% 195% ``` 196% maplist(G, [X_11, ..., X_1n], 197% [X_21, ..., X_2n], 198% ..., 199% [X_m1, ..., X_mn]) :- 200% call(G, X_11, ..., X_m1), 201% call(G, X_12, ..., X_m2), 202% ... 203% call(G, X_1n, ..., X_mn). 204% ``` 205% 206% This family of predicates is deterministic iff Goal is deterministic 207% and List1 is a proper list, i.e., a list that ends in `[]`. 208 209maplist(_, []). 210maplist(Goal, [Elem|Tail]) :- 211 call(Goal, Elem), 212 maplist(Goal, Tail). 213 214maplist(_, [], []). 215maplist(Goal, [Elem1|Tail1], [Elem2|Tail2]) :- 216 call(Goal, Elem1, Elem2), 217 maplist(Goal, Tail1, Tail2). 218 219maplist(_, [], [], []). 220maplist(Goal, [Elem1|Tail1], [Elem2|Tail2], [Elem3|Tail3]) :- 221 call(Goal, Elem1, Elem2, Elem3), 222 maplist(Goal, Tail1, Tail2, Tail3). 223 224maplist(_, [], [], [], []). 225maplist(Goal, [Elem1|Tail1], [Elem2|Tail2], [Elem3|Tail3], [Elem4|Tail4]) :- 226 call(Goal, Elem1, Elem2, Elem3, Elem4), 227 maplist(Goal, Tail1, Tail2, Tail3, Tail4). 228 229 230%! convlist(:Goal, +ListIn, -ListOut) is det. 231% 232% Similar to maplist/3, but elements for which call(Goal, ElemIn, _) 233% fails are omitted from ListOut. For example (using library(yall)): 234% 235% ``` 236% ?- convlist([X,Y]>>(integer(X), Y is X^2), 237% [3, 5, foo, 2], L). 238% L = [9, 25, 4]. 239% ``` 240% 241% @compat Also appears in YAP =|library(maplist)|= and SICStus 242% =|library(lists)|=. 243 244convlist(_, [], []). 245convlist(Goal, [H0|T0], ListOut) :- 246 ( call(Goal, H0, H) 247 -> ListOut = [H|T], 248 convlist(Goal, T0, T) 249 ; convlist(Goal, T0, ListOut) 250 ). 251 252 253 /******************************* 254 * FOLDL * 255 *******************************/ 256 257%! foldl(:Goal, +List, +V0, -V). 258%! foldl(:Goal, +List1, +List2, +V0, -V). 259%! foldl(:Goal, +List1, +List2, +List3, +V0, -V). 260%! foldl(:Goal, +List1, +List2, +List3, +List4, +V0, -V). 261% 262% Fold an ensemble of _m_ (0 <= _m_ <= 4) lists of length _n_ 263% head-to-tail ("fold-left"), using columns of _m_ list elements as 264% arguments for Goal. The `foldl` family of predicates is defined as 265% follows, with `V0` an initial value and `V` the final value of the 266% folding operation: 267% 268% ``` 269% foldl(G, [X_11, ..., X_1n], 270% [X_21, ..., X_2n], 271% ..., 272% [X_m1, ..., X_mn], V0, V) :- 273% call(G, X_11, ..., X_m1, V0, V1), 274% call(G, X_12, ..., X_m2, V1, V2), 275% ... 276% call(G, X_1n, ..., X_mn, V<n-1>, V). 277% ``` 278% 279% No implementation for a corresponding `foldr` is given. A `foldr` 280% implementation would consist in first calling reverse/2 on each of 281% the _m_ input lists, then applying the appropriate `foldl`. This is 282% actually more efficient than using a properly programmed-out 283% recursive algorithm that cannot be tail-call optimized. 284 285foldl(_, [], V, V). 286foldl(Goal, [H|T], V0, V) :- 287 call(Goal, H, V0, V1), 288 foldl(Goal, T, V1, V). 289 290 291foldl(_, [], [], V, V). 292foldl(Goal, [H1|T1], [H2|T2], V0, V) :- 293 call(Goal, H1, H2, V0, V1), 294 foldl(Goal, T1, T2, V1, V). 295 296 297foldl(_, [], [], [], V, V). 298foldl(Goal, [H1|T1], [H2|T2], [H3|T3], V0, V) :- 299 call(Goal, H1, H2, H3, V0, V1), 300 foldl(Goal, T1, T2, T3, V1, V). 301 302 303foldl(_, [], [], [], [], V, V). 304foldl(Goal, [H1|T1], [H2|T2], [H3|T3], [H4|T4], V0, V) :- 305 call(Goal, H1, H2, H3, H4, V0, V1), 306 foldl(Goal, T1, T2, T3, T4, V1, V). 307 308 309 /******************************* 310 * SCANL * 311 *******************************/ 312 313%! scanl(:Goal, +List, +V0, -Values). 314%! scanl(:Goal, +List1, +List2, +V0, -Values). 315%! scanl(:Goal, +List1, +List2, +List3, +V0, -Values). 316%! scanl(:Goal, +List1, +List2, +List3, +List4, +V0, -Values). 317% 318% Scan an ensemble of _m_ (0 <= _m_ <= 4) lists of length _n_ 319% head-to-tail ("scan-left"), using columns of _m_ list elements as 320% arguments for Goal. The `scanl` family of predicates is defined as 321% follows, with `V0` an initial value and `V` the final value of the 322% scanning operation: 323% 324% ``` 325% scanl(G, [X_11, ..., X_1n], 326% [X_21, ..., X_2n], 327% ..., 328% [X_m1, ..., X_mn], V0, [V0, V1, ..., Vn] ) :- 329% call(G, X_11, ..., X_m1, V0, V1), 330% call(G, X_12, ..., X_m2, V1, V2), 331% ... 332% call(G, X_1n, ..., X_mn, V<n-1>, Vn). 333% ``` 334% 335% `scanl` behaves like a `foldl` that collects the sequence of 336% values taken on by the `Vx` accumulator into a list. 337 338scanl(_, [], V, [V]). 339scanl(Goal, [H|T], V, [V|VT]) :- 340 call(Goal, H, V, VH), 341 scanl(Goal, T, VH, VT). 342 343 344scanl(_, [], [], V, [V]). 345scanl(Goal, [H1|T1], [H2|T2], V, [V|VT]) :- 346 call(Goal, H1, H2, V, VH), 347 scanl(Goal, T1, T2, VH, VT). 348 349 350scanl(_, [], [], [], V, [V]). 351scanl(Goal, [H1|T1], [H2|T2], [H3|T3], V, [V|VT]) :- 352 call(Goal, H1, H2, H3, V, VH), 353 scanl(Goal, T1, T2, T3, VH, VT). 354 355 356scanl(_, [], [], [], [], V, [V]). 357scanl(Goal, [H1|T1], [H2|T2], [H3|T3], [H4|T4], V, [V|VT]) :- 358 call(Goal, H1, H2, H3, H4, V, VH), 359 scanl(Goal, T1, T2, T3, T4, VH, VT). 360 361 362 /******************************* 363 * SANDBOX * 364 *******************************/ 365 366:- multifile 367 sandbox:safe_meta_predicate/1. 368 369safe_api(Name/Arity, sandbox:safe_meta_predicate(apply:Name/Arity)). 370 371term_expansion(safe_api, Clauses) :- 372 module_property(apply, exports(API)), 373 maplist(safe_api, API, Clauses). 374 375safe_api