File: arithmetic.pl

package info (click to toggle)
swi-prolog 8.0.2+dfsg-3+deb10u1
  • links: PTS, VCS
  • area: main
  • in suites: buster
  • size: 72,036 kB
  • sloc: ansic: 349,612; perl: 306,654; java: 5,208; cpp: 4,436; sh: 3,042; ruby: 1,594; yacc: 845; makefile: 136; xml: 82; sed: 12; sql: 6
file content (281 lines) | stat: -rw-r--r-- 8,592 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
/*  Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        J.Wielemaker@vu.nl
    WWW:           http://www.swi-prolog.org
    Copyright (c)  2011-2015, 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;
    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

:- module(arithmetic,
          [ arithmetic_function/1,              % +Name/Arity
            arithmetic_expression_value/2       % :Expression, -Value
          ]).
:- use_module(library(error)).
:- use_module(library(lists)).
:- set_prolog_flag(generate_debug_info, false).

/** <module> Extensible arithmetic

This module provides a  portable   partial  replacement  of SWI-Prolog's
user-defined  arithmetic  (evaluable)   functions.    It   defines   the
compatibility  directive  arithmetic_function/1  and  support  for  both
runtime and compile-time evaluation of expressions   that  are a mixture
between Prolog predicates  used  as   functions  and  built-in evaluable
terms.
*/

:- meta_predicate
    arithmetic_function(:),
    arithmetic_expression_value(:, -).
:- multifile
    evaluable/2.                            % Term, Module

%!  arithmetic_function(:NameArity) is det.
%
%   Declare a predicate as an arithmetic function.
%
%   @deprecated This function provides  a   partial  work around for
%   pure Prolog user-defined arithmetic  functions   that  has  been
%   dropped in SWI-Prolog  5.11.23.  Notably,   it  only  deals with
%   expression know at compile time.

arithmetic_function(Term) :-
    throw(error(context_error(nodirective, arithmetic_function(Term)), _)).

arith_decl_clauses(NameArity,
                   [(:- public(PI)),
                    arithmetic:evaluable(Term, Q)
                   ]) :-
    prolog_load_context(module, M),
    strip_module(M:NameArity, Q, Spec),
    (   Q == M
    ->  PI = Name/ImplArity
    ;   PI = Q:Name/ImplArity
    ),
    (   Spec = Name/Arity
    ->  functor(Term, Name, Arity),
        ImplArity is Arity+1
    ;   type_error(predicate_indicator, Term)
    ).

%!  eval_clause(+Term, -Clause) is det.
%
%   Clause is a clause  for   evaluating  the  arithmetic expression
%   Term.

eval_clause(Term, (eval(Gen, M, Result) :- Body)) :-
    functor(Term, Name, Arity),
    functor(Gen, Name, Arity),
    Gen =.. [_|Args],
    eval_args(Args, PlainArgs, M, Goals, [Result is NewTerm]),
    NewTerm =.. [Name|PlainArgs],
    list_conj(Goals, Body).

eval_args([], [], _, Goals, Goals).
eval_args([E0|T0], [A0|T], M, [eval(E0, M, A0)|GT], RT) :-
    eval_args(T0, T, M, GT, RT).

list_conj([One], One) :- !.
list_conj([H|T0], (H,T)) :-
    list_conj(T0, T).

eval_clause(Clause) :-
    current_arithmetic_function(Term),
    eval_clause(Term, Clause).

term_expansion(eval('$builtin', _, _), Clauses) :-
    findall(Clause, eval_clause(Clause), Clauses).


%!  arithmetic_expression_value(:Expression, -Result) is det.
%
%   True  when  Result  unifies  with    the  arithmetic  result  of
%   evaluating Expression.

arithmetic_expression_value(M:Expression, Result) :-
    eval(Expression, M, Result).

eval(Number, _, Result) :-
    number(Number),
    !,
    Result = Number.
eval(Term, M, Result) :-
    evaluable(Term, M2),
    visible(M, M2),
    !,
    call(M2:Term, Result).
eval('$builtin', _, _).


visible(M, M) :- !.
visible(M, Super) :-
    import_module(M, Parent),
    visible(Parent, Super).


                 /*******************************
                 *         COMPILE-TIME         *
                 *******************************/

math_goal_expansion(A is Expr, Goal) :-
    expand_function(Expr, Native, Pre),
    tidy((Pre, A is Native), Goal).
math_goal_expansion(ExprA =:= ExprB, Goal) :-
    expand_function(ExprA, NativeA, PreA),
    expand_function(ExprB, NativeB, PreB),
    tidy((PreA, PreB, NativeA =:= NativeB), Goal).
math_goal_expansion(ExprA =\= ExprB, Goal) :-
    expand_function(ExprA, NativeA, PreA),
    expand_function(ExprB, NativeB, PreB),
    tidy((PreA, PreB, NativeA =\= NativeB), Goal).
math_goal_expansion(ExprA > ExprB, Goal) :-
    expand_function(ExprA, NativeA, PreA),
    expand_function(ExprB, NativeB, PreB),
    tidy((PreA, PreB, NativeA > NativeB), Goal).
math_goal_expansion(ExprA < ExprB, Goal) :-
    expand_function(ExprA, NativeA, PreA),
    expand_function(ExprB, NativeB, PreB),
    tidy((PreA, PreB, NativeA < NativeB), Goal).
math_goal_expansion(ExprA >= ExprB, Goal) :-
    expand_function(ExprA, NativeA, PreA),
    expand_function(ExprB, NativeB, PreB),
    tidy((PreA, PreB, NativeA >= NativeB), Goal).
math_goal_expansion(ExprA =< ExprB, Goal) :-
    expand_function(ExprA, NativeA, PreA),
    expand_function(ExprB, NativeB, PreB),
    tidy((PreA, PreB, NativeA =< NativeB), Goal).

expand_function(Expression, NativeExpression, Goal) :-
    do_expand_function(Expression, NativeExpression, Goal0),
    tidy(Goal0, Goal).

do_expand_function(X, X, true) :-
    evaluable(X),
    !.
do_expand_function(Function, Result, ArgCode) :-
    current_arithmetic_function(Function),
    !,
    Function =.. [Name|Args],
    expand_function_arguments(Args, ArgResults, ArgCode),
    Result =.. [Name|ArgResults].
do_expand_function(Function, Result, (ArgCode, Pred)) :-
    prolog_load_context(module, M),
    evaluable(Function, M2),
    visible(M, M2),
    !,
    Function =.. [Name|Args],
    expand_predicate_arguments(Args, ArgResults, ArgCode),
    append(ArgResults, [Result], PredArgs),
    Pred =.. [Name|PredArgs].
do_expand_function(Function, _, _) :-
    type_error(evaluable, Function).


expand_function_arguments([], [], true).
expand_function_arguments([H0|T0], [H|T], (A,B)) :-
    do_expand_function(H0, H, A),
    expand_function_arguments(T0, T, B).

expand_predicate_arguments([], [], true).
expand_predicate_arguments([H0|T0], [H|T], (A,B)) :-
    do_expand_function(H0, H1, A0),
    (   callable(H1),
        current_arithmetic_function(H1)
    ->  A = (A0, H is H1)
    ;   A = A0,
        H = H1
    ),
    expand_predicate_arguments(T0, T, B).

%!  evaluable(F) is semidet.
%
%   True if F and all its subterms are evaluable terms or variables.

evaluable(F) :-
    var(F),
    !.
evaluable(F) :-
    number(F),
    !.
evaluable([_Code]) :- !.
evaluable(Func) :-                              % Funtional notation.
    functor(Func, ., 2),
    !.
evaluable(F) :-
    string(F),
    !,
    string_length(F, 1).
evaluable(F) :-
    current_arithmetic_function(F),
    (   compound(F)
    ->  forall(arg(_,F,A), evaluable(A))
    ;   true
    ).

%!  tidy(+GoalIn, -GoalOut)
%
%   Cleanup the output from expand_function/3.

tidy(A, A) :-
    var(A),
    !.
tidy(((A,B),C), R) :-
    !,
    tidy((A,B,C), R).
tidy((true,A), R) :-
    !,
    tidy(A, R).
tidy((A,true), R) :-
    !,
    tidy(A, R).
tidy((A, X is Y), R) :-
    var(X), var(Y),
    !,
    tidy(A, R),
    X = Y.
tidy((A,B), (TA,TB)) :-
    !,
    tidy(A, TA),
    tidy(B, TB).
tidy(A, A).


                 /*******************************
                 *        EXPANSION HOOK        *
                 *******************************/

:- multifile
    system:term_expansion/2,
    system:goal_expansion/2.

system:term_expansion((:- arithmetic_function(Term)), Clauses) :-
    arith_decl_clauses(Term, Clauses).

system:goal_expansion(Math, MathGoal) :-
    math_goal_expansion(Math, MathGoal).