406 lines
12 KiB
Prolog
406 lines
12 KiB
Prolog
/* $Id$
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Part of SWI-Prolog
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Author: Jan Wielemaker
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E-mail: wielemak@science.uva.nl
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WWW: http://www.swi-prolog.org
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Copyright (C): 2007, University of Amsterdam
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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As a special exception, if you link this library with other files,
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compiled with a Free Software compiler, to produce an executable, this
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library does not by itself cause the resulting executable to be covered
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by the GNU General Public License. This exception does not however
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invalidate any other reasons why the executable file might be covered by
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the GNU General Public License.
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*/
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:- module((record),
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[ (record)/1, % +Record
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current_record/2, % ?Name, ?Term
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op(1150, fx, record)
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]).
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:- use_module(library(error)).
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/** <module> Access compound arguments by name
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This module creates a set of predicates to create a default instance,
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access and modify records represented as a compound term.
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The full documentation is with record/1, which must be used as a
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_directive_. Here is a simple example declaration and some calls.
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==
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:- record point(x:integer=0, y:integer=0).
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default_point(Point),
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point_x(Point, X),
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set_x_of_point(10, Point, Point1),
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make_point([y(20)], YPoint),
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==
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@author Jan Wielemaker
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@author Richard O'Keefe
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*/
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:- multifile
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error:has_type/2.
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error:has_type(record(M:Name), X) :-
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current_record(Name, M, _, X, IsX), !,
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call(M:IsX).
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%% record(+RecordDef)
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%
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% Define access predicates for a compound-term. RecordDef is of
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% the form <constructor>(<argument>, ...), where each argument
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% is of the form:
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%
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% * <name>[:<type>][=<default>]
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%
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% Used a directive, =|:- record Constructor(Arg, ...)|= is expanded
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% info the following predicates:
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%
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% * <constructor>_<name>(Record, Value)
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% * default_<constructor>(-Record)
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% * is_<constructor>(@Term)
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% * make_<constructor>(+Fields, -Record)
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% * make_<constructor>(+Fields, -Record, -RestFields)
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% * set_<name>_of_<constructor>(+Value, +OldRecord, -New)
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% * set_<name>_of_<constructor>(+Value, !Record)
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% * nb_set_<name>_of_<constructor>(+Value, !Record)
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% * set_<constructor>_fields(+Fields, +Record0, -Record).
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% * set_<constructor>_fields(+Fields, +Record0, -Record, -RestFields).
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% * set_<constructor>_field(+Field, +Record0, -Record).
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% * user:current_record(:<constructor>)
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record(Record) :-
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throw(error(context_error(nodirective, record(Record)), _)).
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%% compile_records(+RecordsDefs, -Clauses) is det.
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%
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% Compile a record specification into a list of clauses.
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compile_records(Spec, Clauses) :-
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phrase(compile_records(Spec), Clauses).
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% maplist(portray_clause, Clauses).
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compile_records(Var) -->
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{ var(Var), !,
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instantiation_error(Var)
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}.
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compile_records((A,B)) -->
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compile_record(A),
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compile_records(B).
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compile_records(A) -->
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compile_record(A).
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%% compile_record(+Record)// is det.
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%
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% Create clauses for Record.
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compile_record(RecordDef) -->
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{ RecordDef =.. [Constructor|Args],
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defaults(Args, Defs, TypedArgs),
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types(TypedArgs, Names, Types),
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atom_concat(default_, Constructor, DefName),
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DefRecord =.. [Constructor|Defs],
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DefClause =.. [DefName,DefRecord],
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length(Names, Arity)
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},
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[ DefClause ],
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access_predicates(Names, 1, Arity, Constructor),
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set_predicates(Names, 1, Arity, Types, Constructor),
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set_field_predicates(Names, 1, Arity, Types, Constructor),
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make_predicate(Constructor),
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is_predicate(Constructor, Types),
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current_clause(RecordDef).
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:- meta_predicate
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current_record(:).
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:- multifile
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current_record/5. % Name, Module, Term, X, IsX
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%% current_record(?Name, :Term)
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%
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% True if Name is the name of a record defined in the module
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% associated with Term and Term is the user-provided record
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% declaration.
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current_record(Name, M:Term) :-
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current_record(Name, M, Term, _, _).
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current_clause(RecordDef) -->
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{ prolog_load_context(module, M),
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functor(RecordDef, Name, _),
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atom_concat(is_, Name, IsName),
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IsX =.. [IsName, X]
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},
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[ (record):current_record(Name, M, RecordDef, X, IsX)
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].
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%% make_predicate(+Constructor)// is det.
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%
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% Creates the make_<constructor>(+Fields, -Record) predicate. This
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% looks like this:
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%
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% ==
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% make_<constructor>(Fields, Record) :-
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% make_<constructor>(Fields, Record, [])
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%
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% make_<constructor>(Fields, Record, RestFields) :-
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% default_<constructor>(Record0),
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% set_<constructor>_fields(Fields, Record0, Record, RestFields).
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%
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% set_<constructor>_fields(Fields, Record0, Record) :-
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% set_<constructor>_fields(Fields, Record0, Record, []).
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%
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% set_<constructor>_fields([], Record, Record, []).
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% set_<constructor>_fields([H|T], Record0, Record, RestFields) :-
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% ( set_<constructor>_field(H, Record0, Record1)
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% -> set_<constructor>_fields(T, Record1, Record, RestFields)
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% ; RestFields = [H|RF],
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% set_<constructor>_fields(T, Record0, Record, RF)
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% ).
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%
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% set_<constructor>_field(<name1>(Value), Record0, Record).
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% ...
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% ==
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make_predicate(Constructor) -->
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{ atomic_list_concat([make_, Constructor], MakePredName),
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atomic_list_concat([default_, Constructor], DefPredName),
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atomic_list_concat([set_, Constructor, '_fields'], SetFieldsName),
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atomic_list_concat([set_, Constructor, '_field'], SetFieldName),
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MakeHead3 =.. [MakePredName, Fields, Record],
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MakeHead4 =.. [MakePredName, Fields, Record, []],
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MakeClause3 = (MakeHead3 :- MakeHead4),
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MakeHead =.. [MakePredName, Fields, Record, RestFields],
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DefGoal =.. [DefPredName, Record0],
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SetGoal =.. [SetFieldsName, Fields, Record0, Record, RestFields],
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MakeClause = (MakeHead :- DefGoal, SetGoal),
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SetHead3 =.. [SetFieldsName, Fields, R0, R],
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SetHead4 =.. [SetFieldsName, Fields, R0, R, []],
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SetClause0 = (SetHead3 :- SetHead4),
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SetClause1 =.. [SetFieldsName, [], R, R, []],
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SetHead2 =.. [SetFieldsName, [H|T], R0, R, RF],
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SetGoal2a =.. [SetFieldName, H, R0, R1],
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SetGoal2b =.. [SetFieldsName, T, R1, R, RF],
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SetGoal2c =.. [SetFieldsName, T, R0, R, RF1],
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SetClause2 = (SetHead2 :- (SetGoal2a -> SetGoal2b ; RF=[H|RF1], SetGoal2c))
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},
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[ MakeClause3, MakeClause, SetClause0, SetClause1, SetClause2 ].
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%% is_predicate(+Constructor, +Types)// is det.
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%
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% Create a clause that tests for a given record type.
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is_predicate(Constructor, Types) -->
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{ type_checks(Types, Vars, Body0),
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clean_body(Body0, Body),
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Term =.. [Constructor|Vars],
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atom_concat(is_, Constructor, Name),
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Head1 =.. [Name,Var],
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Head2 =.. [Name,Term]
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},
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[ (Head1 :- var(Var), !, fail) ],
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( { Body == true }
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-> [ Head2 ]
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; [ (Head2 :- Body) ]
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).
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type_checks([], [], true).
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type_checks([any|T], [_|Vars], Body) :-
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type_checks(T, Vars, Body).
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type_checks([Type|T], [V|Vars], (Goal, Body)) :-
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type_goal(Type, V, Goal),
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type_checks(T, Vars, Body).
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%% type_goal(+Type, +Var, -BodyTerm) is det.
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%
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% Inline type checking calls.
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type_goal(Type, Var, Body) :-
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defined_type(Type, Var, Body), !.
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type_goal(record(Record), Var, Body) :- !,
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atom_concat(is_, Record, Pred),
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Body =.. [Pred,Var].
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type_goal(Record, Var, Body) :-
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atom(Record), !,
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atom_concat(is_, Record, Pred),
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Body =.. [Pred,Var].
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type_goal(Type, _, _) :-
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domain_error(type, Type).
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defined_type(Type, Var, error:Body) :-
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clause(error:has_type(Type, Var), Body).
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clean_body(M:(A0,B0), G) :- !,
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clean_body(M:A0, A),
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clean_body(M:B0, B),
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clean_body((A,B), G).
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clean_body((A0,true), A) :- !,
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clean_body(A0, A).
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clean_body((true,A0), A) :- !,
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clean_body(A0, A).
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clean_body((A0,B0), (A,B)) :-
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clean_body(A0, A),
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clean_body(B0, B).
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clean_body(_:A, A) :-
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predicate_property(A, built_in), !.
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clean_body(A, A).
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%% access_predicates(+Names, +Idx0, +Arity, +Constructor)// is det.
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%
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% Create the <constructor>_<name>(Record, Value) predicates.
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access_predicates([], _, _, _) -->
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[].
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access_predicates([Name|NT], I, Arity, Constructor) -->
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{ atomic_list_concat([Constructor, '_', Name], PredName),
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functor(Record, Constructor, Arity),
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arg(I, Record, Value),
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Clause =.. [PredName, Record, Value],
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I2 is I + 1
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},
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[Clause],
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access_predicates(NT, I2, Arity, Constructor).
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%% set_predicates(+Names, +Idx0, +Arity, +Types, +Constructor)// is det.
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%
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% Create the clauses
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%
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% * set_<name>_of_<constructor>(Value, Old, New)
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% * set_<name>_of_<constructor>(Value, Record)
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set_predicates([], _, _, _, _) -->
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[].
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set_predicates([Name|NT], I, Arity, [Type|TT], Constructor) -->
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{ atomic_list_concat(['set_', Name, '_of_', Constructor], PredName),
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atomic_list_concat(['nb_set_', Name, '_of_', Constructor], NBPredName),
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length(Args, Arity),
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replace_nth(I, Args, Value, NewArgs),
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Old =.. [Constructor|Args],
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New =.. [Constructor|NewArgs],
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Head =.. [PredName, Value, Old, New],
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SetHead =.. [PredName, Value, Term],
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NBSetHead =.. [NBPredName, Value, Term],
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( Type == any
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-> Clause = Head,
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SetClause = (SetHead :- setarg(I, Term, Value)),
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NBSetClause = (NBSetHead :- nb_setarg(I, Term, Value))
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; type_check(Type, Value, MustBe),
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Clause = (Head :- MustBe),
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SetClause = (SetHead :- MustBe,
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setarg(I, Term, Value)),
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NBSetClause = (NBSetHead :- MustBe,
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nb_setarg(I, Term, Value))
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),
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I2 is I + 1
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},
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[ Clause, SetClause, NBSetClause ],
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set_predicates(NT, I2, Arity, TT, Constructor).
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type_check(Type, Value, must_be(Type, Value)) :-
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defined_type(Type, Value, _), !.
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type_check(record(Spec), Value, must_be(record(M:Name), Value)) :- !,
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prolog_load_context(module, C),
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strip_module(C:Spec, M, Name).
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type_check(Atom, Value, Check) :-
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atom(Atom), !,
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type_check(record(Atom), Value, Check).
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%% set_field_predicates(+Names, +Idx0, +Arity, +Types, +Constructor)// is det.
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%
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% Create the clauses
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%
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% * set_<constructor>_field(<name>(Value), Old, New)
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set_field_predicates([], _, _, _, _) -->
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[].
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set_field_predicates([Name|NT], I, Arity, [Type|TT], Constructor) -->
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{ atomic_list_concat(['set_', Constructor, '_field'], FieldPredName),
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length(Args, Arity),
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replace_nth(I, Args, Value, NewArgs),
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Old =.. [Constructor|Args],
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New =.. [Constructor|NewArgs],
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NameTerm =.. [Name, Value],
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SetFieldHead =.. [FieldPredName, NameTerm, Old, New],
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( Type == any
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-> SetField = SetFieldHead
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; type_check(Type, Value, MustBe),
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SetField = (SetFieldHead :- MustBe)
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),
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I2 is I + 1
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},
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[ SetField ],
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set_field_predicates(NT, I2, Arity, TT, Constructor).
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%% replace_nth(+Index, +List, +Element, -NewList) is det.
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%
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% Replace the Nth (1-based) element of a list.
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replace_nth(1, [_|T], V, [V|T]) :- !.
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replace_nth(I, [H|T0], V, [H|T]) :-
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I2 is I - 1,
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replace_nth(I2, T0, V, T).
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%% defaults(+ArgsSpecs, -Defaults, -Args)
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%
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% Strip the default specification from the argument specification.
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defaults([], [], []).
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defaults([Arg=Default|T0], [Default|TD], [Arg|TA]) :- !,
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defaults(T0, TD, TA).
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defaults([Arg|T0], [_|TD], [Arg|TA]) :-
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defaults(T0, TD, TA).
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%% types(+ArgsSpecs, -Defaults, -Args)
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%
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% Strip the default specification from the argument specification.
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types([], [], []).
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types([Name:Type|T0], [Name|TN], [Type|TT]) :- !,
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must_be(atom, Name),
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types(T0, TN, TT).
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types([Name|T0], [Name|TN], [any|TT]) :-
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must_be(atom, Name),
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types(T0, TN, TT).
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/*******************************
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* EXPANSION *
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*******************************/
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:- multifile
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system:term_expansion/2.
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:- dynamic
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system:term_expansion/2.
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system:term_expansion((:- record(Record)), Clauses) :-
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compile_records(Record, Clauses).
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