%-------------------------------------------------------------------------%
%
% Licensed to the Apache Software Foundation (ASF) under one or more
% contributor license agreements.  See the NOTICE file distributed with
% this work for additional information regarding copyright ownership.
% The ASF licenses this file to You under the Apache License, Version 2.0
% (the "License"); you may not use this file except in compliance with
% the License.  You may obtain a copy of the License at
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%      http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS,
% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
% See the License for the specific language governing permissions and
% limitations under the License.
%
%-------------------------------------------------------------------------%
:- module rdfs.

:- interface.
:- import_module string.
:- import_module graph.

:- func rdfs(string) = string is det.

:- pred property(graph, string, string, string).
:- mode property(in, in, in, in) is semidet.
:- mode property(in, in, in, out) is nondet.
:- mode property(in, in, out, in) is nondet.
:- mode property(in, out, in, in) is nondet.
:- mode property(in, in, out, out) is nondet.
:- mode property(in, out, out, out) is multi.

:- pred instance(graph, string, string).
:- mode instance(in, in, in) is semidet.
:- mode instance(in, in, out) is nondet.
:- mode instance(in, out, in) is nondet.
:- mode instance(in, out, out) is multi.

:- pred class(graph, string).
:- mode class(in, in) is semidet.
:- mode class(in, out) is nondet.

:- pred range(graph, string, string).
:- mode range(in, in, in) is semidet.
:- mode range(in, in, out) is nondet.
:- mode range(in, out, in) is nondet.
:- mode range(in, out, out) is nondet.

:- pred domain(graph, string, string).
:- mode domain(in, in, in) is semidet.
:- mode domain(in, in, out) is nondet.
:- mode domain(in, out, in) is nondet.

%-------------------------------------------------------------------------%
:- implementation.
:- import_module rdf.

rdfs(S) = "http://www.w3.org/2000/01/rdf-schema#" ++ S.

:- pred builtin(string, string, string).
:- mode builtin(out, out, out) is multi.

:- pred contains(graph, string, string, string).
:- mode contains(in, out, out, out) is multi.

contains(G, S, P, O) :-
        builtin(S, P, O);
        graph.contains(G, S, P, O).

property(G, S, P, O) :-
        rdfs.contains(G, S, P, O).

property(G, S, P, O) :-
	rdfs.contains(G, X, rdfs("subPropertyOf"), P),
        property(G, S, X, O).

instance(G, R, C) :-
        property(G, R, rdf("type"), C).

%-------------------------------------------------------------------------%
%
% 2.1 rdfs:Resource
%
% All things described by RDF are called resources, and are instances of
% the class rdfs:Resource. This is the class of everything. All other
% classes are subclasses of this class.

instance(G, R, rdfs("Resource")) :-
        property(G, R, _, _);
        property(G, _, R, _);
        property(G, _, _, R).

% rdfs:Resource is an instance of rdfs:Class.

builtin(rdfs("Resource"), rdf("type"), rdfs("Class")).

%-------------------------------------------------------------------------%
%
% 2.2 rdfs:Class
%
% This is the class of resources that are RDF classes.

class(G, C) :-
        instance(G, C, rdfs("Class")).

% rdfs:Class is an instance of rdfs:Class.

builtin(rdfs("Class"), rdf("type"), rdfs("Class")).

%-------------------------------------------------------------------------%
%
% 2.6 rdf:Property
%
% rdf:Property is the class of RDF properties.
% rdf:Property is an instance of rdfs:Class.

builtin(rdf("Property"), rdf("type"), rdfs("Class")).

%-------------------------------------------------------------------------%
%
% 3.1 rdfs:range
%
% rdfs:range is an instance of rdf:Property that is used to state that the
% values of a property are instances of one or more classes.

builtin(rdfs("range"), rdf("type"), rdf("Property")).

range(G, Property, C) :-
        property(G, Property, rdfs("range"), C).

% The triple
%
%     P rdfs:range C
%
% states that P is an instance of the class rdf:Property, that C is an
% instance of the class rdfs:Class and that the resources denoted by the
% objects of triples whose predicate is P are instances of the class C.

instance(G, P, rdf("Property")) :-
        range(G, P, _).

instance(G, C, rdfs("Class")) :-
        range(G, _, C).

instance(G, O, C) :-
        property(G, _, P, O),
        range(G, P, C).

% Where P has more than one rdfs:range property, then the resources
% denoted by the objects of triples with predicate P are instances of all
% the classes stated by the rdfs:range properties.
%
% The rdfs:range property can be applied to itself. The rdfs:range of
% rdfs:range is the class rdfs:Class. This states that any resource that
% is the value of an rdfs:range property is an instance of rdfs:Class.

builtin(rdfs("range"), rdfs("range"), rdfs("Class")).

% The rdfs:range property is applied to properties. This can be
% represented in RDF using the rdfs:domain property. The rdfs:domain of
% rdfs:range is the class rdf:Property. This states that any resource
% with an rdfs:range property is an instance of rdf:Property.

builtin(rdfs("range"), rdfs("domain"), rdf("Property")).

%-------------------------------------------------------------------------%
%
% 3.2 rdfs:domain
%
% rdfs:domain is an instance of rdf:Property that is used to state that
% any resource that has a given property is an instance of one or more
% classes.

builtin(rdfs("domain"), rdf("type"), rdf("Property")).

instance(G, R, C) :-
        property(G, R, P, _),
        domain(G, P, C).

% A triple of the form:
%
%     P rdfs:domain C
%
% states that P is an instance of the class rdf:Property, that C is a
% instance of the class rdfs:Class and that the resources denoted by the
% subjects of triples whose predicate is P are instances of the class C.

domain(G, P, C) :-
        property(G, P, rdfs("domain"), C).

% Where a property P has more than one rdfs:domain property, then the
% resources denoted by subjects of triples with predicate P are instances
% of all the classes stated by the rdfs:domain properties.
%
% The rdfs:domain property may be applied to itself. The rdfs:domain of
% rdfs:domain is the class rdf:Property. This states that any resource
% with an rdfs:domain property is an instance of rdf:Property.

builtin(rdfs("domain"), rdfs("domain"), rdf("Property")).

% The rdfs:range of rdfs:domain is the class rdfs:Class. This states that
% any resource that is the value of an rdfs:domain property is an instance
% of rdfs:Class.

builtin(rdfs("domain"), rdfs("range"), rdfs("Class")).

%-------------------------------------------------------------------------%
%
% 3.3 rdf:type
%
% rdf:type is an instance of rdf:Property that is used to state that a
% resource is an instance of a class.

builtin(rdf("type"), rdf("type"), rdf("Property")).

% A triple of the form:
%
%     R rdf:type C
%
% states that C is an instance of rdfs:Class and R is an instance of C.

instance(G, R, C) :-
        property(G, R, rdf("type"), C).

% The rdfs:domain of rdf:type is rdfs:R. The rdfs:range of
% rdf:type is rdfs:Class.

builtin(rdf("type"), rdfs("domain"), rdfs("Resource")).
builtin(rdf("type"), rdfs("range"), rdfs("Class")).

%-------------------------------------------------------------------------%
%
% 3.4 rdfs:subClassOf
%
% The property rdfs:subClassOf is an instance of rdf:Property that is used
% to state that all the instances of one class are instances of another.

builtin(rdfs("subClassOf"), rdf("type"), rdf("Property")).

instance(G, R, C1) :-
        property(G, C2, rdfs("subClassOf"), C1),
        instance(G, R, C2).

% A triple of the form:
%
%     C1 rdfs:subClassOf C2
%
% states that C1 is an instance of rdfs:Class, C2 is an instance of
% rdfs:Class and C1 is a subclass of C2. The rdfs:subClassOf property
% is transitive.

instance(G, C1, rdfs("Class")) :-
        property(G, _, rdfs("subClassOf"), C1).

instance(G, C2, rdfs("Class")) :-
        property(G, C2, rdfs("subClassOf"), _).

% The rdfs:domain of rdfs:subClassOf is rdfs:Class. The rdfs:range of
% rdfs:subClassOf is rdfs:Class.

builtin(rdfs("subClassOf"), rdfs("domain"), rdfs("Class")).
builtin(rdfs("subClassOf"), rdfs("range"), rdfs("Class")).

%-------------------------------------------------------------------------%
%
% 3.5 rdfs:subPropertyOf
%
% The property rdfs:subPropertyOf is an instance of rdf:Property that is
% used to state that all resources related by one property are also
% related by another.

builtin(rdfs("subPropertyOf"), rdf("type"), rdf("Property")).

% A triple of the form:
%
%     P1 rdfs:subPropertyOf P2
%
% states that P1 is an instance of rdf:Property, P2 is an instance of
% rdf:Property and P1 is a subproperty of P2. The rdfs:subPropertyOf
% property is transitive.

instance(G, P1, rdf("Property")) :-
        property(G, P1, rdfs("subPropertyOf"), _).

instance(G, P2, rdf("Property")) :-
        property(G, _, rdfs("subPropertyOf"), P2).

% The rdfs:domain of rdfs:subPropertyOf is rdf:Property. The rdfs:range
% of rdfs:subPropertyOf is rdf:Property.

builtin(rdfs("subPropertyOf"), rdfs("domain"), rdf("Property")).
builtin(rdfs("subPropertyOf"), rdfs("range"), rdf("Property")).