| 1 | /* This file is part of the project "Hilbert II" - http://www.qedeq.org |
| 2 | * |
| 3 | * Copyright 2000-2014, Michael Meyling <mime@qedeq.org>. |
| 4 | * |
| 5 | * "Hilbert II" is free software; you can redistribute |
| 6 | * it and/or modify it under the terms of the GNU General Public |
| 7 | * License as published by the Free Software Foundation; either |
| 8 | * version 2 of the License, or (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | */ |
| 15 | |
| 16 | package org.qedeq.kernel.bo.logic.wf; |
| 17 | |
| 18 | import org.qedeq.kernel.bo.logic.common.ExistenceChecker; |
| 19 | import org.qedeq.kernel.bo.logic.common.FunctionKey; |
| 20 | import org.qedeq.kernel.bo.logic.common.PredicateKey; |
| 21 | import org.qedeq.kernel.se.common.RuleKey; |
| 22 | |
| 23 | |
| 24 | /** |
| 25 | * This implementation gives always the answer <code>true</code> to the question |
| 26 | * <em>exists this predicate?</em>. |
| 27 | * |
| 28 | * @author Michael Meyling |
| 29 | */ |
| 30 | public final class EverythingExists implements ExistenceChecker { |
| 31 | |
| 32 | /** One and only instance. */ |
| 33 | private static final ExistenceChecker ALWAYS = new EverythingExists(); |
| 34 | |
| 35 | /** |
| 36 | * Hidden constructor. |
| 37 | */ |
| 38 | private EverythingExists() { |
| 39 | // nothing to do |
| 40 | } |
| 41 | |
| 42 | public boolean predicateExists(final String name, final int arguments) { |
| 43 | return true; |
| 44 | } |
| 45 | |
| 46 | public boolean predicateExists(final PredicateKey predicate) { |
| 47 | return true; |
| 48 | } |
| 49 | |
| 50 | public boolean isInitialPredicate(final PredicateKey predicate) { |
| 51 | return true; |
| 52 | } |
| 53 | |
| 54 | public boolean functionExists(final String name, final int arguments) { |
| 55 | return true; |
| 56 | } |
| 57 | |
| 58 | public boolean functionExists(final FunctionKey function) { |
| 59 | return true; |
| 60 | } |
| 61 | |
| 62 | public boolean isInitialFunction(final FunctionKey predicate) { |
| 63 | return true; |
| 64 | } |
| 65 | |
| 66 | public boolean classOperatorExists() { |
| 67 | return true; |
| 68 | } |
| 69 | |
| 70 | public boolean identityOperatorExists() { |
| 71 | return true; |
| 72 | } |
| 73 | |
| 74 | public String getIdentityOperator() { |
| 75 | return NAME_EQUAL; |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Get one instance of this class. |
| 80 | * |
| 81 | * @return Class instance. |
| 82 | */ |
| 83 | public static final ExistenceChecker getInstance() { |
| 84 | return ALWAYS; |
| 85 | } |
| 86 | |
| 87 | public boolean ruleExists(final RuleKey ruleKey) { |
| 88 | return true; |
| 89 | } |
| 90 | |
| 91 | } |