001    /*
002     * Copyright 2002-2004 the original author or authors.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     *      http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    package org.springframework.rules.constraint;
017    
018    /**
019     * Type-safe enums for various conditional or logical operators.
020     *
021     * @author Keith Donald
022     */
023    public abstract class LogicalOperator extends Operator {
024    
025            /**
026             * The <code>AND</code> operator
027             */
028            public static final LogicalOperator AND = new LogicalOperator("and", "&&") {
029                    public CompoundConstraint createConstraint() {
030                            return new And();
031                    }
032            };
033    
034            /**
035             * The <code>OR</code> operator
036             */
037            public static final LogicalOperator OR = new LogicalOperator("or", "||") {
038                    public CompoundConstraint createConstraint() {
039                            return new Or();
040                    }
041            };
042    
043      /**
044       * The <code>XOR</code> operator
045       */
046      public static final LogicalOperator XOR = new LogicalOperator("xor", "^") {
047        public CompoundConstraint createConstraint() {
048          return new XOr();
049        }
050      };
051    
052      private LogicalOperator(String code, String symbol) {
053                    super(code, symbol);
054            }
055    
056            public CompoundConstraint createConstraint() {
057                    throw new UnsupportedOperationException();
058            }
059    
060    }