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ActiveMQ example source code file (UnaryExpression.java)

This example ActiveMQ source code file (UnaryExpression.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

bigdecimal, booleanexpression, booleanexpression, booleanunaryexpression, booleanunaryexpression, expression, in, jmsexception, math, not, object, object, string, string, unaryexpression, util

The ActiveMQ UnaryExpression.java source code

/**
 * 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
 *
 *      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.
 */
package org.apache.activemq.filter;

import java.math.BigDecimal;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;

import javax.jms.JMSException;

/**
 * An expression which performs an operation on two expression values
 * 
 * 
 */
public abstract class UnaryExpression implements Expression {

    private static final BigDecimal BD_LONG_MIN_VALUE = BigDecimal.valueOf(Long.MIN_VALUE);
    protected Expression right;

    public UnaryExpression(Expression left) {
        this.right = left;
    }

    public static Expression createNegate(Expression left) {
        return new UnaryExpression(left) {
            public Object evaluate(MessageEvaluationContext message) throws JMSException {
                Object rvalue = right.evaluate(message);
                if (rvalue == null) {
                    return null;
                }
                if (rvalue instanceof Number) {
                    return negate((Number)rvalue);
                }
                return null;
            }

            public String getExpressionSymbol() {
                return "-";
            }
        };
    }

    public static BooleanExpression createInExpression(PropertyExpression right, List<Object> elements, final boolean not) {

        // Use a HashSet if there are many elements.
        Collection<Object> t;
        if (elements.size() == 0) {
            t = null;
        } else if (elements.size() < 5) {
            t = elements;
        } else {
            t = new HashSet<Object>(elements);
        }
        final Collection inList = t;

        return new BooleanUnaryExpression(right) {
            public Object evaluate(MessageEvaluationContext message) throws JMSException {

                Object rvalue = right.evaluate(message);
                if (rvalue == null) {
                    return null;
                }
                if (rvalue.getClass() != String.class) {
                    return null;
                }

                if ((inList != null && inList.contains(rvalue)) ^ not) {
                    return Boolean.TRUE;
                } else {
                    return Boolean.FALSE;
                }

            }

            public String toString() {
                StringBuffer answer = new StringBuffer();
                answer.append(right);
                answer.append(" ");
                answer.append(getExpressionSymbol());
                answer.append(" ( ");

                int count = 0;
                for (Iterator i = inList.iterator(); i.hasNext();) {
                    Object o = (Object)i.next();
                    if (count != 0) {
                        answer.append(", ");
                    }
                    answer.append(o);
                    count++;
                }

                answer.append(" )");
                return answer.toString();
            }

            public String getExpressionSymbol() {
                if (not) {
                    return "NOT IN";
                } else {
                    return "IN";
                }
            }
        };
    }

    abstract static class BooleanUnaryExpression extends UnaryExpression implements BooleanExpression {
        public BooleanUnaryExpression(Expression left) {
            super(left);
        }

        public boolean matches(MessageEvaluationContext message) throws JMSException {
            Object object = evaluate(message);
            return object != null && object == Boolean.TRUE;
        }
    };

    public static BooleanExpression createNOT(BooleanExpression left) {
        return new BooleanUnaryExpression(left) {
            public Object evaluate(MessageEvaluationContext message) throws JMSException {
                Boolean lvalue = (Boolean)right.evaluate(message);
                if (lvalue == null) {
                    return null;
                }
                return lvalue.booleanValue() ? Boolean.FALSE : Boolean.TRUE;
            }

            public String getExpressionSymbol() {
                return "NOT";
            }
        };
    }

    public static BooleanExpression createXPath(final String xpath) {
        return new XPathExpression(xpath);
    }

    public static BooleanExpression createXQuery(final String xpath) {
        return new XQueryExpression(xpath);
    }

    public static BooleanExpression createBooleanCast(Expression left) {
        return new BooleanUnaryExpression(left) {
            public Object evaluate(MessageEvaluationContext message) throws JMSException {
                Object rvalue = right.evaluate(message);
                if (rvalue == null) {
                    return null;
                }
                if (!rvalue.getClass().equals(Boolean.class)) {
                    return Boolean.FALSE;
                }
                return ((Boolean)rvalue).booleanValue() ? Boolean.TRUE : Boolean.FALSE;
            }

            public String toString() {
                return right.toString();
            }

            public String getExpressionSymbol() {
                return "";
            }
        };
    }

    private static Number negate(Number left) {
        Class clazz = left.getClass();
        if (clazz == Integer.class) {
            return new Integer(-left.intValue());
        } else if (clazz == Long.class) {
            return new Long(-left.longValue());
        } else if (clazz == Float.class) {
            return new Float(-left.floatValue());
        } else if (clazz == Double.class) {
            return new Double(-left.doubleValue());
        } else if (clazz == BigDecimal.class) {
            // We ussually get a big deciamal when we have Long.MIN_VALUE
            // constant in the
            // Selector. Long.MIN_VALUE is too big to store in a Long as a
            // positive so we store it
            // as a Big decimal. But it gets Negated right away.. to here we try
            // to covert it back
            // to a Long.
            BigDecimal bd = (BigDecimal)left;
            bd = bd.negate();

            if (BD_LONG_MIN_VALUE.compareTo(bd) == 0) {
                return Long.valueOf(Long.MIN_VALUE);
            }
            return bd;
        } else {
            throw new RuntimeException("Don't know how to negate: " + left);
        }
    }

    public Expression getRight() {
        return right;
    }

    public void setRight(Expression expression) {
        right = expression;
    }

    /**
     * @see java.lang.Object#toString()
     */
    public String toString() {
        return "(" + getExpressionSymbol() + " " + right.toString() + ")";
    }

    /**
     * TODO: more efficient hashCode()
     * 
     * @see java.lang.Object#hashCode()
     */
    public int hashCode() {
        return toString().hashCode();
    }

    /**
     * TODO: more efficient hashCode()
     * 
     * @see java.lang.Object#equals(java.lang.Object)
     */
    public boolean equals(Object o) {

        if (o == null || !this.getClass().equals(o.getClass())) {
            return false;
        }
        return toString().equals(o.toString());

    }

    /**
     * Returns the symbol that represents this binary expression. For example,
     * addition is represented by "+"
     * 
     * @return
     */
    public abstract String getExpressionSymbol();

}

Other ActiveMQ examples (source code examples)

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