001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.model;
018
019import javax.xml.bind.annotation.XmlAccessType;
020import javax.xml.bind.annotation.XmlAccessorType;
021import javax.xml.bind.annotation.XmlAttribute;
022import javax.xml.bind.annotation.XmlRootElement;
023
024import org.apache.camel.Expression;
025import org.apache.camel.Predicate;
026import org.apache.camel.Processor;
027import org.apache.camel.model.language.ExpressionDefinition;
028import org.apache.camel.processor.LoopProcessor;
029import org.apache.camel.spi.AsPredicate;
030import org.apache.camel.spi.Metadata;
031import org.apache.camel.spi.RouteContext;
032
033/**
034 * Processes a message multiple times
035 *
036 * @version 
037 */
038@Metadata(label = "eip,routing")
039@XmlRootElement(name = "loop")
040@XmlAccessorType(XmlAccessType.FIELD)
041public class LoopDefinition extends ExpressionNode {
042
043    @XmlAttribute
044    private Boolean copy;
045    @XmlAttribute
046    private Boolean doWhile;
047
048    public LoopDefinition() {
049    }
050
051    public LoopDefinition(Expression expression) {
052        super(expression);
053    }
054
055    public LoopDefinition(Predicate predicate) {
056        super(predicate);
057        setDoWhile(true);
058    }
059
060    public LoopDefinition(ExpressionDefinition expression) {
061        super(expression);
062    }
063
064    /**
065     * Enables copy mode so a copy of the input Exchange is used for each iteration.
066     * @return the builder
067     */
068    public LoopDefinition copy() {
069        setCopy(true);
070        return this;
071    }
072
073    public Boolean getCopy() {
074        return copy;
075    }
076
077    public Boolean getDoWhile() {
078        return doWhile;
079    }
080
081    /**
082     * Enables the while loop that loops until the predicate evaluates to false or null.
083     */
084    public void setDoWhile(Boolean doWhile) {
085        this.doWhile = doWhile;
086    }
087
088    /**
089     * If the copy attribute is true, a copy of the input Exchange is used for each iteration.
090     * That means each iteration will start from a copy of the same message.
091     * <p/>
092     * By default loop will loop the same exchange all over, so each iteration may
093     * have different message content.
094     */
095    public void setCopy(Boolean copy) {
096        this.copy = copy;
097    }
098
099    @Override
100    public String toString() {
101        return "Loop[" + getExpression() + " -> " + getOutputs() + "]";
102    }
103    
104    @Override
105    public String getLabel() {
106        return "loop[" + getExpression() + "]";
107    }
108    
109    @Override
110    public Processor createProcessor(RouteContext routeContext) throws Exception {
111        Processor output = this.createChildProcessor(routeContext, true);
112        boolean isCopy = getCopy() != null && getCopy();
113        boolean isWhile = getDoWhile() != null && getDoWhile();
114
115        Predicate predicate = null;
116        Expression expression = null;
117        if (isWhile) {
118            predicate = getExpression().createPredicate(routeContext);
119        } else {
120            expression = getExpression().createExpression(routeContext);
121        }
122        return new LoopProcessor(output, expression, predicate, isCopy);
123    }
124
125    /**
126     * Expression to define how many times we should loop. Notice the expression is only evaluated once, and should return
127     * a number as how many times to loop. A value of zero or negative means no looping. The loop is like a for-loop fashion,
128     * if you want a while loop, then the dynamic router may be a better choice.
129     */
130    @Override
131    public void setExpression(ExpressionDefinition expression) {
132        // override to include javadoc what the expression is used for
133        super.setExpression(expression);
134    }
135}