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.Metadata;
030import org.apache.camel.spi.RouteContext;
031
032/**
033 * Processes a message multiple times
034 *
035 * @version 
036 */
037@Metadata(label = "eip,routing")
038@XmlRootElement(name = "loop")
039@XmlAccessorType(XmlAccessType.FIELD)
040public class LoopDefinition extends ExpressionNode {
041
042    @XmlAttribute
043    private Boolean copy;
044    @XmlAttribute
045    private Boolean doWhile;
046
047    public LoopDefinition() {
048    }
049
050    public LoopDefinition(Expression expression) {
051        super(expression);
052    }
053
054    public LoopDefinition(Predicate predicate) {
055        super(predicate);
056        setDoWhile(true);
057    }
058
059    public LoopDefinition(ExpressionDefinition expression) {
060        super(expression);
061    }
062
063    /**
064     * Enables copy mode so a copy of the input Exchange is used for each iteration.
065     * @return the builder
066     */
067    public LoopDefinition copy() {
068        setCopy(true);
069        return this;
070    }
071
072    public Boolean getCopy() {
073        return copy;
074    }
075
076    public Boolean getDoWhile() {
077        return doWhile;
078    }
079
080    /**
081     * Enables the while loop that loops until the predicate evaluates to false or null.
082     */
083    public void setDoWhile(Boolean doWhile) {
084        this.doWhile = doWhile;
085    }
086
087    /**
088     * If the copy attribute is true, a copy of the input Exchange is used for each iteration.
089     * That means each iteration will start from a copy of the same message.
090     * <p/>
091     * By default loop will loop the same exchange all over, so each iteration may
092     * have different message content.
093     */
094    public void setCopy(Boolean copy) {
095        this.copy = copy;
096    }
097
098    @Override
099    public String toString() {
100        return "Loop[" + getExpression() + " -> " + getOutputs() + "]";
101    }
102    
103    @Override
104    public String getShortName() {
105        return "loop";
106    }
107
108    @Override
109    public String getLabel() {
110        return "loop[" + getExpression() + "]";
111    }
112    
113    @Override
114    public Processor createProcessor(RouteContext routeContext) throws Exception {
115        Processor output = this.createChildProcessor(routeContext, true);
116        boolean isCopy = getCopy() != null && getCopy();
117        boolean isWhile = getDoWhile() != null && getDoWhile();
118
119        Predicate predicate = null;
120        Expression expression = null;
121        if (isWhile) {
122            predicate = getExpression().createPredicate(routeContext);
123        } else {
124            expression = getExpression().createExpression(routeContext);
125        }
126        return new LoopProcessor(output, expression, predicate, isCopy);
127    }
128
129    /**
130     * Expression to define how many times we should loop. Notice the expression is only evaluated once, and should return
131     * 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,
132     * if you want a while loop, then the dynamic router may be a better choice.
133     */
134    @Override
135    public void setExpression(ExpressionDefinition expression) {
136        // override to include javadoc what the expression is used for
137        super.setExpression(expression);
138    }
139}