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 */
017 package org.apache.camel.language.simple;
018
019 import java.util.ArrayList;
020 import java.util.Iterator;
021 import java.util.List;
022 import java.util.regex.Matcher;
023 import java.util.regex.Pattern;
024
025 import org.apache.camel.Exchange;
026 import org.apache.camel.Expression;
027 import org.apache.camel.IsSingleton;
028 import org.apache.camel.Predicate;
029 import org.apache.camel.builder.ExpressionBuilder;
030 import org.apache.camel.builder.PredicateBuilder;
031 import org.apache.camel.builder.ValueBuilder;
032 import org.apache.camel.spi.Language;
033 import org.apache.camel.util.ObjectHelper;
034 import org.apache.commons.logging.Log;
035 import org.apache.commons.logging.LogFactory;
036 import static org.apache.camel.language.simple.SimpleLangaugeOperator.*;
037
038 /**
039 * Abstract base class for Simple languages.
040 */
041 public abstract class SimpleLanguageSupport implements Language, IsSingleton {
042
043 protected static final Pattern PATTERN = Pattern.compile(
044 "^\\$\\{(.+)\\}\\s+(==|>|>=|<|<=|!=|contains|not contains|regex|not regex|in|not in)\\s+(.+)$");
045 protected final Log log = LogFactory.getLog(getClass());
046
047 public Predicate createPredicate(String expression) {
048 return PredicateBuilder.toPredicate(createExpression(expression));
049 }
050
051 public Expression createExpression(String expression) {
052 Matcher matcher = PATTERN.matcher(expression);
053 if (matcher.matches()) {
054 if (log.isDebugEnabled()) {
055 log.debug("Expression is evaluated as operator expression: " + expression);
056 }
057 return createOperatorExpression(matcher, expression);
058 } else if (expression.indexOf("${") >= 0) {
059 if (log.isDebugEnabled()) {
060 log.debug("Expression is evaluated as complex expression: " + expression);
061 }
062 return createComplexConcatExpression(expression);
063 } else {
064 if (log.isDebugEnabled()) {
065 log.debug("Expression is evaluated as simple expression: " + expression);
066 }
067 return createSimpleExpression(expression);
068 }
069 }
070
071 private Expression createOperatorExpression(final Matcher matcher, final String expression) {
072 final Expression left = createSimpleExpression(matcher.group(1));
073 final SimpleLangaugeOperator operator = asOperator(matcher.group(2));
074
075 // the right hand side expression can either be a constant expression wiht ' '
076 // or another simple expression using ${ } placeholders
077 String text = matcher.group(3);
078
079 final Expression right;
080 final Expression rightConverted;
081 // special null handling
082 if ("null".equals(text)) {
083 right = createConstantExpression(null);
084 rightConverted = right;
085 } else {
086 // text can either be a constant enclosed by ' ' or another expression using ${ } placeholders
087 String constant = ObjectHelper.between(text, "'", "'");
088 if (constant == null) {
089 // if no ' ' around then fallback to the text itself
090 constant = text;
091 }
092 String simple = ObjectHelper.between(text, "${", "}");
093
094 right = simple != null ? createSimpleExpression(simple) : createConstantExpression(constant);
095 // to support numeric comparions using > and < operators we must convert the right hand side
096 // to the same type as the left
097 rightConverted = ExpressionBuilder.convertToExpression(right, left);
098 }
099
100 return new Expression() {
101 public Object evaluate(final Exchange exchange) {
102 Predicate predicate = null;
103 if (operator == EQ) {
104 predicate = PredicateBuilder.isEqualTo(left, rightConverted);
105 } else if (operator == GT) {
106 predicate = PredicateBuilder.isGreaterThan(left, rightConverted);
107 } else if (operator == GTE) {
108 predicate = PredicateBuilder.isGreaterThanOrEqualTo(left, rightConverted);
109 } else if (operator == LT) {
110 predicate = PredicateBuilder.isLessThan(left, rightConverted);
111 } else if (operator == LTE) {
112 predicate = PredicateBuilder.isLessThanOrEqualTo(left, rightConverted);
113 } else if (operator == NOT) {
114 predicate = PredicateBuilder.isNotEqualTo(left, rightConverted);
115 } else if (operator == CONTAINS || operator == NOT_CONTAINS) {
116 predicate = PredicateBuilder.contains(left, rightConverted);
117 if (operator == NOT_CONTAINS) {
118 predicate = PredicateBuilder.not(predicate);
119 }
120 } else if (operator == REGEX || operator == NOT_REGEX) {
121 // reg ex should use String pattern, so we evalute the right hand side as a String
122 predicate = PredicateBuilder.regex(left, right.evaluate(exchange, String.class));
123 if (operator == NOT_REGEX) {
124 predicate = PredicateBuilder.not(predicate);
125 }
126 } else if (operator == IN || operator == NOT_IN) {
127 // okay the in operator is a bit more complex as we need to build a list of values
128 // from the right handside expression.
129 // each element on the right handside must be separated by comma (default for create iterator)
130 Iterator it = ObjectHelper.createIterator(right.evaluate(exchange));
131 List<Object> values = new ArrayList<Object>();
132 while (it.hasNext()) {
133 values.add(it.next());
134 }
135 // then reuse value builder to create the in predicate with the list of values
136 ValueBuilder vb = new ValueBuilder(left);
137 predicate = vb.in(values.toArray());
138 if (operator == NOT_IN) {
139 predicate = PredicateBuilder.not(predicate);
140 }
141 }
142
143 if (predicate == null) {
144 throw new IllegalArgumentException("Unsupported operator: " + operator + " for expression: " + expression);
145 }
146 return predicate.matches(exchange);
147 }
148
149 public <T> T evaluate(Exchange exchange, Class<T> type) {
150 Object result = evaluate(exchange);
151 return exchange.getContext().getTypeConverter().convertTo(type, result);
152 }
153
154 @Override
155 public String toString() {
156 return left + " " + operator + " " + right;
157 }
158 };
159 }
160
161 protected Expression createComplexConcatExpression(String expression) {
162 List<Expression> results = new ArrayList<Expression>();
163
164 int pivot = 0;
165 int size = expression.length();
166 while (pivot < size) {
167 int idx = expression.indexOf("${", pivot);
168 if (idx < 0) {
169 results.add(createConstantExpression(expression, pivot, size));
170 break;
171 } else {
172 if (pivot < idx) {
173 results.add(createConstantExpression(expression, pivot, idx));
174 }
175 pivot = idx + 2;
176 int endIdx = expression.indexOf("}", pivot);
177 if (endIdx < 0) {
178 throw new IllegalArgumentException("Expecting } but found end of string for simple expression: " + expression);
179 }
180 String simpleText = expression.substring(pivot, endIdx);
181
182 Expression simpleExpression = createSimpleExpression(simpleText);
183 results.add(simpleExpression);
184 pivot = endIdx + 1;
185 }
186 }
187 return ExpressionBuilder.concatExpression(results, expression);
188 }
189
190 protected Expression createConstantExpression(String expression, int start, int end) {
191 return ExpressionBuilder.constantExpression(expression.substring(start, end));
192 }
193
194 protected Expression createConstantExpression(String expression) {
195 return ExpressionBuilder.constantExpression(expression);
196 }
197
198 /**
199 * Creates the simple expression based on the extracted content from the ${ } place holders
200 *
201 * @param expression the content between ${ and }
202 * @return the expression
203 */
204 protected abstract Expression createSimpleExpression(String expression);
205
206 protected String ifStartsWithReturnRemainder(String prefix, String text) {
207 if (text.startsWith(prefix)) {
208 String remainder = text.substring(prefix.length());
209 if (remainder.length() > 0) {
210 return remainder;
211 }
212 }
213 return null;
214 }
215 }