Moved synapse expression to an isolated package

modules/core/pom.xml

@@ -145,45 +145,6 @@
 					</execution>
 				</executions>
 			</plugin>
-			<plugin>
-				<groupId>org.antlr</groupId>
-				<artifactId>antlr4-maven-plugin</artifactId>
-				<executions>
-					<execution>
-						<id>antlr</id>
-						<phase>generate-sources</phase>
-						<goals>
-							<goal>antlr4</goal>
-						</goals>
-						<configuration>
-							<sourceDirectory>${project.basedir}/src/main/antlr4</sourceDirectory>
-							<arguments>
-								<argument>-visitor</argument>
-							</arguments>
-						</configuration>
-					</execution>
-				</executions>
-			</plugin>
-			<!-- Build Helper Maven Plugin -->
-			<plugin>
-				<groupId>org.codehaus.mojo</groupId>
-				<artifactId>build-helper-maven-plugin</artifactId>
-				<executions>
-					<execution>
-						<id>add-source</id>
-						<phase>generate-sources</phase>
-						<goals>
-							<goal>add-source</goal>
-						</goals>
-						<configuration>
-							<sources>
-								<source>${project.build.directory}/generated-sources/antlr4</source>
-							</sources>
-						</configuration>
-					</execution>
-				</executions>
-			</plugin>
-
 			<!-- Attach a JAR with the test classes so that we can reuse them in other 
 				modules (see http://maven.apache.org/guides/mini/guide-attached-tests.html). -->
 			<plugin>
@@ -544,9 +505,5 @@
 			<groupId>org.apache.logging.log4j</groupId>
 			<artifactId>log4j-slf4j-impl</artifactId>
 		</dependency>
-		<dependency>
-			<groupId>org.antlr</groupId>
-			<artifactId>antlr4-runtime</artifactId>
-		</dependency>
 	</dependencies>
 </project>

modules/core/src/main/java/org/apache/synapse/SynapseConstants.java

@@ -729,4 +729,14 @@ public enum ENDPOINT_TIMEOUT_TYPE { ENDPOINT_TIMEOUT, GLOBAL_TIMEOUT, HTTP_CONNE
 
     public static final String DEFAULT_ERROR_TYPE = "ANY";
     public static final String ERROR_STATS_REPORTED = "ERROR_STATS_REPORTED";
+    public static final String SYNAPSE_EXPRESSION_IDENTIFIER_START = "${";
+    public static final String SYNAPSE_EXPRESSION_IDENTIFIER_END = "}";
+
+    public static final String PAYLOAD = "payload";
+    public static final String PAYLOAD_$ = "$";
+    public static final String HEADERS = "headers";
+    public static final String ATTRIBUTES = "attributes";
+
+    // configure SynapseExpression implementation
+    public static final String SYNAPSE_EXPRESSION_IMPL = "synapse.expression.impl.class";
 }

modules/core/src/main/java/org/apache/synapse/config/xml/PropertyMediatorFactory.java

@@ -22,11 +22,11 @@
 import org.apache.axiom.om.OMAttribute;
 import org.apache.axiom.om.OMElement;
 import org.apache.synapse.Mediator;
+import org.apache.synapse.SynapseConstants;
 import org.apache.synapse.SynapseException;
 import org.apache.synapse.mediators.Value;
 import org.apache.synapse.mediators.builtin.PropertyMediator;
 import org.apache.synapse.util.MediatorPropertyUtils;
-import org.apache.synapse.util.synapse.expression.constants.ExpressionConstants;
 import org.apache.synapse.util.xpath.SynapseJsonPath;
 import org.apache.synapse.util.xpath.SynapseExpression;
 import org.apache.synapse.util.xpath.SynapseXPath;
@@ -85,8 +85,8 @@ public Mediator createSpecificMediator(OMElement elem, Properties properties) {
                 String nameExpression = nameAttributeValue.substring(1, nameAttributeValue.length() - 1);
                 if(nameExpression.startsWith("json-eval(")) {
                     new SynapseJsonPath(nameExpression.substring(10, nameExpression.length() - 1));
-                } else if (nameExpression.startsWith(ExpressionConstants.SYNAPSE_EXPRESSION_IDENTIFIER_START) &&
-                        nameExpression.endsWith(ExpressionConstants.SYNAPSE_EXPRESSION_IDENTIFIER_END)) {
+                } else if (nameExpression.startsWith(SynapseConstants.SYNAPSE_EXPRESSION_IDENTIFIER_START) &&
+                        nameExpression.endsWith(SynapseConstants.SYNAPSE_EXPRESSION_IDENTIFIER_END)) {
                     new SynapseExpression(nameExpression.substring(2, nameExpression.length() - 1));
                 } else {
                     new SynapseXPath(nameExpression);

modules/core/src/main/java/org/apache/synapse/config/xml/SynapsePath.java

@@ -4,13 +4,13 @@
 import org.apache.axiom.om.xpath.AXIOMXPath;
 import org.apache.commons.logging.Log;
 import org.apache.synapse.MessageContext;
+import org.apache.synapse.SynapseConstants;
 import org.apache.synapse.SynapseException;
 import org.apache.synapse.transport.util.MessageHandlerProvider;
 import org.apache.synapse.transport.passthru.PassThroughConstants;
 import org.apache.synapse.transport.passthru.Pipe;
 import org.apache.synapse.transport.passthru.config.PassThroughConfiguration;
 import org.apache.synapse.util.streaming_xpath.custom.components.ParserComponent;
-import org.apache.synapse.util.synapse.expression.constants.ExpressionConstants;
 import org.apache.synapse.util.xpath.DOMSynapseXPathNamespaceMap;
 import org.jaxen.JaxenException;
 
@@ -63,8 +63,8 @@ public SynapsePath(String path, String pathType, Log log) throws JaxenException
 	private String inferPathType(String expression) {
 		if (expression.startsWith("json-eval(")) {
 			return JSON_PATH;
-		} else if (expression.startsWith(ExpressionConstants.SYNAPSE_EXPRESSION_IDENTIFIER_START)
-				&& expression.endsWith(ExpressionConstants.SYNAPSE_EXPRESSION_IDENTIFIER_END)) {
+		} else if (expression.startsWith(SynapseConstants.SYNAPSE_EXPRESSION_IDENTIFIER_START)
+				&& expression.endsWith(SynapseConstants.SYNAPSE_EXPRESSION_IDENTIFIER_END)) {
 			return SYNAPSE_EXPRESSIONS_PATH;
 		} else {
 			return X_PATH;

modules/core/src/main/java/org/apache/synapse/config/xml/SynapsePathFactory.java

@@ -26,7 +26,6 @@
 import org.apache.synapse.SynapseConstants;
 import org.apache.synapse.SynapseException;
 import org.apache.synapse.config.SynapsePropertiesLoader;
-import org.apache.synapse.util.synapse.expression.constants.ExpressionConstants;
 import org.apache.synapse.util.xpath.SynapseJsonPath;
 import org.apache.synapse.util.xpath.SynapseExpression;
 import org.apache.synapse.util.xpath.SynapseXPath;
@@ -51,8 +50,8 @@ public static org.apache.synapse.config.xml.SynapsePath getSynapsePath(OMElement
 
             if(pathAttrib.getAttributeValue().startsWith("json-eval(")) {
                 path = new SynapseJsonPath(pathAttrib.getAttributeValue().substring(10, pathAttrib.getAttributeValue().length() - 1));
-            } else if (pathAttrib.getAttributeValue().startsWith(ExpressionConstants.SYNAPSE_EXPRESSION_IDENTIFIER_START) &&
-                    pathAttrib.getAttributeValue().endsWith(ExpressionConstants.SYNAPSE_EXPRESSION_IDENTIFIER_END)) {
+            } else if (pathAttrib.getAttributeValue().startsWith(SynapseConstants.SYNAPSE_EXPRESSION_IDENTIFIER_START) &&
+                    pathAttrib.getAttributeValue().endsWith(SynapseConstants.SYNAPSE_EXPRESSION_IDENTIFIER_END)) {
                 path = new SynapseExpression(pathAttrib.getAttributeValue().substring(2, pathAttrib.getAttributeValue().length() - 1));
             } else {
                 try {

modules/core/src/main/java/org/apache/synapse/mediators/Value.java

@@ -23,9 +23,9 @@
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.synapse.MessageContext;
+import org.apache.synapse.SynapseConstants;
 import org.apache.synapse.SynapseException;
 import org.apache.synapse.config.xml.SynapsePath;
-import org.apache.synapse.util.synapse.expression.constants.ExpressionConstants;
 import org.apache.synapse.util.xpath.SynapseJsonPath;
 import org.apache.synapse.util.xpath.SynapseXPath;
 import org.apache.synapse.util.xpath.SynapseExpression;
@@ -103,8 +103,8 @@ public SynapsePath getExpression() {
                             new SynapseJsonPath(expressionString.substring(10, expressionString.length() - 1));
                     expression = expressionTypeKey;
 
-                } else if (expressionString.startsWith(ExpressionConstants.SYNAPSE_EXPRESSION_IDENTIFIER_START) &&
-                        expressionString.endsWith(ExpressionConstants.SYNAPSE_EXPRESSION_IDENTIFIER_END)) {
+                } else if (expressionString.startsWith(SynapseConstants.SYNAPSE_EXPRESSION_IDENTIFIER_START) &&
+                        expressionString.endsWith(SynapseConstants.SYNAPSE_EXPRESSION_IDENTIFIER_END)) {
                     expression = new SynapseExpression(
                             expressionString.substring(2, expressionString.length() - 1));
                 } else {

modules/core/src/main/java/org/apache/synapse/mediators/elementary/Target.java

@@ -54,7 +54,6 @@
 import org.apache.synapse.mediators.eip.EIPUtils;
 import org.apache.synapse.util.CallMediatorEnrichUtil;
 import org.apache.synapse.util.InlineExpressionUtil;
-import org.apache.synapse.util.synapse.expression.constants.ExpressionConstants;
 import org.apache.synapse.util.xpath.SynapseJsonPath;
 import org.apache.synapse.util.xpath.SynapseXPath;
 import org.apache.synapse.util.xpath.SynapseXPathConstants;
@@ -248,12 +247,12 @@ public void insert(MessageContext synContext,
                     throw new SynapseException("Variable key cannot be null");
                 }
                 Map<String, Object> result = new HashMap<>();
-                result.put(ExpressionConstants.PAYLOAD, sourceNodeList);
+                result.put(SynapseConstants.PAYLOAD, sourceNodeList);
                 Map transportHeaders = (Map)((Axis2MessageContext) synContext).getAxis2MessageContext()
                         .getProperty(org.apache.axis2.context.MessageContext.TRANSPORT_HEADERS);
                 JsonObject headers = EIPUtils.convertMapToJsonObj(transportHeaders);
-                result.put(ExpressionConstants.HEADERS, headers);
-                result.put(ExpressionConstants.ATTRIBUTES, CallMediatorEnrichUtil.populateTransportAttributes(synContext));
+                result.put(SynapseConstants.HEADERS, headers);
+                result.put(SynapseConstants.ATTRIBUTES, CallMediatorEnrichUtil.populateTransportAttributes(synContext));
                 synContext.setVariable(key, result);
             } else {
                 synLog.error("Action " + action + " is not supported when enriching variables");
@@ -503,12 +502,12 @@ public void insertJson(MessageContext synCtx, Object sourceJsonElement, SynapseL
                         return;
                     }
                     Map<String, Object> result = new HashMap<>();
-                    result.put(ExpressionConstants.PAYLOAD, sourceJsonElement);
+                    result.put(SynapseConstants.PAYLOAD, sourceJsonElement);
                     Map transportHeaders = (Map)((Axis2MessageContext) synCtx).getAxis2MessageContext()
                             .getProperty(org.apache.axis2.context.MessageContext.TRANSPORT_HEADERS);
                     JsonObject headers = EIPUtils.convertMapToJsonObj(transportHeaders);
-                    result.put(ExpressionConstants.HEADERS, headers);
-                    result.put(ExpressionConstants.ATTRIBUTES, CallMediatorEnrichUtil.populateTransportAttributes(synCtx));
+                    result.put(SynapseConstants.HEADERS, headers);
+                    result.put(SynapseConstants.ATTRIBUTES, CallMediatorEnrichUtil.populateTransportAttributes(synCtx));
                     synCtx.setVariable(key, result);
                 }
                 break;

modules/core/src/main/java/org/apache/synapse/util/InlineExpressionUtil.java

@@ -30,7 +30,6 @@
 import org.apache.synapse.SynapseException;
 import org.apache.synapse.config.xml.SynapsePath;
 import org.apache.synapse.util.xpath.SynapseExpression;
-import org.apache.synapse.util.xpath.SynapseExpressionUtils;
 import org.apache.synapse.util.xpath.SynapseJsonPath;
 import org.apache.synapse.util.xpath.SynapseXPath;
 import org.jaxen.JaxenException;
@@ -216,8 +215,14 @@ public static boolean isInlineSynapseExpressionsContentAware(String inlineText)
         while (matcher.find()) {
             // Extract the expression inside ${...}
             String expression = matcher.group(1);
-            if (SynapseExpressionUtils.isSynapseExpressionContentAware(expression)) {
-                return true;
+            try {
+                SynapseExpression synapseExpression = new SynapseExpression(expression);
+                if (synapseExpression.isContentAware()) {
+                    return true;
+                }
+            } catch (JaxenException e) {
+                // If the expression is not a valid synapse expression, continue to the next expression
+                continue;
             }
         }
         return false;

modules/core/src/main/java/org/apache/synapse/util/xpath/SynapseExpression.java

@@ -1,5 +1,5 @@
 /*
- *  Copyright (c) 2024, WSO2 LLC. (http://www.wso2.org) All Rights Reserved.
+ *  Copyright (c) 2025, WSO2 LLC. (http://www.wso2.org) All Rights Reserved.
  *
  *  WSO2 LLC. licenses this file to you under the Apache License,
  *  Version 2.0 (the "License"); you may not use this file except
@@ -15,104 +15,60 @@
  *  specific language governing permissions and limitations
  *  under the License.
  */
-
 package org.apache.synapse.util.xpath;
 
-import org.antlr.v4.runtime.CharStream;
-import org.antlr.v4.runtime.CharStreams;
-import org.antlr.v4.runtime.CommonTokenStream;
-import org.antlr.v4.runtime.tree.ParseTree;
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.synapse.MessageContext;
-
+import org.apache.synapse.SynapseConstants;
+import org.apache.synapse.config.SynapsePropertiesLoader;
 import org.apache.synapse.config.xml.SynapsePath;
-import org.apache.synapse.util.synapse.expression.exception.SyntaxError;
-import org.apache.synapse.util.synapse_expression.ExpressionLexer;
-import org.apache.synapse.util.synapse_expression.ExpressionParser;
-import org.apache.synapse.util.synapse.expression.ast.ExpressionNode;
-import org.apache.synapse.util.synapse.expression.ast.ExpressionResult;
-import org.apache.synapse.util.synapse.expression.context.EvaluationContext;
-import org.apache.synapse.util.synapse.expression.exception.EvaluationException;
-import org.apache.synapse.util.synapse.expression.exception.SyntaxErrorListener;
-import org.apache.synapse.util.synapse.expression.visitor.ExpressionVisitor;
 import org.jaxen.JaxenException;
 
-import java.util.HashMap;
-import java.util.Map;
+import java.lang.reflect.InvocationTargetException;
 
 /**
- * Represents a Synapse Expression
+ * Create a Synapse Expression by loading the implementation class.
  * Syntax ${ + expression +  } ex: expression="${vars.test + 5}"
  */
 public class SynapseExpression extends SynapsePath {
-    private static final Log log = LogFactory.getLog(SynapseExpression.class);
-    private final ExpressionNode expressionNode;
-    private final Map<String, String> namespaceMap = new HashMap<>();
-    private final boolean isContentAware;
 
-    public SynapseExpression(String synapseExpression) throws JaxenException {
-        super(synapseExpression, org.apache.synapse.config.xml.SynapsePath.JSON_PATH, log);
+    private final SynapsePath expression;
 
-        CharStream input = CharStreams.fromString(expression);
-        ExpressionLexer lexer = new ExpressionLexer(input);
-        CommonTokenStream tokens = new CommonTokenStream(lexer);
-        ExpressionParser parser = new ExpressionParser(tokens);
-        parser.removeErrorListeners();
-        SyntaxErrorListener errorListener = new SyntaxErrorListener();
-        parser.addErrorListener(errorListener);
+    private static final Log log = LogFactory.getLog(SynapseExpression.class);
 
-        ParseTree tree = parser.expression();
-        ExpressionVisitor visitor = new ExpressionVisitor();
-        expressionNode = visitor.visit(tree);
-        if (errorListener.hasErrors()) {
-            StringBuilder errorMessage = new StringBuilder("Syntax error in expression: " + synapseExpression);
-            for (SyntaxError error : errorListener.getErrors()) {
-                errorMessage.append(" ").append(error.getMessage());
+    public SynapseExpression(String synapseExpression) throws JaxenException {
+        super(synapseExpression, org.apache.synapse.config.xml.SynapsePath.SYNAPSE_EXPRESSIONS_PATH, log);
+        String expressionClass = SynapsePropertiesLoader.loadSynapseProperties().
+                getProperty(SynapseConstants.SYNAPSE_EXPRESSION_IMPL);
+        if (!StringUtils.isEmpty(expressionClass)) {
+            if (log.isDebugEnabled()) {
+                log.debug("Trying to load the SynapseExpression implementation");
             }
-            throw new JaxenException(errorMessage.toString());
+            try {
+                Class<?> clazz = Class.forName(expressionClass);
+                this.expression = (SynapsePath) clazz.getConstructor(String.class).newInstance(synapseExpression);
+            } catch (ClassNotFoundException | InvocationTargetException | InstantiationException | IllegalAccessException | NoSuchMethodException e) {
+                throw new JaxenException("Error while loading the SynapseExpression implementation class", e);
+            }
+        } else {
+            throw new JaxenException("SynapseExpression implementation class is not defined in the properties");
         }
-        isContentAware = SynapseExpressionUtils.isSynapseExpressionContentAware(synapseExpression);
     }
 
     @Override
     public String stringValueOf(MessageContext synCtx) {
-        if (log.isDebugEnabled()) {
-            log.debug("Evaluating expression (stringValueOf): " + expression);
-        }
-        EvaluationContext context = new EvaluationContext();
-        context.setNamespaceMap(namespaceMap);
-        context.setSynCtx(synCtx);
-        ExpressionResult result = evaluateExpression(context, false);
-        return result != null ? result.asString() : "";
+        return this.expression.stringValueOf(synCtx);
     }
 
     @Override
     public Object objectValueOf(MessageContext synCtx) {
-        if (log.isDebugEnabled()) {
-            log.debug("Evaluating expression (objectValueOf): " + expression);
-        }
-        EvaluationContext context = new EvaluationContext();
-        context.setNamespaceMap(namespaceMap);
-        context.setSynCtx(synCtx);
-        ExpressionResult result = evaluateExpression(context, true);
-        return result != null ? result.getValue() : "";
-    }
-
-    private ExpressionResult evaluateExpression(EvaluationContext context, boolean isObjectValue) {
-        try {
-            return expressionNode.evaluate(context, isObjectValue);
-        } catch (EvaluationException e) {
-            log.warn("Error evaluating expression: " + expression + " cause : " + e.getMessage());
-            return null;
-        }
-    }
-
-    public void addNamespace(String var1, String var2) throws JaxenException {
-        namespaceMap.put(var1, var2);
+        return this.expression.objectValueOf(synCtx);
     }
 
+    @Override
     public boolean isContentAware() {
-        return this.isContentAware;
+        return this.expression.isContentAware();
     }
 }