Fix content aware logic

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

@@ -18,6 +18,7 @@
 
 package org.apache.synapse.util.xpath;
 
+import org.apache.synapse.util.synapse.expression.constants.ExpressionConstants;
 import org.jaxen.JaxenException;
 
 import java.util.regex.Matcher;
@@ -38,35 +39,78 @@ public class SynapseExpressionUtils {
      * @return true if the synapse expression is content aware, false otherwise
      */
     public static boolean isSynapseExpressionContentAware(String synapseExpression) {
-
-        // TODO : Need to improve the content aware detection logic
-        if (synapseExpression.equals("payload") || synapseExpression.equals("$")
-                || synapseExpression.contains("payload.") || synapseExpression.contains("$.")) {
+        boolean isContentAware = false;
+        if (synapseExpression.equals("payload") || synapseExpression.equals("$")) {
             return true;
-        } else if (synapseExpression.contains("xpath(")) {
-            // TODO change the regex to support xpath + variable syntax
-            Pattern pattern = Pattern.compile("xpath\\(['\"](.*?)['\"]\\s*(,\\s*['\"](.*?)['\"])?\\)?");
-            Matcher matcher = pattern.matcher(synapseExpression);
-            // Find all matches
-            while (matcher.find()) {
-                if (matcher.group(2) != null) {
-                    // evaluating xpath on a variable so not content aware
-                    continue;
-                }
-                String xpath = matcher.group(1);
-                try {
-                    SynapseXPath synapseXPath = new SynapseXPath(xpath);
-                    if (synapseXPath.isContentAware()) {
-                        return true;
+        } else {
+            if (synapseExpression.contains(ExpressionConstants.PAYLOAD_$)
+                    || synapseExpression.contains(ExpressionConstants.PAYLOAD)) {
+                isContentAware = checkForPayloadReference(synapseExpression);
+            }
+            if (!isContentAware && synapseExpression.contains("xpath(")) {
+                // TODO change the regex to support xpath + variable syntax
+                Pattern pattern = Pattern.compile("xpath\\(['\"](.*?)['\"]\\s*(,\\s*['\"](.*?)['\"])?\\)?");
+                Matcher matcher = pattern.matcher(synapseExpression);
+                // Find all matches
+                while (matcher.find()) {
+                    if (matcher.group(2) != null) {
+                        // evaluating xpath on a variable so not content aware
+                        continue;
+                    }
+                    String xpath = matcher.group(1);
+                    try {
+                        SynapseXPath synapseXPath = new SynapseXPath(xpath);
+                        if (synapseXPath.isContentAware()) {
+                            isContentAware = true;
+                        }
+                    } catch (JaxenException e) {
+                        // Ignore the exception and continue
                     }
-                } catch (JaxenException e) {
-                    // Ignore the exception and continue
                 }
             }
+            return isContentAware;
+        }
+    }
+
+    private static boolean checkForPayloadReference(String expr) {
+        if (expr == null || expr.isEmpty()) {
+            return false;
+        }
+        return findKeyword(expr, ExpressionConstants.PAYLOAD)
+                || findKeyword(expr, ExpressionConstants.PAYLOAD_$);
+    }
+
+    private static boolean findKeyword(String expr, String keyword) {
+        int index = expr.indexOf(keyword);
+        while (index != -1) {
+            if (isValidCharBeforeKeyword(expr, index)
+                    && isValidCharAfterKeyword(expr, index, keyword.length())) {
+                return true;
+            }
+            index = expr.indexOf(keyword, index + 1);
         }
         return false;
     }
 
+    private static boolean isValidCharBeforeKeyword(String expr, int startIndex) {
+        if (startIndex > 0) {
+            char prev = expr.charAt(startIndex - 1);
+            return !Character.isLetterOrDigit(prev) && prev != '_' && prev != '.'
+                    && prev != '"' && prev != '\'';
+        }
+        return true;
+    }
+
+    private static boolean isValidCharAfterKeyword(String expr, int startIndex, int keywordLen) {
+        int afterIndex = startIndex + keywordLen;
+        if (afterIndex < expr.length()) {
+            char next = expr.charAt(afterIndex);
+            return !Character.isLetterOrDigit(next) && next != '_'
+                    && next != '"' && next != '\'';
+        }
+        return true;
+    }
+
     public static boolean isVariableXPathExpression(String synapseExpression) {
 
         Matcher matcher = pattern.matcher(synapseExpression);

modules/core/src/test/java/org/apache/synapse/util/synapse/expression/ContentAwarenessTest.java

@@ -0,0 +1,91 @@
+/*
+ *  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
+ *  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.synapse.util.synapse.expression;
+
+import org.apache.synapse.util.xpath.SynapseExpression;
+import org.jaxen.JaxenException;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Test class for content awareness in the Synapse Expressions.
+ */
+public class ContentAwarenessTest {
+
+    @Test
+    public void testPayloadAccess() throws JaxenException {
+        SynapseExpression synapsePath = new SynapseExpression("payload");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("$");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("payload.name");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("$.name");
+        Assert.assertTrue(synapsePath.isContentAware());
+    }
+
+    @Test
+    public void testComplexUsages() throws JaxenException {
+        SynapseExpression synapsePath = new SynapseExpression("length(payload)");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("5 + length(payload)");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("5 + length(payload[\"payload\"])");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("$..book[?(@.category==payload.category)]");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("$..book[?(@.category==\"payload.category\")]");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("var.books[?(@.category==payload.category)]");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("var.books[?(@.category==$.category)]");
+        Assert.assertTrue(synapsePath.isContentAware());
+    }
+
+    @Test
+    public void testWithXpath() throws JaxenException {
+        SynapseExpression synapsePath = new SynapseExpression("xpath(\"$ctx:name\")");
+        Assert.assertFalse(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("xpath(\"//student\")");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("xpath(\"/student\")");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("xpath(\"//*\") + var.a$bc");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("xpath(\"$ctx:bla\") + $.age");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("var.num1 + var.[\"payload\"] + xpath(\"//num3\")");
+        Assert.assertTrue(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("var.num1 + var.[\"payload\"] + xpath(\"$ctx:num3\")");
+        Assert.assertFalse(synapsePath.isContentAware());
+    }
+
+    @Test
+    public void testNegativeCases() throws JaxenException {
+        SynapseExpression synapsePath = new SynapseExpression("length(var.abc)");
+        Assert.assertFalse(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("var[\"payload\"]");
+        Assert.assertFalse(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("5 + var[\"payload\"].age");
+        Assert.assertFalse(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("var.a$.bc");
+        Assert.assertFalse(synapsePath.isContentAware());
+        synapsePath = new SynapseExpression("var.books[?(@.category==\"payload.category\")]");
+        Assert.assertFalse(synapsePath.isContentAware());
+    }
+}