anonymizer with test

Signed-off-by: Jialiang Liang <jiallian@amazon.com>

Author: RyanL1997

ppl/src/main/java/org/opensearch/sql/ppl/utils/PPLQueryDataAnonymizer.java

@@ -72,6 +72,7 @@
 import org.opensearch.sql.ast.tree.Patterns;
 import org.opensearch.sql.ast.tree.Project;
 import org.opensearch.sql.ast.tree.RangeBin;
+import org.opensearch.sql.ast.tree.Regex;
 import org.opensearch.sql.ast.tree.RareTopN;
 import org.opensearch.sql.ast.tree.Relation;
 import org.opensearch.sql.ast.tree.Rename;
@@ -442,6 +443,20 @@ public String visitParse(Parse node, String context) {
         : StringUtils.format("%s | %s %s '%s'", child, commandName, source, regex);
   }
 
+  @Override
+  public String visitRegex(Regex node, String context) {
+    String child = node.getChild().get(0).accept(this, context);
+    String operator = node.isNegated() ? "!=" : "=";
+    String pattern = MASK_LITERAL;
+    
+    if (node.getField() != null) {
+      String field = visitExpression(node.getField());
+      return StringUtils.format("%s | regex %s%s%s", child, field, operator, pattern);
+    } else {
+      return StringUtils.format("%s | regex %s", child, pattern);
+    }
+  }
+
   @Override
   public String visitFlatten(Flatten node, String context) {
     String child = node.getChild().getFirst().accept(this, context);
@@ -734,5 +749,11 @@ public String visitCast(Cast node, String context) {
       String expr = analyze(node.getExpression(), context);
       return StringUtils.format("cast(%s as %s)", expr, node.getConvertedType().toString());
     }
+
+    @Override
+    public String visitQualifiedName(
+        org.opensearch.sql.ast.expression.QualifiedName node, String context) {
+      return String.join(".", node.getParts());
+    }
   }
 }

ppl/src/test/java/org/opensearch/sql/ppl/utils/PPLQueryDataAnonymizerTest.java

@@ -511,6 +511,17 @@ public void testPatterns() {
                 + " variable_count_threshold=5"));
   }
 
+  @Test
+  public void testRegex() {
+    assertEquals("source=t | regex field=***", anonymize("source=t | regex field='pattern'"));
+    assertEquals(
+        "source=t | regex field!=***", anonymize("source=t | regex field!='pattern'"));
+    assertEquals("source=t | regex ***", anonymize("source=t | regex 'pattern'"));
+    assertEquals(
+        "source=t | regex email=*** | fields + email",
+        anonymize("source=t | regex email='.*@domain.com' | fields email"));
+  }
+
   private String anonymize(String query) {
     AstBuilder astBuilder = new AstBuilder(query, settings);
     return anonymize(astBuilder.visit(parser.parse(query)));