update to Java 21

README.md

@@ -190,7 +190,7 @@ file.
 
 - The project uses the `maven-shade-plugin` for Maven to create a shaded JAR.
 - The project uses the `com.github.johnrengelman.shadow` plugin for Gradle to create a shaded JAR.
-- Both Maven and Gradle configurations are set to use Java 11.
+- Both Maven and Gradle configurations are set to use Java 21.
 
 ## Running the jar file
 

build.gradle

@@ -9,7 +9,7 @@ version = '1.0-SNAPSHOT'
 
 java {
     toolchain {
-        languageVersion = JavaLanguageVersion.of(11)
+        languageVersion = JavaLanguageVersion.of(21)
     }
 }
 

pom.xml

@@ -12,8 +12,8 @@
     <url>http://maven.apache.org</url>
 
     <properties>
-        <maven.compiler.source>11</maven.compiler.source>
-        <maven.compiler.target>11</maven.compiler.target>
+        <maven.compiler.source>21</maven.compiler.source>
+        <maven.compiler.target>21</maven.compiler.target>
     </properties>
 
     <dependencies>

src/main/java/org/perlonjava/runtime/HashSpecialVariable.java

@@ -1,13 +1,11 @@
 package org.perlonjava.runtime;
 
 import java.util.AbstractMap;
-import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
-import java.util.regex.PatternSyntaxException;
 
 import static org.perlonjava.runtime.RuntimeScalarCache.scalarUndef;
 
@@ -28,36 +26,16 @@ public class HashSpecialVariable extends AbstractMap<String, RuntimeScalar> {
      */
     public HashSpecialVariable(Matcher matcher) {
         this.matcher = matcher;
-        this.namedGroups = extractNamedGroups(matcher.pattern());
-    }
-
-    /**
-     * Extracts named groups and their indices from the given pattern.
-     *
-     * @param pattern the regex pattern
-     * @return a map of named group names to their indices
-     */
-    private Map<String, Integer> extractNamedGroups(Pattern pattern) {
-        Map<String, Integer> namedGroups = new HashMap<>();
-        String regex = pattern.toString();
-        Matcher groupMatcher = Pattern.compile("\\(\\?<([a-zA-Z][a-zA-Z0-9]*)>").matcher(regex);
-        int index = 1; // Group indices start at 1
-
-        while (groupMatcher.find()) {
-            String groupName = groupMatcher.group(1);
-            namedGroups.put(groupName, index++);
-        }
-
-        return namedGroups;
+        this.namedGroups = matcher.pattern().namedGroups();  // Use Java 20's built-in namedGroups support
     }
 
     @Override
     public Set<Entry<String, RuntimeScalar>> entrySet() {
         Set<Entry<String, RuntimeScalar>> entries = new HashSet<>();
         for (String name : namedGroups.keySet()) {
-            int groupIndex = namedGroups.get(name);
-            if (groupIndex != -1 && matcher.group(name) != null) {
-                entries.add(new SimpleEntry<>(name, new RuntimeScalar(matcher.group(name))));
+            String matchedValue = matcher.group(name);  // Use Matcher.group(String name)
+            if (matchedValue != null) {
+                entries.add(new SimpleEntry<>(name, new RuntimeScalar(matchedValue)));
             }
         }
         return entries;
@@ -67,9 +45,9 @@ public Set<Entry<String, RuntimeScalar>> entrySet() {
     public RuntimeScalar get(Object key) {
         if (key instanceof String) {
             String name = (String) key;
-            int groupIndex = namedGroups.getOrDefault(name, -1);
-            if (groupIndex != -1 && matcher.group(groupIndex) != null) {
-                return new RuntimeScalar(matcher.group(groupIndex));
+            String matchedValue = matcher.group(name);  // Use Matcher.group(String name)
+            if (matchedValue != null) {
+                return new RuntimeScalar(matchedValue);
             }
         }
         return scalarUndef;