From 30861ca7a5eb746ce01704ddce164074342ae6b3 Mon Sep 17 00:00:00 2001
From: "Flavio S. Glock" <fglock@gmail.com>
Date: Fri, 18 Oct 2024 16:40:32 +0200
Subject: [PATCH] regex variable %+ wip

---
 misc/test/regex_named_capture.pl              | 32 ++++++++
 .../runtime/HashSpecialVariable.java          | 77 +++++++++++++++++++
 2 files changed, 109 insertions(+)
 create mode 100644 misc/test/regex_named_capture.pl
 create mode 100644 src/main/java/org/perlonjava/runtime/HashSpecialVariable.java

diff --git a/misc/test/regex_named_capture.pl b/misc/test/regex_named_capture.pl
new file mode 100644
index 00000000..e103d45a
--- /dev/null
+++ b/misc/test/regex_named_capture.pl
@@ -0,0 +1,32 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+use Test::More tests => 4;
+
+# Test case 1: Simple named capture
+my $string1 = 'foo';
+if ($string1 =~ /(?<foo>foo)/) {
+    is($+{foo}, 'foo', 'Test case 1: Named capture for "foo"');
+} else {
+    fail('Test case 1: Pattern did not match');
+}
+
+# Test case 2: Multiple named captures
+my $string2 = 'barbaz';
+if ($string2 =~ /(?<bar>bar)(?<baz>baz)/) {
+    is($+{bar}, 'bar', 'Test case 2: Named capture for "bar"');
+    is($+{baz}, 'baz', 'Test case 2: Named capture for "baz"');
+} else {
+    fail('Test case 2: Pattern did not match');
+}
+
+# Test case 3: Overlapping named captures
+my $string3 = 'foobar';
+if ($string3 =~ /(?<foo>foo)(?<bar>bar)|(?<foo>foobar)/) {
+    is($+{foo}, 'foo', 'Test case 3: Overlapping named capture for "foo"');
+} else {
+    fail('Test case 3: Pattern did not match');
+}
+
+done_testing();
+
diff --git a/src/main/java/org/perlonjava/runtime/HashSpecialVariable.java b/src/main/java/org/perlonjava/runtime/HashSpecialVariable.java
new file mode 100644
index 00000000..65d53846
--- /dev/null
+++ b/src/main/java/org/perlonjava/runtime/HashSpecialVariable.java
@@ -0,0 +1,77 @@
+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;
+
+/**
+ * HashSpecialVariable provides a dynamic view over named capturing groups
+ * in a Matcher object, reflecting the current state of the Matcher.
+ * This implements the Perl special variable %+.
+ */
+public class HashSpecialVariable extends AbstractMap<String, RuntimeScalar> {
+
+    private final Matcher matcher;
+    private final Map<String, Integer> namedGroups;
+
+    /**
+     * Constructs a HashSpecialVariable for the given Matcher.
+     *
+     * @param matcher the Matcher object to query for named capturing groups
+     */
+    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;
+    }
+
+    @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))));
+            }
+        }
+        return entries;
+    }
+
+    @Override
+    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));
+            }
+        }
+        return scalarUndef;
+    }
+}