fix pack() WIP - refactoring

Author: fglock

src/main/java/org/perlonjava/operators/Pack.java

@@ -1,14 +1,14 @@
 package org.perlonjava.operators;
 
 import org.perlonjava.runtime.*;
+import org.perlonjava.operators.pack.*;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
 import java.util.Map;
 import java.util.HashMap;
-
 /**
  * Provides functionality to pack a list of scalars into a binary string
  * based on a specified template, similar to Perl's pack function.

src/main/java/org/perlonjava/operators/pack/NullPadHandler.java

@@ -0,0 +1,20 @@
+package org.perlonjava.operators.pack;
+
+import org.perlonjava.runtime.RuntimeScalar;
+import java.io.ByteArrayOutputStream;
+import java.util.List;
+
+/**
+ * Handles 'x' format - null padding
+ */
+public class NullPadHandler implements PackFormatHandler {
+    @Override
+    public int pack(ByteArrayOutputStream output, List<RuntimeScalar> values,
+                    int valueIndex, int count, PackModifiers modifiers) {
+        // 'x' doesn't consume any values, just writes null bytes
+        for (int j = 0; j < count; j++) {
+            output.write(0);
+        }
+        return 0; // consumes no values
+    }
+}

src/main/java/org/perlonjava/operators/pack/PackFormatHandler.java

@@ -0,0 +1,23 @@
+package org.perlonjava.operators.pack;
+
+import org.perlonjava.runtime.RuntimeScalar;
+import java.io.ByteArrayOutputStream;
+import java.util.List;
+
+/**
+ * Interface for handling pack format characters
+ */
+public interface PackFormatHandler {
+    /**
+     * Pack values according to this format
+     *
+     * @param output The output stream to write to
+     * @param values The list of values to pack
+     * @param valueIndex Current position in values list
+     * @param count Repeat count (Integer.MAX_VALUE for *)
+     * @param modifiers Format modifiers (endianness, etc.)
+     * @return number of values consumed from the values list
+     */
+    int pack(ByteArrayOutputStream output, List<RuntimeScalar> values,
+             int valueIndex, int count, PackModifiers modifiers);
+}

src/main/java/org/perlonjava/operators/pack/PackModifiers.java

@@ -0,0 +1,18 @@
+package org.perlonjava.operators.pack;
+
+/**
+ * Holds format modifiers like endianness
+ */
+public class PackModifiers {
+    public final boolean bigEndian;
+    public final boolean littleEndian;
+    public final boolean nativeSize;
+
+    public PackModifiers(boolean bigEndian, boolean littleEndian, boolean nativeSize) {
+        this.bigEndian = bigEndian;
+        this.littleEndian = littleEndian;
+        this.nativeSize = nativeSize;
+    }
+
+    public static PackModifiers DEFAULT = new PackModifiers(false, false, false);
+}