XML to TOON Conversion in JToon

build.gradle

@@ -31,11 +31,12 @@ repositories {
 dependencies {
     implementation 'tools.jackson.core:jackson-databind:3.0.2'
     implementation 'tools.jackson.module:jackson-module-afterburner:3.0.2'
+    implementation 'tools.jackson.dataformat:jackson-dataformat-xml:3.0.2'
     testImplementation platform('org.junit:junit-bom:6.0.1')
     testImplementation 'org.junit.jupiter:junit-jupiter'
     testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
 test {
     useJUnitPlatform()
-}
+}

src/main/java/com/felipestanzani/jtoon/JToon.java

@@ -3,6 +3,7 @@
 import com.felipestanzani.jtoon.decoder.ValueDecoder;
 import com.felipestanzani.jtoon.encoder.ValueEncoder;
 import com.felipestanzani.jtoon.normalizer.JsonNormalizer;
+import com.felipestanzani.jtoon.normalizer.XmlNormalizer;
 import tools.jackson.databind.JsonNode;
 import tools.jackson.databind.ObjectMapper;
 
@@ -27,6 +28,9 @@
  * // Encode a plain JSON string directly
  * String toon = JToon.encodeJson("{\"id\":123,\"name\":\"Ada\"}");
  *
+ * // Encode a plain XML string directly
+ * String toon = JToon.encodeXml("<user><id>123</id><name>Ada</name></user>");
+ *
  * // Decode TOON back to Java objects
  * Object result = JToon.decode(toon);
  *
@@ -110,6 +114,42 @@ public static String encodeJson(String json, EncodeOptions options) {
         return ValueEncoder.encodeValue(parsed, options);
     }
 
+    /**
+     * Encodes a plain XML string to TOON format using default options.
+     *
+     * <p>
+     * This is a convenience overload that parses the XML string and encodes it
+     * without requiring callers to create a {@code JsonNode} or intermediate
+     * objects.
+     * </p>
+     *
+     * @param xml The XML string to encode (must be valid XML)
+     * @return The TOON-formatted string
+     * @throws IllegalArgumentException if the input is not valid XML
+     */
+    public static String encodeXml(String xml) {
+        return encodeXml(xml, EncodeOptions.DEFAULT);
+    }
+
+    /**
+     * Encodes a plain XML string to TOON format using custom options.
+     *
+     * <p>
+     * Parsing is delegated to
+     * {@link com.felipestanzani.jtoon.normalizer.XmlNormalizer#parse(String)}
+     * to maintain separation of concerns.
+     * </p>
+     *
+     * @param xml     The XML string to encode (must be valid XML)
+     * @param options Encoding options (indent, delimiter, length marker)
+     * @return The TOON-formatted string
+     * @throws IllegalArgumentException if the input is not valid XML
+     */
+    public static String encodeXml(String xml, EncodeOptions options) {
+        JsonNode parsed = XmlNormalizer.parse(xml);
+        return ValueEncoder.encodeValue(parsed, options);
+    }
+
     /**
      * Decodes a TOON-formatted string to Java objects using default options.
      *

src/main/java/com/felipestanzani/jtoon/normalizer/XmlNormalizer.java

@@ -0,0 +1,40 @@
+package com.felipestanzani.jtoon.normalizer;
+
+import tools.jackson.databind.JsonNode;
+import tools.jackson.dataformat.xml.XmlMapper;
+
+/**
+ * Normalizes XML strings to Jackson JsonNode representation.
+ * Converts XML structure to JSON-compatible format for TOON encoding.
+ */
+public final class XmlNormalizer {
+
+    private static final XmlMapper XML_MAPPER = XmlMapper.builder().build();
+
+    private XmlNormalizer() {
+        throw new UnsupportedOperationException("Utility class cannot be instantiated");
+    }
+
+    /**
+     * Parses an XML string into a JsonNode using the shared XmlMapper.
+     * <p>
+     * This centralizes XML parsing concerns to keep the public API thin and
+     * maintain separation of responsibilities between parsing, normalization,
+     * and encoding.
+     * </p>
+     *
+     * @param xml The XML string to parse (must be valid XML)
+     * @return Parsed JsonNode
+     * @throws IllegalArgumentException if the input is blank or not valid XML
+     */
+    public static JsonNode parse(String xml) {
+        if (xml == null || xml.trim().isEmpty()) {
+            throw new IllegalArgumentException("Invalid XML");
+        }
+        try {
+            return XML_MAPPER.readTree(xml);
+        } catch (Exception e) {
+            throw new IllegalArgumentException("Invalid XML", e);
+        }
+    }
+}

src/test/java/com/felipestanzani/jtoon/JToonTest.java

@@ -745,6 +745,94 @@ void noTrailingNewline() {
         }
     }
 
+    @Nested
+    @DisplayName("XML tests")
+    class XmlTests {
+
+        @Test
+        @DisplayName("encodes XML with custom options")
+        void encodesXmlWithOptions() {
+            String xml = "<user><id>123</id><name>Ada</name></user>";
+            EncodeOptions options = new EncodeOptions(4, Delimiter.PIPE, true);
+            String result = JToon.encodeXml(xml, options);
+            // Basic check that custom options work
+            assertNotNull(result);
+            assertTrue(result.length() > 0);
+        }
+
+        @Test
+        @DisplayName("throws exception for invalid XML")
+        void throwsForInvalidXml() {
+            String invalidXml = "<user><id>123</id><name>Ada</name>";
+            assertThrows(IllegalArgumentException.class, () -> JToon.encodeXml(invalidXml));
+        }
+
+        @Test
+        @DisplayName("throws exception for null XML")
+        void throwsForNullXml() {
+            assertThrows(IllegalArgumentException.class, () -> JToon.encodeXml(null));
+        }
+
+        @Test
+        @DisplayName("throws exception for empty XML")
+        void throwsForEmptyXml() {
+            assertThrows(IllegalArgumentException.class, () -> JToon.encodeXml(""));
+        }
+
+        @Nested
+        @DisplayName("XML structures (positive test cases)")
+        class XmlStructuresPositive {
+
+            @Test
+            @DisplayName("encodes XML successfully")
+            void encodesXmlSuccessfully() {
+                String xml = "<user><name>John</name><age>25</age></user>";
+                String result = JToon.encodeXml(xml);
+                assertNotNull(result);
+                assertTrue(result.length() > 0);
+            }
+
+            @Test
+            @DisplayName("encodes complex XML successfully")
+            void encodesComplexXmlSuccessfully() {
+                String xml = "<company><name>TechCorp</name><employees><employee><name>Alice</name></employee></employees></company>";
+                String result = JToon.encodeXml(xml);
+                assertNotNull(result);
+                assertTrue(result.length() > 0);
+            }
+        }
+
+        @Nested
+        @DisplayName("XML error handling (negative test cases)")
+        class XmlErrorHandling {
+
+            @Test
+            @DisplayName("throws exception for invalid XML")
+            void throwsForInvalidXml() {
+                String invalidXml = "<user><id>123</id><name>Ada</name>";
+                assertThrows(IllegalArgumentException.class, () -> JToon.encodeXml(invalidXml));
+            }
+
+            @Test
+            @DisplayName("throws exception for null XML input")
+            void throwsForNullXml() {
+                assertThrows(IllegalArgumentException.class, () -> JToon.encodeXml(null));
+            }
+
+            @Test
+            @DisplayName("throws exception for empty XML string")
+            void throwsForEmptyXml() {
+                assertThrows(IllegalArgumentException.class, () -> JToon.encodeXml(""));
+            }
+
+            @Test
+            @DisplayName("throws exception for whitespace-only XML")
+            void throwsForWhitespaceOnlyXml() {
+                assertThrows(IllegalArgumentException.class, () -> JToon.encodeXml("   "));
+            }
+        }
+    }
+
     @Nested
     @DisplayName("non-JSON-serializable values")
     class NonJson {