Fix writer for immutable objects

src/main/java/blue/endless/jankson/api/Jankson.java

@@ -239,7 +239,7 @@ public static <T> T readJson(Reader r, JsonReaderOptions opts, Class<T> clazz) t
 	}
 
 	public static void writeJson(Object obj, Writer writer) throws SyntaxError, IOException {
-		writeJson(obj, new ObjectReaderFactory(), writer, JsonWriterOptions.STRICT);
+		writeJson(obj, new ObjectReaderFactory(), writer, JsonWriterOptions.DEFAULTS);
 	}
 
 	public static void writeJson(Object obj, ObjectReaderFactory factory, Writer writer, JsonWriterOptions options) throws SyntaxError, IOException {

src/main/java/blue/endless/jankson/api/io/ObjectWriter.java

@@ -142,7 +142,7 @@ public static StructuredDataFunction<?> getObjectWriter(Type type, StructuredDat
 		}
 
 		if (Map.class.isAssignableFrom(targetClass)) {
-			if (subject instanceof Map map) {
+			if (subject instanceof Map) {
 				// Map<Object, Object> is incorrect, but we cannot construct MapFunction<?, ?>
 				return new MapFunction<Object, Object>(type, (Map<Object, Object>) subject);
 			}

src/main/java/blue/endless/jankson/api/io/StructuredDataReader.java

@@ -27,6 +27,7 @@
 import java.io.IOException;
 
 import blue.endless.jankson.api.SyntaxError;
+import blue.endless.jankson.impl.io.SingleStructuredDataReader;
 
 public interface StructuredDataReader {
 
@@ -47,4 +48,12 @@ public default void transferTo(StructuredDataWriter writer) throws SyntaxError,
 			writer.write(d);
 		}
 	}
+
+	public static StructuredDataReader of(StructuredData data) {
+		return new SingleStructuredDataReader(data);
+	}
+
+	public static StructuredDataReader of(String value) {
+		return new SingleStructuredDataReader(new StructuredData(StructuredData.Type.PRIMITIVE, value));
+	}
 }

src/main/java/blue/endless/jankson/api/io/TomlReader.java

@@ -46,7 +46,6 @@
 
 public class TomlReader extends AbstractStructuredDataReader {
 
-
 	/**
 	 * Unfortunately, because of the unpredictable order here, we need to crystallize the config down into an object before we can emit anything.
 	 */

src/main/java/blue/endless/jankson/impl/io/SingleStructuredDataReader.java

@@ -0,0 +1,54 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2018-2024 Falkreon (Isaac Ellingson)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package blue.endless.jankson.impl.io;
+
+import java.io.IOException;
+
+import blue.endless.jankson.api.SyntaxError;
+import blue.endless.jankson.api.io.StructuredData;
+import blue.endless.jankson.api.io.StructuredDataReader;
+
+/**
+ * StructuredDataReader that will provide a single data record and then complete.
+ */
+public class SingleStructuredDataReader implements StructuredDataReader {
+	private boolean hasNext = true;
+	private final StructuredData value;
+
+	public SingleStructuredDataReader(StructuredData value) {
+		this.value = value;
+	}
+
+	@Override
+	public StructuredData next() throws SyntaxError, IOException {
+		hasNext = false;
+		return value;
+	}
+
+	@Override
+	public boolean hasNext() {
+		return hasNext;
+	}
+}

src/main/java/blue/endless/jankson/impl/io/objectwriter/ObjectFunction.java

@@ -84,6 +84,7 @@ public T getResult() {
 	@SuppressWarnings("unchecked")
 	@Override
 	protected void process(StructuredData data) throws SyntaxError, IOException {
+
 		if (delegate != null) {
 			delegate.write(data);
 			checkDelegate();
@@ -135,6 +136,7 @@ protected void process(StructuredData data) throws SyntaxError, IOException {
 					delegate = (StructuredDataFunction<Object>) ObjectWriter.getObjectWriter(fieldType, data, null);
 					if (delegate != null) {
 						delegate.write(data);
+						checkDelegate();
 					} else {
 						throw new IllegalStateException("Oops");
 					}

src/main/java/blue/endless/jankson/impl/io/objectwriter/factory/InstanceFactory.java

@@ -42,7 +42,7 @@ public static Object[] arrangeArguments(Executable method, Map<String, Object> a
 			String serializedName = parameters[i].getName();
 			SerializedName annotation = parameters[i].getAnnotation(SerializedName.class);
 			if (annotation != null) serializedName = annotation.value();
-			if (!arguments.containsKey(serializedName)) throw new InstantiationException("No value supplied for required field \""+serializedName+"\".");
+			if (!arguments.containsKey(serializedName)) throw new InstantiationException("No value supplied for required field \""+serializedName+"\". ("+arguments+")");
 			arrangedArguments[i] = arguments.get(serializedName);
 		}
 		return arrangedArguments;

src/test/java/blue/endless/jankson/TestJsonReader.java

@@ -146,6 +146,6 @@ public void testBetterRead() throws IOException, SyntaxError {
 
 		record Release(String id, String releaseTime, String resources, String time, String type, String url) {}
 		Release[] releases = Jankson.readJson(new StringReader(subject), JsonReaderOptions.UNSPECIFIED, Release[].class);
-		System.out.println(Arrays.toString(releases));
+		//System.out.println(Arrays.toString(releases));
 	}
 }

src/test/java/blue/endless/jankson/TestObjectWriter.java

@@ -346,4 +346,36 @@ public void testFull() throws SyntaxError, IOException {
 
 		Assertions.assertEquals(expected, actual);
 	}
+
+	public static class ImmutableConfig {
+
+		final int x;
+		final int y;
+
+		public ImmutableConfig(@SerializedName("x") int x, @SerializedName("y") int y) {
+			this.x = x;
+			this.y = y;
+		}
+
+		public int getX() { return x; }
+		public int getY() { return y; }
+
+	}
+
+	@Test
+	public void testImmutable() throws SyntaxError, IOException {
+		String subject = """
+			{ "x": 12, "y": 24 }
+			""";
+
+		StringReader stringReader = new StringReader(subject);
+		JsonReader reader = new JsonReader(stringReader);
+		ObjectWriter<ImmutableConfig> writer = new ObjectWriter<>(ImmutableConfig.class);
+		reader.transferTo(writer);
+
+		ImmutableConfig config = writer.toObject();
+
+		Assertions.assertEquals(12, config.x);
+		Assertions.assertEquals(24, config.y);
+	}
 }