Add lists

6 files changed, 72 insertions, 3 deletions

diff --git a/gson/src/main/java/moe/nea/jcp/gson/GsonRecordBuilder.java b/gson/src/main/java/moe/nea/jcp/gson/GsonRecordBuilder.java
index ded1953..43498ac 100644
--- a/gson/src/main/java/moe/nea/jcp/gson/GsonRecordBuilder.java
+++ b/gson/src/main/java/moe/nea/jcp/gson/GsonRecordBuilder.java
@@ -23,9 +23,8 @@ public class GsonRecordBuilder extends GsonRecordView implements RecordBuilder<J
 		return Result.cast(Stream.of(this.complete(), other.complete())
 		                         .flatMap(it -> ((JsonObject) it).entrySet().stream())
 		                         .map(it -> next.add(it.getKey(), it.getValue()))
-		                         .reduce((left, right) -> left.appendErrors(right.errors()))
-		                         .map(it -> it.map(unit -> next))
-		                         .orElse(Result.ok(next)));
+		                         .reduce(Result.ok(Unit.INSTANCE), (left, right) -> left.appendErrors(right.errors()))
+		                         .map(unit -> next));
 	}
 
 	@Override
diff --git a/gson/src/test/java/moe/nea/jcp/gson/test/TestBasic.java b/gson/src/test/java/moe/nea/jcp/gson/test/TestBasic.java
index 58727f2..861656e 100644
--- a/gson/src/test/java/moe/nea/jcp/gson/test/TestBasic.java
+++ b/gson/src/test/java/moe/nea/jcp/gson/test/TestBasic.java
@@ -1,5 +1,6 @@
 package moe.nea.jcp.gson.test;
 
+import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonNull;
 import com.google.gson.JsonObject;
@@ -10,6 +11,7 @@ import moe.nea.pcj.Codec;
 import moe.nea.pcj.Decode;
 import moe.nea.pcj.Result;
 import moe.nea.pcj.json.AtField;
+import moe.nea.pcj.json.AtIndex;
 import moe.nea.pcj.json.DuplicateJsonKey;
 import moe.nea.pcj.json.JsonLikeError;
 import moe.nea.pcj.json.JsonLikeOperations;
@@ -21,6 +23,7 @@ import org.junit.jupiter.api.Test;
 
 import java.util.Arrays;
 import java.util.HashSet;
+import java.util.List;
 import java.util.stream.Collectors;
 
 public class TestBasic {
@@ -55,6 +58,14 @@ public class TestBasic {
 		throw new IllegalArgumentException("Cannot convert " + arg + " to json object");
 	}
 
+	static JsonArray mkJsonArray(Object... args) {
+		JsonArray array = new JsonArray();
+		for (Object arg : args) {
+			array.add(mkPrim(arg));
+		}
+		return array;
+	}
+
 	static JsonObject mkJsonObject(Object... args) {
 		JsonObject obj = new JsonObject();
 		for (int i = 0; i < args.length; i += 2) {
@@ -99,6 +110,7 @@ public class TestBasic {
 		assertFail(decode(codec, mkJsonObject("foo", "fooValue", "bar", "test")),
 		           new AtField("bar", new UnexpectedJsonElement("number", mkPrim("test"))));
 	}
+
 	@Test
 	void testDuplicateKeys() {
 		var codec = RecordJoiners.join(
@@ -110,5 +122,14 @@ public class TestBasic {
 		assertFail(codec.encode(new TestObject("", 0), GsonOperations.INSTANCE),
 		           new DuplicateJsonKey("foo"));
 	}
+
+	@Test
+	void testList() {
+		var codec = codecs.STRING.fieldOf("hello").codec().listOf();
+		assertSuccess(decode(codec, mkJsonArray(mkJsonObject("hello", "foo"), mkJsonObject("hello", "bar"))),
+		              List.of("foo", "bar"));
+		assertFail(decode(codec, mkJsonArray("foo", mkJsonObject("hello", "bar"))),
+		           new AtIndex(0, new UnexpectedJsonElement("object", mkPrim("foo"))));
+	}
 }
 
diff --git a/src/main/java/moe/nea/pcj/Result.java b/src/main/java/moe/nea/pcj/Result.java
index 22c94f9..af5398e 100644
--- a/src/main/java/moe/nea/pcj/Result.java
+++ b/src/main/java/moe/nea/pcj/Result.java
@@ -7,6 +7,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.function.Consumer;
 import java.util.function.Function;
 
 public sealed interface Result<Good, Bad> permits Result.Ok, Result.Fail {
diff --git a/src/main/java/moe/nea/pcj/json/AtIndex.java b/src/main/java/moe/nea/pcj/json/AtIndex.java
new file mode 100644
index 0000000..ec01112
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/AtIndex.java
@@ -0,0 +1,4 @@
+package moe.nea.pcj.json;
+
+public record AtIndex(int index, JsonLikeError error) implements JsonLikeError {
+}
diff --git a/src/main/java/moe/nea/pcj/json/JsonCodec.java b/src/main/java/moe/nea/pcj/json/JsonCodec.java
index 65f4a5e..6195bee 100644
--- a/src/main/java/moe/nea/pcj/json/JsonCodec.java
+++ b/src/main/java/moe/nea/pcj/json/JsonCodec.java
@@ -2,11 +2,51 @@ package moe.nea.pcj.json;
 
 import moe.nea.pcj.Codec;
 import moe.nea.pcj.Result;
+import moe.nea.pcj.Unit;
+
+import java.util.ArrayList;
+import java.util.List;
 
 public interface JsonCodec<T, Format> extends Codec<
 		T, Format, JsonLikeOperations<Format>,
 		JsonLikeError, JsonLikeError> {
 
+	default JsonCodec<List<T>, Format> listOf() {
+		return new JsonCodec<>() {
+			@Override
+			public Result<Format, JsonLikeError> encode(List<T> data, JsonLikeOperations<Format> ops) {
+				var list = ops.createList();
+				var erros = new ArrayList<JsonLikeError>();
+				for (int i = 0; i < data.size(); i++) {
+					var datum = data.get(i);
+					final var index = i;
+					var result = JsonCodec.this.encode(datum, ops)
+					                           .mapError(it -> new AtIndex(index, it));
+					erros.addAll(result.errors());
+					result.valueOrPartial().ifPresent(list::add);
+				}
+				return Result.<Format, JsonLikeError>ok(list.complete()).appendErrors(erros);
+			}
+
+			@Override
+			public Result<List<T>, JsonLikeError> decode(Format format, JsonLikeOperations<Format> ops) {
+				var view = Result.<ListView<Format>, JsonLikeError>cast(ops.getList(format));
+				return view.flatMap(elements -> {
+					var acc = new ArrayList<T>(elements.length());
+					var errors = new ArrayList<JsonLikeError>();
+					for (int i = 0; i < elements.length(); i++) {
+						final var index = i;
+						var result = JsonCodec.this.decode(elements.getUnsafe(i), ops)
+						                           .mapError(it -> new AtIndex(index, it));
+						errors.addAll(result.errors());
+						result.valueOrPartial().ifPresent(acc::add);
+					}
+					return Result.<List<T>, JsonLikeError>ok(acc).appendErrors(errors);
+				});
+			}
+		};
+	}
+
 	default MapCodec<T, Format> fieldOf(String key) {
 		return new MapCodec<>() {
 			@Override
diff --git a/src/main/java/moe/nea/pcj/json/MapCodec.java b/src/main/java/moe/nea/pcj/json/MapCodec.java
index 468e4cf..4b76150 100644
--- a/src/main/java/moe/nea/pcj/json/MapCodec.java
+++ b/src/main/java/moe/nea/pcj/json/MapCodec.java
@@ -11,6 +11,10 @@ public interface MapCodec<T, Format> {
 
 	Result<RecordBuilder<Format>, JsonLikeError> encode(T value, JsonLikeOperations<Format> ops);
 
+	default JsonCodec<T, Format> codec() {
+		return RecordJoiners.join(withGetter(it -> it), it -> it);
+	}
+
 	default <O> RecordCodec<O, T, Format> withGetter(Function<O, T> getter) {
 		return new RecordCodec<>(this, getter);
 	}