wip

15 files changed, 262 insertions, 0 deletions

diff --git a/src/main/java/moe/nea/pcj/json/AtField.java b/src/main/java/moe/nea/pcj/json/AtField.java
new file mode 100644
index 0000000..3780e38
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/AtField.java
@@ -0,0 +1,4 @@
+package moe.nea.pcj.json;
+
+public record AtField(String field, JsonLikeError error) implements JsonLikeError {
+}
diff --git a/src/main/java/moe/nea/pcj/json/BasicCodecs.java b/src/main/java/moe/nea/pcj/json/BasicCodecs.java
new file mode 100644
index 0000000..8f957f9
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/BasicCodecs.java
@@ -0,0 +1,51 @@
+package moe.nea.pcj.json;
+
+import moe.nea.pcj.Result;
+
+public class BasicCodecs<Format> {
+	protected BasicCodecs() {}
+
+	public static <Format> BasicCodecs<Format> create() {
+		return new BasicCodecs<>();
+	}
+
+	public final JsonCodec<String, Format> STRING = new JsonCodec<>() {
+		@Override
+		public Result<String, ? extends JsonLikeError> decode(Format format, JsonLikeOperations<Format> ops) {
+			return ops.getString(format);
+		}
+
+		@Override
+		public Result<Format, ? extends JsonLikeError> encode(String data, JsonLikeOperations<Format> ops) {
+			return Result.ok(ops.createString(data));
+		}
+	};
+
+	public final JsonCodec<Float, Format> FLOAT = new JsonCodec<Float, Format>() {
+		@Override
+		public Result<? extends Float, ? extends JsonLikeError> decode(Format format, JsonLikeOperations<Format> ops) {
+			return ops.getNumeric(format).map(Number::floatValue);
+		}
+
+		@Override
+		public Result<? extends Format, ? extends JsonLikeError> encode(Float data, JsonLikeOperations<Format> ops) {
+			return Result.ok(ops.createNumeric(data));
+		}
+	};
+
+	public final JsonCodec<Integer, Format> INTEGER = new JsonCodec<>() {
+		@Override
+		public Result<? extends Integer, ? extends JsonLikeError> decode(Format format, JsonLikeOperations<Format> ops) {
+			return ops.getNumeric(format).map(Number::intValue); // TODO: filter for valid ints
+		}
+
+		@Override
+		public Result<? extends Format, ? extends JsonLikeError> encode(Integer data, JsonLikeOperations<Format> ops) {
+			return Result.ok(ops.createNumeric(data));
+		}
+	};
+
+	public <T> JsonCodec<T, Format> objectCodec() {
+
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/moe/nea/pcj/json/DuplicateJsonKey.java b/src/main/java/moe/nea/pcj/json/DuplicateJsonKey.java
new file mode 100644
index 0000000..13d81db
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/DuplicateJsonKey.java
@@ -0,0 +1,4 @@
+package moe.nea.pcj.json;
+
+public record DuplicateJsonKey(String key) implements JsonLikeError {
+}
diff --git a/src/main/java/moe/nea/pcj/json/JsonCodec.java b/src/main/java/moe/nea/pcj/json/JsonCodec.java
new file mode 100644
index 0000000..65f4a5e
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/JsonCodec.java
@@ -0,0 +1,31 @@
+package moe.nea.pcj.json;
+
+import moe.nea.pcj.Codec;
+import moe.nea.pcj.Result;
+
+public interface JsonCodec<T, Format> extends Codec<
+		T, Format, JsonLikeOperations<Format>,
+		JsonLikeError, JsonLikeError> {
+
+	default MapCodec<T, Format> fieldOf(String key) {
+		return new MapCodec<>() {
+			@Override
+			public Result<T, JsonLikeError> decode(RecordView<Format> record, JsonLikeOperations<Format> ops) {
+				return record.get(key)
+				             .map(element -> Result.<T, JsonLikeError>cast(
+						             JsonCodec.this.decode(element, ops)
+						                           .mapError(it -> new AtField(key, it))))
+				             .orElseGet(() -> Result.fail(new MissingKey(key)));
+			}
+
+			@Override
+			public Result<RecordBuilder<Format>, JsonLikeError> encode(T value, JsonLikeOperations<Format> ops) {
+				var record = ops.createObject();
+				return Result.<Format, JsonLikeError>cast(JsonCodec.this.encode(value, ops))
+				             .<JsonLikeError>mapError(it -> new AtField(key, it))
+				             .flatMap(json -> Result.cast(record.add(key, json).map(unit -> record)));
+			}
+
+		};
+	}
+}
diff --git a/src/main/java/moe/nea/pcj/json/JsonLikeError.java b/src/main/java/moe/nea/pcj/json/JsonLikeError.java
new file mode 100644
index 0000000..609bd84
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/JsonLikeError.java
@@ -0,0 +1,4 @@
+package moe.nea.pcj.json;
+
+public interface JsonLikeError {
+}
diff --git a/src/main/java/moe/nea/pcj/json/JsonLikeOperations.java b/src/main/java/moe/nea/pcj/json/JsonLikeOperations.java
new file mode 100644
index 0000000..7bb0162
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/JsonLikeOperations.java
@@ -0,0 +1,32 @@
+package moe.nea.pcj.json;
+
+import moe.nea.pcj.Operation;
+import moe.nea.pcj.Result;
+import moe.nea.pcj.Unit;
+
+public interface JsonLikeOperations<Format> extends Operation<Format> {
+
+	Format createNull(Unit value);
+
+	Result<Unit, ? extends JsonLikeError> getNull(Format element);
+
+	Format createNumeric(Number value);
+
+	Result<Number, ? extends JsonLikeError> getNumeric(Format element);
+
+	Format createString(String value);
+
+	Result<String, ? extends JsonLikeError> getString(Format element);
+
+	Format createBoolean(boolean value);
+
+	Result<Boolean, ? extends JsonLikeError> getBoolean(Format format);
+
+	RecordBuilder<Format> createObject();
+
+	Result<? extends RecordView<Format>, ? extends JsonLikeError> getObject(Format format);
+
+	ListBuilder<Format, Format> createList();
+
+	Result<? extends ListView<Format>, ? extends JsonLikeError> getList(Format format);
+}
diff --git a/src/main/java/moe/nea/pcj/json/ListBuilder.java b/src/main/java/moe/nea/pcj/json/ListBuilder.java
new file mode 100644
index 0000000..c6e9220
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/ListBuilder.java
@@ -0,0 +1,9 @@
+package moe.nea.pcj.json;
+
+public interface ListBuilder<Format, ElementFormat> extends ListView<ElementFormat> {
+	Format complete();
+
+	void add(ElementFormat value);
+
+	void set(int index, ElementFormat value);
+}
diff --git a/src/main/java/moe/nea/pcj/json/ListView.java b/src/main/java/moe/nea/pcj/json/ListView.java
new file mode 100644
index 0000000..dcc6e37
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/ListView.java
@@ -0,0 +1,14 @@
+package moe.nea.pcj.json;
+
+import java.util.Optional;
+
+public interface ListView<Format> {
+	int length();
+
+	default Optional<Format> getSafe(int index) {
+		if (index < 0 || index >= length()) return Optional.empty();
+		return Optional.of(getUnsafe(index));
+	}
+
+	Format getUnsafe(int index);
+}
diff --git a/src/main/java/moe/nea/pcj/json/MapCodec.java b/src/main/java/moe/nea/pcj/json/MapCodec.java
new file mode 100644
index 0000000..468e4cf
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/MapCodec.java
@@ -0,0 +1,17 @@
+package moe.nea.pcj.json;
+
+import moe.nea.pcj.Result;
+
+import java.util.function.Function;
+
+public interface MapCodec<T, Format> {
+	Result<T, JsonLikeError> decode(
+			RecordView<Format> record,
+			JsonLikeOperations<Format> ops);
+
+	Result<RecordBuilder<Format>, JsonLikeError> encode(T value, JsonLikeOperations<Format> ops);
+
+	default <O> RecordCodec<O, T, Format> withGetter(Function<O, T> getter) {
+		return new RecordCodec<>(this, getter);
+	}
+}
diff --git a/src/main/java/moe/nea/pcj/json/MissingKey.java b/src/main/java/moe/nea/pcj/json/MissingKey.java
new file mode 100644
index 0000000..3dad05c
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/MissingKey.java
@@ -0,0 +1,4 @@
+package moe.nea.pcj.json;
+
+public record MissingKey(String missingKey) implements JsonLikeError {
+}
diff --git a/src/main/java/moe/nea/pcj/json/RecordBuilder.java b/src/main/java/moe/nea/pcj/json/RecordBuilder.java
new file mode 100644
index 0000000..c610f27
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/RecordBuilder.java
@@ -0,0 +1,12 @@
+package moe.nea.pcj.json;
+
+import moe.nea.pcj.Result;
+import moe.nea.pcj.Unit;
+
+public interface RecordBuilder<ElementFormat> extends RecordView<ElementFormat> {
+	Result<Unit, JsonLikeError> add(String key, ElementFormat value);
+
+	Result<RecordBuilder<ElementFormat>, JsonLikeError> mergeWith(RecordBuilder<ElementFormat> other);
+
+	ElementFormat complete();
+}
diff --git a/src/main/java/moe/nea/pcj/json/RecordCodec.java b/src/main/java/moe/nea/pcj/json/RecordCodec.java
new file mode 100644
index 0000000..7ba8815
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/RecordCodec.java
@@ -0,0 +1,59 @@
+package moe.nea.pcj.json;
+
+import moe.nea.pcj.Codec;
+import moe.nea.pcj.Result;
+import moe.nea.pcj.Tuple;
+
+import java.util.function.Function;
+import java.util.stream.Stream;
+
+public record RecordCodec<O, T, Format>(
+		MapCodec<T, Format> codec,
+		Function<O, T> getter
+) {
+
+	private Result<RecordBuilder<Format>, JsonLikeError> enc(O data, JsonLikeOperations<Format> ops) {
+		return codec().encode(getter().apply(data), ops);
+	}
+
+	private Result<T, JsonLikeError> dec(RecordView<Format> data, JsonLikeOperations<Format> ops) {
+		return codec().decode(data, ops);
+	}
+
+	private static <Format> Result<RecordBuilder<Format>, JsonLikeError> merge(Result<RecordBuilder<Format>, JsonLikeError> left, Result<RecordBuilder<Format>, JsonLikeError> right) {
+		return left.flatMap(l -> right.flatMap(l::mergeWith));
+	}
+
+	abstract static class RecordCompleteCodec<O, Format> implements JsonCodec<O, Format> {
+		@Override
+		public Result<O, JsonLikeError> decode(Format format, JsonLikeOperations<Format> ops) {
+			return Result.<RecordView<Format>, JsonLikeError>cast(ops.getObject(format))
+			             .flatMap(record -> (decode(record, ops)));
+		}
+
+		protected abstract Result<O, JsonLikeError> decode(RecordView<Format> record, JsonLikeOperations<Format> ops);
+	}
+
+	public static <T1, T2, O, Format> JsonCodec<O, Format> join(
+			RecordCodec<O, T1, Format> arg1,
+			RecordCodec<O, T2, Format> arg2,
+			Tuple.Func2<O, T1, T2> joiner
+	) {
+		return new RecordCompleteCodec<>() {
+
+			@Override
+			public Result<Format, JsonLikeError> encode(O data, JsonLikeOperations<Format> ops) {
+				return Stream.of(arg1.enc(data, ops), arg2.enc(data, ops))
+				             .reduce(Result.ok(ops.createObject()), RecordCodec::merge)
+				             .map(RecordBuilder::complete);
+			}
+
+			@Override
+			public Result<O, JsonLikeError> decode(RecordView<Format> format, JsonLikeOperations<Format> ops) {
+				return Tuple.Tuple2.collect(new Tuple.Tuple2<>(arg1, arg2)
+						                            .map(it -> it.dec(format, ops), it -> it.dec(format, ops)))
+				                   .map(it -> it.applyTo(joiner));
+			}
+		};
+	}
+}
diff --git a/src/main/java/moe/nea/pcj/json/RecordView.java b/src/main/java/moe/nea/pcj/json/RecordView.java
new file mode 100644
index 0000000..968a936
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/RecordView.java
@@ -0,0 +1,10 @@
+package moe.nea.pcj.json;
+
+import java.util.Collection;
+import java.util.Optional;
+
+public interface RecordView<Format> {
+	Collection<String> getKeys();
+
+	Optional<Format> get(String key);
+}
diff --git a/src/main/java/moe/nea/pcj/json/UnexpectedJsonElement.java b/src/main/java/moe/nea/pcj/json/UnexpectedJsonElement.java
new file mode 100644
index 0000000..7bee7c1
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/UnexpectedJsonElement.java
@@ -0,0 +1,7 @@
+package moe.nea.pcj.json;
+
+public record UnexpectedJsonElement(
+		String expectedType,
+		Object actualJsonObject
+) implements JsonLikeError {
+}
diff --git a/src/main/java/moe/nea/pcj/json/package-info.java b/src/main/java/moe/nea/pcj/json/package-info.java
new file mode 100644
index 0000000..a5aace0
--- /dev/null
+++ b/src/main/java/moe/nea/pcj/json/package-info.java
@@ -0,0 +1,4 @@
+@NullMarked
+package moe.nea.pcj.json;
+
+import org.jspecify.annotations.NullMarked;
\ No newline at end of file