Json ADT

library/src/main/java/com/dslplatform/json/adt/JsonArray.java

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+package com.dslplatform.json.adt;
+
+// uncomment for java 21
+// public record JsonArray(DslJsonValue[] value) implements JsonValue { }
+
+public final class JsonArray implements JsonValue {
+    public final JsonValue[] value;
+
+    public JsonArray(JsonValue[] value) {
+        this.value = value;
+    }
+}

library/src/main/java/com/dslplatform/json/adt/JsonBoolean.java

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+package com.dslplatform.json.adt;
+
+// uncomment for java 21
+// public record JsonBoolean(boolean value) implements JsonValue {
+//     public static final JsonBoolean TRUE = new JsonBoolean(true);
+//     public static final JsonBoolean FALSE = new JsonBoolean(false);
+// }
+
+public final class JsonBoolean implements JsonValue {
+    public static final JsonBoolean TRUE = new JsonBoolean(true);
+    public static final JsonBoolean FALSE = new JsonBoolean(false);
+
+    public final boolean value;
+
+    private JsonBoolean(boolean value) {
+        this.value = value;
+    }
+}

library/src/main/java/com/dslplatform/json/adt/JsonNull.java

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+package com.dslplatform.json.adt;
+
+public final class JsonNull implements JsonValue {
+    private JsonNull() {}
+    public static final JsonNull INSTANCE = new JsonNull();
+}

library/src/main/java/com/dslplatform/json/adt/JsonNumber.java

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+package com.dslplatform.json.adt;
+
+// uncomment for java 21
+// public record JsonNumber(double value) implements JsonValue { }
+
+public final class JsonNumber implements JsonValue {
+    public final double value;
+
+    public JsonNumber(double value) {
+        this.value = value;
+    }
+}

library/src/main/java/com/dslplatform/json/adt/JsonObject.java

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+package com.dslplatform.json.adt;
+
+// uncomment for java 21
+// public record JsonObject(Entry[] value) implements JsonValue {
+//     public record Entry(String name, JsonValue value) {}
+// }
+
+public final class JsonObject implements JsonValue {
+    public final Entry[] value;
+
+    public JsonObject(Entry[] value) {
+        this.value = value;
+    }
+
+    public static class Entry {
+        public final String name;
+        public final JsonValue value;
+
+        public Entry(String name, JsonValue value) {
+            this.name = name;
+            this.value = value;
+        }
+    }
+}

library/src/main/java/com/dslplatform/json/adt/JsonString.java

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+package com.dslplatform.json.adt;
+
+// uncomment for java 21
+// public record JsonString(String value) implements JsonValue { }
+
+public final class JsonString implements JsonValue {
+    public final String value;
+
+    public JsonString(String value) {
+        this.value = value;
+    }
+}

library/src/main/java/com/dslplatform/json/adt/JsonValue.java

@@ -0,0 +1,5 @@
+package com.dslplatform.json.adt;
+
+// uncomment for java 21
+public /*sealed*/ interface JsonValue /*permits DslJsonArray, DslJsonBoolean, JsonNull, DslJsonNumber, DslJsonObject, DslJsonString*/ {
+}

library/src/main/java/com/dslplatform/json/adt/JsonValueConverter.java

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+package com.dslplatform.json.adt;
+
+import com.dslplatform.json.*;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+
+@JsonConverter(target = JsonValue.class)
+public abstract class JsonValueConverter {
+
+    public static JsonValue read(JsonReader reader) throws IOException {
+        if (reader.wasNull()) {
+            return JsonNull.INSTANCE;
+        } else if (reader.wasTrue()) {
+            return JsonBoolean.TRUE;
+        } else if (reader.wasFalse()) {
+            return JsonBoolean.FALSE;
+        } else if (reader.last() == '{') {
+            reader.getNextToken();
+            HashMap<String, JsonValue> elements = new HashMap<>();
+            while (reader.last() != '}') {
+                String key = reader.readKey();
+                assert reader.getNextToken() == ':';
+                elements.put(key, read(reader));
+                reader.getNextToken();
+                if (reader.last() == ',') reader.getNextToken();
+            }
+            return new JsonObject(elements.entrySet().stream().map(e -> new JsonObject.Entry(e.getKey(), e.getValue())).toArray(JsonObject.Entry[]::new));
+        } else if (reader.last() == '[') {
+            reader.getNextToken();
+            ArrayList<JsonValue> elements = new ArrayList<>();
+            while (reader.last() != ']') {
+                elements.add(read(reader));
+                reader.getNextToken();
+                if (reader.last() == ',') reader.getNextToken();
+            }
+            return new JsonArray(elements.toArray(new JsonValue[0]));
+        } else if (reader.last() == '\"') {
+            return new JsonString(StringConverter.deserialize(reader));
+        } else {
+            return new JsonNumber(NumberConverter.deserializeDouble(reader));
+        }
+    }
+
+    public static void write(JsonWriter writer, JsonValue value) {
+        if (value == null || value == JsonNull.INSTANCE) writer.writeNull();
+        if (value == JsonBoolean.TRUE) writer.writeAscii("true");
+        else if (value == JsonBoolean.FALSE) writer.writeAscii("false");
+        else if (value instanceof JsonObject) {
+            JsonObject o = (JsonObject) value;
+            writer.writeAscii("{");
+            boolean first = true;
+            for (int i = 0; i < o.value.length; i++) {
+                if (!first) writer.writeAscii(",");
+                JsonObject.Entry entry = o.value[i];
+                writer.writeString(entry.name);
+                writer.writeAscii(":");
+                write(writer, entry.value);
+                first = false;
+            }
+            writer.writeAscii("}");
+        } else if (value instanceof JsonArray) {
+            JsonArray a = (JsonArray) value;
+            writer.writeAscii("[");
+            boolean first = true;
+            for (int i = 0; i <a.value.length; i++) {
+                if (!first) writer.writeAscii(",");
+                write(writer, a.value[i]);
+                first = false;
+            }
+            writer.writeAscii("]");
+        } else if (value instanceof JsonString) {
+            StringConverter.serialize(((JsonString)value).value, writer);
+        } else if (value instanceof JsonNumber) {
+            NumberConverter.serialize(((JsonNumber)value).value, writer);
+        } else {
+            throw new NotSupportedJsonValueTypeException();
+        }
+    }
+
+    public final static class NotSupportedJsonValueTypeException extends RuntimeException {}
+}