From 133e1d75f9fa7810ecf164cc1096209155101c53 Mon Sep 17 00:00:00 2001
From: JFronny <git@akbvopenfl1.hopto.org>
Date: Tue, 30 Apr 2024 15:53:01 +0200
Subject: [PATCH] feat(serialize-databind): implement alternate API for parsing
 via ADTs. Probably still need to figure out how to ensure unchecked
 exceptions are not propagated

---
 .../jfronny/commons/serialize/RToken.java     | 12 +++
 .../commons/serialize/SerializeReader.java    | 84 ++++++++++++++++++-
 2 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 commons-serialize/src/main/java/io/gitlab/jfronny/commons/serialize/RToken.java

diff --git a/commons-serialize/src/main/java/io/gitlab/jfronny/commons/serialize/RToken.java b/commons-serialize/src/main/java/io/gitlab/jfronny/commons/serialize/RToken.java
new file mode 100644
index 0000000..f8c4e04
--- /dev/null
+++ b/commons-serialize/src/main/java/io/gitlab/jfronny/commons/serialize/RToken.java
@@ -0,0 +1,12 @@
+package io.gitlab.jfronny.commons.serialize;
+
+public sealed interface RToken {
+    enum Simple implements RToken {
+        BEGIN_ARRAY, END_ARRAY, BEGIN_OBJECT, END_OBJECT, NULL, END_DOCUMENT
+    }
+
+    record Name(java.lang.String name) implements RToken {}
+    record String(java.lang.String value) implements RToken {}
+    record Number(java.lang.Number value) implements RToken {}
+    record Boolean(boolean value) implements RToken {}
+}
diff --git a/commons-serialize/src/main/java/io/gitlab/jfronny/commons/serialize/SerializeReader.java b/commons-serialize/src/main/java/io/gitlab/jfronny/commons/serialize/SerializeReader.java
index a997921..2b58f95 100644
--- a/commons-serialize/src/main/java/io/gitlab/jfronny/commons/serialize/SerializeReader.java
+++ b/commons-serialize/src/main/java/io/gitlab/jfronny/commons/serialize/SerializeReader.java
@@ -1,8 +1,23 @@
 package io.gitlab.jfronny.commons.serialize;
 
 import io.gitlab.jfronny.commons.SamWithReceiver;
+import io.gitlab.jfronny.commons.throwable.ExceptionWrapper;
+import org.jetbrains.annotations.NotNull;
 
-public abstract class SerializeReader<TEx extends Exception, T extends SerializeReader<TEx, T>> implements AutoCloseable {
+import java.util.Iterator;
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+/**
+ * A reader for serialized data.
+ * Although it is marked as {@link Iterable}, you should make sure iteration is only done once, since it <b>consumes tokens</b>!
+ *
+ * @param <TEx> the exception type
+ * @param <T>   the reader type
+ */
+public abstract class SerializeReader<TEx extends Exception, T extends SerializeReader<TEx, T>> implements AutoCloseable, Iterable<RToken> {
     protected boolean lenient = false;
     protected boolean serializeSpecialFloatingPointValues = false;
 
@@ -67,6 +82,69 @@ public abstract class SerializeReader<TEx extends Exception, T extends Serialize
     @Override
     public abstract void close() throws TEx;
 
+    /**
+     * Returns the next token alongside its value as an {@link RToken} and advances the reader.
+     *
+     * @return the next token
+     * @throws TEx if an error occurs
+     */
+    public RToken next() throws TEx {
+        return switch (peek()) {
+            case BEGIN_ARRAY -> RToken.Simple.BEGIN_ARRAY;
+            case END_ARRAY -> RToken.Simple.END_ARRAY;
+            case BEGIN_OBJECT -> RToken.Simple.BEGIN_OBJECT;
+            case END_OBJECT -> RToken.Simple.END_OBJECT;
+            case NAME -> new RToken.Name(nextName());
+            case STRING -> new RToken.String(nextString());
+            case NUMBER -> new RToken.Number(nextNumber());
+            case BOOLEAN -> new RToken.Boolean(nextBoolean());
+            case NULL -> {
+                nextNull();
+                yield RToken.Simple.NULL;
+            }
+            case END_DOCUMENT -> RToken.Simple.END_DOCUMENT;
+        };
+    }
+
+    /**
+     * Returns a {@link Stream} of the tokens within the current object or array.
+     * The stream consumes tokens and advances the reader, so it is not possible to iterate over the tokens more than once.
+     * Additionally, iteration may throw {@link RuntimeException}s created with {@link ExceptionWrapper#wrap(Throwable)} around {@link TEx}.
+     * @return a stream of the tokens
+     */
+    public @NotNull Stream<RToken> stream() {
+        return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator(), Spliterator.NONNULL | Spliterator.ORDERED), false);
+    }
+
+    /**
+     * Returns an {@link Iterator} over the tokens within the current object or array.
+     * The iterator consumes tokens and advances the reader, so it is not possible to iterate over the tokens more than once.
+     * Additionally, iteration may throw {@link RuntimeException}s created with {@link ExceptionWrapper#wrap(Throwable)} around {@link TEx}.
+     * @return an iterator over the tokens
+     */
+    @Override
+    public @NotNull Iterator<RToken> iterator() {
+        return new Iterator<>() {
+            @Override
+            public boolean hasNext() {
+                try {
+                    return SerializeReader.this.hasNext();
+                } catch (Exception e) {
+                    throw ExceptionWrapper.wrap(e);
+                }
+            }
+
+            @Override
+            public RToken next() {
+                try {
+                    return SerializeReader.this.next();
+                } catch (Exception e) {
+                    throw ExceptionWrapper.wrap(e);
+                }
+            }
+        };
+    }
+
     /**
      * Copies the current element to the writer.
      *
@@ -113,6 +191,10 @@ public abstract class SerializeReader<TEx extends Exception, T extends Serialize
         return getClass().getSimpleName() + locationString();
     }
 
+    /**
+     * Used to provide toString and location information in error messages. Format should resemble that in {@code serialize-json}.
+     * @return a string representation of the location of the reader
+     */
     protected String locationString() {
         return " at path " + getPath();
     }