Core: Refactor variants to enable moving interfaces to API module

core/src/main/java/org/apache/iceberg/variants/LogicalType.java

@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.iceberg.variants;
+
+enum LogicalType {
+  NULL,
+  BOOLEAN,
+  EXACT_NUMERIC,
+  FLOAT,
+  DOUBLE,
+  DATE,
+  TIMESTAMPTZ,
+  TIMESTAMPNTZ,
+  BINARY,
+  STRING,
+  ARRAY,
+  OBJECT
+}

core/src/main/java/org/apache/iceberg/variants/PhysicalType.java

@@ -0,0 +1,103 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.iceberg.variants;
+
+import java.math.BigDecimal;
+import java.nio.ByteBuffer;
+import java.util.List;
+import java.util.Map;
+
+public enum PhysicalType {
+  NULL(LogicalType.NULL, Void.class),
+  BOOLEAN_TRUE(LogicalType.BOOLEAN, Boolean.class),
+  BOOLEAN_FALSE(LogicalType.BOOLEAN, Boolean.class),
+  INT8(LogicalType.EXACT_NUMERIC, Byte.class),
+  INT16(LogicalType.EXACT_NUMERIC, Short.class),
+  INT32(LogicalType.EXACT_NUMERIC, Integer.class),
+  INT64(LogicalType.EXACT_NUMERIC, Long.class),
+  DOUBLE(LogicalType.DOUBLE, Double.class),
+  DECIMAL4(LogicalType.EXACT_NUMERIC, BigDecimal.class),
+  DECIMAL8(LogicalType.EXACT_NUMERIC, BigDecimal.class),
+  DECIMAL16(LogicalType.EXACT_NUMERIC, BigDecimal.class),
+  DATE(LogicalType.DATE, Integer.class),
+  TIMESTAMPTZ(LogicalType.TIMESTAMPTZ, Long.class),
+  TIMESTAMPNTZ(LogicalType.TIMESTAMPNTZ, Long.class),
+  FLOAT(LogicalType.FLOAT, Float.class),
+  BINARY(LogicalType.BINARY, ByteBuffer.class),
+  STRING(LogicalType.STRING, String.class),
+  ARRAY(LogicalType.ARRAY, List.class),
+  OBJECT(LogicalType.OBJECT, Map.class);
+
+  private final LogicalType logicalType;
+  private final Class<?> javaClass;
+
+  PhysicalType(LogicalType logicalType, Class<?> javaClass) {
+    this.logicalType = logicalType;
+    this.javaClass = javaClass;
+  }
+
+  LogicalType toLogicalType() {
+    return logicalType;
+  }
+
+  public Class<?> javaClass() {
+    return javaClass;
+  }
+
+  public static PhysicalType from(int primitiveType) {
+    switch (primitiveType) {
+      case Primitives.TYPE_NULL:
+        return NULL;
+      case Primitives.TYPE_TRUE:
+        return BOOLEAN_TRUE;
+      case Primitives.TYPE_FALSE:
+        return BOOLEAN_FALSE;
+      case Primitives.TYPE_INT8:
+        return INT8;
+      case Primitives.TYPE_INT16:
+        return INT16;
+      case Primitives.TYPE_INT32:
+        return INT32;
+      case Primitives.TYPE_INT64:
+        return INT64;
+      case Primitives.TYPE_DATE:
+        return DATE;
+      case Primitives.TYPE_TIMESTAMPTZ:
+        return TIMESTAMPTZ;
+      case Primitives.TYPE_TIMESTAMPNTZ:
+        return TIMESTAMPNTZ;
+      case Primitives.TYPE_FLOAT:
+        return FLOAT;
+      case Primitives.TYPE_DOUBLE:
+        return DOUBLE;
+      case Primitives.TYPE_DECIMAL4:
+        return DECIMAL4;
+      case Primitives.TYPE_DECIMAL8:
+        return DECIMAL8;
+      case Primitives.TYPE_DECIMAL16:
+        return DECIMAL16;
+      case Primitives.TYPE_BINARY:
+        return BINARY;
+      case Primitives.TYPE_STRING:
+        return STRING;
+    }
+
+    throw new UnsupportedOperationException("Unknown primitive physical type: " + primitiveType);
+  }
+}

core/src/main/java/org/apache/iceberg/variants/PrimitiveWrapper.java

@@ -23,8 +23,6 @@
 import java.nio.ByteOrder;
 import java.nio.charset.StandardCharsets;
 import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
-import org.apache.iceberg.variants.Variants.PhysicalType;
-import org.apache.iceberg.variants.Variants.Primitives;
 
 class PrimitiveWrapper<T> implements VariantPrimitive<T> {
   private static final byte NULL_HEADER = VariantUtil.primitiveHeader(Primitives.TYPE_NULL);

core/src/main/java/org/apache/iceberg/variants/Primitives.java

@@ -0,0 +1,43 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.iceberg.variants;
+
+class Primitives {
+  static final int TYPE_NULL = 0;
+  static final int TYPE_TRUE = 1;
+  static final int TYPE_FALSE = 2;
+  static final int TYPE_INT8 = 3;
+  static final int TYPE_INT16 = 4;
+  static final int TYPE_INT32 = 5;
+  static final int TYPE_INT64 = 6;
+  static final int TYPE_DOUBLE = 7;
+  static final int TYPE_DECIMAL4 = 8;
+  static final int TYPE_DECIMAL8 = 9;
+  static final int TYPE_DECIMAL16 = 10;
+  static final int TYPE_DATE = 11;
+  static final int TYPE_TIMESTAMPTZ = 12; // equivalent to timestamptz
+  static final int TYPE_TIMESTAMPNTZ = 13; // equivalent to timestamp
+  static final int TYPE_FLOAT = 14;
+  static final int TYPE_BINARY = 15;
+  static final int TYPE_STRING = 16;
+
+  static final int PRIMITIVE_TYPE_SHIFT = 2;
+
+  private Primitives() {}
+}

core/src/main/java/org/apache/iceberg/variants/SerializedMetadata.java

@@ -112,6 +112,18 @@ public ByteBuffer buffer() {
     return metadata;
   }
 
+  @Override
+  public int sizeInBytes() {
+    return buffer().remaining();
+  }
+
+  @Override
+  public int writeTo(ByteBuffer buffer, int offset) {
+    ByteBuffer value = buffer();
+    VariantUtil.writeBufferAbsolute(buffer, offset, value);
+    return value.remaining();
+  }
+
   @Override
   public String toString() {
     return VariantMetadata.asString(this);

core/src/main/java/org/apache/iceberg/variants/SerializedPrimitive.java

@@ -43,12 +43,12 @@ static SerializedPrimitive from(ByteBuffer value, int header) {
   }
 
   private final ByteBuffer value;
-  private final Variants.PhysicalType type;
+  private final PhysicalType type;
   private Object primitive = null;
 
   private SerializedPrimitive(ByteBuffer value, int header) {
     this.value = value;
-    this.type = Variants.PhysicalType.from(header >> PRIMITIVE_TYPE_SHIFT);
+    this.type = PhysicalType.from(header >> PRIMITIVE_TYPE_SHIFT);
   }
 
   private Object read() {
@@ -111,7 +111,7 @@ private Object read() {
   }
 
   @Override
-  public Variants.PhysicalType type() {
+  public PhysicalType type() {
     return type;
   }
 

core/src/main/java/org/apache/iceberg/variants/SerializedShortString.java

@@ -50,8 +50,8 @@ private SerializedShortString(ByteBuffer value, int header) {
   }
 
   @Override
-  public Variants.PhysicalType type() {
-    return Variants.PhysicalType.STRING;
+  public PhysicalType type() {
+    return PhysicalType.STRING;
   }
 
   @Override

core/src/main/java/org/apache/iceberg/variants/VariantArray.java

@@ -27,8 +27,8 @@ public interface VariantArray extends VariantValue {
   int numElements();
 
   @Override
-  default Variants.PhysicalType type() {
-    return Variants.PhysicalType.ARRAY;
+  default PhysicalType type() {
+    return PhysicalType.ARRAY;
   }
 
   @Override

core/src/main/java/org/apache/iceberg/variants/VariantMetadata.java

@@ -18,10 +18,11 @@
  */
 package org.apache.iceberg.variants;
 
+import java.nio.ByteBuffer;
 import java.util.NoSuchElementException;
 
 /** A variant metadata dictionary. */
-public interface VariantMetadata extends Variants.Serialized {
+public interface VariantMetadata {
   /** Returns the ID for a {@code name} in the dictionary, or -1 if not present. */
   int id(String name);
 
@@ -35,6 +36,20 @@ public interface VariantMetadata extends Variants.Serialized {
   /** Returns the size of the metadata dictionary. */
   int dictionarySize();
 
+  /** Returns the serialized size in bytes of this value. */
+  int sizeInBytes();
+
+  /**
+   * Writes this value to the buffer at the given offset, ignoring the buffer's position and limit.
+   *
+   * <p>{@link #sizeInBytes()} bytes will be written to the buffer.
+   *
+   * @param buffer a ByteBuffer to write serialized metadata into
+   * @param offset starting offset to write serialized metadata
+   * @return the number of bytes written
+   */
+  int writeTo(ByteBuffer buffer, int offset);
+
   static String asString(VariantMetadata metadata) {
     StringBuilder builder = new StringBuilder();
 

core/src/main/java/org/apache/iceberg/variants/VariantObject.java

@@ -30,8 +30,8 @@ public interface VariantObject extends VariantValue {
   int numFields();
 
   @Override
-  default Variants.PhysicalType type() {
-    return Variants.PhysicalType.OBJECT;
+  default PhysicalType type() {
+    return PhysicalType.OBJECT;
   }
 
   @Override

core/src/main/java/org/apache/iceberg/variants/VariantUtil.java

@@ -165,7 +165,7 @@ static int sizeOf(int maxValue) {
   }
 
   static byte primitiveHeader(int primitiveType) {
-    return (byte) (primitiveType << Variants.Primitives.PRIMITIVE_TYPE_SHIFT);
+    return (byte) (primitiveType << Primitives.PRIMITIVE_TYPE_SHIFT);
   }
 
   static byte objectHeader(boolean isLarge, int fieldIdSize, int offsetSize) {

core/src/main/java/org/apache/iceberg/variants/VariantValue.java

@@ -19,7 +19,6 @@
 package org.apache.iceberg.variants;
 
 import java.nio.ByteBuffer;
-import org.apache.iceberg.variants.Variants.PhysicalType;
 
 /** A variant value. */
 public interface VariantValue {