lang/java/avro/src/main/java/org/apache/avro/Conversions.java

/*
 * 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
 *
 *     https://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.avro;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Collection;
import java.util.Map;
import java.util.UUID;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericEnumSymbol;
import org.apache.avro.generic.GenericFixed;
import org.apache.avro.generic.IndexedRecord;

public class Conversions {

  public static class UUIDConversion extends Conversion<UUID> {
    @Override
    public Class<UUID> getConvertedType() {
      return UUID.class;
    }

    @Override
    public Schema getRecommendedSchema() {
      return LogicalTypes.uuid().addToSchema(Schema.create(Schema.Type.STRING));
    }

    @Override
    public String getLogicalTypeName() {
      return "uuid";
    }

    @Override
    public UUID fromCharSequence(CharSequence value, Schema schema, LogicalType type) {
      return UUID.fromString(value.toString());
    }

    @Override
    public CharSequence toCharSequence(UUID value, Schema schema, LogicalType type) {
      return value.toString();
    }
  }

  public static class DecimalConversion extends Conversion<BigDecimal> {
    @Override
    public Class<BigDecimal> getConvertedType() {
      return BigDecimal.class;
    }

    @Override
    public Schema getRecommendedSchema() {
      throw new UnsupportedOperationException("No recommended schema for decimal (scale is required)");
    }

    @Override
    public String getLogicalTypeName() {
      return "decimal";
    }

    @Override
    public BigDecimal fromBytes(ByteBuffer value, Schema schema, LogicalType type) {
      int scale = ((LogicalTypes.Decimal) type).getScale();
      // always copy the bytes out because BigInteger has no offset/length ctor
      byte[] bytes = new byte[value.remaining()];
      value.duplicate().get(bytes);
      return new BigDecimal(new BigInteger(bytes), scale);
    }

    @Override
    public ByteBuffer toBytes(BigDecimal value, Schema schema, LogicalType type) {
      int scale = ((LogicalTypes.Decimal) type).getScale();
      if (scale != value.scale()) {
        throw new AvroTypeException("Cannot encode decimal with scale " + value.scale() + " as scale " + scale);
      }
      return ByteBuffer.wrap(value.unscaledValue().toByteArray());
    }

    @Override
    public BigDecimal fromFixed(GenericFixed value, Schema schema, LogicalType type) {
      int scale = ((LogicalTypes.Decimal) type).getScale();
      return new BigDecimal(new BigInteger(value.bytes()), scale);
    }

    @Override
    public GenericFixed toFixed(BigDecimal value, Schema schema, LogicalType type) {
      int scale = ((LogicalTypes.Decimal) type).getScale();
      if (scale != value.scale()) {
        throw new AvroTypeException("Cannot encode decimal with scale " + value.scale() + " as scale " + scale);
      }

      byte fillByte = (byte) (value.signum() < 0 ? 0xFF : 0x00);
      byte[] unscaled = value.unscaledValue().toByteArray();
      byte[] bytes = new byte[schema.getFixedSize()];
      int offset = bytes.length - unscaled.length;

      // Fill the front of the array and copy remaining with unscaled values
      Arrays.fill(bytes, 0, offset, fillByte);
      System.arraycopy(unscaled, 0, bytes, offset, bytes.length - offset);

      return new GenericData.Fixed(schema, bytes);
    }
  }

  /**
   * Convert a underlying representation of a logical type (such as a ByteBuffer)
   * to a higher level object (such as a BigDecimal).
   *
   * @param datum      The object to be converted.
   * @param schema     The schema of datum. Cannot be null if datum is not null.
   * @param type       The {@link org.apache.avro.LogicalType} of datum. Cannot be
   *                   null if datum is not null.
   * @param conversion The tool used to finish the conversion. Cannot be null if
   *                   datum is not null.
   * @return The result object, which is a high level object of the logical type.
   *         If a null datum is passed in, a null value will be returned.
   * @throws IllegalArgumentException if a null schema, type or conversion is
   *                                  passed in while datum is not null.
   */
  public static Object convertToLogicalType(Object datum, Schema schema, LogicalType type, Conversion<?> conversion) {
    if (datum == null) {
      return null;
    }

    if (schema == null || type == null || conversion == null) {
      throw new IllegalArgumentException("Parameters cannot be null! Parameter values:"
          + Arrays.deepToString(new Object[] { datum, schema, type, conversion }));
    }

    try {
      switch (schema.getType()) {
      case RECORD:
        return conversion.fromRecord((IndexedRecord) datum, schema, type);
      case ENUM:
        return conversion.fromEnumSymbol((GenericEnumSymbol) datum, schema, type);
      case ARRAY:
        return conversion.fromArray((Collection) datum, schema, type);
      case MAP:
        return conversion.fromMap((Map<?, ?>) datum, schema, type);
      case FIXED:
        return conversion.fromFixed((GenericFixed) datum, schema, type);
      case STRING:
        return conversion.fromCharSequence((CharSequence) datum, schema, type);
      case BYTES:
        return conversion.fromBytes((ByteBuffer) datum, schema, type);
      case INT:
        return conversion.fromInt((Integer) datum, schema, type);
      case LONG:
        return conversion.fromLong((Long) datum, schema, type);
      case FLOAT:
        return conversion.fromFloat((Float) datum, schema, type);
      case DOUBLE:
        return conversion.fromDouble((Double) datum, schema, type);
      case BOOLEAN:
        return conversion.fromBoolean((Boolean) datum, schema, type);
      }
      return datum;
    } catch (ClassCastException e) {
      throw new AvroRuntimeException(
          "Cannot convert " + datum + ":" + datum.getClass().getSimpleName() + ": expected generic type", e);
    }
  }

  /**
   * Convert a high level representation of a logical type (such as a BigDecimal)
   * to the its underlying representation object (such as a ByteBuffer)
   *
   * @param datum      The object to be converted.
   * @param schema     The schema of datum. Cannot be null if datum is not null.
   * @param type       The {@link org.apache.avro.LogicalType} of datum. Cannot be
   *                   null if datum is not null.
   * @param conversion The tool used to finish the conversion. Cannot be null if
   *                   datum is not null.
   * @return The result object, which is an underlying representation object of
   *         the logical type. If the input param datum is null, a null value will
   *         be returned.
   * @throws IllegalArgumentException if a null schema, type or conversion is
   *                                  passed in while datum is not null.
   */
  public static <T> Object convertToRawType(Object datum, Schema schema, LogicalType type, Conversion<T> conversion) {
    if (datum == null) {
      return null;
    }

    if (schema == null || type == null || conversion == null) {
      throw new IllegalArgumentException("Parameters cannot be null! Parameter values:"
          + Arrays.deepToString(new Object[] { datum, schema, type, conversion }));
    }

    try {
      Class<T> fromClass = conversion.getConvertedType();
      switch (schema.getType()) {
      case RECORD:
        return conversion.toRecord(fromClass.cast(datum), schema, type);
      case ENUM:
        return conversion.toEnumSymbol(fromClass.cast(datum), schema, type);
      case ARRAY:
        return conversion.toArray(fromClass.cast(datum), schema, type);
      case MAP:
        return conversion.toMap(fromClass.cast(datum), schema, type);
      case FIXED:
        return conversion.toFixed(fromClass.cast(datum), schema, type);
      case STRING:
        return conversion.toCharSequence(fromClass.cast(datum), schema, type);
      case BYTES:
        return conversion.toBytes(fromClass.cast(datum), schema, type);
      case INT:
        return conversion.toInt(fromClass.cast(datum), schema, type);
      case LONG:
        return conversion.toLong(fromClass.cast(datum), schema, type);
      case FLOAT:
        return conversion.toFloat(fromClass.cast(datum), schema, type);
      case DOUBLE:
        return conversion.toDouble(fromClass.cast(datum), schema, type);
      case BOOLEAN:
        return conversion.toBoolean(fromClass.cast(datum), schema, type);
      }
      return datum;
    } catch (ClassCastException e) {
      throw new AvroRuntimeException(
          "Cannot convert " + datum + ":" + datum.getClass().getSimpleName() + ": expected logical type", e);
    }
  }

}