/*
* Licensed 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 com.facebook.presto.operator.scalar;
import com.facebook.presto.metadata.BoundVariables;
import com.facebook.presto.metadata.FunctionRegistry;
import com.facebook.presto.metadata.SqlOperator;
import com.facebook.presto.server.SliceSerializer;
import com.facebook.presto.spi.ConnectorSession;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.function.OperatorType;
import com.facebook.presto.spi.type.StandardTypes;
import com.facebook.presto.spi.type.Type;
import com.facebook.presto.spi.type.TypeManager;
import com.facebook.presto.spi.type.TypeSignatureParameter;
import com.facebook.presto.util.JsonUtil.JsonGeneratorWriter;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import com.google.common.collect.ImmutableList;
import io.airlift.json.ObjectMapperProvider;
import io.airlift.slice.DynamicSliceOutput;
import io.airlift.slice.Slice;
import io.airlift.slice.SliceOutput;
import java.io.IOException;
import java.lang.invoke.MethodHandle;
import static com.facebook.presto.metadata.Signature.typeVariable;
import static com.facebook.presto.operator.scalar.JsonOperators.JSON_FACTORY;
import static com.facebook.presto.spi.StandardErrorCode.INVALID_CAST_ARGUMENT;
import static com.facebook.presto.spi.type.TypeSignature.parseTypeSignature;
import static com.facebook.presto.util.Failures.checkCondition;
import static com.facebook.presto.util.JsonUtil.canCastToJson;
import static com.facebook.presto.util.JsonUtil.createJsonGenerator;
import static com.facebook.presto.util.Reflection.methodHandle;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Throwables.throwIfUnchecked;
public class ArrayToJsonCast
extends SqlOperator
{
public static final ArrayToJsonCast ARRAY_TO_JSON = new ArrayToJsonCast();
private static final Supplier<ObjectMapper> OBJECT_MAPPER = Suppliers.memoize(() -> new ObjectMapperProvider().get().registerModule(new SimpleModule().addSerializer(Slice.class, new SliceSerializer())));
private static final MethodHandle METHOD_HANDLE = methodHandle(ArrayToJsonCast.class, "toJson", JsonGeneratorWriter.class, ConnectorSession.class, Block.class);
private ArrayToJsonCast()
{
super(OperatorType.CAST,
ImmutableList.of(typeVariable("T")),
ImmutableList.of(),
parseTypeSignature(StandardTypes.JSON),
ImmutableList.of(parseTypeSignature("array(T)")));
}
@Override
public ScalarFunctionImplementation specialize(BoundVariables boundVariables, int arity, TypeManager typeManager, FunctionRegistry functionRegistry)
{
checkArgument(arity == 1, "Expected arity to be 1");
Type type = boundVariables.getTypeVariable("T");
Type arrayType = typeManager.getParameterizedType(StandardTypes.ARRAY, ImmutableList.of(TypeSignatureParameter.of(type.getTypeSignature())));
checkCondition(canCastToJson(arrayType), INVALID_CAST_ARGUMENT, "Cannot cast %s to JSON", arrayType);
JsonGeneratorWriter writer = JsonGeneratorWriter.createJsonGeneratorWriter(type);
MethodHandle methodHandle = METHOD_HANDLE.bindTo(writer);
return new ScalarFunctionImplementation(false, ImmutableList.of(false), methodHandle, isDeterministic());
}
public static Slice toJson(JsonGeneratorWriter writer, ConnectorSession session, Block block)
{
try {
SliceOutput output = new DynamicSliceOutput(40);
try (JsonGenerator jsonGenerator = createJsonGenerator(JSON_FACTORY, output)) {
jsonGenerator.writeStartArray();
for (int i = 0; i < block.getPositionCount(); i++) {
writer.writeJsonValue(jsonGenerator, block, i, session);
}
jsonGenerator.writeEndArray();
}
return output.slice();
}
catch (IOException e) {
throwIfUnchecked(e);
throw new RuntimeException(e);
}
}
}