/*
* 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.annotation.UsedByGeneratedCode;
import com.facebook.presto.metadata.BoundVariables;
import com.facebook.presto.metadata.FunctionRegistry;
import com.facebook.presto.metadata.SqlOperator;
import com.facebook.presto.spi.ConnectorSession;
import com.facebook.presto.spi.PrestoException;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.block.BlockBuilder;
import com.facebook.presto.spi.block.BlockBuilderStatus;
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.type.ArrayType;
import com.google.common.collect.ImmutableList;
import io.airlift.slice.Slice;
import java.lang.invoke.MethodHandle;
import java.util.List;
import static com.facebook.presto.metadata.Signature.typeVariable;
import static com.facebook.presto.spi.StandardErrorCode.INVALID_CAST_ARGUMENT;
import static com.facebook.presto.spi.type.TypeSignature.parseTypeSignature;
import static com.facebook.presto.type.TypeJsonUtils.appendToBlockBuilder;
import static com.facebook.presto.type.TypeJsonUtils.canCastFromJson;
import static com.facebook.presto.type.TypeJsonUtils.stackRepresentationToObject;
import static com.facebook.presto.util.Failures.checkCondition;
import static com.facebook.presto.util.Reflection.methodHandle;
import static com.google.common.base.Preconditions.checkArgument;
public class JsonToArrayCast
extends SqlOperator
{
public static final JsonToArrayCast JSON_TO_ARRAY = new JsonToArrayCast();
private static final MethodHandle METHOD_HANDLE = methodHandle(JsonToArrayCast.class, "toArray", Type.class, ConnectorSession.class, Slice.class);
private JsonToArrayCast()
{
super(OperatorType.CAST,
ImmutableList.of(typeVariable("T")),
ImmutableList.of(),
parseTypeSignature("array(T)"),
ImmutableList.of(parseTypeSignature(StandardTypes.JSON)));
}
@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(canCastFromJson(arrayType), INVALID_CAST_ARGUMENT, "Cannot cast JSON to %s", arrayType);
MethodHandle methodHandle = METHOD_HANDLE.bindTo(arrayType);
return new ScalarFunctionImplementation(true, ImmutableList.of(false), methodHandle, isDeterministic());
}
@UsedByGeneratedCode
public static Block toArray(Type arrayType, ConnectorSession connectorSession, Slice json)
{
try {
List<?> array = (List<?>) stackRepresentationToObject(connectorSession, json, arrayType);
if (array == null) {
return null;
}
Type elementType = ((ArrayType) arrayType).getElementType();
BlockBuilder blockBuilder = elementType.createBlockBuilder(new BlockBuilderStatus(), array.size());
for (Object element : array) {
appendToBlockBuilder(elementType, element, blockBuilder);
}
return blockBuilder.build();
}
catch (RuntimeException e) {
throw new PrestoException(INVALID_CAST_ARGUMENT, "Value cannot be cast to " + arrayType, e);
}
}
}