/*
* 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.FunctionKind;
import com.facebook.presto.metadata.FunctionRegistry;
import com.facebook.presto.metadata.Signature;
import com.facebook.presto.metadata.SqlScalarFunction;
import com.facebook.presto.spi.PageBuilder;
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.type.Type;
import com.facebook.presto.spi.type.TypeManager;
import com.facebook.presto.sql.gen.VarArgsToArrayAdapterGenerator;
import com.google.common.collect.ImmutableList;
import java.lang.invoke.MethodHandle;
import java.util.Optional;
import static com.facebook.presto.metadata.Signature.typeVariable;
import static com.facebook.presto.spi.StandardErrorCode.INVALID_FUNCTION_ARGUMENT;
import static com.facebook.presto.spi.type.TypeSignature.parseTypeSignature;
import static com.facebook.presto.sql.gen.VarArgsToArrayAdapterGenerator.generateVarArgsToArrayAdapter;
import static com.facebook.presto.util.Reflection.methodHandle;
import static java.util.Collections.nCopies;
public final class ArrayConcatFunction
extends SqlScalarFunction
{
public static final ArrayConcatFunction ARRAY_CONCAT_FUNCTION = new ArrayConcatFunction();
private static final String FUNCTION_NAME = "concat";
private static final String DESCRIPTION = "Concatenates given arrays";
private static final MethodHandle METHOD_HANDLE = methodHandle(ArrayConcatFunction.class, "concat", Type.class, Object.class, Block[].class);
private static final MethodHandle USER_STATE_FACTORY = methodHandle(ArrayConcatFunction.class, "createState", Type.class);
private ArrayConcatFunction()
{
super(new Signature(FUNCTION_NAME,
FunctionKind.SCALAR,
ImmutableList.of(typeVariable("E")),
ImmutableList.of(),
parseTypeSignature("array(E)"),
ImmutableList.of(parseTypeSignature("array(E)")),
true));
}
@Override
public boolean isHidden()
{
return false;
}
@Override
public boolean isDeterministic()
{
return true;
}
@Override
public String getDescription()
{
return DESCRIPTION;
}
@Override
public ScalarFunctionImplementation specialize(BoundVariables boundVariables, int arity, TypeManager typeManager, FunctionRegistry functionRegistry)
{
if (arity < 2) {
throw new PrestoException(INVALID_FUNCTION_ARGUMENT, "There must be two or more arguments to " + FUNCTION_NAME);
}
Type elementType = boundVariables.getTypeVariable("E");
VarArgsToArrayAdapterGenerator.MethodHandleAndConstructor methodHandleAndConstructor = generateVarArgsToArrayAdapter(
Block.class,
Block.class,
arity,
METHOD_HANDLE.bindTo(elementType),
USER_STATE_FACTORY.bindTo(elementType));
return new ScalarFunctionImplementation(
false,
nCopies(arity, false),
nCopies(arity, false),
methodHandleAndConstructor.getMethodHandle(),
Optional.of(methodHandleAndConstructor.getConstructor()),
isDeterministic());
}
@UsedByGeneratedCode
public static Object createState(Type elementType)
{
return new PageBuilder(ImmutableList.of(elementType));
}
@UsedByGeneratedCode
public static Block concat(Type elementType, Object state, Block[] blocks)
{
int resultPositionCount = 0;
// fast path when there is at most one non empty block
Block nonEmptyBlock = null;
for (int i = 0; i < blocks.length; i++) {
resultPositionCount += blocks[i].getPositionCount();
if (blocks[i].getPositionCount() > 0) {
nonEmptyBlock = blocks[i];
}
}
if (nonEmptyBlock == null) {
return blocks[0];
}
if (resultPositionCount == nonEmptyBlock.getPositionCount()) {
return nonEmptyBlock;
}
PageBuilder pageBuilder = (PageBuilder) state;
if (pageBuilder.isFull()) {
pageBuilder.reset();
}
BlockBuilder blockBuilder = pageBuilder.getBlockBuilder(0);
for (int blockIndex = 0; blockIndex < blocks.length; blockIndex++) {
Block block = blocks[blockIndex];
for (int i = 0; i < block.getPositionCount(); i++) {
elementType.appendTo(block, i, blockBuilder);
}
}
pageBuilder.declarePositions(resultPositionCount);
return blockBuilder.getRegion(blockBuilder.getPositionCount() - resultPositionCount, resultPositionCount);
}
}