ArrayConstructor.java
/*
* 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.bytecode.BytecodeBlock;
import com.facebook.presto.bytecode.CallSiteBinder;
import com.facebook.presto.bytecode.ClassDefinition;
import com.facebook.presto.bytecode.DynamicClassLoader;
import com.facebook.presto.bytecode.MethodDefinition;
import com.facebook.presto.bytecode.Parameter;
import com.facebook.presto.bytecode.Scope;
import com.facebook.presto.bytecode.Variable;
import com.facebook.presto.bytecode.control.IfStatement;
import com.facebook.presto.bytecode.expression.BytecodeExpression;
import com.facebook.presto.common.QualifiedObjectName;
import com.facebook.presto.common.block.Block;
import com.facebook.presto.common.block.BlockBuilder;
import com.facebook.presto.common.block.BlockBuilderStatus;
import com.facebook.presto.common.type.Type;
import com.facebook.presto.metadata.BoundVariables;
import com.facebook.presto.metadata.FunctionAndTypeManager;
import com.facebook.presto.metadata.SqlScalarFunction;
import com.facebook.presto.spi.function.FunctionKind;
import com.facebook.presto.spi.function.Signature;
import com.facebook.presto.spi.function.SqlFunctionVisibility;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.primitives.Primitives;
import java.lang.invoke.MethodHandle;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Map;
import static com.facebook.presto.bytecode.Access.FINAL;
import static com.facebook.presto.bytecode.Access.PRIVATE;
import static com.facebook.presto.bytecode.Access.PUBLIC;
import static com.facebook.presto.bytecode.Access.STATIC;
import static com.facebook.presto.bytecode.Access.a;
import static com.facebook.presto.bytecode.Parameter.arg;
import static com.facebook.presto.bytecode.ParameterizedType.type;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.constantInt;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.constantNull;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.equal;
import static com.facebook.presto.common.type.TypeSignature.parseTypeSignature;
import static com.facebook.presto.metadata.BuiltInTypeAndFunctionNamespaceManager.JAVA_BUILTIN_NAMESPACE;
import static com.facebook.presto.operator.scalar.ScalarFunctionImplementationChoice.ArgumentProperty.valueTypeArgumentProperty;
import static com.facebook.presto.operator.scalar.ScalarFunctionImplementationChoice.NullConvention.USE_BOXED_TYPE;
import static com.facebook.presto.spi.StandardErrorCode.NOT_SUPPORTED;
import static com.facebook.presto.spi.function.Signature.typeVariable;
import static com.facebook.presto.spi.function.SqlFunctionVisibility.HIDDEN;
import static com.facebook.presto.sql.gen.SqlTypeBytecodeExpression.constantType;
import static com.facebook.presto.util.CompilerUtils.defineClass;
import static com.facebook.presto.util.CompilerUtils.makeClassName;
import static com.facebook.presto.util.Failures.checkCondition;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static java.lang.invoke.MethodHandles.lookup;
import static java.util.Collections.nCopies;
public final class ArrayConstructor
extends SqlScalarFunction
{
public static final ArrayConstructor ARRAY_CONSTRUCTOR = new ArrayConstructor();
public ArrayConstructor()
{
super(new Signature(QualifiedObjectName.valueOf(JAVA_BUILTIN_NAMESPACE, "array_constructor"),
FunctionKind.SCALAR,
ImmutableList.of(typeVariable("E")),
ImmutableList.of(),
parseTypeSignature("array(E)"),
ImmutableList.of(parseTypeSignature("E"), parseTypeSignature("E")),
true));
}
@Override
public SqlFunctionVisibility getVisibility()
{
return HIDDEN;
}
@Override
public boolean isDeterministic()
{
return true;
}
@Override
public boolean isCalledOnNullInput()
{
return true;
}
@Override
public String getDescription()
{
// Internal function, doesn't need a description
return null;
}
@Override
public BuiltInScalarFunctionImplementation specialize(BoundVariables boundVariables, int arity, FunctionAndTypeManager functionAndTypeManager)
{
Map<String, Type> types = boundVariables.getTypeVariables();
checkArgument(types.size() == 1, "Can only construct arrays from exactly matching types");
ImmutableList.Builder<Class<?>> builder = ImmutableList.builder();
Type type = types.get("E");
for (int i = 0; i < arity; i++) {
if (type.getJavaType().isPrimitive()) {
builder.add(Primitives.wrap(type.getJavaType()));
}
else {
builder.add(type.getJavaType());
}
}
ImmutableList<Class<?>> stackTypes = builder.build();
Class<?> clazz = generateArrayConstructor(stackTypes, type);
MethodHandle methodHandle;
try {
Method method = clazz.getMethod("arrayConstructor", stackTypes.toArray(new Class<?>[stackTypes.size()]));
methodHandle = lookup().unreflect(method);
}
catch (ReflectiveOperationException e) {
throw new RuntimeException(e);
}
return new BuiltInScalarFunctionImplementation(
false,
nCopies(stackTypes.size(), valueTypeArgumentProperty(USE_BOXED_TYPE)),
methodHandle);
}
private static Class<?> generateArrayConstructor(List<Class<?>> stackTypes, Type elementType)
{
checkCondition(stackTypes.size() <= 254, NOT_SUPPORTED, "Too many arguments for array constructor");
List<String> stackTypeNames = stackTypes.stream()
.map(Class::getSimpleName)
.collect(toImmutableList());
ClassDefinition definition = new ClassDefinition(
a(PUBLIC, FINAL),
makeClassName(Joiner.on("").join(stackTypeNames) + "ArrayConstructor"),
type(Object.class));
// Generate constructor
definition.declareDefaultConstructor(a(PRIVATE));
// Generate arrayConstructor()
ImmutableList.Builder<Parameter> parameters = ImmutableList.builder();
for (int i = 0; i < stackTypes.size(); i++) {
Class<?> stackType = stackTypes.get(i);
parameters.add(arg("arg" + i, stackType));
}
MethodDefinition method = definition.declareMethod(a(PUBLIC, STATIC), "arrayConstructor", type(Block.class), parameters.build());
Scope scope = method.getScope();
BytecodeBlock body = method.getBody();
Variable blockBuilderVariable = scope.declareVariable(BlockBuilder.class, "blockBuilder");
CallSiteBinder binder = new CallSiteBinder();
BytecodeExpression createBlockBuilder = blockBuilderVariable.set(
constantType(binder, elementType).invoke("createBlockBuilder", BlockBuilder.class, constantNull(BlockBuilderStatus.class), constantInt(stackTypes.size())));
body.append(createBlockBuilder);
for (int i = 0; i < stackTypes.size(); i++) {
Variable argument = scope.getVariable("arg" + i);
IfStatement ifStatement = new IfStatement()
.condition(equal(argument, constantNull(stackTypes.get(i))))
.ifTrue(blockBuilderVariable.invoke("appendNull", BlockBuilder.class).pop())
.ifFalse(constantType(binder, elementType).writeValue(blockBuilderVariable, argument.cast(elementType.getJavaType())));
body.append(ifStatement);
}
body.append(blockBuilderVariable.invoke("build", Block.class).ret());
return defineClass(definition, Object.class, binder.getBindings(), new DynamicClassLoader(ArrayConstructor.class.getClassLoader()));
}
}