io.trino.sql.gen.IsNullCodeGenerator Maven / Gradle / Ivy
/*
* 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 io.trino.sql.gen;
import io.airlift.bytecode.BytecodeBlock;
import io.airlift.bytecode.BytecodeNode;
import io.airlift.bytecode.Variable;
import io.trino.sql.relational.RowExpression;
import io.trino.sql.relational.SpecialForm;
import static com.google.common.base.Preconditions.checkArgument;
import static io.airlift.bytecode.expression.BytecodeExpressions.constantFalse;
import static io.airlift.bytecode.instruction.Constant.loadBoolean;
import static io.trino.type.UnknownType.UNKNOWN;
import static java.util.Objects.requireNonNull;
public class IsNullCodeGenerator
implements BytecodeGenerator
{
private final RowExpression argument;
public IsNullCodeGenerator(SpecialForm specialForm)
{
requireNonNull(specialForm, "specialForm is null");
checkArgument(specialForm.arguments().size() == 1);
argument = specialForm.arguments().get(0);
}
@Override
public BytecodeNode generateExpression(BytecodeGeneratorContext generatorContext)
{
if (argument.type().equals(UNKNOWN)) {
return loadBoolean(true);
}
BytecodeNode value = generatorContext.generate(argument);
// evaluate the expression, pop the produced value, and load the null flag
Variable wasNull = generatorContext.wasNull();
BytecodeBlock block = new BytecodeBlock()
.comment("is null")
.append(value)
.pop(argument.type().getJavaType())
.append(wasNull);
// clear the null flag
block.append(wasNull.set(constantFalse()));
return block;
}
}