/*
* Licensed to CRATE Technology GmbH ("Crate") under one or more contributor
* license agreements. See the NOTICE file distributed with this work for
* additional information regarding copyright ownership. Crate licenses
* this file to you 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.
*
* However, if you have executed another commercial license agreement
* with Crate these terms will supersede the license and you may use the
* software solely pursuant to the terms of the relevant commercial agreement.
*/
package io.crate.operation.predicate;
import com.google.common.base.Preconditions;
import io.crate.metadata.*;
import io.crate.operation.Input;
import io.crate.planner.symbol.Function;
import io.crate.planner.symbol.Literal;
import io.crate.planner.symbol.Symbol;
import io.crate.planner.symbol.SymbolType;
import io.crate.types.DataType;
import io.crate.types.DataTypes;
import java.util.List;
public class IsNullPredicate<T> extends Scalar<Boolean, T> {
public static final String NAME = "op_isnull";
private final FunctionInfo info;
public static void register(PredicateModule module) {
module.register(NAME, new Resolver());
}
private static FunctionInfo generateInfo(List<DataType> types) {
return new FunctionInfo(new FunctionIdent(NAME, types), DataTypes.BOOLEAN, FunctionInfo.Type.PREDICATE);
}
IsNullPredicate(FunctionInfo info) {
this.info = info;
}
@Override
public FunctionInfo info() {
return info;
}
@Override
public Symbol normalizeSymbol(Function symbol) {
assert (symbol != null);
assert (symbol.arguments().size() == 1);
Symbol arg = symbol.arguments().get(0);
if (arg.equals(Literal.NULL) || arg.symbolType() == SymbolType.DYNAMIC_REFERENCE) {
return Literal.newLiteral(true);
} else if (arg.symbolType().isValueSymbol()) {
return Literal.newLiteral(((Input) arg).value() == null);
}
return symbol;
}
@Override
public Boolean evaluate(Input[] args) {
assert args.length == 1;
return args[0] == null || args[0].value() == null;
}
private static class Resolver implements DynamicFunctionResolver {
@Override
public FunctionImplementation<Function> getForTypes(List<DataType> dataTypes) throws IllegalArgumentException {
Preconditions.checkArgument(
dataTypes.size() == 1, "the is null predicate takes only 1 argument");
return new IsNullPredicate<>(generateInfo(dataTypes));
}
}
}