flink-table/flink-table-planner/src/main/java/org/apache/flink/table/planner/expressions/converter/converters/JsonExistsConverter.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.
 */

package org.apache.flink.table.planner.expressions.converter.converters;

import org.apache.flink.annotation.Internal;
import org.apache.flink.table.api.JsonExistsOnError;
import org.apache.flink.table.api.TableException;
import org.apache.flink.table.expressions.CallExpression;
import org.apache.flink.table.expressions.ValueLiteralExpression;
import org.apache.flink.table.functions.BuiltInFunctionDefinitions;
import org.apache.flink.table.planner.expressions.converter.CallExpressionConvertRule;
import org.apache.flink.table.planner.functions.sql.FlinkSqlOperatorTable;

import org.apache.calcite.rex.RexNode;
import org.apache.calcite.sql.SqlJsonExistsErrorBehavior;

import java.util.LinkedList;
import java.util.List;

/** Conversion for {@link BuiltInFunctionDefinitions#JSON_EXISTS}. */
@Internal
class JsonExistsConverter extends CustomizedConverter {
    @Override
    public RexNode convert(CallExpression call, CallExpressionConvertRule.ConvertContext context) {
        checkArgumentNumber(call, 2, 3);

        final List<RexNode> operands = new LinkedList<>();
        operands.add(context.toRexNode(call.getChildren().get(0)));
        operands.add(context.toRexNode(call.getChildren().get(1)));

        if (call.getChildren().size() >= 3) {
            ((ValueLiteralExpression) call.getChildren().get(2))
                    .getValueAs(JsonExistsOnError.class)
                    .map(this::convertErrorBehavior)
                    .ifPresent(
                            onErrorBehavior ->
                                    operands.add(
                                            context.getRelBuilder()
                                                    .getRexBuilder()
                                                    .makeFlag(onErrorBehavior)));
        }

        return context.getRelBuilder().call(FlinkSqlOperatorTable.JSON_EXISTS, operands);
    }

    private SqlJsonExistsErrorBehavior convertErrorBehavior(JsonExistsOnError onError) {
        switch (onError) {
            case TRUE:
                return SqlJsonExistsErrorBehavior.TRUE;
            case FALSE:
                return SqlJsonExistsErrorBehavior.FALSE;
            case UNKNOWN:
                return SqlJsonExistsErrorBehavior.UNKNOWN;
            case ERROR:
                return SqlJsonExistsErrorBehavior.ERROR;
            default:
                throw new TableException("Unknown ON ERROR behavior: " + onError);
        }
    }
}