org.apache.calcite.adapter.csv.JsonEnumerator.java Source code

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Here is the source code for org.apache.calcite.adapter.csv.JsonEnumerator.java

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/*
 * 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.calcite.adapter.csv;

import org.apache.calcite.linq4j.Enumerator;
import org.apache.calcite.linq4j.Linq4j;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.File;
import java.io.IOException;
import java.util.List;

/** Enumerator that reads from a JSON file. */
class JsonEnumerator implements Enumerator<Object[]> {
    private final Enumerator<Object> enumerator;

    public JsonEnumerator(File file) {
        try {
            final ObjectMapper mapper = new ObjectMapper();
            mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
            mapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
            mapper.configure(JsonParser.Feature.ALLOW_COMMENTS, true);
            // noinspection unchecked
            List<Object> list = mapper.readValue(file, List.class);
            enumerator = Linq4j.enumerator(list);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public Object[] current() {
        return new Object[] { enumerator.current() };
    }

    public boolean moveNext() {
        return enumerator.moveNext();
    }

    public void reset() {
        enumerator.reset();
    }

    public void close() {
        try {
            enumerator.close();
        } catch (Exception e) {
            throw new RuntimeException("Error closing JSON reader", e);
        }
    }
}

// End JsonEnumerator.java