src/main/java/net/hydromatic/optiq/impl/csv/JsonEnumerator.java

/*
// Licensed to Julian Hyde under one or more contributor license
// agreements. See the NOTICE file distributed with this work for
// additional information regarding copyright ownership.
//
// Julian Hyde 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 net.hydromatic.optiq.impl.csv;

import net.hydromatic.linq4j.Enumerator;
import net.hydromatic.linq4j.Linq4j;

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

import java.io.*;
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 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