YamlOperations.java

/*
 * Portions of this software was developed by employees of the National Institute
 * of Standards and Technology (NIST), an agency of the Federal Government and is
 * being made available as a public service. Pursuant to title 17 United States
 * Code Section 105, works of NIST employees are not subject to copyright
 * protection in the United States. This software may be subject to foreign
 * copyright. Permission in the United States and in foreign countries, to the
 * extent that NIST may hold copyright, to use, copy, modify, create derivative
 * works, and distribute this software and its documentation without fee is hereby
 * granted on a non-exclusive basis, provided that this notice and disclaimer
 * of warranty appears in all copies.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
 */

package gov.nist.secauto.metaschema.databind.io.yaml;

import org.json.JSONException;
import org.json.JSONObject;
import org.yaml.snakeyaml.DumperOptions;
import org.yaml.snakeyaml.LoaderOptions;
import org.yaml.snakeyaml.Yaml;
import org.yaml.snakeyaml.constructor.Constructor;
import org.yaml.snakeyaml.nodes.Tag;
import org.yaml.snakeyaml.representer.Representer;
import org.yaml.snakeyaml.resolver.Resolver;

import java.io.BufferedReader;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Map;

import edu.umd.cs.findbugs.annotations.NonNull;

public final class YamlOperations {
  private static final Yaml YAML_PARSER;

  static {
    LoaderOptions loaderOptions = new LoaderOptions();
    loaderOptions.setCodePointLimit(Integer.MAX_VALUE - 1); // 2GB
    Constructor constructor = new Constructor(loaderOptions);
    DumperOptions dumperOptions = new DumperOptions();
    Representer representer = new Representer(dumperOptions);
    YAML_PARSER = new Yaml(constructor, representer, dumperOptions, loaderOptions, new Resolver() {
      @Override
      protected void addImplicitResolvers() {
        addImplicitResolver(Tag.BOOL, BOOL, "yYnNtTfFoO");
        addImplicitResolver(Tag.INT, INT, "-+0123456789");
        addImplicitResolver(Tag.FLOAT, FLOAT, "-+0123456789.");
        addImplicitResolver(Tag.MERGE, MERGE, "<");
        addImplicitResolver(Tag.NULL, NULL, "~nN\0");
        addImplicitResolver(Tag.NULL, EMPTY, null);
        // addImplicitResolver(Tag.TIMESTAMP, TIMESTAMP, "0123456789");
      }
    });
  }

  private YamlOperations() {
    // disable construction
  }

  /**
   * Parse the data represented in YAML in the provided {@code target}, producing
   * an mapping of field names to Java object values.
   *
   * @param target
   *          the YAML file to parse
   * @return the mapping of field names to Java object values
   * @throws IOException
   *           if an error occurred while parsing the YAML content
   */
  @SuppressWarnings({ "unchecked", "null" })
  @NonNull
  public static Map<String, Object> parseYaml(Path target) throws IOException {
    try (BufferedReader reader = Files.newBufferedReader(target.toAbsolutePath(), StandardCharsets.UTF_8)) {
      return (Map<String, Object>) YAML_PARSER.load(reader);
    }
  }

  /**
   * Converts the provided YAML {@code map} into JSON.
   *
   * @param map
   *          the YAML map
   * @return the JSON object
   * @throws JSONException
   *           if an error occurred while building the JSON tree
   */
  public static JSONObject yamlToJson(@NonNull Map<String, Object> map) {
    return new JSONObject(map);
  }
}