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Carrot2 Text Clustering Library

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/*
 * Carrot2 project.
 *
 * Copyright (C) 2002-2020, Dawid Weiss, Stanisław Osiński.
 * All rights reserved.
 *
 * Refer to the full license file "carrot2.LICENSE"
 * in the root folder of the repository checkout or at:
 * https://www.carrot2.org/carrot2.LICENSE
 */
package org.carrot2.util;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Locale;
import java.util.Objects;

public class ClassRelativeResourceLookup implements ResourceLookup {
  private final Class clazz;

  public ClassRelativeResourceLookup(Class clazz) {
    this.clazz = clazz;
  }

  @Override
  public InputStream open(String resource) throws IOException {
    checkExists(resource);
    return clazz.getResourceAsStream(Objects.requireNonNull(resource));
  }

  private void checkExists(String resource) throws IOException {
    if (!exists(resource)) {
      throw new IOException(
          String.format(
              Locale.ROOT,
              "Resource %s does not exist relative to class %s.",
              resource,
              clazz.getName()));
    }
  }

  @Override
  public boolean exists(String resource) {
    return clazz.getResource(resource) != null;
  }

  @Override
  public String pathOf(String resource) {
    URL existingResource = clazz.getResource(resource);
    return existingResource != null
        ? existingResource.toExternalForm()
        : String.format(Locale.ROOT, "resource::(%s)/%s", clazz.getName(), resource);
  }
}