content: /*
   * 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.cassandra.index.sai.utils;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.nio.charset.StandardCharsets;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  /**
   * A simple wrapper of a <a href="https://nlp.stanford.edu/projects/glove/">glove</a> model that loads a set of
   * word -> embedding mappings into a {@link WordVector} object. The embeddings are represented a fixed dimension
   * float[].
   * <p>
   * The glove model provides a consistently valid embedding for each word that can be used for testing graph
   * implementations that use embeddings.
   */
  public class Glove
  {
      public static WordVector parse(InputStream inputStream) throws IOException
      {
          BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8), 1024 * 1024);
  
          Map<String, Vector> wordVectorMap = new HashMap<>();
          int dimension = -1;
  
          while (reader.ready())
          {
              String line = reader.readLine();
  
              String parts[] = line.split(" ");
  
              String word = parts[0];
  
              float[] vectorArray = new float[parts.length - 1];
  
              for (int index = 1; index < parts.length; index++)
                  vectorArray[index - 1] = Float.parseFloat(parts[index]);
  
              Vector vector = new Vector(vectorArray);
              if (wordVectorMap.isEmpty())
                  dimension = vector.dimension();
              else if (vector.dimension() != dimension)
                  throw new IOException("Vectors must all be of the same dimension");
              wordVectorMap.put(word, vector);
          }
          return new WordVector(wordVectorMap, dimension);
      }
  
      public static class WordVector
      {
          private final Map<String, Vector> wordVectorMap;
          private final int dimension;
          private final List<String> words;
  
          public WordVector(Map<String, Vector> wordVectorMap, int dimension)
          {
              this.wordVectorMap = wordVectorMap;
              this.dimension = dimension;
              this.words = new ArrayList<>(wordVectorMap.size());
              this.words.addAll(wordVectorMap.keySet());
          }
  
          public int size()
          {
              return wordVectorMap.size();
          }
  
          public int dimension()
          {
              return dimension;
          }
  
          public String word(int index)
          {
              return words.get(index);
          }
  
          public float[] vector(int index)
          {
              return wordVectorMap.get(words.get(index)).vector;
          }
  
          public float[] vector(String word)
          {
              return wordVectorMap.get(word).vector;
          }
      }
  
      public static class Vector
      {
          private final float[] vector;
  
          public Vector(float[] vector)
          {
              this.vector = vector;
          }
  
          public int dimension()
          {
              return vector.length;
          }
      }
  }
  