content: /*
   * Copyright (C) 2009-2024 Lightbend Inc. <https://www.lightbend.com>
   */
  
  /*
   * Adapted from github.com/twitter/hpack with this license:
   *
   * Copyright 2014 Twitter, Inc.
   *
   * Licensed 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 akka.http.shaded.com.twitter.hpack;
  
  import java.io.IOException;
  import java.io.OutputStream;
  
  final class HuffmanEncoder {
  
    private final int[] codes;
    private final byte[] lengths;
  
    /**
     * Creates a new Huffman encoder with the specified Huffman coding.
     * @param codes   the Huffman codes indexed by symbol
     * @param lengths the length of each Huffman code
     */
    HuffmanEncoder(int[] codes, byte[] lengths) {
      this.codes = codes;
      this.lengths = lengths;
    }
  
    /**
     * Compresses the input string literal using the Huffman coding.
     * @param  out  the output stream for the compressed data
     * @param  data the string literal to be Huffman encoded
     * @param  off  the start offset in the data
     * @param  len  the number of bytes to encode
     * @throws IOException if an I/O error occurs. In particular,
     *         an <code>IOException</code> may be thrown if the
     *         output stream has been closed.
     */
    public void encode(OutputStream out, String string) throws IOException {
      if (out == null) {
        throw new NullPointerException("out");
      } else if (string == null) {
        throw new NullPointerException("string");
      }
  
      long current = 0;
      int n = 0;
      int len = string.length();
  
      for (int i = 0; i < len; i++) {
        int b = string.charAt(i) & 0xFF;
        int code = codes[b];
        int nbits = lengths[b];
  
        current <<= nbits;
        current |= code;
        n += nbits;
  
        while (n >= 8) {
          n -= 8;
          out.write(((int)(current >> n)));
        }
      }
  
      if (n > 0) {
        current <<= (8 - n);
        current |= (0xFF >>> n); // this should be EOS symbol
        out.write((int)current);
      }
    }
  
    /**
     * Returns the number of bytes required to Huffman encode the input string literal.
     * @param  data the string literal to be Huffman encoded
     * @return the number of bytes required to Huffman encode <code>data</code>
     */
    public int getEncodedLength(String data) {
      if (data == null) {
        throw new NullPointerException("data");
      }
      long len = 0;
      for (int i = 0; i < data.length(); i++) {
        len += lengths[data.charAt(i) & 0xFF];
      }
      return (int)((len + 7) >> 3);
    }
  }
  