Compressor.java

package com.hypixel.hytale.builtin.hytalegenerator.datastructures.compression;

import javax.annotation.Nonnull;

public class Compressor {
   private final int MIN_RUN = 7;

   public Compressor() {
   }

   @Nonnull
   public <T> CompressedArray<T> compressOnReference(@Nonnull T[] in) {
      int currentRun = 0;
      int resultIndex = 0;
      Object runObj = null;
      Object[] result = new Object[in.length];

      for(int i = 0; i < result.length; ++i) {
         if (in[i] != runObj && currentRun >= 7) {
            result[resultIndex] = new Run(runObj, currentRun);
            currentRun = 0;
            ++resultIndex;
            runObj = in[i];
         } else if (in[i] != runObj && currentRun < 7) {
            while(currentRun > 0) {
               result[resultIndex] = runObj;
               ++resultIndex;
               --currentRun;
            }

            currentRun = 0;
            runObj = in[i];
         } else {
            ++currentRun;
         }
      }

      if (currentRun >= 7) {
         result[resultIndex] = new Run(runObj, currentRun);
      } else {
         while(currentRun > 0) {
            result[resultIndex] = runObj;
            ++resultIndex;
            --currentRun;
         }
      }

      Object[] trimmedResult = new Object[resultIndex];
      System.arraycopy(result, 0, trimmedResult, 0, trimmedResult.length);
      return new CompressedArray<T>(trimmedResult, in.length);
   }

   @Nonnull
   public <T> T[] decompress(@Nonnull CompressedArray<T> compressedArray) {
      int caIndex = 0;
      int runIndex = 0;
      int outIndex = 0;
      Object[] ca = compressedArray.data;

      Object[] out;
      for(out = new Object[compressedArray.initialLength]; caIndex < ca.length; ++caIndex) {
         if (ca[caIndex] instanceof Run) {
            Run run = (Run)ca[caIndex];

            for(int var8 = 0; var8 < run.length; ++var8) {
               out[outIndex++] = run.obj;
            }
         } else {
            out[outIndex++] = ca[caIndex];
         }
      }

      return (T[])out;
   }

   public static class Run {
      Object obj;
      int length;

      private Run(Object obj, int length) {
         this.obj = obj;
         this.length = length;
      }
   }

   public static class CompressedArray<T> {
      private final Object[] data;
      private final int initialLength;

      private CompressedArray(Object[] data, int initialLength) {
         this.data = data;
         this.initialLength = initialLength;
      }
   }
}