AbbreviationMap.java

package com.hypixel.hytale.server.core.command.system;

import it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap;
import java.util.Collections;
import java.util.Map;
import java.util.Objects;
import javax.annotation.Nonnull;

public class AbbreviationMap<Value> {
   private final Map<String, Value> abbreviationMap;

   public AbbreviationMap(@Nonnull Map<String, Value> abbreviationMap) {
      this.abbreviationMap = abbreviationMap;
   }

   public Value get(@Nonnull String abbreviation) {
      return (Value)this.abbreviationMap.get(abbreviation.toLowerCase());
   }

   @Nonnull
   public static <V> AbbreviationMapBuilder<V> create() {
      return new AbbreviationMapBuilder<V>();
   }

   public static class AbbreviationMapBuilder<Value> {
      private final Map<String, Value> keys = new Object2ObjectOpenHashMap<String, Value>();

      public AbbreviationMapBuilder() {
      }

      @Nonnull
      public AbbreviationMapBuilder<Value> put(@Nonnull String key, @Nonnull Value value) {
         if (this.keys.putIfAbsent(key.toLowerCase(), value) != null) {
            throw new IllegalArgumentException("Cannot have values with the same key in AbbreviationMap: " + key);
         } else {
            return this;
         }
      }

      @Nonnull
      public AbbreviationMap<Value> build() {
         Object2ObjectOpenHashMap<String, Value> abbreviationMap = new Object2ObjectOpenHashMap<String, Value>();

         for(Map.Entry<String, Value> entry : this.keys.entrySet()) {
            this.appendAbbreviation((String)entry.getKey(), entry.getValue(), abbreviationMap);
         }

         abbreviationMap.values().removeIf(Objects::isNull);
         abbreviationMap.trim();
         return new AbbreviationMap<Value>(Collections.unmodifiableMap(abbreviationMap));
      }

      private void appendAbbreviation(@Nonnull String key, @Nonnull Value value, @Nonnull Map<String, Value> map) {
         map.put(key, value);

         for(int i = 1; i < key.length(); ++i) {
            String substring = key.substring(0, key.length() - i);
            Value existingAbbreviationValue = (Value)map.get(substring);
            if (existingAbbreviationValue == null) {
               map.put(substring, value);
            } else if (!this.keys.containsKey(substring) && !existingAbbreviationValue.equals(value)) {
               map.put(substring, (Object)null);
            }
         }

      }
   }
}