add observers

src/main/java/carpet/settings/ParsedRule.java

@@ -25,20 +25,6 @@ public final class ParsedRule<T> implements Comparable<ParsedRule> {
     public final T defaultValue;
     public final String defaultAsString;
 
-    public static <T> T callConstructor(Class<T> cls)
-    {
-        try
-        {
-            Constructor<T> constr = cls.getDeclaredConstructor();
-            constr.setAccessible(true);
-            return constr.newInstance();
-        }
-        catch (ReflectiveOperationException e)
-        {
-            throw new RuntimeException(e);
-        }
-    }
-
     ParsedRule(Field field, Rule rule)
     {
         this.field = field;
@@ -73,6 +59,19 @@ public final class ParsedRule<T> implements Comparable<ParsedRule> {
             this.validators.add(callConstructor(Validator._STRICT.class));
     }
 
+    private <T> T callConstructor(Class<T> cls)
+    {
+        try
+        {
+            Constructor<T> constr = cls.getDeclaredConstructor();
+            constr.setAccessible(true);
+            return constr.newInstance();
+        }
+        catch (ReflectiveOperationException e)
+        {
+            throw new RuntimeException(e);
+        }
+    }
 
     public ParsedRule<T> set(ServerCommandSource source, String value)
     {
@@ -115,8 +114,11 @@ public final class ParsedRule<T> implements Comparable<ParsedRule> {
                     return null;
                 }
             }
+            if (!value.equals(get()))
+            {
                 this.field.set(null, value);
-
+                SettingsManager.notifyRuleChanged(this, stringValue);
+            }
         }
         catch (IllegalAccessException e)
         {

src/main/java/carpet/settings/SettingsManager.java

@@ -8,9 +8,24 @@ import org.apache.commons.lang3.tuple.Pair;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
-import java.io.*;
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.PrintStream;
 import java.lang.reflect.Field;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.function.BiConsumer;
 import java.util.stream.Collectors;
 
 public class SettingsManager
@@ -18,7 +33,8 @@ public class SettingsManager
     private static final Logger LOG = LogManager.getLogger();
     private static Map<String, ParsedRule<?>> rules = new HashMap<>();
     public boolean locked;
-    MinecraftServer server;
+    private MinecraftServer server;
+    private static List<BiConsumer<ParsedRule<?>, String>> observers = new ArrayList<>();
 
     public SettingsManager(MinecraftServer server)
     {
@@ -26,7 +42,6 @@ public class SettingsManager
         loadConfigurationFromConf();
     }
 
-
     public static void parseSettingsClass(Class settingsClass)
     {
         for (Field f : settingsClass.getDeclaredFields())
@@ -38,6 +53,16 @@ public class SettingsManager
         }
     }
 
+    public static void addRuleObserver(BiConsumer<ParsedRule<?>, String> observer)
+    {
+        observers.add(observer);
+    }
+
+    static void notifyRuleChanged(ParsedRule<?> rule, String userTypedValue)
+    {
+        observers.forEach(observer -> observer.accept(rule, userTypedValue));
+    }
+
     public static Iterable<String> getCategories()
     {
         Set<String> categories = new HashSet<>();
@@ -88,7 +113,6 @@ public class SettingsManager
     }
 
 
-
     private void writeSettingsToConf(Map<String, String> values)
     {
         if (locked)
@@ -141,7 +165,7 @@ public class SettingsManager
     }
 
 
-    public Pair<Map<String, String>,Boolean> readSettingsFromConf()
+    private Pair<Map<String, String>,Boolean> readSettingsFromConf()
     {
         try
         {