Implement ADD and REMOVE changers to ExprMetadata

src/main/java/ch/njol/skript/expressions/ExprMetadata.java

@@ -18,18 +18,8 @@
  */
 package ch.njol.skript.expressions;
 
-import java.lang.reflect.Array;
-import java.util.ArrayList;
-import java.util.List;
-
-import org.bukkit.event.Event;
-import org.bukkit.metadata.FixedMetadataValue;
-import org.bukkit.metadata.MetadataValue;
-import org.bukkit.metadata.Metadatable;
-import org.jetbrains.annotations.Nullable;
-
 import ch.njol.skript.Skript;
-import ch.njol.skript.classes.Changer;
+import ch.njol.skript.classes.Changer.ChangeMode;
 import ch.njol.skript.doc.Description;
 import ch.njol.skript.doc.Examples;
 import ch.njol.skript.doc.Name;
@@ -38,101 +28,139 @@
 import ch.njol.skript.lang.ExpressionType;
 import ch.njol.skript.lang.SkriptParser;
 import ch.njol.skript.lang.util.SimpleExpression;
-import org.skriptlang.skript.lang.converter.Converters;
 import ch.njol.skript.util.Utils;
 import ch.njol.util.Kleenean;
 import ch.njol.util.coll.CollectionUtils;
+import org.bukkit.event.Event;
+import org.bukkit.metadata.FixedMetadataValue;
+import org.bukkit.metadata.MetadataValue;
+import org.bukkit.metadata.Metadatable;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.UnknownNullability;
+import org.skriptlang.skript.lang.arithmetic.Arithmetics;
+import org.skriptlang.skript.lang.arithmetic.Operation;
+import org.skriptlang.skript.lang.arithmetic.OperationInfo;
+import org.skriptlang.skript.lang.arithmetic.Operator;
+import org.skriptlang.skript.lang.converter.Converters;
+
+import java.lang.reflect.Array;
+import java.util.ArrayList;
+import java.util.List;
 
 @Name("Metadata")
-@Description("Metadata is a way to store temporary data on entities, blocks and more that " +
-		"disappears after a server restart.")
-@Examples({"set metadata value \"healer\" of player to true",
-		"broadcast \"%metadata value \"\"healer\"\" of player%\"",
-		"clear metadata value \"healer\" of player"})
-@Since("2.2-dev36")
-@SuppressWarnings({"unchecked", "null"})
+@Description("Metadata is a way to store temporary data on entities, blocks and more that disappears after a server restart.")
+@Examples({
+	"set metadata value \"healer\" of player to true",
+	"broadcast \"%metadata value \"\"healer\"\" of player%\"",
+	"clear metadata value \"healer\" of player"
+})
+@Since("2.2-dev36, INSERT VERSION (add, remove)")
 public class ExprMetadata<T> extends SimpleExpression<T> {
 
 	static {
+		//noinspection unchecked
 		Skript.registerExpression(ExprMetadata.class, Object.class, ExpressionType.PROPERTY,
 				"metadata [(value|tag)[s]] %strings% of %metadataholders%",
 				"%metadataholders%'[s] metadata [(value|tag)[s]] %string%"
 		);
 	}
 
-	private ExprMetadata<?> source;
-	@Nullable
-	private Expression<String> values;
-	@Nullable
-	private Expression<Metadatable> holders;
-	private Class<? extends T>[] types;
-	private Class<T> superType;
+	private final ExprMetadata<?> source;
+	private final Class<? extends T>[] types;
+	private final Class<T> superType;
+
+	private @UnknownNullability Expression<String> keys;
+	private @UnknownNullability Expression<Metadatable> holders;
 
 	public ExprMetadata() {
+		//noinspection unchecked
 		this(null, (Class<? extends T>) Object.class);
 	}
 
+	@SafeVarargs
 	private ExprMetadata(ExprMetadata<?> source, Class<? extends T>... types) {
 		this.source = source;
 		if (source != null) {
-			this.values = source.values;
+			this.keys = source.keys;
 			this.holders = source.holders;
 		}
 		this.types = types;
+		//noinspection unchecked
 		this.superType = (Class<T>) Utils.getSuperType(types);
 	}
 
 	@Override
 	public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelayed, SkriptParser.ParseResult parseResult) {
 		holders = (Expression<Metadatable>) exprs[matchedPattern ^ 1];
-		values = (Expression<String>) exprs[matchedPattern];
+		keys = (Expression<String>) exprs[matchedPattern];
 		return true;
 	}
 
 	@Override
-	@Nullable
-	protected T[] get(Event e) {
+	protected T @Nullable [] get(Event event) {
 		List<Object> values = new ArrayList<>();
-		for (String value : this.values.getArray(e)) {
-			for (Metadatable holder : holders.getArray(e)) {
-				List<MetadataValue> metadata = holder.getMetadata(value);
+		String[] keys = this.keys.getArray(event);
+		for (Metadatable holder : holders.getArray(event)) {
+			for (String key : keys) {
+				List<MetadataValue> metadata = holder.getMetadata(key);
 				if (!metadata.isEmpty())
 					values.add(metadata.get(metadata.size() - 1).value()); // adds the most recent metadata value
 			}
 		}
 		try {
 			return Converters.convert(values.toArray(), types, superType);
-		} catch (ClassCastException e1) {
+		} catch (ClassCastException exception) {
+			//noinspection unchecked
 			return (T[]) Array.newInstance(superType, 0);
 		}
 	}
 
 	@Override
-	@Nullable
-	public Class<?>[] acceptChange(Changer.ChangeMode mode) {
-		if (mode == Changer.ChangeMode.DELETE || mode == Changer.ChangeMode.SET)
-			return CollectionUtils.array(Object.class);
-		return null;
+	public Class<?> @Nullable [] acceptChange(ChangeMode mode) {
+		return switch (mode) {
+			case SET, ADD, REMOVE, DELETE -> CollectionUtils.array(Object.class);
+			default -> null;
+		};
 	}
 
 	@Override
-	public void change(Event e, @Nullable Object[] delta, Changer.ChangeMode mode) {
-		for (String value : values.getArray(e)) {
-			for (Metadatable holder : holders.getArray(e)) {
-				switch (mode) {
-					case SET:
-						holder.setMetadata(value, new FixedMetadataValue(Skript.getInstance(), delta[0]));
-						break;
-					case DELETE:
-						holder.removeMetadata(value, Skript.getInstance());
-				}
+	public void change(Event event, Object @Nullable [] delta, ChangeMode mode) {
+		String[] keys = this.keys.getArray(event);
+		for (Metadatable holder : holders.getArray(event)) {
+			for (String key : keys) {
+                switch (mode) {
+                    case SET -> holder.setMetadata(key, new FixedMetadataValue(Skript.getInstance(), delta[0]));
+					case ADD, REMOVE -> {
+						assert delta != null;
+						Operator operator = mode == ChangeMode.ADD ? Operator.ADDITION : Operator.SUBTRACTION;
+						List<MetadataValue> metadata = holder.getMetadata(key);
+						Object value;
+						OperationInfo<?, ?, ?> info;
+						if (metadata.isEmpty() || (value = metadata.get(metadata.size() - 1).value()) == null) {
+							info = Arithmetics.getOperationInfo(operator, delta[0].getClass(), delta[0].getClass());
+							if (info == null)
+								continue;
+							value = Arithmetics.getDefaultValue(info.getLeft());
+							if (value == null)
+								continue;
+						} else {
+							info = Arithmetics.getOperationInfo(operator, value.getClass(), delta[0].getClass());
+							if (info == null)
+								continue;
+						}
+						//noinspection unchecked,rawtypes
+						Object newValue = ((Operation) info.getOperation()).calculate(value, delta[0]);
+						holder.setMetadata(key, new FixedMetadataValue(Skript.getInstance(), newValue));
+					}
+                    case DELETE -> holder.removeMetadata(key, Skript.getInstance());
+                }
 			}
 		}
 	}
 
 	@Override
 	public boolean isSingle() {
-		return holders.isSingle() && values.isSingle();
+		return holders.isSingle() && keys.isSingle();
 	}
 
 	@Override
@@ -141,7 +169,8 @@ public Class<? extends T> getReturnType() {
 	}
 
 	@Override
-	public <R> Expression<? extends R> getConvertedExpression(Class<R>... to) {
+	@SafeVarargs
+	public final <R> Expression<? extends R> getConvertedExpression(Class<R>... to) {
 		return new ExprMetadata<>(this, to);
 	}
 
@@ -151,8 +180,8 @@ public Expression<?> getSource() {
 	}
 
 	@Override
-	public String toString(@Nullable Event e, boolean debug) {
-		return "metadata values " + values.toString(e, debug) + " of " + holders.toString(e, debug);
+	public String toString(@Nullable Event event, boolean debug) {
+		return "metadata values " + keys.toString(event, debug) + " of " + holders.toString(event, debug);
 	}
 
 }

src/test/skript/tests/syntaxes/expressions/ExprMetadata.sk

@@ -0,0 +1,21 @@
+test "metadata value":
+	spawn armor stand at spawn of "world":
+		set metadata "number" of entity to 10
+		assert metadata "number" of entity is 10 with "didn't set metadata value"
+
+		add 5 to metadata "number" of entity
+		assert metadata "number" of entity is 15 with "didn't add to metadata value"
+
+		remove 3 from metadata "number" of entity
+		assert metadata "number" of entity is 12 with "didn't remove from metadata value"
+
+		add "number" to metadata "number" of entity
+		assert metadata "number" of entity is 12 with "added incompatible type to metadata"
+
+		add vector(1, 0, 1) to metadata "vector" of entity
+		assert metadata "vector" of entity is vector(1, 0, 1) with "didn't add to unset metadata value"
+
+		delete metadata "number" and "vector" of entity
+		assert metadata "number" and "vector" of entity are not set with "didn't delete metadata value"
+
+		delete entity