Base Attributes

src/main/java/ch/njol/skript/classes/data/BukkitClasses.java

@@ -37,6 +37,7 @@
 import org.bukkit.OfflinePlayer;
 import org.bukkit.SoundCategory;
 import org.bukkit.World;
+import org.bukkit.attribute.Attribute;
 import org.bukkit.block.Biome;
 import org.bukkit.block.Block;
 import org.bukkit.block.BlockState;
@@ -1751,6 +1752,37 @@ public String getVariableNamePattern() {
 					}
 				}));
 		}
+		EnumUtils<Attribute> attributes = new EnumUtils<>(Attribute.class, "attribute types");
+		Classes.registerClass(new ClassInfo<>(Attribute.class, "attributetype")
+				.user("attribute ?types?")
+				.name("Attribute Type")
+				.description("Represents the type of an attribute. Note that this type does not contain any numerical values."
+						+ "See <a href='https://minecraft.gamepedia.com/Attribute#Attributes'>attribute types</a> for more info.")
+				.defaultExpression(new EventValueExpression<>(Attribute.class))
+				.usage(attributes.getAllNames())
+				.since("INSERT VERSION")
+				.parser(new Parser<Attribute>() {
+					@Override
+					@Nullable
+					public Attribute parse(String input, ParseContext context) {
+						return attributes.parse(input);
+					}
+
+					@Override
+					public String toString(Attribute a, int flags) {
+						return attributes.toString(a, flags);
+					}
+
+					@Override
+					public String toVariableNameString(Attribute a) {
+						return toString(a, 0);
+					}
+
+					@Override
+					public String getVariableNamePattern() {
+						return "[\\sA-Za-z]+";
+					}
+				})
+				.serializer(new EnumSerializer<>(Attribute.class)));
 	}
-
 }

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

@@ -0,0 +1,141 @@
+/**
+ *   This file is part of Skript.
+ *
+ *  Skript is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Skript is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with Skript.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Copyright 2011-2017 Peter Güttinger and contributors
+ */
+package ch.njol.skript.expressions;
+
+import org.bukkit.attribute.Attribute;
+
+import java.util.stream.Stream;
+
+import org.bukkit.attribute.Attributable;
+import org.bukkit.attribute.AttributeInstance;
+import org.bukkit.entity.Entity;
+import org.bukkit.event.Event;
+import org.eclipse.jdt.annotation.Nullable;
+
+import ch.njol.skript.Skript;
+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;
+import ch.njol.skript.doc.Since;
+import ch.njol.skript.expressions.base.PropertyExpression;
+import ch.njol.skript.lang.Expression;
+import ch.njol.skript.lang.ExpressionType;
+import ch.njol.skript.lang.SkriptParser.ParseResult;
+import ch.njol.util.Kleenean;
+import ch.njol.util.coll.CollectionUtils;
+
+@Name("Entity Attribute")
+@Description({"The numerical value of an entity's particular attribute.",
+			 "Note that the movement speed attribute cannot be reliably used for players. For that purpose, use the speed expression instead.",
+			 "Resetting an entity's attribute is only available in Minecraft 1.11 and above."})
+@Examples({"on damage of player:",
+		"	send \"You are wounded!\"",
+		"	set victim's attack speed attribute to 2"})
+@Since("INSERT VERSION")
+public class ExprEntityAttribute extends PropertyExpression<Entity, Number> {
+
+	static {
+		Skript.registerExpression(ExprEntityAttribute.class, Number.class, ExpressionType.COMBINED,
+				"%attributetype% [value] of %entities%",
+				"%entities%'[s] %attributetype% [value]");
+	}
+
+	private static final boolean DEFAULTVALUE_EXISTS = Skript.isRunningMinecraft(1, 11);
+
+	@Nullable
+	private Expression<Attribute> attributes;
+
+	@SuppressWarnings({"null", "unchecked"})
+	@Override
+	public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelayed, ParseResult parseResult) {
+		attributes = (Expression<Attribute>) exprs[matchedPattern];
+		setExpr((Expression<? extends Entity>) exprs[matchedPattern ^ 1]);
+		return true;
+	}
+
+	@SuppressWarnings("null")
+	@Override
+	protected Number[] get(Event e, Entity[] entities) {
+		Attribute a = attributes.getSingle(e);
+		return Stream.of(entities)
+		    .map(ent -> getAttribute(ent, a).getBaseValue())
+		    .toArray(Number[]::new);
+	}
+
+	@Override
+	@Nullable
+	public Class<?>[] acceptChange(ChangeMode mode) {
+		if (mode == ChangeMode.REMOVE_ALL || (mode == ChangeMode.RESET && !DEFAULTVALUE_EXISTS))
+			return null;
+		return CollectionUtils.array(Number.class);
+	}
+
+	@SuppressWarnings("null")
+	@Override
+	public void change(Event e, @Nullable Object[] delta, ChangeMode mode) {
+		Attribute a = attributes.getSingle(e);
+		double d = delta == null ? 0 : ((Number) delta[0]).doubleValue();
+		for (Entity entity : getExpr().getArray(e)) {
+			AttributeInstance ai = getAttribute(entity, a);
+			if(ai != null) {
+				switch(mode) {
+					case ADD:
+						ai.setBaseValue(ai.getBaseValue() + d);
+						break;
+					case SET:
+						ai.setBaseValue(d);
+						break;
+					case DELETE:
+						ai.setBaseValue(0);
+						break;
+					case RESET:
+						ai.setBaseValue(ai.getDefaultValue());
+						break;
+					case REMOVE:
+						ai.setBaseValue(ai.getBaseValue() - d);
+						break;
+					case REMOVE_ALL:
+						assert false;
+				}
+			}
+		}
+	}
+
+	@Override
+	public Class<? extends Number> getReturnType() {
+		return Number.class;
+	}
+
+	@SuppressWarnings("null") 
+	@Override
+	public String toString(@Nullable Event e, boolean debug) {
+		return "entity " + getExpr().toString(e, debug) + "'s " + (attributes == null ? "" : attributes.toString(e, debug)) + "attribute";
+	}
+
+	@Nullable
+	private static AttributeInstance getAttribute(Entity e, @Nullable Attribute a) {
+	    if (a != null && e instanceof Attributable) {
+	        return ((Attributable) e).getAttribute(a);
+	    }
+	   return null;
+	}
+
+}

src/main/resources/lang/english.lang

@@ -1706,6 +1706,22 @@ genes:
 	weak: weak
 	aggressive: aggressive, savage, wild
 
+# -- Attribute Types --
+attribute types:
+	generic_armor: generic armor, armor attribute
+	generic_armor_toughness: generic armor toughness, armor toughness attribute
+	generic_attack_damage: generic attack damage, attack damage attribute
+	generic_attack_knockback: generic attack knockback, attack knockback attribute
+	generic_attack_speed: generic attack speed, attack speed attribute
+	generic_flying_speed: generic flying speed, flying speed attribute
+	generic_follow_range: generic follow range, follow range attribute
+	generic_knockback_resistance: generic knockback resistance, knockback resistance attribute
+	generic_luck: generic luck, luck attribute
+	generic_max_health: generic max health, max health attribute
+	generic_movement_speed: generic movement speed, movement speed attribute
+	horse_jump_strength: horse jump strength, horse jump strength attribute
+	zombie_spawn_reinforcements: zombie spawn reinforcements, zombie spawn reinforcements attribute
+
 # -- Boolean --
 boolean:
 	true:

src/test/skript/tests/regressions/2664-attributes.sk

@@ -0,0 +1,21 @@
+test "attributes 1":
+	spawn cow at location(0, 64, 0, world "world")
+	set {_m} to last spawned cow
+	assert movement speed attribute of {_m} is set with "attribute get failed"
+	set movement speed attribute of {_m} to 3.14
+	assert movement speed attribute of {_m} is 3.14 with "attribute set failed"
+	add 5 to movement speed attribute of {_m}
+	assert movement speed attribute of {_m} is 8.14 with "attribute add failed"
+	remove 4 from movement speed attribute of {_m}
+	assert movement speed attribute of {_m} is 4.14 with "attribute remove ##1 failed"
+	remove 10 from movement speed attribute of {_m}
+	assert movement speed attribute of {_m} is -5.86 with "attribute remove ##2 failed" # Negative attribute values should be safe
+	delete movement speed attribute of {_m}
+	assert movement speed attribute of {_m} is 0 with "attribute delete failed"
+
+test "attributes 2" when minecraft version is not "1.9.4":
+	# Test the Reset ChangeMode only on versions that have it
+	spawn cow at location(0, 65, 0, world "world")
+	set {_m} to last spawned cow
+	reset movement speed attribute of {_m}
+	assert movement speed attribute of {_m} is set with "attribute reset failed" # No need to compare with a fixed constant