Entity/Block Persistence + Entity Despawnable

src/main/java/ch/njol/skript/conditions/CondEntityUnload.java

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+package ch.njol.skript.conditions;
+
+import ch.njol.skript.conditions.base.PropertyCondition;
+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 org.bukkit.entity.LivingEntity;
+
+@Name("Can Despawn")
+@Description({
+	"Check if an entity can despawn when the chunk they're located at is unloaded.",
+	"More information on what and when entities despawn can be found at "
+		+ "<a href=\"https://minecraft.wiki/w/Mob_spawning#Despawning\">reference</a>."
+})
+@Examples({
+	"if last spawned entity can despawn on chunk unload:",
+		"\tmake last spawned entity not despawn on chunk unload"
+})
+@Since("INSERT VERSION")
+public class CondEntityUnload extends PropertyCondition<LivingEntity> {
+
+	static {
+		register(CondEntityUnload.class, PropertyType.CAN, "despawn (on chunk unload|when far away)", "livingentities");
+	}
+
+	@Override
+	public boolean check(LivingEntity entity) {
+		return entity.getRemoveWhenFarAway();
+	}
+
+	@Override
+	protected String getPropertyName() {
+		return "despawn on chunk unload";
+	}
+
+}

src/main/java/ch/njol/skript/conditions/CondIsPersistent.java

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+package ch.njol.skript.conditions;
+
+import ch.njol.skript.conditions.base.PropertyCondition;
+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 org.bukkit.block.Block;
+import org.bukkit.block.data.type.Leaves;
+import org.bukkit.entity.Entity;
+
+@Name("Is Persistent")
+@Description({
+	"Whether entities, players, or leaves are persistent.",
+	"Persistence of entities is whether they are retained through server restarts.",
+	"Persistence of leaves is whether they should decay when not connected to a log block within 6 meters.",
+	"Persistence of players is if the player's playerdata should be saved when they leave the server. "
+		+ "Players' persistence is reset back to 'true' when they join the server.",
+	"Passengers inherit the persistence of their vehicle, meaning a persistent zombie put on a "
+		+ "non-persistent chicken will become non-persistent. This does not apply to players.",
+	"By default, all entities are persistent."
+})
+@Examples({
+	"on spawn:",
+		"\tif event-entity is persistent:",
+			"\t\tmake event-entity not persistent"
+})
+@Since("INSERT VERSION")
+public class CondIsPersistent extends PropertyCondition<Object> {
+
+	static {
+		register(CondIsPersistent.class, "persistent", "entities/blocks");
+	}
+
+	@Override
+	public boolean check(Object object) {
+		if (object instanceof Entity entity) {
+			return entity.isPersistent();
+		} else if (object instanceof Block block && block.getBlockData() instanceof Leaves leaves) {
+			return leaves.isPersistent();
+		}
+		return false;
+	}
+
+	@Override
+	protected String getPropertyName() {
+		return "persistent";
+	}
+
+}

src/main/java/ch/njol/skript/effects/EffEntityUnload.java

@@ -0,0 +1,63 @@
+package ch.njol.skript.effects;
+
+import ch.njol.skript.Skript;
+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.lang.Effect;
+import ch.njol.skript.lang.Expression;
+import ch.njol.skript.lang.SkriptParser.ParseResult;
+import ch.njol.util.Kleenean;
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.event.Event;
+import org.jetbrains.annotations.Nullable;
+
+@Name("Entity Despawn")
+@Description({
+	"Make a living entity despawn when the chunk they're located at is unloaded.",
+	"Setting a custom name on a living entity automatically makes it not despawnable.",
+	"More information on what and when entities despawn can be found at "
+		+ "<a href=\"https://minecraft.wiki/w/Mob_spawning#Despawning\">reference</a>."
+})
+@Examples({
+	"make all entities not despawnable on chunk unload",
+	"spawn zombie at location(0, 0, 0):",
+		"\tforce event-entity to not despawn when far away",
+})
+@Since("INSERT VERSION")
+public class EffEntityUnload extends Effect {
+
+	static {
+		Skript.registerEffect(EffEntityUnload.class,
+			"make %livingentities% despawn[able] (on chunk unload|when far away)",
+			"force %livingentities% to despawn (on chunk unload|when far away)",
+			"prevent %livingentities% from despawning [on chunk unload|when far away]");
+	}
+
+	private Expression<LivingEntity> entities;
+	private boolean despawn;
+
+	@Override
+	public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelayed, ParseResult parseResult) {
+		//noinspection unchecked
+		entities = (Expression<LivingEntity>) exprs[0];
+		despawn = matchedPattern != 2;
+		return true;
+	}
+
+	@Override
+	protected void execute(Event event) {
+		for (LivingEntity entity : entities.getArray(event)) {
+			entity.setRemoveWhenFarAway(despawn);
+		}
+	}
+
+	@Override
+	public String toString(@Nullable Event event, boolean debug) {
+		if (despawn)
+			return "make " + entities.toString(event, debug) + " despawn on chunk unload";
+		return "prevent " + entities.toString(event, debug) + " from despawning on chunk unload";
+	}
+
+}

src/main/java/ch/njol/skript/effects/EffPersistent.java

@@ -0,0 +1,82 @@
+package ch.njol.skript.effects;
+
+import ch.njol.skript.Skript;
+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.lang.Effect;
+import ch.njol.skript.lang.Expression;
+import ch.njol.skript.lang.SkriptParser.ParseResult;
+import ch.njol.util.Kleenean;
+import org.bukkit.block.Block;
+import org.bukkit.block.data.type.Leaves;
+import org.bukkit.entity.Entity;
+import org.bukkit.event.Event;
+import org.jetbrains.annotations.Nullable;
+
+@Name("Persistent")
+@Description({
+	"Make entities, players, or leaves be persistent.",
+	"Persistence of entities is whether they are retained through server restarts.",
+	"Persistence of leaves is whether they should decay when not connected to a log block within 6 meters.",
+	"Persistence of players is if the player's playerdata should be saved when they leave the server. "
+		+ "Players' persistence is reset back to 'true' when they join the server.",
+	"Passengers inherit the persistence of their vehicle, meaning a persistent zombie put on a "
+		+ "non-persistent chicken will become non-persistent. This does not apply to players.",
+	"By default, all entities are persistent."
+})
+@Examples({
+	"prevent all entities from persisting",
+	"force {_leaves} to persist",
+	"",
+	"command /kickcheater <cheater: player>:",
+		"\tpermission: op",
+		"\ttrigger:",
+			"\t\tprevent {_cheater} from persisting",
+			"\t\tkick {_cheater}"
+})
+@Since("INSERT VERSION")
+public class EffPersistent extends Effect {
+
+	static {
+		Skript.registerEffect(EffPersistent.class,
+			"make %entities/blocks% [:not] persist[ent]",
+			"force %entities/blocks% to [:not] persist",
+			"prevent %entities/blocks% from persisting");
+	}
+
+	private Expression<?> source;
+	private boolean persist;
+
+	@Override
+	public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelayed, ParseResult parseResult) {
+		source = exprs[0];
+		if (matchedPattern < 2) {
+			persist = !parseResult.hasTag("not");
+		} else {
+			persist = false;
+		}
+		return true;
+	}
+
+	@Override
+	protected void execute(Event event) {
+		for (Object object : source.getArray(event)) {
+			if (object instanceof Entity entity) {
+				entity.setPersistent(persist);
+			} else if (object instanceof Block block && block.getBlockData() instanceof Leaves leaves) {
+				leaves.setPersistent(persist);
+				block.setBlockData(leaves);
+			}
+		}
+	}
+
+	@Override
+	public String toString(@Nullable Event event, boolean debug) {
+		if (persist)
+			return "make " + source.toString(event, debug) + " persistent";
+		return "prevent " + source.toString(event, debug) + " from persisting";
+	}
+
+}

src/test/skript/tests/syntaxes/effects/EffPersistent.sk

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+test "entity persistence":
+	spawn a zombie, a skeleton and a villager at test-location
+	assert all entities are persistent with "All entities should be persistent by default"
+	prevent all entities from persisting
+	assert all entities are not persistent with "Failed to make all entities not persistent"
+	force all entities to persist
+	assert all entities are persistent with "Failed to make all entities persistent"
+	clear all entities
+
+test "leaves persistence":
+	set {_old} to block data of test-block
+	set test-block to oak leaves
+	prevent test-block from persisting
+	assert test-block is not persistent with "Failed to make leaves not persistent"
+	force test-block to persist
+	assert test-block is persistent with "Failed to make leaves persist"
+	set block data of test-block to {_old}