added is_chunk_generated and docs on reset_chunk

src/main/java/carpet/script/CarpetExpression.java

@@ -134,6 +134,7 @@ import java.util.function.BiFunction;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
+import static carpet.script.utils.WorldTools.canHasChunk;
 import static java.lang.Math.abs;
 import static java.lang.Math.max;
 import static java.lang.Math.min;
@@ -678,6 +679,17 @@ public class CarpetExpression
             return (c_, t_) -> retval;
         });
 
+        this.expr.addLazyFunction("is_chunk_generated", -1, (c, t, lv) ->
+        {
+            BlockValue.LocatorResult locator = BlockValue.fromParams((CarpetContext)c, lv, 0);
+            BlockPos pos = locator.block.getPos();
+            boolean force = false;
+            if (lv.size() > locator.offset)
+                force = lv.get(locator.offset).evalValue(c, Context.BOOLEAN).getBoolean();
+            Value retval = new NumericValue(canHasChunk(((CarpetContext)c).s.getWorld(), new ChunkPos(pos), null, force));
+            return (c_, t_) -> retval;
+        });
+
         this.expr.addLazyFunction("generation_status", -1, (c, t, lv) ->
         {
             BlockValue.LocatorResult locatorResult = BlockValue.fromParams((CarpetContext)c, lv, 0);

src/main/java/carpet/script/utils/WorldTools.java

@@ -0,0 +1,47 @@
+package carpet.script.utils;
+
+import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.math.ChunkPos;
+import net.minecraft.world.chunk.ChunkStatus;
+import net.minecraft.world.storage.RegionFile;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.Map;
+
+public class WorldTools
+{
+
+    public static boolean canHasChunk(ServerWorld world, ChunkPos chpos, Map<String, RegionFile> regionCache, boolean deepcheck)
+    {
+        if (world.getChunk(chpos.x, chpos.z, ChunkStatus.STRUCTURE_STARTS, false) != null)
+            return true;
+        String currentRegionName = "r." + chpos.getRegionX() + "." + chpos.getRegionZ() + ".mca";
+        if (regionCache != null && regionCache.containsKey(currentRegionName))
+        {
+            RegionFile region = regionCache.get(currentRegionName);
+            if (region == null) return false;
+            return region.hasChunk(chpos);
+        }
+        Path regionPath = world.getDimension().getType().getSaveDirectory(
+                world.getSaveHandler().getWorldDir()
+        ).toPath().resolve("region");
+        Path regionFilePath = regionPath.resolve(currentRegionName);
+        File regionFile = regionFilePath.toFile();
+        if (!regionFile.exists())
+        {
+            if (regionCache != null) regionCache.put(currentRegionName, null);
+            return false;
+        }
+        if (!deepcheck) return true; // not using cache in this case.
+        try
+        {
+            RegionFile region = new RegionFile(regionFile, regionPath.toFile());
+            if (regionCache != null) regionCache.put(currentRegionName, region);
+            return region.hasChunk(chpos);
+        }
+        catch (IOException ignored) { }
+        return true;
+    }
+}