Merge branch 'master' into 1.15

# Conflicts:
#	src/main/java/carpet/script/CarpetExpression.java

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

@@ -32,6 +32,8 @@ import com.google.common.collect.Sets;
 import com.mojang.brigadier.StringReader;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
+import it.unimi.dsi.fastutil.longs.LongSet;
+import it.unimi.dsi.fastutil.objects.ObjectSortedSet;
 import net.minecraft.block.BarrierBlock;
 import net.minecraft.block.BedrockBlock;
 import net.minecraft.block.Block;
@@ -617,6 +619,20 @@ public class CarpetExpression
      * but chunks can only be valid in a few states: <code>full</code>, <code>features</code>, <code>liquid_carvers</code>,
      * and <code>structure_starts</code>. Returns <code>null</code> if the chunk is not in memory unless called with optional
      * <code>true</code>.</p>
+     * <h3><code>structures(pos), structures(pos, structure_name)</code></h3>
+     * <p>Returns structure information for a given block position. Note that strucuture information is the same for
+     * all the blocks from the same chunk. <code>structures</code> function can be called with a block, or a block and
+     * a structure name. In the first case it returns a map of structures at a given position, keyed by structure name,
+     * with values indicating the bounding box of the structure - a pair of two 3-value coords (see examples). When
+     * called with an extra structure name, returns list of components for that structure, with their name, direction
+     * and two sets of coordinates indicating the bounding box of the structure piece.</p>
+     * <h3><code>structure_references(pos), structure_references(pos, structure_name)</code></h3>
+     * <p>Returns structure information that a chunk with a given block position is part of.
+     * <code>structure_references</code> function can be called with a block, or a block and
+     * a structure name. In the first case it returns a list of structure names that give chunk belongs to. When
+     * called with an extra structure name, returns list of positions pointing to the lowest block position in chunks that
+     * hold structure starts for these structures. You can query that chunk structures then to get its bounding boxes.</p>
+
      * <h3><code>suffocates(pos)</code></h3>
      * <p>Boolean function, true if the block causes suffocation.</p>
      * <h3><code>power(pos)</code></h3>
@@ -1232,6 +1248,33 @@ public class CarpetExpression
             return LazyValue.NULL;
         });
 
+        this.expr.addLazyFunction("structure_references", -1, (c, t, lv) -> {
+            CarpetContext cc = (CarpetContext)c;
+            BlockValue.LocatorResult locator = BlockValue.fromParams(cc, lv, 0);
+            ServerWorld world = cc.s.getWorld();
+            BlockPos pos = locator.block.getPos();
+            Map<String, LongSet> references = world.getChunk(pos).getStructureReferences();
+            if (lv.size() == locator.offset)
+            {
+                List<Value> referenceList = references.entrySet().stream().
+                        filter(e -> e.getValue()!= null && !e.getValue().isEmpty()).
+                        map(e -> new StringValue(e.getKey())).collect(Collectors.toList());
+                return (_c, _t ) -> ListValue.wrap(referenceList);
+            }
+            String structureName = lv.get(locator.offset).evalValue(c).getString();
+            LongSet structureReferences = references.get(structureName);
+            if (structureReferences == null || structureReferences.isEmpty())
+            {
+                Value ret = ListValue.of();
+                return (_c, _t) -> ret;
+            }
+            Value ret = ListValue.wrap(structureReferences.stream().map(l -> ListValue.of(
+                    new NumericValue(16*ChunkPos.getPackedX(l)),
+                    Value.ZERO,
+                    new NumericValue(16*ChunkPos.getPackedZ(l)))).collect(Collectors.toList()));
+            return (_c, _t) -> ret;
+        });
+
         this.expr.addLazyFunction("structures", -1, (c, t, lv) -> {
             CarpetContext cc = (CarpetContext)c;
             BlockValue.LocatorResult locator = BlockValue.fromParams(cc, lv, 0);