That's one heck of a commit you've got there...

I may have got a bit behind with version control. A lot behind, in fact. Maybe I'll go back and split this sometime - then again, I probably won't. But hey, at least it's here!

src/main/java/electroblob/wizardry/advancement/StructureTrigger.java

@@ -0,0 +1,136 @@
+package electroblob.wizardry.advancement;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonObject;
+import electroblob.wizardry.worldgen.WorldGenSurfaceStructure;
+import net.minecraft.advancements.ICriterionTrigger;
+import net.minecraft.advancements.PlayerAdvancements;
+import net.minecraft.advancements.critereon.AbstractCriterionInstance;
+import net.minecraft.entity.player.EntityPlayerMP;
+import net.minecraft.util.JsonUtils;
+import net.minecraft.util.ResourceLocation;
+import net.minecraft.world.WorldServer;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/** Copied from PositionTrigger and modified to work with wizardry's structures. The majority of any
+ * ICriterionTrigger class is just boilerplate, and this is no exception. */
+public class StructureTrigger implements ICriterionTrigger<StructureTrigger.Instance> {
+
+	private final ResourceLocation id;
+	private final Map<PlayerAdvancements, StructureTrigger.Listeners> listeners = Maps.newHashMap();
+
+	public StructureTrigger(ResourceLocation id){
+		this.id = id;
+	}
+
+	public ResourceLocation getId(){
+		return this.id;
+	}
+
+	public void addListener(PlayerAdvancements advancements, Listener<StructureTrigger.Instance> listener){
+
+		StructureTrigger.Listeners listeners = this.listeners.get(advancements);
+
+		if(listeners == null){
+			listeners = new StructureTrigger.Listeners(advancements);
+			this.listeners.put(advancements, listeners);
+		}
+
+		listeners.add(listener);
+	}
+
+	public void removeListener(PlayerAdvancements advancements, Listener<StructureTrigger.Instance> listener){
+
+		StructureTrigger.Listeners listeners = this.listeners.get(advancements);
+
+		if(listeners != null){
+			listeners.remove(listener);
+
+			if(listeners.isEmpty()){
+				this.listeners.remove(advancements);
+			}
+		}
+	}
+
+	public void removeAllListeners(PlayerAdvancements advancements){
+		this.listeners.remove(advancements);
+	}
+
+	public StructureTrigger.Instance deserializeInstance(JsonObject json, JsonDeserializationContext context){
+		return new StructureTrigger.Instance(this.id, JsonUtils.getString(json, "structure_type"));
+	}
+
+	public void trigger(EntityPlayerMP player){
+
+		StructureTrigger.Listeners listeners = this.listeners.get(player.getAdvancements());
+
+		if(listeners != null){
+			listeners.trigger(player.getServerWorld(), player.posX, player.posY, player.posZ);
+		}
+	}
+
+	public static class Instance extends AbstractCriterionInstance {
+
+		private final WorldGenSurfaceStructure structureType;
+
+		public Instance(ResourceLocation criterionIn, String name){
+			super(criterionIn);
+			this.structureType = WorldGenSurfaceStructure.byName(name);
+		}
+
+		public boolean test(WorldServer world, double x, double y, double z){
+			return structureType.isInsideStructure(world, x, y, z);
+		}
+	}
+
+	static class Listeners {
+
+		private final PlayerAdvancements playerAdvancements;
+		private final Set<Listener<StructureTrigger.Instance>> listeners = Sets.newHashSet();
+
+		public Listeners(PlayerAdvancements advancements){
+			this.playerAdvancements = advancements;
+		}
+
+		public boolean isEmpty(){
+			return this.listeners.isEmpty();
+		}
+
+		public void add(Listener<StructureTrigger.Instance> listener){
+			this.listeners.add(listener);
+		}
+
+		public void remove(Listener<StructureTrigger.Instance> listener){
+			this.listeners.remove(listener);
+		}
+
+		public void trigger(WorldServer world, double x, double y, double z){
+
+			List<Listener<StructureTrigger.Instance>> list = null;
+
+			for(Listener<StructureTrigger.Instance> listener : this.listeners){
+
+				if(listener.getCriterionInstance().test(world, x, y, z)){
+
+					if(list == null){
+						list = Lists.newArrayList();
+					}
+
+					list.add(listener);
+				}
+			}
+
+			if(list != null){
+				for(Listener<StructureTrigger.Instance> listener : list){
+					listener.grantCriterion(this.playerAdvancements);
+				}
+			}
+		}
+	}
+}