Make AdvancementProvider extensible by modders (#8120)

src/main/java/net/minecraftforge/common/extensions/IForgeAdvancementBuilder.java

@@ -0,0 +1,66 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2021.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.common.extensions;
+
+import com.google.common.collect.Maps;
+import net.minecraft.advancements.Advancement;
+import net.minecraft.advancements.AdvancementRewards;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.packs.PackType;
+import net.minecraftforge.common.data.ExistingFileHelper;
+
+import java.util.function.Consumer;
+
+public interface IForgeAdvancementBuilder
+{
+
+    private Advancement.Builder self()
+    {
+        return (Advancement.Builder) this;
+    }
+
+    /**
+     * save function for the {@link Advancement.Builder} which uses the {@link ExistingFileHelper} to check if the parent is already known
+     * @param consumer A {@link Consumer} which the build {@link Advancement} is passed to
+     * @param id The {@link ResourceLocation} for the new {@link Advancement}
+     * @param fileHelper The {@link ExistingFileHelper} where all known {@link Advancement}s are registered
+     * @return The build {@link Advancement}
+     * @throws IllegalStateException is thrown if the parent of the {@link Advancement} is not known
+     */
+    default Advancement save(Consumer<Advancement> consumer ,ResourceLocation id, ExistingFileHelper fileHelper)
+    {
+        boolean canBuild = self().canBuild((advancementId) ->
+        {
+            if (fileHelper.exists(advancementId, PackType.SERVER_DATA, ".json", "advancements"))
+            {
+                return new Advancement(advancementId, null, null, AdvancementRewards.EMPTY, Maps.newHashMap(), null);
+            }
+            return null;
+        });
+        if (!canBuild)
+        {
+            throw new IllegalStateException("Tried to build Advancement without valid Parent!");
+        }
+
+        Advancement advancement = self().build(id);
+        consumer.accept(advancement);
+        return advancement;
+    }
+}