Generalize recipes and implement them

src/main/java/org/spongepowered/api/GameRegistry.java

@@ -34,7 +34,8 @@
 import org.spongepowered.api.item.ItemType;
 import org.spongepowered.api.item.merchant.TradeOfferGenerator;
 import org.spongepowered.api.item.merchant.VillagerRegistry;
-import org.spongepowered.api.item.recipe.RecipeRegistry;
+import org.spongepowered.api.item.recipe.crafting.CraftingRecipeRegistry;
+import org.spongepowered.api.item.recipe.smelting.SmeltingRecipeRegistry;
 import org.spongepowered.api.network.status.Favicon;
 import org.spongepowered.api.plugin.PluginContainer;
 import org.spongepowered.api.plugin.PluginManager;
@@ -44,10 +45,10 @@
 import org.spongepowered.api.registry.RegistryModuleAlreadyRegisteredException;
 import org.spongepowered.api.resourcepack.ResourcePack;
 import org.spongepowered.api.scoreboard.displayslot.DisplaySlot;
-import org.spongepowered.api.statistic.Statistic;
 import org.spongepowered.api.statistic.BlockStatistic;
 import org.spongepowered.api.statistic.EntityStatistic;
 import org.spongepowered.api.statistic.ItemStatistic;
+import org.spongepowered.api.statistic.Statistic;
 import org.spongepowered.api.statistic.StatisticType;
 import org.spongepowered.api.text.format.TextColor;
 import org.spongepowered.api.text.selector.SelectorFactory;
@@ -292,11 +293,18 @@ <T extends CatalogType> GameRegistry registerModule(Class<T> catalogClass, Catal
     Favicon loadFavicon(BufferedImage image) throws IOException;
 
     /**
-     * Retrieves the RecipeRegistry for this GameRegistry.
+     * Retrieves the crafting RecipeRegistry for this GameRegistry.
+     *
+     * @return The crafting recipe registry
+     */
+    CraftingRecipeRegistry getCraftingRecipeRegistry();
+
+    /**
+     * Retrieves the smelting RecipeRegistry for this GameRegistry.
      *
-     * @return The recipe registry
+     * @return The smelting recipe registry
      */
-    RecipeRegistry getRecipeRegistry();
+    SmeltingRecipeRegistry getSmeltingRecipeRegistry();
 
     /**
      * Gets a {@link ResourcePack} that's already been created by its ID.

src/main/java/org/spongepowered/api/item/inventory/crafting/CraftingInventory.java

@@ -25,7 +25,8 @@
 package org.spongepowered.api.item.inventory.crafting;
 
 import org.spongepowered.api.item.inventory.type.GridInventory;
-import org.spongepowered.api.item.recipe.Recipe;
+import org.spongepowered.api.item.recipe.crafting.CraftingRecipe;
+import org.spongepowered.api.world.World;
 
 import java.util.Optional;
 
@@ -51,8 +52,9 @@ public interface CraftingInventory extends GridInventory {
     /**
      * Retrieves the recipe formed by this CraftingInventory, if any.
      *
+     * @param world The world where the item would be crafted in
      * @return The recipe or {@link Optional#empty()} if no recipe is formed
      */
-    Optional<Recipe> getRecipe();
+    Optional<CraftingRecipe> getRecipe(World world);
 
 }

src/main/java/org/spongepowered/api/item/recipe/Recipe.java

@@ -24,52 +24,19 @@
  */
 package org.spongepowered.api.item.recipe;
 
-import org.spongepowered.api.item.ItemType;
-import org.spongepowered.api.item.inventory.ItemStack;
-import org.spongepowered.api.item.inventory.type.GridInventory;
-
-import java.util.List;
-import java.util.Optional;
+import org.spongepowered.api.item.inventory.ItemStackSnapshot;
 
 /**
- * <p>A Recipe represents some craftable recipe in the game.</p>
- *
- * <p>It is essentially a Predicate that checks for if a recipe is valid as well
- * as a function from a crafting matrix to a list of {@link ItemStack}
- * (the crafting result), therefore making it an immutable interface.</p>
- *
- * <p>The passed in ItemGrid is usually a crafting inventory, e.g.
- * a 2x2 or 3x3 crafting matrix.</p>
- *
- * <p>The requirements of a Recipe can be general, they just have to
- * eventually return a boolean given an itemgrid.</p>
+ * A general interface for recipes
  */
 public interface Recipe {
 
     /**
-     * Returns the list of item types that result when successful crafting of
-     * this Recipe is completed.
-     *
-     * @return The resultant list of item types
-     */
-    List<ItemType> getResultTypes();
-
-    /**
-     * Checks if the given {@link GridInventory} fits the required constraints
-     * to craft this Recipe.
-     *
-     * @param grid The ItemGrid to check for validity
-     * @return True if the given input matches this recipe's requirements
-     */
-    boolean isValid(GridInventory grid);
-
-    /**
-     * Returns the results for running this Recipe over an {@link GridInventory}
+     * A general result of this recipe. This result may be customized depending
+     * on the context.
      *
-     * @param grid An ItemGrid as input
-     * @return A list of ItemStacks or {@link Optional#empty()} if the given
-     *          ItemGrid does not match this recipe's requirements.
+     * @return The exemplary result of this recipe
      */
-    Optional<List<ItemStack>> getResults(GridInventory grid);
+    ItemStackSnapshot getExemplaryResult();
 
 }

src/main/java/org/spongepowered/api/item/recipe/RecipeRegistry.java

@@ -24,32 +24,32 @@
  */
 package org.spongepowered.api.item.recipe;
 
-import java.util.Set;
+import java.util.Collection;
 
 /**
  * A RecipeRegistry holds all registered recipes for a given game.
  */
-public interface RecipeRegistry {
+public interface RecipeRegistry<T extends Recipe> {
 
     /**
-     * Registers the given Recipe to make it available to craft.
+     * Registers the given {@link Recipe} to make it available to craft.
      *
-     * @param recipe The Recipe to register
+     * @param recipe The {@link Recipe} to register
      */
-    void register(Recipe recipe);
+    void register(T recipe);
 
     /**
-     * Removes the given Recipe from registration in this registry.
+     * Removes the given {@link Recipe} from registration in this registry.
      *
-     * @param recipe The Recipe to unregister
+     * @param recipe The {@link Recipe} to unregister
      */
-    void remove(Recipe recipe);
+    void remove(T recipe);
 
     /**
      * Retrieves all recipes registered in this registry.
      *
-     * @return All registered recipes
+     * @return An unmodifiable collection of registered recipes
      */
-    Set<Recipe> getRecipes();
+    Collection<T> getRecipes();
 
 }