Add block/meta and item/meta pair classes

src/main/java/com/gtnewhorizon/gtnhlib/eventbus/AutoEventBus.java

@@ -122,7 +122,8 @@ private static void register(ModContainer classOwner, Class<?> target, ObjectSet
         for (MethodInfo method : methods) {
             try {
                 if (method.getOptionalMod() != null) {
-                    if (!optionalMods.computeIfAbsent(method.getOptionalMod(), Loader::isModLoaded)) {
+                    if (!optionalMods
+                            .computeIfAbsent(method.getOptionalMod(), (Predicate<String>) Loader::isModLoaded)) {
                         continue;
                     }
                 }

src/main/java/com/gtnewhorizon/gtnhlib/util/data/BlockMeta.java

@@ -0,0 +1,80 @@
+package com.gtnewhorizon.gtnhlib.util.data;
+
+import javax.annotation.Nonnull;
+
+import net.minecraft.block.Block;
+
+/**
+ * A mutable implementation of {@link ImmutableBlockMeta}. If your API should return a mutable pair, return this
+ * instead. Must follow the same contracts as the immutable version if this is ever upcast to a
+ * {@link ImmutableBlockMeta} in your API. If this type is exposed instead of the immutable interface, assume that the
+ * contained values can change.
+ */
+public class BlockMeta implements ImmutableBlockMeta {
+
+    private Block block;
+    private int meta;
+
+    public BlockMeta() {}
+
+    public BlockMeta(Block block, int meta) {
+        this.block = block;
+        this.meta = meta;
+    }
+
+    @Override
+    @SuppressWarnings("null")
+    public Block getBlock() {
+        return block;
+    }
+
+    @Override
+    public int getBlockMeta() {
+        return meta;
+    }
+
+    /**
+     * Note: see the header comment in {@link ImmutableBlockMeta} for this method's contract.
+     */
+    public BlockMeta setBlock(@Nonnull Block block) {
+        this.block = block;
+
+        return this;
+    }
+
+    /**
+     * Note: see the header comment in {@link ImmutableBlockMeta} for this method's contract.
+     */
+    public BlockMeta setBlockMeta(int meta) {
+        this.meta = meta;
+
+        return this;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((block == null) ? 0 : block.hashCode());
+        result = prime * result + meta;
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null) return false;
+        if (getClass() != obj.getClass()) return false;
+        BlockMeta other = (BlockMeta) obj;
+        if (block == null) {
+            if (other.block != null) return false;
+        } else if (!block.equals(other.block)) return false;
+        if (meta != other.meta) return false;
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        return "BlockMeta [block=" + block + ", meta=" + meta + "]";
+    }
+}

src/main/java/com/gtnewhorizon/gtnhlib/util/data/IMod.java

@@ -0,0 +1,15 @@
+package com.gtnewhorizon.gtnhlib.util.data;
+
+/**
+ * An interface for any mod enums. Represents a mod.
+ */
+public interface IMod {
+
+    boolean isModLoaded();
+
+    /** Gets the mod id. */
+    String getID();
+
+    /** Gets the mod's resource location prefix. */
+    String getResourceLocation();
+}

src/main/java/com/gtnewhorizon/gtnhlib/util/data/ImmutableBlockMeta.java

@@ -0,0 +1,51 @@
+package com.gtnewhorizon.gtnhlib.util.data;
+
+import javax.annotation.Nonnull;
+
+import net.minecraft.block.Block;
+import net.minecraft.item.Item;
+import net.minecraftforge.oredict.OreDictionary;
+
+/**
+ * An immutable block-meta pair. This must not be cast down to its mutable version unless you have a very good reason.
+ * It can be assumed that the values of {@link #getBlock()} and {@link #getBlockMeta()} will never change for this
+ * object if the object is exposed through an API.
+ */
+public interface ImmutableBlockMeta {
+
+    /**
+     * The value of this must not change while this object is exposed via an API.
+     * 
+     * @return The block stored in this pair.
+     */
+    @Nonnull
+    public Block getBlock();
+
+    /**
+     * The value of this must not change while this object is exposed via an API.
+     * 
+     * @return The block's metadata stored in this pair.
+     */
+    public int getBlockMeta();
+
+    /**
+     * Gets the corresponding item for this block. Subclasses may provide a faster implementation.
+     */
+    public default Item getItem() {
+        return Item.getItemFromBlock(getBlock());
+    }
+
+    /**
+     * Checks if this pair matches the given block & meta.
+     * 
+     * @param block The block.
+     * @param meta  The meta. If this parameter or {@link #getBlockMeta()} equals {@link OreDictionary.WILDCARD_VALUE}
+     *              then meta checks are ignored.
+     * @return Whether this pair matches or not.
+     */
+    public default boolean matches(Block block, int meta) {
+        return getBlock() == block
+                && (meta == OreDictionary.WILDCARD_VALUE || getBlockMeta() == OreDictionary.WILDCARD_VALUE
+                        || getBlockMeta() == meta);
+    }
+}

src/main/java/com/gtnewhorizon/gtnhlib/util/data/ImmutableItemMeta.java

@@ -0,0 +1,62 @@
+package com.gtnewhorizon.gtnhlib.util.data;
+
+import javax.annotation.Nonnull;
+
+import net.minecraft.block.Block;
+import net.minecraft.init.Items;
+import net.minecraft.item.Item;
+import net.minecraft.item.ItemStack;
+import net.minecraftforge.oredict.OreDictionary;
+
+/**
+ * An immutable item-meta pair. This must not be cast down to its mutable version unless you have a very good reason. It
+ * can be assumed that the values of {@link #getItem()} and {@link #getItemMeta()} will never change for this object if
+ * the object is exposed through an API.
+ */
+public interface ImmutableItemMeta {
+
+    /**
+     * The value of this must not change while this object is exposed via an API.
+     * 
+     * @return The item stored in this pair.
+     */
+    @Nonnull
+    public Item getItem();
+
+    /**
+     * The value of this must not change while this object is exposed via an API.
+     * 
+     * @return The item's metadata stored in this pair.
+     */
+    public int getItemMeta();
+
+    /**
+     * Gets the corresponding block for this item. Subclasses may provide a faster implementation.
+     */
+    public default Block getBlock() {
+        return Block.getBlockFromItem(getItem());
+    }
+
+    /**
+     * Checks if this pair matches the given ItemStack's item and metadata.
+     */
+    public default boolean matches(ItemStack stack) {
+        if (stack == null) return false;
+
+        return matches(stack.getItem(), Items.feather.getDamage(stack));
+    }
+
+    /**
+     * Checks if this pair matches the given item & meta.
+     * 
+     * @param Item The item.
+     * @param meta The meta. If this parameter or {@link #getItemMeta()} equals {@link OreDictionary.WILDCARD_VALUE}
+     *             then meta checks are ignored.
+     * @return Whether this pair matches or not.
+     */
+    public default boolean matches(Item item, int meta) {
+        return getItem() == item
+                && (meta == OreDictionary.WILDCARD_VALUE || getItemMeta() == OreDictionary.WILDCARD_VALUE
+                        || getItemMeta() == meta);
+    }
+}

src/main/java/com/gtnewhorizon/gtnhlib/util/data/ItemMeta.java

@@ -0,0 +1,79 @@
+package com.gtnewhorizon.gtnhlib.util.data;
+
+import javax.annotation.Nonnull;
+
+import net.minecraft.item.Item;
+
+/**
+ * A mutable implementation of {@link ImmutableItemMeta}. If your API should return a mutable pair, return this instead.
+ * Must follow the same contracts as the immutable version if this is ever upcast to a {@link ImmutableItemMeta} in your
+ * API. If this type is exposed instead of the immutable interface, assume that the contained values can change.
+ */
+public class ItemMeta implements ImmutableItemMeta {
+
+    private Item item;
+    private int meta;
+
+    public ItemMeta() {}
+
+    public ItemMeta(Item item, int meta) {
+        this.item = item;
+        this.meta = meta;
+    }
+
+    @Override
+    @SuppressWarnings("null")
+    public Item getItem() {
+        return item;
+    }
+
+    @Override
+    public int getItemMeta() {
+        return meta;
+    }
+
+    /**
+     * Note: see the header comment in {@link ImmutableItemMeta} for this method's contract.
+     */
+    public ItemMeta setItem(@Nonnull Item item) {
+        this.item = item;
+
+        return this;
+    }
+
+    /**
+     * Note: see the header comment in {@link ImmutableItemMeta} for this method's contract.
+     */
+    public ItemMeta setItemMeta(int meta) {
+        this.meta = meta;
+
+        return this;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((item == null) ? 0 : item.hashCode());
+        result = prime * result + meta;
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null) return false;
+        if (getClass() != obj.getClass()) return false;
+        ItemMeta other = (ItemMeta) obj;
+        if (item == null) {
+            if (other.item != null) return false;
+        } else if (!item.equals(other.item)) return false;
+        if (meta != other.meta) return false;
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        return "ItemMeta [item=" + item + ", meta=" + meta + "]";
+    }
+}

src/main/java/com/gtnewhorizon/gtnhlib/util/data/Lazy.java

@@ -0,0 +1,32 @@
+package com.gtnewhorizon.gtnhlib.util.data;
+
+import java.util.function.Supplier;
+
+/**
+ * Just a container that will lazy-load a value. Can be used in the place of a Supplier<T>
+ */
+public class Lazy<T> implements Supplier<T> {
+
+    private boolean hasValue = false;
+    private T value;
+
+    private Supplier<T> getter;
+
+    public Lazy(Supplier<T> getter) {
+        this.getter = getter;
+    }
+
+    /**
+     * Gets the value. Thread safe.
+     */
+    @Override
+    public synchronized T get() {
+        if (!hasValue) {
+            value = getter.get();
+            getter = null;
+            hasValue = true;
+        }
+
+        return value;
+    }
+}