Add aliases as submodule; API improvements

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "skript-aliases"]
+	path = skript-aliases
+	url = https://github.com/SkriptLang/skript-aliases

build.gradle

@@ -86,6 +86,10 @@ jar {
 		attributes("Name": "ch/njol/skript",
 				"Sealed": "true")
 	}
+
+	from('skript-aliases') {
+	    into('aliases')
+	}
 }
 
 license {

src/main/java/ch/njol/skript/aliases/Aliases.java

@@ -91,19 +91,23 @@ private static AliasesProvider createProvider() {
 		provider.registerCondition("minecraft version", (str) -> {
 			int orNewer = str.indexOf("or newer"); // For example: 1.12 or newer
 			if (orNewer != -1) {
+				@SuppressWarnings("null")
 				Version ver = new Version(str.substring(0, orNewer - 1));
 				return Skript.getMinecraftVersion().compareTo(ver) >= 0;
 			}
 
 			int orOlder = str.indexOf("or older"); // For example: 1.11 or older
 			if (orOlder != -1) {
+				@SuppressWarnings("null")
 				Version ver = new Version(str.substring(0, orOlder - 1));
 				return Skript.getMinecraftVersion().compareTo(ver) <= 0;
 			}
 
 			int to = str.indexOf("to"); // For example: 1.11 to 1.12
 			if (to != -1) {
+				@SuppressWarnings("null")
 				Version first = new Version(str.substring(0, to - 1));
+				@SuppressWarnings("null")
 				Version second = new Version(str.substring(to + 3));
 				Version current = Skript.getMinecraftVersion();
 				return current.compareTo(first) >= 0 && current.compareTo(second) <= 0;
@@ -332,7 +336,7 @@ private final static ItemType parseType(final String s, final ItemType t, final
 			t.add(new ItemData(Material.AIR));
 			return t;
 		} else if (type.matches("\\d+")) {
-			// TODO error: numeric ids are not supported anymore
+			Skript.error("Numeric ids are not supported anymore.");
 			return null;
 		} else if ((i = getAlias(type)) != null) {
 			for (ItemData d : i) {
@@ -521,4 +525,23 @@ public static boolean isSupertypeOf(ItemData first, ItemData second) {
 	public static String getMinecraftId(ItemData data) {
 		return provider.getMinecraftId(data);
 	}
+
+	/**
+	 * Gets an item type that matches the given name.
+	 * If it doesn't exist, an exception is thrown instead.
+	 * 
+	 * <p>Item types provided by this method are updated when aliases are
+	 * reloaded. However, this also means they are tracked by aliases system.
+	 * Generally, they should be put in (static final) fields.
+	 * @param name Name of item to search from aliases.
+	 * @return An item.
+	 * @throws IllegalArgumentException When item is not found.
+	 */
+	public static ItemType javaItemType(String name) {
+		ItemType type = parseItemType(name);
+		if (type == null)
+			throw new IllegalArgumentException("type not found");
+		// TODO type tracking
+		return type;
+	}
 }

src/main/java/ch/njol/skript/aliases/ItemType.java

@@ -194,7 +194,15 @@ public ItemType(BlockState b) {
 		// TODO metadata - spawners, skulls, etc.
 	}
 
+	/**
+	 * Copy constructor.
+	 * @param i Another ItemType.
+	 */
 	private ItemType(ItemType i) {
+		setTo(i);
+	}
+
+	public void setTo(ItemType i) {
 		all = i.all;
 		amount = i.amount;
 		final ItemType bl = i.block, it = i.item;
@@ -217,7 +225,8 @@ public void modified() {
 	}
 
 	/**
-	 * @return amount or 1 if amount == -1
+	 * Returns amount of the item in stack that this type represents.
+	 * @return amount.
 	 */
 	@Override
 	public int getAmount() {
@@ -247,6 +256,11 @@ public void setAmount(final int amount) {
 			block.amount = amount;
 	}
 
+	/**
+	 * Checks if this item type represents one of its items (OR) or all of
+	 * them (AND). If this has only one item, it doesn't matter.
+	 * @return Whether all of the items are represented.
+	 */
 	public boolean isAll() {
 		return all;
 	}