503 lines
18 KiB
Java
503 lines
18 KiB
Java
package com.comphenix.tinyprotocol;
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import java.lang.reflect.Constructor;
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import java.lang.reflect.Field;
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import java.lang.reflect.Method;
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import java.lang.reflect.ParameterizedType;
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import java.lang.reflect.Type;
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import java.util.Arrays;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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import org.bukkit.Bukkit;
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/**
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* An utility class that simplifies reflection in Bukkit plugins.
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*
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* @author Kristian
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*/
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public final class Reflection {
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/**
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* An interface for invoking a specific constructor.
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*/
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public interface ConstructorInvoker {
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/**
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* Invoke a constructor for a specific class.
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*
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* @param arguments - the arguments to pass to the constructor.
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* @return The constructed object.
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*/
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public Object invoke(Object... arguments);
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}
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/**
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* An interface for invoking a specific method.
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*/
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public interface MethodInvoker {
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/**
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* Invoke a method on a specific target object.
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*
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* @param target - the target object, or NULL for a static method.
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* @param arguments - the arguments to pass to the method.
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* @return The return value, or NULL if is void.
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*/
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public Object invoke(Object target, Object... arguments);
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}
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/**
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* An interface for retrieving the field content.
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*
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* @param <T> - field type.
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*/
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public interface FieldAccessor<T> {
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/**
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* Retrieve the content of a field.
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*
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* @param target - the target object, or NULL for a static field.
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* @return The value of the field.
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*/
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public T get(Object target);
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/**
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* Set the content of a field.
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*
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* @param target - the target object, or NULL for a static field.
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* @param value - the new value of the field.
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*/
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public void set(Object target, Object value);
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/**
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* Determine if the given object has this field.
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*
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* @param target - the object to test.
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* @return TRUE if it does, FALSE otherwise.
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*/
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public boolean hasField(Object target);
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}
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// Deduce the net.minecraft.server.v* package
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private static String OBC_PREFIX = Bukkit.getServer().getClass().getPackage().getName();
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private static String NMS_PREFIX = OBC_PREFIX.replace("org.bukkit.craftbukkit", "net.minecraft.server");
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private static String VERSION = OBC_PREFIX.replace("org.bukkit.craftbukkit", "").replace(".", "");
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// Variable replacement
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private static Pattern MATCH_VARIABLE = Pattern.compile("\\{([^\\}]+)\\}");
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private Reflection() {
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// Seal class
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}
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/**
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* Retrieve a field accessor for a specific field type and name.
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*
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* @param target - the target type.
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* @param name - the name of the field, or NULL to ignore.
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* @param fieldType - a compatible field type.
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* @return The field accessor.
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*/
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public static <T> FieldAccessor<T> getField(Class<?> target, String name, Class<T> fieldType) {
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return getField(target, name, fieldType, 0);
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}
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/**
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* Retrieve a field accessor for a specific field type and name.
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*
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* @param className - lookup name of the class, see {@link #getClass(String)}.
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* @param name - the name of the field, or NULL to ignore.
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* @param fieldType - a compatible field type.
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* @return The field accessor.
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*/
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public static <T> FieldAccessor<T> getField(String className, String name, Class<T> fieldType) {
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return getField(getClass(className), name, fieldType, 0);
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}
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/**
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* Retrieve a field accessor for a specific field type and name.
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*
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* @param target - the target type.
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* @param fieldType - a compatible field type.
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* @param index - the number of compatible fields to skip.
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* @return The field accessor.
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*/
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public static <T> FieldAccessor<T> getField(Class<?> target, Class<T> fieldType, int index) {
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return getField(target, null, fieldType, index);
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}
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/**
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* Retrieve a field accessor for a specific field type and name.
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*
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* @param className - lookup name of the class, see {@link #getClass(String)}.
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* @param fieldType - a compatible field type.
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* @param index - the number of compatible fields to skip.
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* @return The field accessor.
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*/
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public static <T> FieldAccessor<T> getField(String className, Class<T> fieldType, int index) {
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return getField(getClass(className), fieldType, index);
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}
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// Common method
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private static <T> FieldAccessor<T> getField(Class<?> target, String name, Class<T> fieldType, int index) {
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for (final Field field : target.getDeclaredFields()) {
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if ((name == null || field.getName().equals(name)) && fieldType.isAssignableFrom(field.getType()) && index-- <= 0) {
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field.setAccessible(true);
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// A function for retrieving a specific field value
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return new FieldAccessor<T>() {
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@Override
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@SuppressWarnings("unchecked")
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public T get(Object target) {
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try {
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return (T) field.get(target);
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} catch (IllegalAccessException e) {
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throw new RuntimeException("Cannot access reflection.", e);
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}
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}
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@Override
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public void set(Object target, Object value) {
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try {
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field.set(target, value);
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} catch (IllegalAccessException e) {
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throw new RuntimeException("Cannot access reflection.", e);
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}
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}
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@Override
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public boolean hasField(Object target) {
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// target instanceof DeclaringClass
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return field.getDeclaringClass().isAssignableFrom(target.getClass());
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}
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};
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}
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}
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// Search in parent classes
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if (target.getSuperclass() != null)
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return getField(target.getSuperclass(), name, fieldType, index);
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throw new IllegalArgumentException("Cannot find field with type " + fieldType);
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}
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/**
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* Retrieves a field with a given type and parameters. This is most useful
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* when dealing with Collections.
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*
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* @param target the target class.
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* @param fieldType Type of the field
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* @param params Variable length array of type parameters
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* @return The field
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*
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* @throws IllegalArgumentException If the field cannot be found
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*/
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public static Field getParameterizedField(Class<?> target, Class<?> fieldType, Class<?>... params) {
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for (Field field : target.getDeclaredFields()) {
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if (field.getType().equals(fieldType)) {
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Type type = field.getGenericType();
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if (type instanceof ParameterizedType) {
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if (Arrays.equals(((ParameterizedType) type).getActualTypeArguments(), params))
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return field;
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}
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}
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}
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throw new IllegalArgumentException("Unable to find a field with type " + fieldType + " and params " + Arrays.toString(params));
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}
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/**
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* Search for the first publicly and privately defined method of the given name and parameter count.
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*
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* @param className - lookup name of the class, see {@link #getClass(String)}.
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* @param methodName - the method name, or NULL to skip.
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* @param params - the expected parameters.
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* @return An object that invokes this specific method.
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* @throws IllegalStateException If we cannot find this method.
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*/
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public static MethodInvoker getMethod(String className, String methodName, Class<?>... params) {
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return getTypedMethod(getClass(className), methodName, null, params);
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}
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/**
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* Search for the first publicly and privately defined method of the given name and parameter count.
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*
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* @param clazz - a class to start with.
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* @param methodName - the method name, or NULL to skip.
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* @param params - the expected parameters.
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* @return An object that invokes this specific method.
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* @throws IllegalStateException If we cannot find this method.
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*/
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public static MethodInvoker getMethod(Class<?> clazz, String methodName, Class<?>... params) {
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return getTypedMethod(clazz, methodName, null, params);
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}
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/**
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* Search for the first publicly and privately defined method of the given name and parameter count.
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*
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* @param clazz - a class to start with.
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* @param methodName - the method name, or NULL to skip.
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* @param returnType - the expected return type, or NULL to ignore.
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* @param params - the expected parameters.
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* @return An object that invokes this specific method.
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* @throws IllegalStateException If we cannot find this method.
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*/
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public static MethodInvoker getTypedMethod(Class<?> clazz, String methodName, Class<?> returnType, Class<?>... params) {
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for (final Method method : clazz.getDeclaredMethods()) {
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if ((methodName == null || method.getName().equals(methodName))
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&& (returnType == null || method.getReturnType().equals(returnType))
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&& Arrays.equals(method.getParameterTypes(), params)) {
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method.setAccessible(true);
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return new MethodInvoker() {
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@Override
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public Object invoke(Object target, Object... arguments) {
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try {
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return method.invoke(target, arguments);
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} catch (Exception e) {
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throw new RuntimeException("Cannot invoke method " + method, e);
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}
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}
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};
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}
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}
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// Search in every superclass
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if (clazz.getSuperclass() != null)
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return getMethod(clazz.getSuperclass(), methodName, params);
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throw new IllegalStateException(String.format("Unable to find method %s (%s).", methodName, Arrays.asList(params)));
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}
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/**
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* Search for the first publically and privately defined constructor of the given name and parameter count.
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*
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* @param className - lookup name of the class, see {@link #getClass(String)}.
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* @param params - the expected parameters.
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* @return An object that invokes this constructor.
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* @throws IllegalStateException If we cannot find this method.
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*/
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public static ConstructorInvoker getConstructor(String className, Class<?>... params) {
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return getConstructor(getClass(className), params);
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}
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/**
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* Search for the first publically and privately defined constructor of the given name and parameter count.
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*
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* @param clazz - a class to start with.
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* @param params - the expected parameters.
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* @return An object that invokes this constructor.
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* @throws IllegalStateException If we cannot find this method.
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*/
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public static ConstructorInvoker getConstructor(Class<?> clazz, Class<?>... params) {
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for (final Constructor<?> constructor : clazz.getDeclaredConstructors()) {
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if (Arrays.equals(constructor.getParameterTypes(), params)) {
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constructor.setAccessible(true);
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return new ConstructorInvoker() {
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@Override
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public Object invoke(Object... arguments) {
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try {
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return constructor.newInstance(arguments);
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} catch (Exception e) {
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throw new RuntimeException("Cannot invoke constructor " + constructor, e);
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}
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}
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};
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}
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}
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throw new IllegalStateException(String.format("Unable to find constructor for %s (%s).", clazz, Arrays.asList(params)));
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}
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/**
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* Retrieve a class from its full name, without knowing its type on compile time.
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* <p>
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* This is useful when looking up fields by a NMS or OBC type.
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* <p>
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*
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* @see {@link #getClass()} for more information.
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* @param lookupName - the class name with variables.
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* @return The class.
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*/
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public static Class<Object> getUntypedClass(String lookupName) {
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@SuppressWarnings({ "rawtypes", "unchecked" })
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Class<Object> clazz = (Class) getClass(lookupName);
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return clazz;
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}
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/**
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* Retrieve a class from its full name with alternatives, without knowing its type on compile time.
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* <p>
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* This is useful when looking up fields by a NMS or OBC type.
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* <p>
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*
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* @see {@link #getClass()} for more information.
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* @param lookupName - the class name with variables.
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* @param aliases - alternative names for this class.
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* @return The class.
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*/
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public static Class<Object> getUntypedClass(String lookupName, String... aliases) {
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@SuppressWarnings({ "rawtypes", "unchecked" })
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Class<Object> clazz = (Class) getClass(lookupName, aliases);
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return clazz;
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}
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/**
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* Retrieve a class from its full name.
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* <p>
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* Strings enclosed with curly brackets - such as {TEXT} - will be replaced according to the following table:
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* <p>
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* <table border="1">
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* <tr>
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* <th>Variable</th>
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* <th>Content</th>
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* </tr>
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* <tr>
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* <td>{nms}</td>
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* <td>Actual package name of net.minecraft.server.VERSION</td>
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* </tr>
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* <tr>
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* <td>{obc}</td>
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* <td>Actual pacakge name of org.bukkit.craftbukkit.VERSION</td>
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* </tr>
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* <tr>
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* <td>{version}</td>
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* <td>The current Minecraft package VERSION, if any.</td>
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* </tr>
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* </table>
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*
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* @param lookupName - the class name with variables.
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* @return The looked up class.
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* @throws IllegalArgumentException If a variable or class could not be found.
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*/
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public static Class<?> getClass(String lookupName) {
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return getCanonicalClass(expandVariables(lookupName));
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}
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/**
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* Retrieve the first class that matches the full class name.
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* <p>
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* Strings enclosed with curly brackets - such as {TEXT} - will be replaced according to the following table:
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* <p>
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* <table border="1">
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* <tr>
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* <th>Variable</th>
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* <th>Content</th>
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* </tr>
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* <tr>
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* <td>{nms}</td>
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* <td>Actual package name of net.minecraft.server.VERSION</td>
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* </tr>
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* <tr>
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* <td>{obc}</td>
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* <td>Actual pacakge name of org.bukkit.craftbukkit.VERSION</td>
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* </tr>
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* <tr>
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* <td>{version}</td>
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* <td>The current Minecraft package VERSION, if any.</td>
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* </tr>
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* </table>
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*
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* @param lookupName - the class name with variables.
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* @param aliases - alternative names for this class.
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* @return Class object.
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* @throws RuntimeException If we are unable to find any of the given classes.
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*/
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public static Class<?> getClass(String lookupName, String... aliases) {
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try {
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// Try the main class first
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return getClass(lookupName);
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} catch (RuntimeException e) {
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Class<?> success = null;
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// Try every alias too
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for (String alias : aliases) {
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try {
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success = getClass(alias);
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break;
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} catch (RuntimeException e1) {
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// e1.printStackTrace();
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}
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}
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if (success != null) {
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return success;
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} else {
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// Hack failed
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throw new RuntimeException(String.format("Unable to find %s (%s)", lookupName, String.join(",", aliases)));
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}
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}
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}
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/**
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* Retrieve a class in the net.minecraft.server.VERSION.* package.
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*
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* @param name - the name of the class, excluding the package.
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* @throws IllegalArgumentException If the class doesn't exist.
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*/
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public static Class<?> getMinecraftClass(String name) {
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return getCanonicalClass(NMS_PREFIX + "." + name);
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}
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/**
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* Retrieve a class in the org.bukkit.craftbukkit.VERSION.* package.
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*
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* @param name - the name of the class, excluding the package.
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* @throws IllegalArgumentException If the class doesn't exist.
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*/
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public static Class<?> getCraftBukkitClass(String name) {
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return getCanonicalClass(OBC_PREFIX + "." + name);
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}
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/**
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* Retrieve a class by its canonical name.
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*
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* @param canonicalName - the canonical name.
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* @return The class.
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*/
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private static Class<?> getCanonicalClass(String canonicalName) {
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try {
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return Class.forName(canonicalName);
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} catch (ClassNotFoundException e) {
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throw new IllegalArgumentException("Cannot find " + canonicalName, e);
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}
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}
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/**
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* Expand variables such as "{nms}" and "{obc}" to their corresponding packages.
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*
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* @param name - the full name of the class.
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* @return The expanded string.
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*/
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private static String expandVariables(String name) {
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StringBuffer output = new StringBuffer();
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Matcher matcher = MATCH_VARIABLE.matcher(name);
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while (matcher.find()) {
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String variable = matcher.group(1);
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String replacement = "";
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// Expand all detected variables
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if ("nms".equalsIgnoreCase(variable))
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replacement = NMS_PREFIX;
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else if ("obc".equalsIgnoreCase(variable))
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replacement = OBC_PREFIX;
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else if ("version".equalsIgnoreCase(variable))
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replacement = VERSION;
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else
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throw new IllegalArgumentException("Unknown variable: " + variable);
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// Assume the expanded variables are all packages, and append a dot
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if (replacement.length() > 0 && matcher.end() < name.length() && name.charAt(matcher.end()) != '.')
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replacement += ".";
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matcher.appendReplacement(output, Matcher.quoteReplacement(replacement));
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}
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matcher.appendTail(output);
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return output.toString();
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}
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}
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