content: package org.gcontracts.util;
  
  import java.lang.reflect.Constructor;
  import java.lang.reflect.Field;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Modifier;
  import java.sql.SQLException;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  
  /**
   * This class has been pulled from the Spring framework, spring-core module.
   *
   * Simple utility class for working with the reflection API and handling
   * reflection exceptions.
   *
   * <p>Only intended for internal use.
   *
   * @author Juergen Hoeller
   * @author Rob Harrop
   * @author Rod Johnson
   * @author Costin Leau
   * @author Sam Brannen
   * @since 1.2.2
   */
  public abstract class ReflectionUtils {
  
  	/**
  	 * Attempt to find a {@link Field field} on the supplied {@link Class} with the
  	 * supplied <code>name</code>. Searches all superclasses up to {@link Object}.
  	 * @param clazz the class to introspect
  	 * @param name the name of the field
  	 * @return the corresponding Field object, or <code>null</code> if not found
  	 */
  	public static Field findField(Class<?> clazz, String name) {
  		return findField(clazz, name, null);
  	}
  
  	/**
  	 * Attempt to find a {@link Field field} on the supplied {@link Class} with the
  	 * supplied <code>name</code> and/or {@link Class type}. Searches all superclasses
  	 * up to {@link Object}.
  	 * @param clazz the class to introspect
  	 * @param name the name of the field (may be <code>null</code> if type is specified)
  	 * @param type the type of the field (may be <code>null</code> if name is specified)
  	 * @return the corresponding Field object, or <code>null</code> if not found
  	 */
  	public static Field findField(Class<?> clazz, String name, Class<?> type) {
  		Class<?> searchType = clazz;
  		while (!Object.class.equals(searchType) && searchType != null) {
  			Field[] fields = searchType.getDeclaredFields();
  			for (Field field : fields) {
  				if ((name == null || name.equals(field.getName())) && (type == null || type.equals(field.getType()))) {
  					return field;
  				}
  			}
  			searchType = searchType.getSuperclass();
  		}
  		return null;
  	}
  
  	/**
  	 * Set the field represented by the supplied {@link Field field object} on the
  	 * specified {@link Object target object} to the specified <code>value</code>.
  	 * In accordance with {@link Field#set(Object, Object)} semantics, the new value
  	 * is automatically unwrapped if the underlying field has a primitive type.
  	 * <p>Thrown exceptions are handled via a call to {@link #handleReflectionException(Exception)}.
  	 * @param field the field to set
  	 * @param target the target object on which to set the field
  	 * @param value the value to set; may be <code>null</code>
  	 */
  	public static void setField(Field field, Object target, Object value) {
  		try {
  			field.set(target, value);
  		}
  		catch (IllegalAccessException ex) {
  			handleReflectionException(ex);
  			throw new IllegalStateException("Unexpected reflection exception - " + ex.getClass().getName() + ": "
  					+ ex.getMessage());
  		}
  	}
  
  	/**
  	 * Get the field represented by the supplied {@link Field field object} on the
  	 * specified {@link Object target object}. In accordance with {@link Field#get(Object)}
  	 * semantics, the returned value is automatically wrapped if the underlying field
  	 * has a primitive type.
  	 * <p>Thrown exceptions are handled via a call to {@link #handleReflectionException(Exception)}.
  	 * @param field the field to get
  	 * @param target the target object from which to get the field
  	 * @return the field's current value
  	 */
  	public static Object getField(Field field, Object target) {
  		try {
  			return field.get(target);
  		}
  		catch (IllegalAccessException ex) {
  			handleReflectionException(ex);
  			throw new IllegalStateException(
  					"Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());
  		}
  	}
  
  	/**
  	 * Attempt to find a {@link Method} on the supplied class with the supplied name
  	 * and no parameters. Searches all superclasses up to <code>Object</code>.
  	 * <p>Returns <code>null</code> if no {@link Method} can be found.
  	 * @param clazz the class to introspect
  	 * @param name the name of the method
  	 * @return the Method object, or <code>null</code> if none found
  	 */
  	public static Method findMethod(Class<?> clazz, String name) {
  		return findMethod(clazz, name, new Class[0]);
  	}
  
  	/**
  	 * Attempt to find a {@link Method} on the supplied class with the supplied name
  	 * and parameter types. Searches all superclasses up to <code>Object</code>.
  	 * <p>Returns <code>null</code> if no {@link Method} can be found.
  	 * @param clazz the class to introspect
  	 * @param name the name of the method
  	 * @param paramTypes the parameter types of the method
  	 * (may be <code>null</code> to indicate any signature)
  	 * @return the Method object, or <code>null</code> if none found
  	 */
  	public static Method findMethod(Class<?> clazz, String name, Class<?>... paramTypes) {
  		Class<?> searchType = clazz;
  		while (searchType != null) {
  			Method[] methods = (searchType.isInterface() ? searchType.getMethods() : searchType.getDeclaredMethods());
  			for (Method method : methods) {
  				if (name.equals(method.getName())
  						&& (paramTypes == null || Arrays.equals(paramTypes, method.getParameterTypes()))) {
  					return method;
  				}
  			}
  			searchType = searchType.getSuperclass();
  		}
  		return null;
  	}
  
  	/**
  	 * Invoke the specified {@link Method} against the supplied target object with no arguments.
  	 * The target object can be <code>null</code> when invoking a static {@link Method}.
  	 * <p>Thrown exceptions are handled via a call to {@link #handleReflectionException}.
  	 * @param method the method to invoke
  	 * @param target the target object to invoke the method on
  	 * @return the invocation result, if any
  	 * @see #invokeMethod(java.lang.reflect.Method, Object, Object[])
  	 */
  	public static Object invokeMethod(Method method, Object target) {
  		return invokeMethod(method, target, new Object[0]);
  	}
  
  	/**
  	 * Invoke the specified {@link Method} against the supplied target object with the
  	 * supplied arguments. The target object can be <code>null</code> when invoking a
  	 * static {@link Method}.
  	 * <p>Thrown exceptions are handled via a call to {@link #handleReflectionException}.
  	 * @param method the method to invoke
  	 * @param target the target object to invoke the method on
  	 * @param args the invocation arguments (may be <code>null</code>)
  	 * @return the invocation result, if any
  	 */
  	public static Object invokeMethod(Method method, Object target, Object... args) {
  		try {
  			return method.invoke(target, args);
  		}
  		catch (Exception ex) {
  			handleReflectionException(ex);
  		}
  		throw new IllegalStateException("Should never get here");
  	}
  
  	/**
  	 * Invoke the specified JDBC API {@link Method} against the supplied target
  	 * object with no arguments.
  	 * @param method the method to invoke
  	 * @param target the target object to invoke the method on
  	 * @return the invocation result, if any
  	 * @throws SQLException the JDBC API SQLException to rethrow (if any)
  	 * @see #invokeJdbcMethod(java.lang.reflect.Method, Object, Object[])
  	 */
  	public static Object invokeJdbcMethod(Method method, Object target) throws SQLException {
  		return invokeJdbcMethod(method, target, new Object[0]);
  	}
  
  	/**
  	 * Invoke the specified JDBC API {@link Method} against the supplied target
  	 * object with the supplied arguments.
  	 * @param method the method to invoke
  	 * @param target the target object to invoke the method on
  	 * @param args the invocation arguments (may be <code>null</code>)
  	 * @return the invocation result, if any
  	 * @throws SQLException the JDBC API SQLException to rethrow (if any)
  	 * @see #invokeMethod(java.lang.reflect.Method, Object, Object[])
  	 */
  	public static Object invokeJdbcMethod(Method method, Object target, Object... args) throws SQLException {
  		try {
  			return method.invoke(target, args);
  		}
  		catch (IllegalAccessException ex) {
  			handleReflectionException(ex);
  		}
  		catch (InvocationTargetException ex) {
  			if (ex.getTargetException() instanceof SQLException) {
  				throw (SQLException) ex.getTargetException();
  			}
  			handleInvocationTargetException(ex);
  		}
  		throw new IllegalStateException("Should never get here");
  	}
  
  	/**
  	 * Handle the given reflection exception. Should only be called if no
  	 * checked exception is expected to be thrown by the target method.
  	 * <p>Throws the underlying RuntimeException or Error in case of an
  	 * InvocationTargetException with such a root cause. Throws an
  	 * IllegalStateException with an appropriate message else.
  	 * @param ex the reflection exception to handle
  	 */
  	public static void handleReflectionException(Exception ex) {
  		if (ex instanceof NoSuchMethodException) {
  			throw new IllegalStateException("Method not found: " + ex.getMessage());
  		}
  		if (ex instanceof IllegalAccessException) {
  			throw new IllegalStateException("Could not access method: " + ex.getMessage());
  		}
  		if (ex instanceof InvocationTargetException) {
  			handleInvocationTargetException((InvocationTargetException) ex);
  		}
  		if (ex instanceof RuntimeException) {
  			throw (RuntimeException) ex;
  		}
  		handleUnexpectedException(ex);
  	}
  
  	/**
  	 * Handle the given invocation target exception. Should only be called if no
  	 * checked exception is expected to be thrown by the target method.
  	 * <p>Throws the underlying RuntimeException or Error in case of such a root
  	 * cause. Throws an IllegalStateException else.
  	 * @param ex the invocation target exception to handle
  	 */
  	public static void handleInvocationTargetException(InvocationTargetException ex) {
  		rethrowRuntimeException(ex.getTargetException());
  	}
  
  	/**
  	 * Rethrow the given {@link Throwable exception}, which is presumably the
  	 * <em>target exception</em> of an {@link InvocationTargetException}. Should
  	 * only be called if no checked exception is expected to be thrown by the
  	 * target method.
  	 * <p>Rethrows the underlying exception cast to an {@link RuntimeException} or
  	 * {@link Error} if appropriate; otherwise, throws an
  	 * {@link IllegalStateException}.
  	 * @param ex the exception to rethrow
  	 * @throws RuntimeException the rethrown exception
  	 */
  	public static void rethrowRuntimeException(Throwable ex) {
  		if (ex instanceof RuntimeException) {
  			throw (RuntimeException) ex;
  		}
  		if (ex instanceof Error) {
  			throw (Error) ex;
  		}
  		handleUnexpectedException(ex);
  	}
  
  	/**
  	 * Rethrow the given {@link Throwable exception}, which is presumably the
  	 * <em>target exception</em> of an {@link InvocationTargetException}. Should
  	 * only be called if no checked exception is expected to be thrown by the
  	 * target method.
  	 * <p>Rethrows the underlying exception cast to an {@link Exception} or
  	 * {@link Error} if appropriate; otherwise, throws an
  	 * {@link IllegalStateException}.
  	 * @param ex the exception to rethrow
  	 * @throws Exception the rethrown exception (in case of a checked exception)
  	 */
  	public static void rethrowException(Throwable ex) throws Exception {
  		if (ex instanceof Exception) {
  			throw (Exception) ex;
  		}
  		if (ex instanceof Error) {
  			throw (Error) ex;
  		}
  		handleUnexpectedException(ex);
  	}
  
  	/**
  	 * Throws an IllegalStateException with the given exception as root cause.
  	 * @param ex the unexpected exception
  	 */
  	private static void handleUnexpectedException(Throwable ex) {
  		throw new IllegalStateException("Unexpected exception thrown", ex);
  	}
  
  	/**
  	 * Determine whether the given method explicitly declares the given
  	 * exception or one of its superclasses, which means that an exception of
  	 * that type can be propagated as-is within a reflective invocation.
  	 * @param method the declaring method
  	 * @param exceptionType the exception to throw
  	 * @return <code>true</code> if the exception can be thrown as-is;
  	 * <code>false</code> if it needs to be wrapped
  	 */
  	public static boolean declaresException(Method method, Class<?> exceptionType) {
  		Class<?>[] declaredExceptions = method.getExceptionTypes();
  		for (Class<?> declaredException : declaredExceptions) {
  			if (declaredException.isAssignableFrom(exceptionType)) {
  				return true;
  			}
  		}
  		return false;
  	}
  
  	/**
  	 * Determine whether the given field is a "public static final" constant.
  	 * @param field the field to check
  	 */
  	public static boolean isPublicStaticFinal(Field field) {
  		int modifiers = field.getModifiers();
  		return (Modifier.isPublic(modifiers) && Modifier.isStatic(modifiers) && Modifier.isFinal(modifiers));
  	}
  
  	/**
  	 * Determine whether the given method is an "equals" method.
  	 * @see java.lang.Object#equals(Object)
  	 */
  	public static boolean isEqualsMethod(Method method) {
  		if (method == null || !method.getName().equals("equals")) {
  			return false;
  		}
  		Class<?>[] paramTypes = method.getParameterTypes();
  		return (paramTypes.length == 1 && paramTypes[0] == Object.class);
  	}
  
  	/**
  	 * Determine whether the given method is a "hashCode" method.
  	 * @see java.lang.Object#hashCode()
  	 */
  	public static boolean isHashCodeMethod(Method method) {
  		return (method != null && method.getName().equals("hashCode") && method.getParameterTypes().length == 0);
  	}
  
  	/**
  	 * Determine whether the given method is a "toString" method.
  	 * @see java.lang.Object#toString()
  	 */
  	public static boolean isToStringMethod(Method method) {
  		return (method != null && method.getName().equals("toString") && method.getParameterTypes().length == 0);
  	}
  
  	/**
  	 * Make the given field accessible, explicitly setting it accessible if
  	 * necessary. The <code>setAccessible(true)</code> method is only called
  	 * when actually necessary, to avoid unnecessary conflicts with a JVM
  	 * SecurityManager (if active).
  	 * @param field the field to make accessible
  	 * @see java.lang.reflect.Field#setAccessible
  	 */
  	public static void makeAccessible(Field field) {
  		if ((!Modifier.isPublic(field.getModifiers()) || !Modifier.isPublic(field.getDeclaringClass().getModifiers()) ||
  				Modifier.isFinal(field.getModifiers())) && !field.isAccessible()) {
  			field.setAccessible(true);
  		}
  	}
  
  	/**
  	 * Make the given method accessible, explicitly setting it accessible if
  	 * necessary. The <code>setAccessible(true)</code> method is only called
  	 * when actually necessary, to avoid unnecessary conflicts with a JVM
  	 * SecurityManager (if active).
  	 * @param method the method to make accessible
  	 * @see java.lang.reflect.Method#setAccessible
  	 */
  	public static void makeAccessible(Method method) {
  		if ((!Modifier.isPublic(method.getModifiers()) || !Modifier.isPublic(method.getDeclaringClass().getModifiers()))
  				&& !method.isAccessible()) {
  			method.setAccessible(true);
  		}
  	}
  
  	/**
  	 * Make the given constructor accessible, explicitly setting it accessible
  	 * if necessary. The <code>setAccessible(true)</code> method is only called
  	 * when actually necessary, to avoid unnecessary conflicts with a JVM
  	 * SecurityManager (if active).
  	 * @param ctor the constructor to make accessible
  	 * @see java.lang.reflect.Constructor#setAccessible
  	 */
  	public static void makeAccessible(Constructor<?> ctor) {
  		if ((!Modifier.isPublic(ctor.getModifiers()) || !Modifier.isPublic(ctor.getDeclaringClass().getModifiers()))
  				&& !ctor.isAccessible()) {
  			ctor.setAccessible(true);
  		}
  	}
  
  	/**
  	 * Perform the given callback operation on all matching methods of the given
  	 * class and superclasses.
  	 * <p>The same named method occurring on subclass and superclass will appear
  	 * twice, unless excluded by a {@link MethodFilter}.
  	 * @param clazz class to start looking at
  	 * @param mc the callback to invoke for each method
  	 * @see #doWithMethods(Class, MethodCallback, MethodFilter)
  	 */
  	public static void doWithMethods(Class<?> clazz, MethodCallback mc) throws IllegalArgumentException {
  		doWithMethods(clazz, mc, null);
  	}
  
  	/**
  	 * Perform the given callback operation on all matching methods of the given
  	 * class and superclasses (or given interface and super-interfaces).
  	 * <p>The same named method occurring on subclass and superclass will appear
  	 * twice, unless excluded by the specified {@link MethodFilter}.
  	 * @param clazz class to start looking at
  	 * @param mc the callback to invoke for each method
  	 * @param mf the filter that determines the methods to apply the callback to
  	 */
  	public static void doWithMethods(Class<?> clazz, MethodCallback mc, MethodFilter mf)
  			throws IllegalArgumentException {
  
  		// Keep backing up the inheritance hierarchy.
  		Method[] methods = clazz.getDeclaredMethods();
  		for (Method method : methods) {
  			if (mf != null && !mf.matches(method)) {
  				continue;
  			}
  			try {
  				mc.doWith(method);
  			}
  			catch (IllegalAccessException ex) {
  				throw new IllegalStateException("Shouldn't be illegal to access method '" + method.getName()
  						+ "': " + ex);
  			}
  		}
  		if (clazz.getSuperclass() != null) {
  			doWithMethods(clazz.getSuperclass(), mc, mf);
  		}
  		else if (clazz.isInterface()) {
  			for (Class<?> superIfc : clazz.getInterfaces()) {
  				doWithMethods(superIfc, mc, mf);
  			}
  		}
  	}
  
  	/**
  	 * Get all declared methods on the leaf class and all superclasses. Leaf
  	 * class methods are included first.
  	 */
  	public static Method[] getAllDeclaredMethods(Class<?> leafClass) throws IllegalArgumentException {
  		final List<Method> methods = new ArrayList<Method>(32);
  		doWithMethods(leafClass, new MethodCallback() {
  			public void doWith(Method method) {
  				methods.add(method);
  			}
  		});
  		return methods.toArray(new Method[methods.size()]);
  	}
  
  	/**
  	 * Invoke the given callback on all fields in the target class, going up the
  	 * class hierarchy to get all declared fields.
  	 * @param clazz the target class to analyze
  	 * @param fc the callback to invoke for each field
  	 */
  	public static void doWithFields(Class<?> clazz, FieldCallback fc) throws IllegalArgumentException {
  		doWithFields(clazz, fc, null);
  	}
  
  	/**
  	 * Invoke the given callback on all fields in the target class, going up the
  	 * class hierarchy to get all declared fields.
  	 * @param clazz the target class to analyze
  	 * @param fc the callback to invoke for each field
  	 * @param ff the filter that determines the fields to apply the callback to
  	 */
  	public static void doWithFields(Class<?> clazz, FieldCallback fc, FieldFilter ff)
  			throws IllegalArgumentException {
  
  		// Keep backing up the inheritance hierarchy.
  		Class<?> targetClass = clazz;
  		do {
  			Field[] fields = targetClass.getDeclaredFields();
  			for (Field field : fields) {
  				// Skip static and final fields.
  				if (ff != null && !ff.matches(field)) {
  					continue;
  				}
  				try {
  					fc.doWith(field);
  				}
  				catch (IllegalAccessException ex) {
  					throw new IllegalStateException(
  							"Shouldn't be illegal to access field '" + field.getName() + "': " + ex);
  				}
  			}
  			targetClass = targetClass.getSuperclass();
  		}
  		while (targetClass != null && targetClass != Object.class);
  	}
  
  	/**
  	 * Given the source object and the destination, which must be the same class
  	 * or a subclass, copy all fields, including inherited fields. Designed to
  	 * work on objects with public no-arg constructors.
  	 * @throws IllegalArgumentException if the arguments are incompatible
  	 */
  	public static void shallowCopyFieldState(final Object src, final Object dest) throws IllegalArgumentException {
  		if (src == null) {
  			throw new IllegalArgumentException("Source for field copy cannot be null");
  		}
  		if (dest == null) {
  			throw new IllegalArgumentException("Destination for field copy cannot be null");
  		}
  		if (!src.getClass().isAssignableFrom(dest.getClass())) {
  			throw new IllegalArgumentException("Destination class [" + dest.getClass().getName()
  					+ "] must be same or subclass as source class [" + src.getClass().getName() + "]");
  		}
  		doWithFields(src.getClass(), new FieldCallback() {
  			public void doWith(Field field) throws IllegalArgumentException, IllegalAccessException {
  				makeAccessible(field);
  				Object srcValue = field.get(src);
  				field.set(dest, srcValue);
  			}
  		}, COPYABLE_FIELDS);
  	}
  
  
  	/**
  	 * Action to take on each method.
  	 */
  	public interface MethodCallback {
  
  		/**
  		 * Perform an operation using the given method.
  		 * @param method the method to operate on
  		 */
  		void doWith(Method method) throws IllegalArgumentException, IllegalAccessException;
  	}
  
  
  	/**
  	 * Callback optionally used to method fields to be operated on by a method callback.
  	 */
  	public interface MethodFilter {
  
  		/**
  		 * Determine whether the given method matches.
  		 * @param method the method to check
  		 */
  		boolean matches(Method method);
  	}
  
  
  	/**
  	 * Callback interface invoked on each field in the hierarchy.
  	 */
  	public interface FieldCallback {
  
  		/**
  		 * Perform an operation using the given field.
  		 * @param field the field to operate on
  		 */
  		void doWith(Field field) throws IllegalArgumentException, IllegalAccessException;
  	}
  
  
  	/**
  	 * Callback optionally used to filter fields to be operated on by a field callback.
  	 */
  	public interface FieldFilter {
  
  		/**
  		 * Determine whether the given field matches.
  		 * @param field the field to check
  		 */
  		boolean matches(Field field);
  	}
  
  
  	/**
  	 * Pre-built FieldFilter that matches all non-static, non-final fields.
  	 */
  	public static FieldFilter COPYABLE_FIELDS = new FieldFilter() {
  
  		public boolean matches(Field field) {
  			return !(Modifier.isStatic(field.getModifiers()) || Modifier.isFinal(field.getModifiers()));
  		}
  	};
  
  
  	/**
  	 * Pre-built MethodFilter that matches all non-bridge methods.
  	 */
  	public static MethodFilter NON_BRIDGED_METHODS = new MethodFilter() {
  
  		public boolean matches(Method method) {
  			return !method.isBridge();
  		}
  	};
  
  
  	/**
  	 * Pre-built MethodFilter that matches all non-bridge methods
  	 * which are not declared on <code>java.lang.Object</code>.
  	 */
  	public static MethodFilter USER_DECLARED_METHODS = new MethodFilter() {
  
  		public boolean matches(Method method) {
  			return (!method.isBridge() && method.getDeclaringClass() != Object.class);
  		}
  	};
  
  }