src/jdk.dynalink/share/classes/jdk/dynalink/internal/InternalTypeUtilities.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
 package jdk.dynalink.internal;

 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
 import jdk.dynalink.linker.support.TypeUtilities;

 /**
  * Various static utility methods for testing type relationships; internal to Dynalink.
  */
 public class InternalTypeUtilities {
     private InternalTypeUtilities() {
     }

     /**
      * Returns true if either of the types is assignable from the other.
      * @param c1 one type
      * @param c2 another type
      * @return true if either c1 is assignable from c2 or c2 is assignable from c1.
      */
     public static boolean areAssignable(final Class<?> c1, final Class<?> c2) {
         return c1.isAssignableFrom(c2) || c2.isAssignableFrom(c1);
     }

     /**
      * Return true if it is safe to strongly reference a class from the referred
      * class loader from a class associated with the referring class loader
      * without risking a class loader memory leak. Generally, it is only safe
      * to reference classes from the same or ancestor class loader. {@code null}
      * indicates the system class loader; classes from it can always be
      * directly referenced, and it can only directly reference classes from
      * itself. This method can be used by language runtimes to ensure they are
      * using weak references in their linkages when they need to link to methods
      * in unrelated class loaders.
      *
      * @param referrerLoader the referrer class loader.
      * @param referredLoader the referred class loader
      * @return true if it is safe to strongly reference the class from referred
      * in referred.
      * @throws SecurityException if the caller does not have the
      * {@code RuntimePermission("getClassLoader")} permission and the method
      * needs to traverse the parent class loader chain.
      */
     public static boolean canReferenceDirectly(final ClassLoader referrerLoader, final ClassLoader referredLoader) {
         if(referredLoader == null) {
             // Can always refer directly to a system class
             return true;
         }
         if(referrerLoader == null) {
             // System classes can't refer directly to any non-system class
             return false;
         }
         // Otherwise, can only refer directly to classes residing in same or
         // parent class loader.

         ClassLoader referrer = referrerLoader;
         do {
             if(referrer == referredLoader) {
                 return true;
             }
             referrer = referrer.getParent();
         } while(referrer != null);
         return false;
     }

     /**
      * Given two types represented by c1 and c2, returns a type that is their
      * most specific common supertype for purposes of lossless conversions.
      *
      * @param c1 one type
      * @param c2 another type
      * @return their most common superclass or superinterface for purposes of
      * lossless conversions. If they have several unrelated superinterfaces as
      * their most specific common type, or the types themselves are completely
      * unrelated interfaces, {@link java.lang.Object} is returned.
      */
     public static Class<?> getCommonLosslessConversionType(final Class<?> c1, final Class<?> c2) {
         if(c1 == c2) {
             return c1;
         } else if (c1 == void.class || c2 == void.class) {
             return Object.class;
         } else if(TypeUtilities.isConvertibleWithoutLoss(c2, c1)) {
             return c1;
         } else if(TypeUtilities.isConvertibleWithoutLoss(c1, c2)) {
             return c2;
         } else if(c1.isPrimitive() && c2.isPrimitive()) {
             if((c1 == byte.class && c2 == char.class) || (c1 == char.class && c2 == byte.class)) {
                 // byte + char = int
                 return int.class;
             } else if((c1 == short.class && c2 == char.class) || (c1 == char.class && c2 == short.class)) {
                 // short + char = int
                 return int.class;
             } else if((c1 == int.class && c2 == float.class) || (c1 == float.class && c2 == int.class)) {
                 // int + float = double
                 return double.class;
             }
         }
         // For all other cases. This will handle long + (float|double) = Number case as well as boolean + anything = Object case too.
         return getMostSpecificCommonTypeUnequalNonprimitives(c1, c2);
     }

     private static Class<?> getMostSpecificCommonTypeUnequalNonprimitives(final Class<?> c1, final Class<?> c2) {
         final Class<?> npc1 = c1.isPrimitive() ? TypeUtilities.getWrapperType(c1) : c1;
         final Class<?> npc2 = c2.isPrimitive() ? TypeUtilities.getWrapperType(c2) : c2;
         final Set<Class<?>> a1 = getAssignables(npc1, npc2);
         final Set<Class<?>> a2 = getAssignables(npc2, npc1);
         a1.retainAll(a2);
         if(a1.isEmpty()) {
             // Can happen when at least one of the arguments is an interface,
             // as they don't have Object at the root of their hierarchy.
             return Object.class;
         }
         // Gather maximally specific elements. Yes, there can be more than one
         // thank to interfaces. I.e., if you call this method for String.class
         // and Number.class, you'll have Comparable, Serializable, and Object
         // as maximal elements.
         final List<Class<?>> max = new ArrayList<>();
         outer: for(final Class<?> clazz: a1) {
             for(final Iterator<Class<?>> maxiter = max.iterator(); maxiter.hasNext();) {
                 final Class<?> maxClazz = maxiter.next();
                 if(TypeUtilities.isSubtype(maxClazz, clazz)) {
                     // It can't be maximal, if there's already a more specific
                     // maximal than it.
                     continue outer;
                 }
                 if(TypeUtilities.isSubtype(clazz, maxClazz)) {
                     // If it's more specific than a currently maximal element,
                     // that currently maximal is no longer a maximal.
                     maxiter.remove();
                 }
             }
             // If we get here, no current maximal is more specific than the
             // current class, so it is considered maximal as well
             max.add(clazz);
         }
         if(max.size() > 1) {
             return Object.class;
         }
         return max.get(0);
     }

     private static Set<Class<?>> getAssignables(final Class<?> c1, final Class<?> c2) {
         final Set<Class<?>> s = new HashSet<>();
         collectAssignables(c1, c2, s);
         return s;
     }

     private static void collectAssignables(final Class<?> c1, final Class<?> c2, final Set<Class<?>> s) {
         if(c1.isAssignableFrom(c2)) {
             s.add(c1);
         }
         final Class<?> sc = c1.getSuperclass();
         if(sc != null) {
             collectAssignables(sc, c2, s);
         }
         final Class<?>[] itf = c1.getInterfaces();
         for(int i = 0; i < itf.length; ++i) {
             collectAssignables(itf[i], c2, s);
         }
     }
 }
	/*
	* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package jdk.dynalink.internal;

	import java.util.ArrayList;
	import java.util.HashSet;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Set;
	import jdk.dynalink.linker.support.TypeUtilities;

	/**
	* Various static utility methods for testing type relationships; internal to Dynalink.
	*/
	public class InternalTypeUtilities {
	private InternalTypeUtilities() {
	}

	/**
	* Returns true if either of the types is assignable from the other.
	* @param c1 one type
	* @param c2 another type
	* @return true if either c1 is assignable from c2 or c2 is assignable from c1.
	*/
	public static boolean areAssignable(final Class<?> c1, final Class<?> c2) {
	return c1.isAssignableFrom(c2) \|\| c2.isAssignableFrom(c1);
	}

	/**
	* Return true if it is safe to strongly reference a class from the referred
	* class loader from a class associated with the referring class loader
	* without risking a class loader memory leak. Generally, it is only safe
	* to reference classes from the same or ancestor class loader. {@code null}
	* indicates the system class loader; classes from it can always be
	* directly referenced, and it can only directly reference classes from
	* itself. This method can be used by language runtimes to ensure they are
	* using weak references in their linkages when they need to link to methods
	* in unrelated class loaders.
	*
	* @param referrerLoader the referrer class loader.
	* @param referredLoader the referred class loader
	* @return true if it is safe to strongly reference the class from referred
	* in referred.
	* @throws SecurityException if the caller does not have the
	* {@code RuntimePermission("getClassLoader")} permission and the method
	* needs to traverse the parent class loader chain.
	*/
	public static boolean canReferenceDirectly(final ClassLoader referrerLoader, final ClassLoader referredLoader) {
	if(referredLoader == null) {
	// Can always refer directly to a system class
	return true;
	}
	if(referrerLoader == null) {
	// System classes can't refer directly to any non-system class
	return false;
	}
	// Otherwise, can only refer directly to classes residing in same or
	// parent class loader.

	ClassLoader referrer = referrerLoader;
	do {
	if(referrer == referredLoader) {
	return true;
	}
	referrer = referrer.getParent();
	} while(referrer != null);
	return false;
	}

	/**
	* Given two types represented by c1 and c2, returns a type that is their
	* most specific common supertype for purposes of lossless conversions.
	*
	* @param c1 one type
	* @param c2 another type
	* @return their most common superclass or superinterface for purposes of
	* lossless conversions. If they have several unrelated superinterfaces as
	* their most specific common type, or the types themselves are completely
	* unrelated interfaces, {@link java.lang.Object} is returned.
	*/
	public static Class<?> getCommonLosslessConversionType(final Class<?> c1, final Class<?> c2) {
	if(c1 == c2) {
	return c1;
	} else if (c1 == void.class \|\| c2 == void.class) {
	return Object.class;
	} else if(TypeUtilities.isConvertibleWithoutLoss(c2, c1)) {
	return c1;
	} else if(TypeUtilities.isConvertibleWithoutLoss(c1, c2)) {
	return c2;
	} else if(c1.isPrimitive() && c2.isPrimitive()) {
	if((c1 == byte.class && c2 == char.class) \|\| (c1 == char.class && c2 == byte.class)) {
	// byte + char = int
	return int.class;
	} else if((c1 == short.class && c2 == char.class) \|\| (c1 == char.class && c2 == short.class)) {
	// short + char = int
	return int.class;
	} else if((c1 == int.class && c2 == float.class) \|\| (c1 == float.class && c2 == int.class)) {
	// int + float = double
	return double.class;
	}
	}
	// For all other cases. This will handle long + (float\|double) = Number case as well as boolean + anything = Object case too.
	return getMostSpecificCommonTypeUnequalNonprimitives(c1, c2);
	}

	private static Class<?> getMostSpecificCommonTypeUnequalNonprimitives(final Class<?> c1, final Class<?> c2) {
	final Class<?> npc1 = c1.isPrimitive() ? TypeUtilities.getWrapperType(c1) : c1;
	final Class<?> npc2 = c2.isPrimitive() ? TypeUtilities.getWrapperType(c2) : c2;
	final Set<Class<?>> a1 = getAssignables(npc1, npc2);
	final Set<Class<?>> a2 = getAssignables(npc2, npc1);
	a1.retainAll(a2);
	if(a1.isEmpty()) {
	// Can happen when at least one of the arguments is an interface,
	// as they don't have Object at the root of their hierarchy.
	return Object.class;
	}
	// Gather maximally specific elements. Yes, there can be more than one
	// thank to interfaces. I.e., if you call this method for String.class
	// and Number.class, you'll have Comparable, Serializable, and Object
	// as maximal elements.
	final List<Class<?>> max = new ArrayList<>();
	outer: for(final Class<?> clazz: a1) {
	for(final Iterator<Class<?>> maxiter = max.iterator(); maxiter.hasNext();) {
	final Class<?> maxClazz = maxiter.next();
	if(TypeUtilities.isSubtype(maxClazz, clazz)) {
	// It can't be maximal, if there's already a more specific
	// maximal than it.
	continue outer;
	}
	if(TypeUtilities.isSubtype(clazz, maxClazz)) {
	// If it's more specific than a currently maximal element,
	// that currently maximal is no longer a maximal.
	maxiter.remove();
	}
	}
	// If we get here, no current maximal is more specific than the
	// current class, so it is considered maximal as well
	max.add(clazz);
	}
	if(max.size() > 1) {
	return Object.class;
	}
	return max.get(0);
	}

	private static Set<Class<?>> getAssignables(final Class<?> c1, final Class<?> c2) {
	final Set<Class<?>> s = new HashSet<>();
	collectAssignables(c1, c2, s);
	return s;
	}

	private static void collectAssignables(final Class<?> c1, final Class<?> c2, final Set<Class<?>> s) {
	if(c1.isAssignableFrom(c2)) {
	s.add(c1);
	}
	final Class<?> sc = c1.getSuperclass();
	if(sc != null) {
	collectAssignables(sc, c2, s);
	}
	final Class<?>[] itf = c1.getInterfaces();
	for(int i = 0; i < itf.length; ++i) {
	collectAssignables(itf[i], c2, s);
	}
	}
	}