Initial revision

From-SVN: r102074

libjava/classpath/gnu/java/beans/decoder/MethodFinder.java

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+/* gnu.java.beans.decoder.MethodFinder
+   Copyright (C) 2004 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+ 
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package gnu.java.beans.decoder;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
+import java.util.HashMap;
+
+class MethodFinder
+{
+	/** Provides a mapping between a wrapper class and its corresponding primitive's type. */
+	private static HashMap typeMapping = new HashMap();
+
+	static {
+		typeMapping.put(Byte.class, Byte.TYPE);
+		typeMapping.put(Short.class, Short.TYPE);
+		typeMapping.put(Integer.class, Integer.TYPE);
+		typeMapping.put(Long.class, Long.TYPE);
+		typeMapping.put(Float.class, Float.TYPE);
+		typeMapping.put(Double.class, Double.TYPE);
+
+		typeMapping.put(Character.class, Character.TYPE);
+		typeMapping.put(Boolean.class, Boolean.TYPE);
+	}
+
+	private MethodFinder()
+	{
+	}
+
+	/** Searches a Method which can accept the given arguments.
+	 *
+	 * @param klass
+	 * @param name
+	 * @param arguments
+	 * @return
+	 * @throws NoSuchMethodException
+	 */
+	static Method getMethod(Class klass, String name, Object[] arguments)
+		throws NoSuchMethodException
+	{
+		// prepares array containing the types of the arguments
+		Class[] argumentTypes = getArgumentTypes(arguments);
+
+		Method[] methods = klass.getMethods();
+
+		// iterates over all public methods
+		for (int i = 0; i < methods.length; i++)
+		{
+			if (methods[i].getName().equals(name))
+			{
+				if (matchingArgumentTypes(methods[i].getParameterTypes(),
+					argumentTypes))
+					return methods[i];
+			}
+		}
+
+		throw new NoSuchMethodException(
+			"Could not find a matching method named "
+				+ name
+				+ "() in class "
+				+ klass);
+	}
+
+	static Constructor getConstructor(Class klass, Object[] arguments)
+		throws NoSuchMethodException
+	{
+		Class[] argumentTypes = getArgumentTypes(arguments);
+		Constructor[] constructors = klass.getConstructors();
+
+		// iterates over all public methods
+		for (int i = 0; i < constructors.length; i++)
+		{
+			if (matchingArgumentTypes(constructors[i].getParameterTypes(),
+				argumentTypes))
+				return constructors[i];
+		}
+
+		throw new NoSuchMethodException(
+			"Could not find a matching constructor in class " + klass);
+	}
+
+	/** Transforms an array of argument objects into an array of argument types.
+	 * For each argument being null the argument is null, too. An argument type
+	 * being null means: Accepts everything (although this can be ambigous).
+	 * 
+	 * @param arguments
+	 * @return
+	 */
+	private static Class[] getArgumentTypes(Object[] arguments)
+	{
+		if (arguments == null)
+			return new Class[0];
+
+		// prepares array containing the types of the arguments
+		Class[] argumentTypes = new Class[arguments.length];
+		for (int i = 0; i < arguments.length; i++)
+			argumentTypes[i] =
+				(arguments[i] == null) ? null : arguments[i].getClass();
+		return argumentTypes;
+	}
+
+	/** Tests whether the argument types supplied to the method argument types
+	 * are assignable. In addition to the assignment specifications this method
+	 * handles the primitive's wrapper classes as if they were of their
+	 * primitive type (e.g Boolean.class equals Boolean.TYPE).
+	 * When a supplied argument type is null it is assumed that no argument
+	 * object was supplied for it and the test for this particular parameter will
+	 * pass.
+	 *
+	 * @param methodArgTypes
+	 * @param suppliedArgTypes
+	 * @return
+	 */
+	private static boolean matchingArgumentTypes(
+		Class[] methodArgTypes,
+		Class[] suppliedArgTypes)
+	{
+		if (methodArgTypes.length != suppliedArgTypes.length)
+			return false;
+
+		for (int i = 0; i < methodArgTypes.length; i++)
+		{
+			if (suppliedArgTypes[i] == null)
+			{
+				// by definition a non-existant argument type (null) can be converted to everything
+				continue;
+			}
+			else if (typeMapping.containsKey(suppliedArgTypes[i]))
+			{
+				Class primitiveType =
+					(Class) typeMapping.get(suppliedArgTypes[i]);
+				if (!(methodArgTypes[i].isAssignableFrom(suppliedArgTypes[i])
+					|| methodArgTypes[i].isAssignableFrom(primitiveType)))
+					return false;
+			}
+			else if (!methodArgTypes[i].isAssignableFrom(suppliedArgTypes[i]))
+				return false;
+		}
+
+		return true;
+	}
+}