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Diffstat (limited to 'libjava/classpath/java/beans/Statement.java')
| -rw-r--r-- | libjava/classpath/java/beans/Statement.java | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/libjava/classpath/java/beans/Statement.java b/libjava/classpath/java/beans/Statement.java new file mode 100644 index 00000000000..01f86dd286f --- /dev/null +++ b/libjava/classpath/java/beans/Statement.java @@ -0,0 +1,326 @@ +/* java.beans.Statement + 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 java.beans; + +import java.lang.reflect.Array; +import java.lang.reflect.Constructor; +import java.lang.reflect.Method; + +/** + * class Statement + * + * A Statement captures the execution of an object method. It stores + * the object, the method to call, and the arguments to the method and + * provides the ability to execute the method on the object, using the + * provided arguments. + * + * @since 1.4 + */ +public class Statement +{ + private Object target; + private String methodName; + private Object[] arguments; + + // One or the other of these will get a value after execute is + // called once, but not both. + private transient Method method; + private transient Constructor ctor; + + /** + * Constructs a statement representing the invocation of + * object.methodName(arg[0], arg[1], ...); + * + * @param target The object to invoke the method on. + * @param methodName The object method to invoke. + * @param arguments An array of arguments to pass to the method. + */ + public Statement(Object target, String methodName, Object[] arguments) + { + this.target = target; + this.methodName = methodName; + this.arguments = arguments; + } + + /** + * Execute the statement. + * + * Finds the specified method in the target object and calls it with + * the arguments given in the constructor. + * + * The most specific method according to the JLS(15.11) is used when + * there are multiple methods with the same name. + * + * Execute performs some special handling for methods and + * parameters: + * + * Static methods can be executed by providing the class as a + * target. + * + * The method name new is reserved to call the constructor + * new() will construct an object and return it. Not useful unless + * an expression :-) + * + * If the target is an array, get and set as defined in + * java.util.List are recognized as valid methods and mapped to the + * methods of the same name in java.lang.reflect.Array. + * + * The native datatype wrappers Boolean, Byte, Character, Double, + * Float, Integer, Long, and Short will map to methods that have + * native datatypes as parameters, in the same way as Method.invoke. + * However, these wrappers also select methods that actually take + * the wrapper type as an argument. + * + * The Sun spec doesn't deal with overloading between int and + * Integer carefully. If there are two methods, one that takes an + * Integer and the other taking an int, the method chosen is not + * specified, and can depend on the order in which the methods are + * declared in the source file. + * + * @throws Exception if an exception occurs while locating or + * invoking the method. + */ + public void execute() throws Exception + { + doExecute(); + } + + private static Class wrappers[] = + { + Boolean.class, Byte.class, Character.class, Double.class, Float.class, + Integer.class, Long.class, Short.class + }; + + private static Class natives[] = + { + Boolean.TYPE, Byte.TYPE, Character.TYPE, Double.TYPE, Float.TYPE, + Integer.TYPE, Long.TYPE, Short.TYPE + }; + + // Given a wrapper class, return the native class for it. For + // example, if c is Integer, Integer.TYPE is returned. + private Class unwrap(Class c) + { + for (int i = 0; i < wrappers.length; i++) + if (c == wrappers[i]) + return natives[i]; + return null; + } + + // Return true if all args can be assigned to params, false + // otherwise. Arrays are guaranteed to be the same length. + private boolean compatible(Class[] params, Class[] args) + { + for (int i = 0; i < params.length; i++) + { + // Treat Integer like int if appropriate + Class nativeType = unwrap(args[i]); + if (nativeType != null && params[i].isPrimitive() + && params[i].isAssignableFrom(nativeType)) + continue; + if (params[i].isAssignableFrom(args[i])) + continue; + + return false; + } + return true; + } + + /** + * Return true if the method arguments in first are more specific + * than the method arguments in second, i.e. all args in first can + * be assigned to those in second. + * + * A method is more specific if all parameters can also be fed to + * the less specific method, because, e.g. the less specific method + * accepts a base class of the equivalent argument for the more + * specific one. + * + * @param first a <code>Class[]</code> value + * @param second a <code>Class[]</code> value + * @return a <code>boolean</code> value + */ + private boolean moreSpecific(Class[] first, Class[] second) + { + for (int j=0; j < first.length; j++) + { + if (second[j].isAssignableFrom(first[j])) + continue; + return false; + } + return true; + } + + final Object doExecute() throws Exception + { + Class klazz = (target instanceof Class) + ? (Class) target : target.getClass(); + Object args[] = (arguments == null) ? new Object[0] : arguments; + Class argTypes[] = new Class[args.length]; + for (int i = 0; i < args.length; i++) + argTypes[i] = args[i].getClass(); + + if (target.getClass().isArray()) + { + // FIXME: invoke may have to be used. For now, cast to Number + // and hope for the best. If caller didn't behave, we go boom + // and throw the exception. + if (methodName.equals("get") && argTypes.length == 1) + return Array.get(target, ((Number)args[0]).intValue()); + if (methodName.equals("set") && argTypes.length == 2) + { + Object obj = Array.get(target, ((Number)args[0]).intValue()); + Array.set(target, ((Number)args[0]).intValue(), args[1]); + return obj; + } + throw new NoSuchMethodException("No matching method for statement " + toString()); + } + + // If we already cached the method, just use it. + if (method != null) + return method.invoke(target, args); + else if (ctor != null) + return ctor.newInstance(args); + + // Find a matching method to call. JDK seems to go through all + // this to find the method to call. + + // if method name or length don't match, skip + // Need to go through each arg + // If arg is wrapper - check if method arg is matchable builtin + // or same type or super + // - check that method arg is same or super + + if (methodName.equals("new") && target instanceof Class) + { + Constructor ctors[] = klazz.getConstructors(); + for (int i = 0; i < ctors.length; i++) + { + // Skip methods with wrong number of args. + Class ptypes[] = ctors[i].getParameterTypes(); + System.out.println("ptypeslen = " + ptypes.length); + System.out.println("ptypes = " + ptypes); + System.out.println("ctor = " + ctors[i].getName()); + for (int j=0; j < ptypes.length; j++) { + System.out.println("param = " + ptypes[i].getName()); + + } + + + if (ptypes.length != args.length) + continue; + + // Check if method matches + if (!compatible(ptypes, argTypes)) + continue; + + // Use method[i] if it is more specific. + // FIXME: should this check both directions and throw if + // neither is more specific? + if (ctor == null) + { + ctor = ctors[i]; + continue; + } + Class mptypes[] = ctor.getParameterTypes(); + if (moreSpecific(ptypes, mptypes)) + ctor = ctors[i]; + } + if (ctor == null) + throw new InstantiationException("No matching constructor for statement " + toString()); + return ctor.newInstance(args); + } + + Method methods[] = klazz.getMethods(); + + for (int i = 0; i < methods.length; i++) + { + // Skip methods with wrong name or number of args. + if (!methods[i].getName().equals(methodName)) + continue; + Class ptypes[] = methods[i].getParameterTypes(); + if (ptypes.length != args.length) + continue; + + // Check if method matches + if (!compatible(ptypes, argTypes)) + continue; + + // Use method[i] if it is more specific. + // FIXME: should this check both directions and throw if + // neither is more specific? + if (method == null) + { + method = methods[i]; + continue; + } + Class mptypes[] = method.getParameterTypes(); + if (moreSpecific(ptypes, mptypes)) + method = methods[i]; + } + if (method == null) + throw new NoSuchMethodException("No matching method for statement " + toString()); + return method.invoke(target, args); + } + + + + /** Return the statement arguments. */ + public Object[] getArguments() { return arguments; } + + /** Return the statement method name. */ + public String getMethodName() { return methodName; } + + /** Return the statement object. */ + public Object getTarget() { return target; } + + /** Return a string representation. */ + public String toString() + { + String result = target.getClass().getName() + "." + methodName + "("; + String sep = ""; + for (int i = 0; i < arguments.length; i++) + { + result = result + sep + arguments[i].getClass().getName(); + sep = ", "; + } + result = result + ")"; + return result; + } +} |