Support of varargs, an example

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Support of varargs, an example

Pascal Meheut
I do not know if someone has already done some work on it but I needed
it so I coded it. I did not did a lot of testing but it seems to work
fine with obvious cases like printf and even pure varargs methods like
foo(...)

The modifications are minor and only in Reflect.java (see attachment).
To still compile with any Jdk, I guess that the calls to
method.isVarArgs() would have to be replaced by some
MethodUtils.isVarArgs(Method method) calling isVarArgs by reflection...
Anyway, this is just a prototype.



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package bsh;

import java.lang.reflect.*;
import java.util.Vector;

/**
 * All of the reflection API code lies here.  It is in the form of static
 * utilities.  Maybe this belongs in LHS.java or a generic object
 * wrapper class.
 *
 * @author Pat Niemeyer
 * @author Daniel Leuck
 */
/*
        Note: This class is messy.  The method and field resolution need to be
        rewritten.  Various methods in here catch NoSuchMethod or NoSuchField
        exceptions during their searches.  These should be rewritten to avoid
        having to catch the exceptions.  Method lookups are now cached at a high
        level so they are less important, however the logic is messy.
*/
class Reflect
{
    /**
                Invoke method on arbitrary object instance.
                invocation may be static (through the object instance) or dynamic.
                Object may be a bsh scripted object (bsh.This type).
          @return the result of the method call
        */
    public static Object invokeObjectMethod(
                Object object, String methodName, Object[] args,
                Interpreter interpreter, CallStack callstack, SimpleNode callerInfo )
                throws ReflectError, EvalError, InvocationTargetException
        {
                // Bsh scripted object
                if ( object instanceof This && !This.isExposedThisMethod(methodName) )
                        return ((This)object).invokeMethod(
                                methodName, args, interpreter, callstack, callerInfo,
                                false/*delcaredOnly*/
                        );

                // Plain Java object, find the java method
                try {
                        BshClassManager bcm =
                                interpreter == null ? null : interpreter.getClassManager();
                        Class clas = object.getClass();

                        Method method = resolveExpectedJavaMethod(
                                bcm, clas, object, methodName, args, false );

                        return invokeMethod( method, object, args );
                } catch ( UtilEvalError e ) {
                        throw e.toEvalError( callerInfo, callstack );
                }
    }

    /**
                Invoke a method known to be static.
                No object instance is needed and there is no possibility of the
                method being a bsh scripted method.
        */
    public static Object invokeStaticMethod(
                BshClassManager bcm, Class clas, String methodName, Object [] args )
        throws ReflectError, UtilEvalError, InvocationTargetException
    {
        Interpreter.debug("invoke static Method");
        Method method = resolveExpectedJavaMethod(
                        bcm, clas, null, methodName, args, true );
                return invokeMethod( method, null, args );
    }

        /**
                Invoke the Java method on the specified object, performing needed
          type mappings on arguments and return values.
                @param args may be null
        */
        static Object invokeMethod(
                Method method, Object object, Object[] args )
                throws ReflectError, InvocationTargetException
        {
      if(method.isVarArgs())
      {
        return invokeVarArgsMethod(method, object, args);
      }
      else
      {
        return invokeNormalMethod(method, object, args);
      }
    }
   
    static Object invokeNormalMethod(
        Method method, Object object, Object[] args )
        throws ReflectError, InvocationTargetException
    {
                if ( args == null )
                        args = new Object[0];

                logInvokeMethod( "Invoking method (entry): ", method, args );

                // Map types to assignable forms, need to keep this fast...
                Object [] tmpArgs = new Object [ args.length ];
                Class [] types = method.getParameterTypes();
                try {
                        for (int i=0; i<args.length; i++)
                                tmpArgs[i] = Types.castObject(
                                        args[i]/*rhs*/, types[i]/*lhsType*/, Types.ASSIGNMENT );
                } catch ( UtilEvalError e ) {
                        throw new InterpreterError(
                                "illegal argument type in method invocation: "+e );
                }

                // unwrap any primitives
                tmpArgs = Primitive.unwrap( tmpArgs );

                logInvokeMethod( "Invoking method (after massaging values): ",
                        method, tmpArgs );

                try {
                        Object returnValue = method.invoke( object, tmpArgs );
                        if ( returnValue == null )
                                returnValue = Primitive.NULL;
                        Class returnType = method.getReturnType();

                        return Primitive.wrap( returnValue, returnType );
                } catch( IllegalAccessException e ) {
                        throw new ReflectError( "Cannot access method "
                                + StringUtil.methodString(
                                        method.getName(), method.getParameterTypes() )
                                + " in '" + method.getDeclaringClass() + "' :" + e );
                }
        }
   
    static Object invokeVarArgsMethod(
        Method method, Object object, Object[] args )
        throws ReflectError, InvocationTargetException
    {
        if ( args == null )
            args = new Object[0];

        logInvokeMethod( "Invoking method (entry): ", method, args );

        // Map types to assignable forms, need to keep this fast...
        Class [] types = method.getParameterTypes();
        Object [] tmpArgs = new Object [ types.length ];
        try {
            for (int i=0; i<types.length-1; i++)
                tmpArgs[i] = Types.castObject(
                    args[i]/*rhs*/, types[i]/*lhsType*/, Types.ASSIGNMENT );
        } catch ( UtilEvalError e ) {
            throw new InterpreterError(
                "illegal argument type in method invocation: "+e );
        }

        Object[] varArgs=new Object[ args.length - types.length+1 ];
        try {
          for (int i=types.length-1, j=0; i<args.length; i++, j++)
            varArgs[j] = Types.castObject(
                  args[i]/*rhs*/, Object.class /*lhsType*/, Types.ASSIGNMENT );
      } catch ( UtilEvalError e ) {
          throw new InterpreterError(
              "illegal argument type in method invocation: "+e );
      }
      varArgs = Primitive.unwrap( varArgs );
      tmpArgs[types.length-1]=varArgs;
     
        // unwrap any primitives
        tmpArgs = Primitive.unwrap( tmpArgs );

        logInvokeMethod( "Invoking method (after massaging values): ",
            method, tmpArgs );

        try {
            Object returnValue = method.invoke( object, tmpArgs );
            if ( returnValue == null )
                returnValue = Primitive.NULL;
            Class returnType = method.getReturnType();

            return Primitive.wrap( returnValue, returnType );
        } catch( IllegalAccessException e ) {
            throw new ReflectError( "Cannot access method "
                + StringUtil.methodString(
                    method.getName(), method.getParameterTypes() )
                + " in '" + method.getDeclaringClass() + "' :" + e );
        }
    }


        public static Object getIndex(Object array, int index)
        throws ReflectError, UtilTargetError
    {
                if ( Interpreter.DEBUG )
                        Interpreter.debug("getIndex: "+array+", index="+index);
        try {
            Object val = Array.get(array, index);
            return Primitive.wrap( val, array.getClass().getComponentType() );
        }
        catch( ArrayIndexOutOfBoundsException  e1 ) {
                        throw new UtilTargetError( e1 );
        } catch(Exception e) {
            throw new ReflectError("Array access:" + e);
        }
    }

    public static void setIndex(Object array, int index, Object val)
        throws ReflectError, UtilTargetError
    {
        try {
            val = Primitive.unwrap(val);
            Array.set(array, index, val);
        }
        catch( ArrayStoreException e2 ) {
                        throw new UtilTargetError( e2 );
        } catch( IllegalArgumentException e1 ) {
                        throw new UtilTargetError(
                                new ArrayStoreException( e1.toString() ) );
        } catch(Exception e) {
            throw new ReflectError("Array access:" + e);
        }
    }

    public static Object getStaticFieldValue(Class clas, String fieldName)
        throws UtilEvalError, ReflectError
    {
        return getFieldValue( clas, null, fieldName, true/*onlystatic*/);
    }

        /**
         * Check for a field with the given name in a java object or scripted object
         * if the field exists fetch the value, if not check for a property value.
         * If neither is found return Primitive.VOID.
         */
    public static Object getObjectFieldValue( Object object, String fieldName )
        throws UtilEvalError, ReflectError
    {
                if ( object instanceof This ) {
                        This t = (This)object;
                        return t.namespace.getVariableOrProperty(fieldName, null);
                } else {
                        try {
                                return getFieldValue(
                                        object.getClass(), object, fieldName, false/*onlystatic*/);
                        } catch ( ReflectError e ) {
                                // no field, try property acces

                                if ( hasObjectPropertyGetter( object.getClass(), fieldName ) )
                                        return getObjectProperty( object, fieldName );
                                else
                                        throw e;
                        }
                }
    }

        static LHS getLHSStaticField(Class clas, String fieldName)
        throws UtilEvalError, ReflectError
    {
        Field f = resolveExpectedJavaField(
                        clas, fieldName, true/*onlystatic*/);
        return new LHS(f);
    }

        /**
                Get an LHS reference to an object field.

                This method also deals with the field style property access.
                In the field does not exist we check for a property setter.
        */
    static LHS getLHSObjectField( Object object, String fieldName )
        throws UtilEvalError, ReflectError
    {
                if ( object instanceof This )
                {
                        // I guess this is when we pass it as an argument?
                        // Setting locally
                        boolean recurse = false;
                        return new LHS( ((This)object).namespace, fieldName, recurse );
                }

                try {
                        Field f = resolveExpectedJavaField(
                                object.getClass(), fieldName, false/*staticOnly*/ );
                        return new LHS(object, f);
                } catch ( ReflectError e )
                {
                        // not a field, try property access
                        if ( hasObjectPropertySetter( object.getClass(), fieldName ) )
                                return new LHS( object, fieldName );
                        else
                                throw e;
                }
    }

    private static Object getFieldValue(
                Class clas, Object object, String fieldName, boolean staticOnly )
                throws UtilEvalError, ReflectError
    {
        try {
            Field f = resolveExpectedJavaField( clas, fieldName, staticOnly );

            Object value = f.get(object);
            Class returnType = f.getType();
            return Primitive.wrap( value, returnType );

        } catch( NullPointerException e ) { // shouldn't happen
            throw new ReflectError(
                                "???" + fieldName + " is not a static field.");
        } catch(IllegalAccessException e) {
            throw new ReflectError("Can't access field: " + fieldName);
        }
    }

        /*
                Note: this method and resolveExpectedJavaField should be rewritten
                to invert this logic so that no exceptions need to be caught
                unecessarily.  This is just a temporary impl.
                @return the field or null if not found
        */
    protected static Field resolveJavaField(
                Class clas, String fieldName, boolean staticOnly )
        throws UtilEvalError
    {
                try {
                        return resolveExpectedJavaField( clas, fieldName, staticOnly );
                } catch ( ReflectError e ) {
                        return null;
                }
        }

        /**
                @throws ReflectError if the field is not found.
        */
        /*
                Note: this should really just throw NoSuchFieldException... need
                to change related signatures and code.
        */
    protected static Field resolveExpectedJavaField(
                Class clas, String fieldName, boolean staticOnly
        )
        throws UtilEvalError, ReflectError
    {
                Field field;
        try {
                        if ( Capabilities.haveAccessibility() )
                                field = findAccessibleField( clas, fieldName );
                        else
                                // Class getField() finds only public (and in interfaces, etc.)
                                field = clas.getField(fieldName);
        }
        catch( NoSuchFieldException e) {
            throw new ReflectError("No such field: " + fieldName );
                } catch ( SecurityException e ) {
                        throw new UtilTargetError(
                        "Security Exception while searching fields of: "+clas,
                        e );
                }

                if ( staticOnly && !Modifier.isStatic( field.getModifiers() ) )
                        throw new UtilEvalError(
                                "Can't reach instance field: "+fieldName
                                +" from static context: "+clas.getName() );

                return field;
    }

        /**
                Used when accessibility capability is available to locate an occurrance
                of the field in the most derived class or superclass and set its
                accessibility flag.
                Note that this method is not needed in the simple non accessible
                case because we don't have to hunt for fields.
                Note that classes may declare overlapping private fields, so the
                distinction about the most derived is important.  Java doesn't normally
                allow this kind of access (super won't show private variables) so
                there is no real syntax for specifying which class scope to use...

                @return the Field or throws NoSuchFieldException
                @throws NoSuchFieldException if the field is not found
        */
        /*
                This method should be rewritten to use getFields() and avoid catching
                exceptions during the search.
        */
        private static Field findAccessibleField( Class clas, String fieldName )
                throws UtilEvalError, NoSuchFieldException
        {
                Field field;

                // Quick check catches public fields include those in interfaces
                try {
                        field = clas.getField(fieldName);
                        ReflectManager.RMSetAccessible( field );
                        return field;
                } catch ( NoSuchFieldException e ) { }

                // Now, on with the hunt...
                while ( clas != null )
                {
                        try {
                                field = clas.getDeclaredField(fieldName);
                                ReflectManager.RMSetAccessible( field );
                                return field;

                                // Not found, fall through to next class

                        } catch(NoSuchFieldException e) { }

                        clas = clas.getSuperclass();
                }
                throw new NoSuchFieldException( fieldName );
        }

        /**
                This method wraps resolveJavaMethod() and expects a non-null method
          result. If the method is not found it throws a descriptive ReflectError.
        */
    protected static Method resolveExpectedJavaMethod(
                BshClassManager bcm, Class clas, Object object,
                String name, Object[] args, boolean staticOnly )
        throws ReflectError, UtilEvalError
    {
                if ( object == Primitive.NULL )
                        throw new UtilTargetError( new NullPointerException(
                                "Attempt to invoke method " +name+" on null value" ) );

                Class [] types = Types.getTypes(args);
                Method method = resolveJavaMethod( bcm, clas, name, types, staticOnly );

                if ( method == null )
                        throw new ReflectError(
                                ( staticOnly ? "Static method " : "Method " )
                                + StringUtil.methodString(name, types) +
                                " not found in class'" + clas.getName() + "'");

                return method;
        }

    /**
        The full blown resolver method.  All other method invocation methods
                delegate to this.  The method may be static or dynamic unless
                staticOnly is set (in which case object may be null).
                If staticOnly is set then only static methods will be located.
                <p/>

                This method performs caching (caches discovered methods through the
          class manager and utilizes cached methods.)
          <p/>

          This method determines whether to attempt to use non-public methods
          based on Capabilities.haveAccessibility() and will set the accessibilty
          flag on the method as necessary.
          <p/>

                If, when directed to find a static method, this method locates a more
                specific matching instance method it will throw a descriptive exception
                analogous to the error that the Java compiler would produce.
                Note: as of 2.0.x this is a problem because there is no way to work
                around this with a cast.
                <p/>

                @param staticOnly
                        The method located must be static, the object param may be null.
                @return the method or null if no matching method was found.
        */
    protected static Method resolveJavaMethod(
                BshClassManager bcm, Class clas, String name,
                Class [] types, boolean staticOnly )
                throws UtilEvalError
    {
                if ( clas == null )
                        throw new InterpreterError("null class");

                // Lookup previously cached method
                Method method = null;
                if ( bcm == null )
                        Interpreter.debug("resolveJavaMethod UNOPTIMIZED lookup");
                else
                        method = bcm.getResolvedMethod( clas, name, types, staticOnly );

                if ( method == null )
                {
                        boolean publicOnly = !Capabilities.haveAccessibility();
                        // Searching for the method may, itself be a priviledged action
                        try {
                                method = findOverloadedMethod( clas, name, types, publicOnly );
                        } catch ( SecurityException e ) {
                                throw new UtilTargetError(
                                "Security Exception while searching methods of: "+clas,
                                e );
                        }

                        checkFoundStaticMethod( method, staticOnly, clas );

                        // This is the first time we've seen this method, set accessibility
                        // Note: even if it's a public method, we may have found it in a
                        // non-public class
                        if ( method != null && !publicOnly ) {
                                try {
                                        ReflectManager.RMSetAccessible( method );
                                } catch ( UtilEvalError e ) { /*ignore*/ }
                        }

                        // If succeeded cache the resolved method.
                        if ( method != null && bcm != null )
                                bcm.cacheResolvedMethod( clas, types, method );
                }

                return method;
        }

        /**
                Get the candidate methods by searching the class and interface graph
          of baseClass and resolve the most specific.
          @return the method or null for not found
         */
        private static Method findOverloadedMethod(
                Class baseClass, String methodName, Class[] types, boolean publicOnly )
        {
                if ( Interpreter.DEBUG )
                        Interpreter.debug( "Searching for method: "+
                                StringUtil.methodString(methodName, types)
                                + " in '" + baseClass.getName() + "'" );

                Method [] methods = getCandidateMethods(
                        baseClass, methodName, types.length, publicOnly );

                if ( Interpreter.DEBUG )
                        Interpreter.debug("Looking for most specific method: "+methodName);
                Method method = findMostSpecificMethod( types, methods );

                return method;
        }

        /**
                Climb the class and interface inheritence graph of the type and collect
                all methods matching the specified name and criterion.  If publicOnly
                is true then only public methods in *public* classes or interfaces will
                be returned.  In the normal (non-accessible) case this addresses the
                problem that arises when a package private class or private inner class
                implements a public interface or derives from a public type.
          <p/>

          This method primarily just delegates to gatherMethodsRecursive()
          @see #gatherMethodsRecursive(
                        Class, String, int, boolean, java.util.Vector)
        */
        static Method[] getCandidateMethods(
                Class baseClass, String methodName, int numArgs,
                boolean publicOnly )
        {
                Vector  candidates = gatherMethodsRecursive(
                        baseClass, methodName, numArgs, publicOnly, null/*candidates*/);

                // return the methods in an array
                Method [] ma = new Method[ candidates.size() ];
                candidates.copyInto( ma );
                return ma;
        }

        /**
                Accumulate all methods, optionally including non-public methods,
          class and interface, in the inheritence tree of baseClass.

                This method is analogous to Class getMethods() which returns all public
                methods in the inheritence tree.

                In the normal (non-accessible) case this also addresses the problem
                that arises when a package private class or private inner class
                implements a public interface or derives from a public type.  In other
                words, sometimes we'll find public methods that we can't use directly
                and we have to find the same public method in a parent class or
                interface.

                @return the candidate methods vector
        */
        private static Vector gatherMethodsRecursive(
                Class baseClass, String methodName, int numArgs,
                boolean publicOnly, Vector candidates )
        {
                if ( candidates == null )
                        candidates = new Vector();

                // Add methods of the current class to the vector.
                // In public case be careful to only add methods from a public class
                // and to use getMethods() instead of getDeclaredMethods()
                // (This addresses secure environments)
                if ( publicOnly ) {
                        if ( isPublic(baseClass) )
                                addCandidates( baseClass.getMethods(),
                                        methodName, numArgs, publicOnly, candidates );
                } else
                        addCandidates( baseClass.getDeclaredMethods(),
                                methodName, numArgs, publicOnly, candidates );

                // Does the class or interface implement interfaces?
                Class [] intfs = baseClass.getInterfaces();
                for( int i=0; i< intfs.length; i++ )
                        gatherMethodsRecursive(  intfs[i],
                                methodName, numArgs, publicOnly, candidates );

                // Do we have a superclass? (interfaces don't, etc.)
                Class superclass = baseClass.getSuperclass();
                if ( superclass != null )
                        gatherMethodsRecursive( superclass,
                                methodName, numArgs, publicOnly, candidates );

                return candidates;
        }

        private static Vector addCandidates(
                Method [] methods, String methodName,
                int numArgs, boolean publicOnly, Vector candidates  )
        {
                for ( int i = 0; i < methods.length; i++ )
                {
                        Method m = methods[i];
                        if (  m.getName().equals( methodName ))
            {
                                if(( m.getParameterTypes().length == numArgs
                    || (m.isVarArgs() && m.getParameterTypes().length-1 <= numArgs))
                                && ( !publicOnly || isPublic( m ) ))
                {
                    candidates.add( m );
                }
               
            }

                }
                return candidates;
        }

        /**
                Primary object constructor
                This method is simpler than those that must resolve general method
                invocation because constructors are not inherited.
         <p/>
         This method determines whether to attempt to use non-public constructors
         based on Capabilities.haveAccessibility() and will set the accessibilty
         flag on the method as necessary.
         <p/>
        */
    static Object constructObject( Class clas, Object[] args )
        throws ReflectError, InvocationTargetException
    {
                if ( clas.isInterface() )
                        throw new ReflectError(
                                "Can't create instance of an interface: "+clas);

        Object obj = null;
        Class[] types = Types.getTypes(args);
        Constructor con = null;

                // Find the constructor.
                // (there are no inherited constructors to worry about)
                Constructor[] constructors =
                        Capabilities.haveAccessibility() ?
                                clas.getDeclaredConstructors() : clas.getConstructors() ;

                if ( Interpreter.DEBUG )
                        Interpreter.debug("Looking for most specific constructor: "+clas);
                con = findMostSpecificConstructor(types, constructors);
                if ( con == null )
                        throw cantFindConstructor( clas, types );

                if ( !isPublic( con ) )
                        try {
                                ReflectManager.RMSetAccessible( con );
                        } catch ( UtilEvalError e ) { /*ignore*/ }

        args=Primitive.unwrap( args );
        try {
            obj = con.newInstance( args );
        } catch(InstantiationException e) {
            throw new ReflectError("The class "+clas+" is abstract ");
        } catch(IllegalAccessException e) {
            throw new ReflectError(
                                "We don't have permission to create an instance."
                                +"Use setAccessibility(true) to enable access." );
        } catch(IllegalArgumentException e) {
            throw new ReflectError("The number of arguments was wrong");
        }
                if (obj == null)
            throw new ReflectError("Couldn't construct the object");

        return obj;
    }

    /*
        This method should parallel findMostSpecificMethod()
                The only reason it can't be combined is that Method and Constructor
                don't have a common interface for their signatures
    */
    static Constructor findMostSpecificConstructor(
                Class[] idealMatch, Constructor[] constructors)
    {
                int match = findMostSpecificConstructorIndex(idealMatch, constructors );
                return ( match == -1 ) ? null : constructors[ match ];
    }

    static int findMostSpecificConstructorIndex(
                Class[] idealMatch, Constructor[] constructors)
    {
                Class [][] candidates = new Class [ constructors.length ] [];
                for(int i=0; i< candidates.length; i++ )
                        candidates[i] = constructors[i].getParameterTypes();

                return findMostSpecificSignature( idealMatch, candidates );
    }

        /**
                Find the best match for signature idealMatch.
                It is assumed that the methods array holds only valid candidates
                (e.g. method name and number of args already matched).
                This method currently does not take into account Java 5 covariant
                return types... which I think will require that we find the most
                derived return type of otherwise identical best matches.

          @see #findMostSpecificSignature(Class[], Class[][])
                @param methods the set of candidate method which differ only in the
          types of their arguments.
        */
        static Method findMostSpecificMethod(
                Class[] idealMatch, Method[] methods )
        {
                // copy signatures into array for findMostSpecificMethod()
                Class [][] candidateSigs = new Class [ methods.length ][];
                for(int i=0; i<methods.length; i++)
        {
          if(methods[i].isVarArgs())
          {
            candidateSigs[i]=new Class[idealMatch.length];
            Class[] varargsTypes=methods[i].getParameterTypes();
            for(int j=0; j<varargsTypes.length-1; j++)
            {
              candidateSigs[i][j]=varargsTypes[j];
            }
            for(int j=varargsTypes.length; j<idealMatch.length; j++)
            {
              candidateSigs[i][j]=Object.class;
            }
          }
          else
          {
                        candidateSigs[i] = methods[i].getParameterTypes();
          }
        }

                int match = findMostSpecificSignature( idealMatch, candidateSigs );
                return match == -1 ? null : methods[match];
        }

        /**
        Implement JLS 15.11.2
                Return the index of the most specific arguments match or -1 if no
                match is found.
                This method is used by both methods and constructors (which
          unfortunately don't share a common interface for signature info).

         @return the index of the most specific candidate

         */
        /*
         Note: Two methods which are equally specific should not be allowed by
         the Java compiler.  In this case BeanShell currently chooses the first
         one it finds.  We could add a test for this case here (I believe) by
         adding another isSignatureAssignable() in the other direction between
         the target and "best" match.  If the assignment works both ways then
         neither is more specific and they are ambiguous.  I'll leave this test
         out for now because I'm not sure how much another test would impact
         performance.  Method selection is now cached at a high level, so a few
         friendly extraneous tests shouldn't be a problem.
        */
        static int findMostSpecificSignature(
                Class [] idealMatch, Class [][] candidates )
        {
                for ( int round = Types.FIRST_ROUND_ASSIGNABLE;
                          round <= Types.LAST_ROUND_ASSIGNABLE; round++ )
                {
                        Class [] bestMatch = null;
                        int bestMatchIndex = -1;

                        for (int i=0; i < candidates.length; i++)
                        {
                                Class[] targetMatch = candidates[i];

                                // If idealMatch fits targetMatch and this is the first match
                                // or targetMatch is more specific than the best match, make it
                                // the new best match.
                                if ( Types.isSignatureAssignable(
                                                idealMatch, targetMatch, round )
                                        && ( (bestMatch == null) ||
                                                Types.isSignatureAssignable( targetMatch, bestMatch,
                                                        Types.JAVA_BASE_ASSIGNABLE )
                                                )
                                )
                                {
                                        bestMatch = targetMatch;
                                        bestMatchIndex = i;
                                }
                        }

                        if ( bestMatch != null )
                                return bestMatchIndex;
                }

                return -1;
        }

        static String accessorName( String getorset, String propName ) {
        return getorset
                        + String.valueOf(Character.toUpperCase(propName.charAt(0)))
                        + propName.substring(1);
        }

    public static boolean hasObjectPropertyGetter(
                Class clas, String propName )
        {
                String getterName = accessorName("get", propName );
                try {
                        clas.getMethod( getterName, new Class [0] );
                        return true;
                } catch ( NoSuchMethodException e ) { /* fall through */ }
                getterName = accessorName("is", propName );
                try {
                        Method m = clas.getMethod( getterName, new Class [0] );
                        return ( m.getReturnType() == Boolean.TYPE );
                } catch ( NoSuchMethodException e ) {
                        return false;
                }
        }

    public static boolean hasObjectPropertySetter(
                Class clas, String propName )
        {
                String setterName = accessorName("set", propName );
                Method [] methods = clas.getMethods();

                // we don't know the right hand side of the assignment yet.
                // has at least one setter of the right name?
                for(int i=0; i<methods.length; i++)
                        if ( methods[i].getName().equals( setterName ) )
                                return true;
                return false;
        }

    public static Object getObjectProperty(
                Object obj, String propName )
        throws UtilEvalError, ReflectError
    {
        Object[] args = new Object[] { };

        Interpreter.debug("property access: ");
                Method method = null;

                Exception e1=null, e2=null;
                try {
                        String accessorName = accessorName( "get", propName );
                        method = resolveExpectedJavaMethod(
                                null/*bcm*/, obj.getClass(), obj, accessorName, args, false );
                } catch ( Exception e ) {
                        e1 = e;
                }
                if ( method == null )
                        try {
                                String accessorName = accessorName( "is", propName );
                                method = resolveExpectedJavaMethod(
                                        null/*bcm*/, obj.getClass(), obj,
                                        accessorName, args, false );
                                if ( method.getReturnType() != Boolean.TYPE )
                                        method = null;
                        } catch ( Exception e ) {
                                e2 = e;
                        }
                if ( method == null )
                        throw new ReflectError("Error in property getter: "
                                +e1 + (e2!=null?" : "+e2:"") );

        try {
                        return invokeMethod( method, obj, args );
        }
        catch(InvocationTargetException e)
        {
            throw new UtilEvalError("Property accessor threw exception: "
                                +e.getTargetException() );
        }
    }

    public static void setObjectProperty(
                Object obj, String propName, Object value)
        throws ReflectError, UtilEvalError
    {    
        String accessorName = accessorName( "set", propName );
        Object[] args = new Object[] { value };

        Interpreter.debug("property access: ");
        try {
                        Method method = resolveExpectedJavaMethod(
                                null/*bcm*/, obj.getClass(), obj, accessorName, args, false );
                        invokeMethod( method, obj, args );
        }
        catch ( InvocationTargetException e )
        {
            throw new UtilEvalError("Property accessor threw exception: "
                                +e.getTargetException() );
        }
    }

    /**
                Return a more human readable version of the type name.
                Specifically, array types are returned with postfix "[]" dimensions.
                e.g. return "int []" for integer array instead of "class [I" as
                would be returned by Class getName() in that case.
        */
    public static String normalizeClassName(Class type)
    {
        if ( !type.isArray() )
            return type.getName();

        StringBuffer className = new StringBuffer();
        try {
            className.append( getArrayBaseType(type).getName() +" ");
            for(int i = 0; i < getArrayDimensions(type); i++)
                className.append("[]");
        } catch( ReflectError e ) { /*shouldn't happen*/ }

        return className.toString();
    }

        /**
                returns the dimensionality of the Class
                returns 0 if the Class is not an array class
        */
    public static int getArrayDimensions(Class arrayClass)
    {
        if ( !arrayClass.isArray() )
            return 0;

        return arrayClass.getName().lastIndexOf('[') + 1;  // why so cute?
    }

    /**

                Returns the base type of an array Class.
    throws ReflectError if the Class is not an array class.
        */
    public static Class getArrayBaseType(Class arrayClass) throws ReflectError
    {
        if ( !arrayClass.isArray() )
            throw new ReflectError("The class is not an array.");

                return arrayClass.getComponentType();

    }

        /**
                A command may be implemented as a compiled Java class containing one or
                more static invoke() methods of the correct signature.  The invoke()
                methods must accept two additional leading arguments of the interpreter
                and callstack, respectively. e.g. invoke(interpreter, callstack, ... )
                This method adds the arguments and invokes the static method, returning
                the result.
        */
        public static Object invokeCompiledCommand(
                Class commandClass, Object [] args, Interpreter interpreter,
                CallStack callstack )
                throws UtilEvalError
        {
        // add interpereter and namespace to args list
        Object[] invokeArgs = new Object[args.length + 2];
        invokeArgs[0] = interpreter;
        invokeArgs[1] = callstack;
        System.arraycopy( args, 0, invokeArgs, 2, args.length );
                BshClassManager bcm = interpreter.getClassManager();
                try {
        return Reflect.invokeStaticMethod(
                                bcm, commandClass, "invoke", invokeArgs );
                } catch ( InvocationTargetException e ) {
                        throw new UtilEvalError(
                                "Error in compiled command: "+e.getTargetException() );
                } catch ( ReflectError e ) {
                        throw new UtilEvalError("Error invoking compiled command: "+e );
                }
        }

        private static void logInvokeMethod(
                String msg, Method method, Object[] args )
        {
                if ( Interpreter.DEBUG )
                {
                        Interpreter.debug( msg +method+" with args:" );
                        for(int i=0; i<args.length; i++)
                                Interpreter.debug(
                                        "args["+i+"] = "+args[i]
                                        +" type = "+args[i].getClass() );
                }
        }

        private static void checkFoundStaticMethod(
                Method method, boolean staticOnly, Class clas )
                throws UtilEvalError
        {
                // We're looking for a static method but found an instance method
                if ( method != null && staticOnly && !isStatic( method ) )
                        throw new UtilEvalError(
                                "Cannot reach instance method: "
                                + StringUtil.methodString(
                                        method.getName(), method.getParameterTypes() )
                                + " from static context: "+ clas.getName() );
        }

        private static ReflectError cantFindConstructor(
                Class clas, Class [] types )
        {
                if ( types.length == 0 )
                        return new ReflectError(
                                "Can't find default constructor for: "+clas);
                else
                        return new ReflectError(
                                "Can't find constructor: "
                                        + StringUtil.methodString( clas.getName(), types )
                                        +" in class: "+ clas.getName() );
        }

        private static boolean isPublic( Class c ) {
                return Modifier.isPublic( c.getModifiers() );
        }
        private static boolean isPublic( Method m ) {
                return Modifier.isPublic( m.getModifiers() );
        }
        private static boolean isPublic( Constructor c ) {
                return Modifier.isPublic( c.getModifiers() );
        }
        private static boolean isStatic( Method m ) {
                return Modifier.isStatic( m.getModifiers() );
        }
}


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