Groovy example source code file (DefaultTypeTransformation.java)

This example Groovy source code file (DefaultTypeTransformation.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Groovy tags/keywords

character, class, collection, collection, double, groovycastexception, io, iterator, list, math, number, number, object, object, reflection, string, string, util

The Groovy DefaultTypeTransformation.java source code

/*
 * Copyright 2003-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.codehaus.groovy.runtime.typehandling;

import groovy.lang.GString;
import groovy.lang.GroovyRuntimeException;
import org.codehaus.groovy.reflection.ReflectionCache;
import org.codehaus.groovy.runtime.*;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Array;
import java.lang.reflect.Modifier;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.*;

/**
 * Class providing various type conversions, coercions and boxing/unboxing operations.
 *
 * @author Guillaume Laforge
 */
public class DefaultTypeTransformation {
    
    protected static final Object[] EMPTY_ARGUMENTS = {};
    protected static final BigInteger ONE_NEG = new BigInteger("-1");
    
    //  --------------------------------------------------------
    //                  unboxing methods
    //  --------------------------------------------------------       
    
    public static byte byteUnbox(Object value) {
        Number n = castToNumber(value, byte.class);
        return n.byteValue();
    }

    public static char charUnbox(Object value) {
        return castToChar(value);
    }

    public static short shortUnbox(Object value) {
        Number n = castToNumber(value, short.class);
        return n.shortValue();
    }

    public static int intUnbox(Object value) {
        Number n = castToNumber(value, int.class);
        return n.intValue();
    }

    public static boolean booleanUnbox(Object value) {
        return castToBoolean(value);
    }

    public static long longUnbox(Object value) {
        Number n = castToNumber(value, long.class);
        return n.longValue();
    }

    public static float floatUnbox(Object value) {
        Number n = castToNumber(value, float.class);
        return n.floatValue();
    }

    public static double doubleUnbox(Object value) {
        Number n = castToNumber(value, double.class);
        return n.doubleValue();
    } 

    //  --------------------------------------------------------
    //                  boxing methods
    //  --------------------------------------------------------       
    
    public static Object box(boolean value) {
        return value ? Boolean.TRUE : Boolean.FALSE;
    }

    public static Object box(byte value) {
        return Byte.valueOf(value);
    }

    public static Object box(char value) {
        return Character.valueOf(value);
    }

    public static Object box(short value) {
        return Short.valueOf(value);
    }

    public static Object box(int value) {
        return Integer.valueOf(value);
    }

    public static Object box(long value) {
        return Long.valueOf(value);
    }

    public static Object box(float value) {
        return Float.valueOf(value);
    }

    public static Object box(double value) {
        return Double.valueOf(value);
    }
    
    public static Number castToNumber(Object object) {
        // default to Number class in exception details, else use the specified Number subtype.
        return castToNumber(object, Number.class);
    }
    
    public static Number castToNumber(Object object, Class type) {
        if (object instanceof Number)
            return (Number) object;
        if (object instanceof Character) {
            return Integer.valueOf(((Character) object).charValue());
        }
        if (object instanceof GString) {
            String c = ((GString) object).toString();
            if (c.length() == 1) {
                return Integer.valueOf(c.charAt(0));
            } else {
                throw new GroovyCastException(c, type);
            }
        }
        if (object instanceof String) {
            String c = (String) object;
            if (c.length() == 1) {
                return Integer.valueOf(c.charAt(0));
            } else {
                throw new GroovyCastException(c, type);
            }
        }
        throw new GroovyCastException(object, type);
    }

    /**
     * Method used for coercing an object to a boolean value,
     * thanks to an <code>asBoolean() method added on types. 
     *
     * @param object to coerce to a boolean value
     * @return a boolean value
     */
    public static boolean castToBoolean(Object object) {
        // null is always false
        if (object == null) {
            return false;
        }

        // if the object is not null, try to call an asBoolean() method on the object
        return (Boolean)InvokerHelper.invokeMethod(object, "asBoolean", InvokerHelper.EMPTY_ARGS);
    }
    
    public static char castToChar(Object object) {
        if (object instanceof Character) {
            return ((Character) object).charValue();            
        } else if (object instanceof Number) {
            Number value = (Number) object;
            return (char) value.intValue();
        } else {
            String text = object.toString();
            if (text.length() == 1) {
                return text.charAt(0);
            }
            else {
                throw new GroovyCastException(text,char.class);
            }
        }
    }
    
    public static Object castToType(Object object, Class type) {
        if (object == null) {
            return null;
        }

        if (type == Object.class)
          return object;

        final Class aClass = object.getClass();
        if (type == aClass) return object;
        // TODO we should move these methods to groovy method, like g$asType() so that
        // we can use operator overloading to customize on a per-type basis
        if (ReflectionCache.isArray(type)) {
            return asArray(object, type);

        }
        if (ReflectionCache.isAssignableFrom(type, aClass)) {
            return object;
        }
        if (Collection.class.isAssignableFrom(type)) {
            int modifiers = type.getModifiers();
            Collection answer;
            if (object instanceof Collection && type.isAssignableFrom(HashSet.class) &&
                    (type == HashSet.class || Modifier.isAbstract(modifiers) || Modifier.isInterface(modifiers))) {
                return new HashSet((Collection)object);
            }
            if (aClass.isArray()) {
                if (type.isAssignableFrom(ArrayList.class) && (Modifier.isAbstract(modifiers) || Modifier.isInterface(modifiers))) {
                    answer = new ArrayList();
                } else {
                    // let's call the collections constructor
                    // passing in the list wrapper
                    try {
                        answer = (Collection) type.newInstance();
                    }
                    catch (Exception e) {
                        throw new GroovyCastException("Could not instantiate instance of: " + type.getName() + ". Reason: " + e);
                    }
                }

                // we cannot just wrap in a List as we support primitive type arrays
                int length = Array.getLength(object);
                for (int i = 0; i < length; i++) {
                    Object element = Array.get(object, i);
                    answer.add(element);
                }
                return answer;
            }
        }
        if (type == String.class) {
            return object.toString();
        } else if (type == Character.class) {
            return box(castToChar(object));
        } else if (type == Boolean.class) {
            return box(castToBoolean(object));
        } else if (type == Class.class) {
            return castToClass(object);
        } else if (Number.class.isAssignableFrom(type)) {
            Number n = castToNumber(object, type);
            if (type == Byte.class) {
                return new Byte(n.byteValue());
            } else if (type == Character.class) {
                return new Character((char) n.intValue());
            } else if (type == Short.class) {
                return new Short(n.shortValue());
            } else if (type == Integer.class) {
                return Integer.valueOf(n.intValue());
            } else if (type == Long.class) {
                return new Long(n.longValue());
            } else if (type == Float.class) {
                return new Float(n.floatValue());
            } else if (type == Double.class) {
                Double answer = new Double(n.doubleValue());
                //throw a runtime exception if conversion would be out-of-range for the type.
                if (!(n instanceof Double) && (answer.doubleValue() == Double.NEGATIVE_INFINITY
                        || answer.doubleValue() == Double.POSITIVE_INFINITY)) {
                    throw new GroovyRuntimeException("Automatic coercion of " + n.getClass().getName()
                            + " value " + n + " to double failed.  Value is out of range.");
                }
                return answer;
            } else if (type == BigDecimal.class) {
                if (n instanceof Float || n instanceof Double) {
                    return new BigDecimal(n.doubleValue());
                }
                return new BigDecimal(n.toString());
            } else if (type == BigInteger.class) {
                if (object instanceof Float || object instanceof Double) {
                    BigDecimal bd = new BigDecimal(n.doubleValue());
                    return bd.toBigInteger();
                } else if (object instanceof BigDecimal) {
                    return ((BigDecimal) object).toBigInteger();
                } else {
                    return new BigInteger(n.toString());
                }
            }
        } else if (type.isPrimitive()) {
            if (type == boolean.class) {
               return box(booleanUnbox(object)); 
            } else if (type == byte.class) {
                return box(byteUnbox(object));
            } else if (type == char.class) {
                return box(charUnbox(object));
            } else if (type == short.class) {
                return box(shortUnbox(object));
            } else if (type == int.class) {
                return box(intUnbox(object));
            } else if (type == long.class) {
                return box(longUnbox(object));
            } else if (type == float.class) {
                return box(floatUnbox(object));
            } else if (type == double.class) {
                Double answer = new Double(doubleUnbox(object));
                //throw a runtime exception if conversion would be out-of-range for the type.
                if (!(object instanceof Double) && (answer.doubleValue() == Double.NEGATIVE_INFINITY
                        || answer.doubleValue() == Double.POSITIVE_INFINITY)) {
                    throw new GroovyRuntimeException("Automatic coercion of " + aClass.getName()
                            + " value " + object + " to double failed.  Value is out of range.");
                }
                return answer;
            }
        } else if (object instanceof String && type.isEnum()) {
            return Enum.valueOf(type, (String) object);
        } else if (object instanceof GString && type.isEnum()) {
            return Enum.valueOf(type, object.toString());
        }
        Object[] args = null;
        if (object instanceof Collection) {
            // let's try invoke the constructor with the list as arguments
            // such as for creating a Dimension, Point, Color etc.
            Collection collection = (Collection) object;
            args = collection.toArray();
        } else if (object instanceof Object[]) {
            args = (Object[]) object;
        } else if (object instanceof Map) {
            // emulate named params constructor
            args = new Object[1];
            args[0] = object;
        }
        Exception nested = null;
        if (args != null) {
            try {
                return InvokerHelper.invokeConstructorOf(type, args);
            } catch (InvokerInvocationException iie){
                throw iie;
            } catch (Exception e) {
                // let's ignore exception and return the original object
                // as the caller has more context to be able to throw a more
                // meaningful exception (but stash to get message later)
                nested = e;
            }
        }
        GroovyCastException gce;
        if (nested != null) {
            gce = new GroovyCastException(object, type, nested);
        } else {
            gce = new GroovyCastException(object, type);
        }
        throw gce;
    }

    private static Class castToClass(Object object) {
        try {
            return Class.forName(object.toString());
        } catch (Exception e) {
            throw new GroovyCastException(object, Class.class, e);
        }
    }

    public static Object asArray(Object object, Class type) {
        if (type.isAssignableFrom(object.getClass())) {
            return object;
        }
        Collection list = asCollection(object);
        int size = list.size();
        Class elementType = type.getComponentType();
        Object array = Array.newInstance(elementType, size);
        int idx = 0;

        if (boolean.class.equals(elementType)) {
            for (Iterator iter = list.iterator(); iter.hasNext(); idx++) {
                Object element = iter.next();
                Array.setBoolean(array, idx, booleanUnbox(element));
            }
        }
        else if (byte.class.equals(elementType)) {
            for (Iterator iter = list.iterator(); iter.hasNext(); idx++) {
                Object element = iter.next();
                Array.setByte(array, idx, byteUnbox(element));
            }
        }
        else if (char.class.equals(elementType)) {
            for (Iterator iter = list.iterator(); iter.hasNext(); idx++) {
                Object element = iter.next();
                Array.setChar(array, idx, charUnbox(element));
            }
        }
        else if (double.class.equals(elementType)) {
            for (Iterator iter = list.iterator(); iter.hasNext(); idx++) {
                Object element = iter.next();
                Array.setDouble(array, idx, doubleUnbox(element));
            }
        }
        else if (float.class.equals(elementType)) {
            for (Iterator iter = list.iterator(); iter.hasNext(); idx++) {
                Object element = iter.next();
                Array.setFloat(array, idx, floatUnbox(element));
            }
        }
        else if (int.class.equals(elementType)) {
            for (Iterator iter = list.iterator(); iter.hasNext(); idx++) {
                Object element = iter.next();
                Array.setInt(array, idx, intUnbox(element));
            }
        }
        else if (long.class.equals(elementType)) {
            for (Iterator iter = list.iterator(); iter.hasNext(); idx++) {
                Object element = iter.next();
                Array.setLong(array, idx, longUnbox(element));
            }
        }
        else if (short.class.equals(elementType)) {
            for (Iterator iter = list.iterator(); iter.hasNext(); idx++) {
                Object element = iter.next();
                Array.setShort(array, idx, shortUnbox(element));
            }
        }
        else {
            for (Iterator iter = list.iterator(); iter.hasNext(); idx++) {
                Object element = iter.next();
                Object coercedElement = castToType(element, elementType);
                Array.set(array, idx, coercedElement);
            }
        }
        return array;
    }
    
    public static <T> Collection asCollection(T[] value) {
        return arrayAsCollection(value);
    }

    public static Collection asCollection(Object value) {
        if (value == null) {
            return Collections.EMPTY_LIST;
        }
        else if (value instanceof Collection) {
            return (Collection) value;
        }
        else if (value instanceof Map) {
            Map map = (Map) value;
            return map.entrySet();
        }
        else if (value.getClass().isArray()) {
            return arrayAsCollection(value);
        }
        else if (value instanceof MethodClosure) {
            MethodClosure method = (MethodClosure) value;
            IteratorClosureAdapter adapter = new IteratorClosureAdapter(method.getDelegate());
            method.call(adapter);
            return adapter.asList();
        }
        else if (value instanceof String) {
            return DefaultGroovyMethods.toList((String) value);
        }
        else if (value instanceof GString) {
            return DefaultGroovyMethods.toList(value.toString());
        }
        else if (value instanceof File) {
            try {
                return DefaultGroovyMethods.readLines((File) value);
            }
            catch (IOException e) {
                throw new GroovyRuntimeException("Error reading file: " + value, e);
            }
        }
        else if (isEnumSubclass(value)) {
            Object[] values = (Object[])InvokerHelper.invokeMethod(value, "values", new Object[0]);
            return Arrays.asList(values);
        }
        else {
            // let's assume it's a collection of 1
            return Collections.singletonList(value);
        }
    }

    public static Collection arrayAsCollection(Object value) {
        if (value.getClass().getComponentType().isPrimitive()) {
            return primitiveArrayToList(value);
        }
        return arrayAsCollection((Object[]) value);
    }

    public static <T> Collection arrayAsCollection(T[] value) {
        return Arrays.asList((T[]) value);
    }

    /**
     * Determines whether the value object is a Class object representing a
     * subclass of java.lang.Enum. Uses class name check to avoid breaking on
     * pre-Java 5 JREs.
     *
     * @param value an object
     * @return true if the object is an Enum
     */
    public static boolean isEnumSubclass(Object value) {
        if (value instanceof Class) {
            Class superclass = ((Class)value).getSuperclass();
            while (superclass != null) {
                if (superclass.getName().equals("java.lang.Enum")) {
                    return true;
                }
                superclass = superclass.getSuperclass();
            }
        }

        return false;
    }
    
    /**
     * Allows conversion of arrays into a mutable List
     *
     * @param array an array
     * @return the array as a List
     */
    public static List primitiveArrayToList(Object array) {
        int size = Array.getLength(array);
        List list = new ArrayList(size);
        for (int i = 0; i < size; i++) {
            Object item = Array.get(array, i);
            if (item != null && item.getClass().isArray() && item.getClass().getComponentType().isPrimitive()) {
                item = primitiveArrayToList(item);
            }
            list.add(item);
        }
        return list;
    }
    
    public static Object[] primitiveArrayBox(Object array) {
        int size = Array.getLength(array);
        Object[] ret = (Object[]) Array.newInstance(ReflectionCache.autoboxType(array.getClass().getComponentType()), size);
        for (int i = 0; i < size; i++) {
            ret[i]=Array.get(array, i);
        }
        return ret;
    }
    
    /**
     * Compares the two objects handling nulls gracefully and performing numeric type coercion if required
     */
    public static int compareTo(Object left, Object right) {
        return compareToWithEqualityCheck(left, right, false);
    }

    private static int compareToWithEqualityCheck(Object left, Object right, boolean equalityCheckOnly) {
        if (left == right) {
            return 0;
        }
        if (left == null) {
            return -1;
        }
        else if (right == null) {
            return 1;
        }
        if (left instanceof Comparable) {
            if (left instanceof Number) {
                if (isValidCharacterString(right)) {
                    return DefaultGroovyMethods.compareTo((Number) left, (Character) box(castToChar(right)));
                }
                if (right instanceof Character || right instanceof Number) {
                    return DefaultGroovyMethods.compareTo((Number) left, castToNumber(right));
                }
            }
            else if (left instanceof Character) {
                if (isValidCharacterString(right)) {
                    return DefaultGroovyMethods.compareTo((Character)left,(Character)box(castToChar(right)));
                }
                if (right instanceof Number) {
                    return DefaultGroovyMethods.compareTo((Character)left,(Number)right);
                }
            }
            else if (right instanceof Number) {
                if (isValidCharacterString(left)) {
                    return DefaultGroovyMethods.compareTo((Character)box(castToChar(left)),(Number) right);
                }
            }
            else if (left instanceof String && right instanceof Character) {
                return ((String) left).compareTo(right.toString());
            }
            else if (left instanceof String && right instanceof GString) {
                return ((String) left).compareTo(right.toString());
            }
            if (!equalityCheckOnly || left.getClass().isAssignableFrom(right.getClass())
                    || (right.getClass() != Object.class && right.getClass().isAssignableFrom(left.getClass())) //GROOVY-4046
                    || (left instanceof GString && right instanceof String)) {
                Comparable comparable = (Comparable) left;
                return comparable.compareTo(right);
            }
        }

        if (equalityCheckOnly) {
            return -1; // anything other than 0
        }
        throw new GroovyRuntimeException("Cannot compare " + left.getClass().getName() + " with value '" +
                left + "' and " + right.getClass().getName() + " with value '" + right + "'");
    }

    public static boolean compareEqual(Object left, Object right) {
        if (left == right) return true;
        if (left == null || right == null) return false;
        if (left instanceof Comparable) {
            return compareToWithEqualityCheck(left, right, true) == 0;
        }
        // handle arrays on both sides as special case for efficiency
        Class leftClass = left.getClass();
        Class rightClass = right.getClass();
        if (leftClass.isArray() && rightClass.isArray()) {
            return compareArrayEqual(left, right);
        }
        if (leftClass.isArray() && leftClass.getComponentType().isPrimitive()) {
            left = primitiveArrayToList(left);
        }
        if (rightClass.isArray() && rightClass.getComponentType().isPrimitive()) {
            right = primitiveArrayToList(right);
        }
        if (left instanceof Object[] && right instanceof List) {
            return DefaultGroovyMethods.equals((Object[]) left, (List) right);
        }
        if (left instanceof List && right instanceof Object[]) {
            return DefaultGroovyMethods.equals((List) left, (Object[]) right);
        }
        if (left instanceof List && right instanceof List) {
            return DefaultGroovyMethods.equals((List) left, (List) right);
        }
        if (left instanceof Map.Entry && right instanceof Map.Entry) {
            Object k1 = ((Map.Entry)left).getKey();
            Object k2 = ((Map.Entry)right).getKey();
            if (k1 == k2 || (k1 != null && k1.equals(k2))) {
                Object v1 = ((Map.Entry)left).getValue();
                Object v2 = ((Map.Entry)right).getValue();
                if (v1 == v2 || (v1 != null && DefaultTypeTransformation.compareEqual(v1, v2)))
                    return true;
            }
            return false;
        }
        return ((Boolean) InvokerHelper.invokeMethod(left, "equals", right)).booleanValue();
    }

    public static boolean compareArrayEqual(Object left, Object right) {
        if (left == null) {
            return right == null;
        }
        if (right == null) {
            return false;
        }
        if (Array.getLength(left) != Array.getLength(right)) {
            return false;
        }
        for (int i = 0; i < Array.getLength(left); i++) {
            Object l = Array.get(left, i);
            Object r = Array.get(right, i);
            if (!compareEqual(l, r)) return false;
        }
        return true;
    }

    /**
     * @return true if the given value is a valid character string (i.e. has length of 1)
     */
    private static boolean isValidCharacterString(Object value) {
        if (value instanceof String) {
            String s = (String) value;
            if (s.length() == 1) {
                return true;
            }
        }
        return false;
    }

    public static int[] convertToIntArray(Object a) {
        int[] ans = null;

        // conservative coding
        if (a.getClass().getName().equals("[I")) {
            ans = (int[]) a;
        }
        else {
            Object[] ia = (Object[]) a;
            ans = new int[ia.length];
            for (int i = 0; i < ia.length; i++) {
                if (ia[i] == null) {
                    continue;
                }
                ans[i] = ((Number) ia[i]).intValue();
            }
        }
        return ans;
    }

    public static boolean[] convertToBooleanArray(Object a) {
        boolean[] ans = null;

        // conservative coding
        if (a instanceof boolean[]) {
            ans = (boolean[]) a;
        } else {
            Object[] ia = (Object[]) a;
            ans = new boolean[ia.length];
            for (int i = 0; i < ia.length; i++) {
                if (ia[i] == null) continue;
                ans[i] = ((Boolean) ia[i]).booleanValue();
            }
        }
        return ans;
    }

    public static byte[] convertToByteArray(Object a) {
        byte[] ans = null;

        // conservative coding
        if (a instanceof byte[]) {
            ans = (byte[]) a;
        } else {
            Object[] ia = (Object[]) a;
            ans = new byte[ia.length];
            for (int i = 0; i < ia.length; i++) {
                if (ia[i] != null) {
                    ans[i] = ((Number) ia[i]).byteValue();
                }
            }
        }
        return ans;
    }

    public static short[] convertToShortArray(Object a) {
        short[] ans = null;

        // conservative coding
        if (a instanceof short[]) {
            ans = (short[]) a;
        } else {
            Object[] ia = (Object[]) a;
            ans = new short[ia.length];
            for (int i = 0; i < ia.length; i++) {
                ans[i] = ((Number) ia[i]).shortValue();
            }
        }
        return ans;
    }

    public static char[] convertToCharArray(Object a) {
        char[] ans = null;

        // conservative coding
        if (a instanceof char[]) {
            ans = (char[]) a;
        } else {
            Object[] ia = (Object[]) a;
            ans = new char[ia.length];
            for (int i = 0; i < ia.length; i++) {
                if (ia[i] == null) {
                    continue;
                }
                ans[i] = ((Character) ia[i]).charValue();
            }
        }
        return ans;
    }

    public static long[] convertToLongArray(Object a) {
        long[] ans = null;

        // conservative coding
        if (a instanceof long[]) {
            ans = (long[]) a;
        } else {
            Object[] ia = (Object[]) a;
            ans = new long[ia.length];
            for (int i = 0; i < ia.length; i++) {
                if (ia[i] == null) {
                    continue;
                }
                ans[i] = ((Number) ia[i]).longValue();
            }
        }
        return ans;
    }

    public static float[] convertToFloatArray(Object a) {
        float[] ans = null;

        // conservative coding
        if (a instanceof float[]) {
            ans = (float[]) a;
        } else {
            Object[] ia = (Object[]) a;
            ans = new float[ia.length];
            for (int i = 0; i < ia.length; i++) {
                if (ia[i] == null) {
                    continue;
                }
                ans[i] = ((Number) ia[i]).floatValue();
            }
        }
        return ans;
    }

    public static double[] convertToDoubleArray(Object a) {
        double[] ans = null;

        // conservative coding
        if (a instanceof double[]) {
            ans = (double[]) a;
        } else {
            Object[] ia = (Object[]) a;
            ans = new double[ia.length];
            for (int i = 0; i < ia.length; i++) {
                if (ia[i] == null) {
                    continue;
                }
                ans[i] = ((Number) ia[i]).doubleValue();
            }
        }
        return ans;
    }

    public static Object convertToPrimitiveArray(Object a, Class type) {
        if (type == Byte.TYPE) {
            return convertToByteArray(a);
        }
        if (type == Boolean.TYPE) {
            return convertToBooleanArray(a);
        }
        if (type == Short.TYPE) {
            return convertToShortArray(a);
        }
        if (type == Character.TYPE) {
            return convertToCharArray(a);
        }
        if (type == Integer.TYPE) {
            return convertToIntArray(a);
        }
        if (type == Long.TYPE) {
            return convertToLongArray(a);
        }
        if (type == Float.TYPE) {
            return convertToFloatArray(a);
        }
        if (type == Double.TYPE) {
            return convertToDoubleArray(a);
        }
        else {
            return a;
        }
    }
    
    public static Character getCharFromSizeOneString(Object value) {
        if (value instanceof GString) value = value.toString();
        if (value instanceof String) {
            String s = (String) value;
            if (s.length() != 1) throw new IllegalArgumentException("String of length 1 expected but got a bigger one");
            return new Character(s.charAt(0));
        } else {
            return ((Character) value);
        }
    }

}