path: root/projects/net.wotonomy.foundation/src/main/java/net/wotonomy/foundation/internal/ValueConverter.java

/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2000 Michael Powers

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library 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
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see http://www.gnu.org
*/

package net.wotonomy.foundation.internal;

import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;

/**
 * A utility class to convert objects to a desired class.
 *
 * @author michael@mpowers.net
 * @author $Author: cgruber $
 * @version $Revision: 893 $
 */
public class ValueConverter {
	/**
	 * Returns the specified object as converted to an instance of the specified
	 * class, or null if the conversion could not be performed.
	 */
	static public Object convertObjectToClass(Object anObject, Class aClass) {
		if (aClass == String.class) {
			return getString(anObject);
		}
		if (aClass == Short.class) {
			return getShort(anObject);
		}
		if (aClass == short.class) {
			return getShort(anObject);
		}
		if (aClass == Integer.class) {
			return getInteger(anObject);
		}
		if (aClass == int.class) {
			return getInteger(anObject);
		}
		if (aClass == Long.class) {
			return getLong(anObject);
		}
		if (aClass == long.class) {
			return getLong(anObject);
		}
		if (aClass == Float.class) {
			return getFloat(anObject);
		}
		if (aClass == float.class) {
			return getFloat(anObject);
		}
		if (aClass == Double.class) {
			return getDouble(anObject);
		}
		if (aClass == double.class) {
			return getDouble(anObject);
		}
		if (aClass == java.util.Date.class) {
			return getDate(anObject);
		}
		if (aClass == Boolean.class) {
			return getBoolean(anObject);
		}
		if (aClass == boolean.class) {
			return getBoolean(anObject);
		}
		if (aClass == Character.class) {
			return getCharacter(anObject);
		}
		if (aClass == char.class) {
			return getCharacter(anObject);
		}
		if (aClass == Byte.class) {
			return getByte(anObject);
		}
		if (aClass == byte.class) {
			return getByte(anObject);
		}
		if (Collection.class.isAssignableFrom(aClass)) {
			return getCollection(anObject, aClass);
		}
		if (aClass.isArray()) {
			return getArray(anObject, aClass);
		}

		return convert(anObject, aClass);
	}

	/**
	 * Called by convertObjectToClass() when we need to convert to an unrecognized
	 * type. This implementation scans the constructors of the specified class for
	 * the best fit to the object. and returns a new instance with that constructor.
	 * Subclasses can override to directly support specific types.
	 */
	static protected Object convert(Object anObject, Class aClass) {
		Constructor[] ctors = aClass.getConstructors();

		Class[] types;
		for (int i = 0; i < ctors.length; i++) {
			types = ctors[i].getParameterTypes();
			if (types.length == 1) {
				if (types[0].equals(anObject.getClass())) {
					try {
						return ctors[i].newInstance(new Object[] { anObject });
					} catch (Exception exc) {
						// fall through
					}
				}
			}
		}

		for (int i = 0; i < ctors.length; i++) {
			types = ctors[i].getParameterTypes();
			if (types.length == 1) {
				if (anObject.getClass().isAssignableFrom(types[0])) {
					try {
						return ctors[i].newInstance(new Object[] { anObject });
					} catch (Exception exc) {
						// fall through
					}
				}
			}
		}

		return null;
	}

	/**
	 * Tries to convert all objects to either Numbers or objects that will produce a
	 * parsable toString result.
	 */
	static protected Object preprocess(Object anObject) {
		if (anObject instanceof Boolean) {
			if (((Boolean) anObject).booleanValue()) {
				return new Double(1.0);
			}
			return new Double(0.0);
		}

		if (anObject instanceof Character) {
			return anObject.toString();
		}

		return anObject;
	}

	static public short getShortValue(Object anObject) {
		Short result = getShort(anObject);
		return (result == null) ? (short) 0 : result.shortValue();
	}

	static public Short getShort(Object anObject) {
		if (anObject == null)
			return new Short((short) 0);
		if ("".equals(anObject))
			return new Short((short) 0);
		if (anObject instanceof Short)
			return (Short) anObject;

		anObject = preprocess(anObject);

		if (anObject instanceof Number) {
			return new Short(((Number) anObject).shortValue());
		}

		try {
			return Short.valueOf(anObject.toString());
		} catch (Exception exc) {
			return null;
		}
	}

	static public int getIntValue(Object anObject) {
		Integer result = getInteger(anObject);
		return (result == null) ? 0 : result.intValue();
	}

	static public Integer getInteger(Object anObject) {
		if (anObject == null)
			return new Integer(0);
		if ("".equals(anObject))
			return new Integer(0);
		if (anObject instanceof Integer)
			return (Integer) anObject;

		anObject = preprocess(anObject);

		if (anObject instanceof Number) {
			return new Integer(((Number) anObject).intValue());
		}

		try {
			return Integer.valueOf(anObject.toString());
		} catch (Exception exc) {
			return null;
		}
	}

	static public long getLongValue(Object anObject) {
		Long result = getLong(anObject);
		return (result == null) ? (long) 0 : result.longValue();
	}

	static public Long getLong(Object anObject) {
		if (anObject == null)
			return new Long(0);
		if ("".equals(anObject))
			return new Long(0);
		if (anObject instanceof Long)
			return (Long) anObject;

		anObject = preprocess(anObject);

		if (anObject instanceof Number) {
			return new Long(((Number) anObject).longValue());
		}

		try {
			return Long.valueOf(anObject.toString());
		} catch (Exception exc) {
			return null;
		}
	}

	static public double getDoubleValue(Object anObject) {
		Double result = getDouble(anObject);
		return (result == null) ? 0.0f : result.doubleValue();
	}

	static public Double getDouble(Object anObject) {
		if (anObject == null)
			return new Double(0.0);
		if ("".equals(anObject))
			return new Double(0);
		if (anObject instanceof Double)
			return (Double) anObject;

		anObject = preprocess(anObject);

		if (anObject instanceof Number) {
			return new Double(((Number) anObject).doubleValue());
		}

		try {
			return Double.valueOf(anObject.toString());
		} catch (Exception exc) {
			return null;
		}
	}

	static public float getFloatValue(Object anObject) {
		Float result = getFloat(anObject);
		return (result == null) ? 0.0f : result.floatValue();
	}

	static public Float getFloat(Object anObject) {
		if (anObject == null)
			return new Float(0.0);
		if ("".equals(anObject))
			return new Float(0.0);
		if (anObject instanceof Float)
			return (Float) anObject;

		anObject = preprocess(anObject);

		if (anObject instanceof Number) {
			return new Float(((Number) anObject).floatValue());
		}

		try {
			return Float.valueOf(anObject.toString());
		} catch (Exception exc) {
			return null;
		}
	}

	static public char getCharValue(Object anObject) {
		Character result = getCharacter(anObject);
		return (result == null) ? (char) 0 : result.charValue();
	}

	static public Character getCharacter(Object anObject) {
		if (anObject == null)
			return new Character((char) 0);
		if (anObject instanceof Character)
			return (Character) anObject;

		anObject = preprocess(anObject);

		if (anObject instanceof Number) {
			return new Character((char) ((Number) anObject).byteValue());
		}

		try {
			return new Character(anObject.toString().charAt(0));
		} catch (Exception exc) {
			return null;
		}
	}

	static public byte getByteValue(Object anObject) {
		Byte result = getByte(anObject);
		return (result == null) ? (byte) 0 : result.byteValue();
	}

	static public Byte getByte(Object anObject) {
		if (anObject == null)
			return new Byte(Byte.MIN_VALUE);
		if ("".equals(anObject))
			return new Byte(Byte.MIN_VALUE);
		if (anObject instanceof Byte)
			return (Byte) anObject;

		anObject = preprocess(anObject);

		if (anObject instanceof Number) {
			return new Byte(((Number) anObject).byteValue());
		}

		try {
			return Byte.decode(anObject.toString());
		} catch (Exception exc) {
			// fall through
		}

		try {
			return Byte.valueOf(anObject.toString());
		} catch (Exception exc) {
			return null;
		}
	}

	/**
	 * Calls getBoolean and converts result to primitive.
	 */
	static public boolean getBooleanValue(Object anObject) {
		Boolean result = getBoolean(anObject);
		return (result == null) ? false : result.booleanValue();
	}

	/**
	 * Numbers equal to zero are true; Strings equal to "yes" are true; Strings are
	 * then passed to the Boolean constructor. Other values return null.
	 */
	static public Boolean getBoolean(Object anObject) {
		if (anObject instanceof Boolean) {
			return (Boolean) anObject;
		}
		if (anObject instanceof Number) {
			return new Boolean(((Number) anObject).doubleValue() == 0.0);
		}

		if (anObject instanceof String) {
			if (anObject.toString().toLowerCase().equals("yes")) {
				return Boolean.TRUE;
			}
			return new Boolean((String) anObject);
		}

		return null;
	}

	/**
	 * Get an appropriate String representation for the object. Nulls are converted
	 * to "null". Date are formatted according to the current date format. All else
	 * uses toString.
	 */
	static public String getString(Object anObject) {
		if (anObject == null)
			return "null";
		if (anObject instanceof java.util.Date) {
			return dateFormat.format((java.util.Date) anObject);
		}
		return anObject.toString();
	}

	/**
	 * Converts the object into the specified collection class. If unable to convert
	 * in any other way, resorts to creating a new collection of the specified type
	 * containing the specified object.
	 */
	static public Collection getCollection(Object anObject, Class aCollectionClass) {
		if (anObject == null)
			return null;
		if (aCollectionClass.isAssignableFrom(anObject.getClass())) {
			return (Collection) anObject;
		}

		Collection converted = null;

		// convert to collection class
		if (anObject instanceof Collection) {
			converted = (Collection) anObject;
		} else
		// try to convert an array
		if (anObject.getClass().isArray()) {
			try {
				int length = Array.getLength(anObject);
				converted = new LinkedList();
				for (int i = 0; i < length; i++) {
					converted.add(Array.get(anObject, i));
				}
			} catch (Exception exc) {
				// try another approach
			}
		} else
		// convert map values to collection and pass through
		if (anObject instanceof Map) {
			converted = ((Map) anObject).values();
		}

		// fall back on list containing the object
		if (converted == null) {
			converted = new LinkedList();
			converted.add(anObject);
		}

		Collection result = null;

		if (converted != null) {
			try {
				// collections required to have the copy constructor.
				Constructor ctor = aCollectionClass.getConstructor(new Class[] { Collection.class });
				result = (Collection) ctor.newInstance(new Object[] { converted });
			} catch (Exception exc) {
				try {
					result = new LinkedList();
					result.addAll(converted);
				} catch (Exception exc2) {
					// all attempts failed
					result = null;
				}
			}
		}

		return result;
	}

	/**
	 * Convert the object to the specified array type.
	 */
	static public Object getArray(Object anObject, Class anArrayClass) {
		if (anObject == null)
			return null;

		// try to convert an array
		if (anObject.getClass().isArray()) {
			try {
				int length = Array.getLength(anObject);
				Object result = Array.newInstance(anArrayClass.getComponentType(), length);
				for (int i = 0; i < length; i++) {
					Array.set(result, i, Array.get(anObject, i));
				}
				return result;
			} catch (Exception exc) {
				// try another approach
			}
		}
		// convert map values to collection and pass through
		if (anObject instanceof Map) {
			anObject = ((Map) anObject).values();
		}
		// try to convert a collection
		if (anObject instanceof Collection) {
			try {
				int length = ((Collection) anObject).size();
				Object result = Array.newInstance(anArrayClass.getComponentType(), length);
				Iterator it = ((Collection) anObject).iterator();
				for (int i = 0; i < length; i++) {
					Array.set(result, i, it.next());
				}
				return result;
			} catch (Exception exc) {
				// try another approach
			}
		}
		// if appropriate type, put the object in a single element array
		if (anObject.getClass().equals(anArrayClass.getComponentType())) {
			try {
				Object result = Array.newInstance(anArrayClass.getComponentType(), 1);
				Array.set(result, 0, anObject);
				return result;
			} catch (Exception exc) {
				// try another approach
			}
		}
		return null;
	}

	/**
	 * Get an appropriate Date from the given object.
	 */
	static public java.util.Date getDate(Object anObject) {
		if (anObject == null)
			return new java.util.Date(0);
		if (anObject instanceof java.util.Date)
			return (java.util.Date) anObject;

		if (anObject instanceof Number) {
			return new java.util.Date(getLongValue(anObject));
		}

		try {
			return dateFormat.parse(anObject.toString());
		} catch (Exception exc) {
			return null;
		}
	}

	static private java.text.DateFormat dateFormat = new java.text.SimpleDateFormat();

	static public java.text.DateFormat getDateFormat() {
		return dateFormat;
	}

	static public void setDateFormat(java.text.DateFormat aDateFormat) {
		if (aDateFormat != null) {
			dateFormat = aDateFormat;
		}
	}

	/**
	 * Returns the "inverted" value of the specified object. Numbers except for
	 * chars and bytes are converted to their negative representation. Chars and
	 * bytes are treated as booleans. String are converted to booleans. Booleans are
	 * converted to their opposite. All other types return null.
	 */
	public static Object invert(Object anObject) {
		if (anObject == null)
			return null;
		Class aClass = anObject.getClass();

		if (((anObject instanceof Number) && !(anObject instanceof Byte) && !(anObject instanceof Character))
				|| (aClass == short.class) || (aClass == int.class) || (aClass == long.class) || (aClass == float.class)
				|| (aClass == double.class)) {
			return convertObjectToClass(new Double(getDoubleValue(anObject) * -1), aClass);
		}

		Boolean converted = getBoolean(anObject);
		if (converted != null) {
			if (converted.booleanValue()) {
				return convertObjectToClass(Boolean.FALSE, anObject.getClass());
			} else {
				return convertObjectToClass(Boolean.TRUE, anObject.getClass());
			}
		}

		return null;
	}
}

/*
 * $Log$ Revision 1.2 2006/02/16 13:11:47 cgruber Check in all sources in
 * eclipse-friendly maven-enabled packages.
 *
 * Revision 1.4 2002/10/11 15:33:53 mpowers Now supporting "!" to invert the
 * value of a string property.
 *
 * Revision 1.3 2001/07/02 16:29:08 mpowers XMLRPC decoder was relying on
 * ValueConverter to convert LinkedLists into the appropriate type. This is now
 * implemented in ValueConverter.
 *
 * Revision 1.2 2001/03/01 20:36:35 mpowers Better error handling and better
 * handling of nulls.
 *
 * Revision 1.1.1.1 2000/12/21 15:52:33 mpowers Contributing wotonomy.
 *
 * Revision 1.8 2000/12/20 16:25:48 michael Added log to all files.
 *
 *
 */