bundles/org.eclipse.core.databinding/src/org/eclipse/core/databinding/conversion/NumberToStringConverter.java

/*******************************************************************************
 * Copyright (c) 2007 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 ******************************************************************************/

package org.eclipse.core.databinding.conversion;

import java.math.BigInteger;

import com.ibm.icu.text.NumberFormat;

/**
 * Converts a Number to a String using <code>NumberFormat.format(...)</code>.
 * This class is thread safe.
 * 
 * @since 1.0
 */
public class NumberToStringConverter extends Converter {
	private final NumberFormat numberFormat;
	private final Class fromType;
	private boolean fromTypeIsLong;
	private boolean fromTypeIsDecimalType;
	private boolean fromTypeIsBigInteger;

	/**
	 * Constructs a new instance.
	 * <p>
	 * Private to restrict public instantiation.
	 * </p>
	 * 
	 * @param numberFormat
	 * @param fromType
	 */
	private NumberToStringConverter(NumberFormat numberFormat, Class fromType) {
		super(fromType, String.class);

		this.numberFormat = numberFormat;
		this.fromType = fromType;

		if (Integer.class.equals(fromType) || Integer.TYPE.equals(fromType)
				|| Long.class.equals(fromType) || Long.TYPE.equals(fromType)) {
			fromTypeIsLong = true;
		} else if (Float.class.equals(fromType) || Float.TYPE.equals(fromType)
				|| Double.class.equals(fromType)
				|| Double.TYPE.equals(fromType)) {
			fromTypeIsDecimalType = true;
		} else if (BigInteger.class.equals(fromType)) {
			fromTypeIsBigInteger = true;
		}
	}

	/**
	 * Converts the provided <code>fromObject</code> to a <code>String</code>.
	 * If the converter was constructed for an object type, non primitive, a
	 * <code>fromObject</code> of <code>null</code> will be converted to an
	 * empty string.
	 * 
	 * @param fromObject
	 *            value to convert. May be <code>null</code> if the converter
	 *            was constructed for a non primitive type.
	 * @see org.eclipse.core.databinding.conversion.IConverter#convert(java.lang.Object)
	 */
	public Object convert(Object fromObject) {
		// Null is allowed when the type is not primitve.
		if (fromObject == null && !fromType.isPrimitive()) {
			return ""; //$NON-NLS-1$
		}

		Number number = (Number) fromObject;
		String result = null;
		if (fromTypeIsLong) {
			synchronized (numberFormat) {
				result = numberFormat.format(number.longValue());
			}
		} else if (fromTypeIsDecimalType) {
			synchronized (numberFormat) {
				result = numberFormat.format(number.doubleValue());
			}
		} else if (fromTypeIsBigInteger) {
			synchronized (numberFormat) {
				result = numberFormat.format((BigInteger) number);
			}
		}

		return result;
	}

	/**
	 * @param primitive
	 *            <code>true</code> if the type is a double
	 * @return Double converter for the default locale
	 */
	public static NumberToStringConverter fromDouble(boolean primitive) {
		return fromDouble(NumberFormat.getNumberInstance(), primitive);
	}

	/**
	 * @param numberFormat
	 * @param primitive
	 * @return Double converter with the provided numberFormat
	 */
	public static NumberToStringConverter fromDouble(NumberFormat numberFormat,
			boolean primitive) {
		return new NumberToStringConverter(numberFormat,
				(primitive) ? Double.TYPE : Double.class);
	}

	/**
	 * @param primitive
	 *            <code>true</code> if the type is a long
	 * @return Long converter for the default locale
	 */
	public static NumberToStringConverter fromLong(boolean primitive) {
		return fromLong(NumberFormat.getIntegerInstance(), primitive);
	}

	/**
	 * @param numberFormat
	 * @param primitive
	 * @return Long convert with the provided numberFormat
	 */
	public static NumberToStringConverter fromLong(NumberFormat numberFormat,
			boolean primitive) {
		return new NumberToStringConverter(numberFormat,
				(primitive) ? Long.TYPE : Long.class);
	}

	/**
	 * @param primitive
	 *            <code>true</code> if the type is a float
	 * @return Float converter for the default locale
	 */
	public static NumberToStringConverter fromFloat(boolean primitive) {
		return fromFloat(NumberFormat.getNumberInstance(), primitive);
	}

	/**
	 * @param numberFormat
	 * @param primitive
	 * @return Float converter with the provided numberFormat
	 */
	public static NumberToStringConverter fromFloat(NumberFormat numberFormat,
			boolean primitive) {
		return new NumberToStringConverter(numberFormat,
				(primitive) ? Float.TYPE : Float.class);
	}

	/**
	 * @param primitive
	 *            <code>true</code> if the type is a int
	 * @return Integer converter for the default locale
	 */
	public static NumberToStringConverter fromInteger(boolean primitive) {
		return fromInteger(NumberFormat.getIntegerInstance(), primitive);
	}

	/**
	 * @param numberFormat
	 * @param primitive
	 * @return Integer converter with the provided numberFormat
	 */
	public static NumberToStringConverter fromInteger(
			NumberFormat numberFormat, boolean primitive) {
		return new NumberToStringConverter(numberFormat,
				(primitive) ? Integer.TYPE : Integer.class);
	}

	/**
	 * @return BigInteger convert for the default locale
	 */
	public static NumberToStringConverter fromBigInteger() {
		return fromBigInteger(NumberFormat.getIntegerInstance());
	}

	/**
	 * @param numberFormat
	 * @return BigInteger converter with the provided numberFormat
	 */
	public static NumberToStringConverter fromBigInteger(
			NumberFormat numberFormat) {
		return new NumberToStringConverter(numberFormat, BigInteger.class);
	}
}