package cern.colt.matrix.impl;


/**
 * Factory producing implementations of {@link cern.colt.matrix.impl.Former} via method create();
 * Implementations of can use existing libraries such as corejava.PrintfFormat or corejava.Format or other.
 * Serves to isolate the interface of String formatting from the actual implementation.
 * If you want to plug in a different String formatting implementation, simply replace this class with your alternative.
 *
 * @author wolfgang.hoschek@cern.ch
 * @version 1.0, 21/07/00
 */
public class FormerFactory {
/**
 * Constructs and returns a new format instance.
 * @param s the format string following printf conventions.
 * The string has a prefix, a format code and a suffix. The prefix and suffix
 * become part of the formatted output. The format code directs the
 * formatting of the (single) parameter to be formatted. The code has the
 * following structure
 * <ul>
 * <li> a % (required)
 * <li> a modifier (optional)
 * <dl>
 * <dt> + <dd> forces display of + for positive numbers
 * <dt> 0 <dd> show leading zeroes
 * <dt> - <dd> align left in the field
 * <dt> space <dd> prepend a space in front of positive numbers
 * <dt> # <dd> use "alternate" format. Add 0 or 0x for octal or hexadecimal numbers. Don't suppress trailing zeroes in general floating point format.
 * </dl>
 * <li> an integer denoting field width (optional)
 * <li> a period followed by an integer denoting precision (optional)
 * <li> a format descriptor (required)
 * <dl>
 * <dt>f <dd> floating point number in fixed format
 * <dt>e, E <dd> floating point number in exponential notation (scientific format). The E format results in an uppercase E for the exponent (1.14130E+003), the e format in a lowercase e.
 * <dt>g, G <dd> floating point number in general format (fixed format for small numbers, exponential format for large numbers). Trailing zeroes are suppressed. The G format results in an uppercase E for the exponent (if any), the g format in a lowercase e.
 * <dt>d, i <dd> integer in decimal
 * <dt>x <dd> integer in hexadecimal
 * <dt>o <dd> integer in octal
 * <dt>s <dd> string
 * <dt>c <dd> character
 * </dl>
 * </ul>
 * @exception IllegalArgumentException if bad format
 */
public Former create(final String format) {
	return new Former() {
		//private FormatStringBuffer f = (format!=null ? new corejava.FormatStringBuffer(format) : null);
		private corejava.Format f = (format!=null ? new corejava.Format(format) : null);
		//private corejava.PrintfFormat f = (format!=null ? new corejava.PrintfFormat(format) : null);
		public String form(double value) {
			if (f==null || value == Double.POSITIVE_INFINITY || value == Double.NEGATIVE_INFINITY || value != value) {
				// value != value <==> Double.isNaN(value)
				// Work around bug in corejava.Format.form() for inf, -inf, NaN
				return String.valueOf(value);
			}
		//return f.format(value).toString();
		return f.format(value);
		//return f.sprintf(value);
		}
	};
}
}