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Stochastice Performance Logic is a formalism for capturing performance assumptions. It is, for example, possible to capture assumption that newer version of a function bar is faster than the previous version or that library foobar is faster than library barfoo when rendering antialiased text. The purpose of this framework is to allow evaluation of SPL formulas inside Java applications.

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/*
 * Copyright 2015 Charles University in Prague
 * Copyright 2015 Vojtech Horky
 * 
 * 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 cz.cuni.mff.d3s.spl.utils;

import java.util.List;

/** Various string utilities.
 */
public class StringUtils {
	
	/** Perform reverse of split on a list.
	 * 
	 * @param list Members to be joined.
	 * @return String representation of all members, connected by comma.
	 */
	public static String join(List list) {
		if (list.isEmpty()) {
			return "";
		}
		StringBuilder result = new StringBuilder();
		boolean afterFirst = false;
		for (Object o : list) {
			if (afterFirst) {
				result.append(',');
			}
			result.append(o.toString());
			afterFirst = true;
		}
		return result.toString();
	}
	
	/** Perform reverse of split on a list.
	 * 
	 * @param array Members to be joined.
	 * @param sep Separator between individual members of the array.
	 * @return String representation of all members, delimited by the separator.
	 */
	public static String join(Object[] array, String sep) {
		if (array.length == 0) {
			return "";
		}
		StringBuilder result = new StringBuilder();
		boolean afterFirst = false;
		for (Object o : array) {
			if (afterFirst) {
				result.append(sep);
			}
			result.append(o.toString());
			afterFirst = true;
		}
		return result.toString();
	}
	
	/** Perform revers of split on all arguments.
	 * 
	 * @param objects Objects to be joined.
	 * @return String representation of all objects, connected by comma.
	 */
	public static String join(Object... objects) {
		return join(objects, ",");
	}
	
	/** Format time in reasonable units.
	 *  
	 * @param nanos Time duration in nanoseconds.
	 * @return Reasonable representation of the given name with unit appended.
	 */
	public static String formatTimeUnits(double nanos) {
		if (nanos < 1000) {
			return String.format("%.0fns", nanos);
		}
		double micros = nanos / 1000;
		if (micros < 1000) {
			return String.format("%.0fus", micros);
		}
		double millis = micros / 1000;
		if (millis < 1000) {
			return String.format("%.0fms", millis);
		}
		double sec = millis / 1000;
		millis = millis - sec * 1000;
		return String.format("%.0fs %.fms", sec, millis);
	}
}