Numbers.java

package tc.oc.commons.core.util;

import com.google.common.collect.Range;

public class Numbers {

    /**
     * Get the value of the given numeric type that best represents positive infinity.
     * @throws java.lang.ReflectiveOperationException if this fails, which should not happen with the primitive types
     */
    public static <T extends Number> T positiveInfinity(Class<T> type) throws ReflectiveOperationException {
        try {
            return type.cast(type.getField("POSITIVE_INFINITY").get(null));
        }
        catch(NoSuchFieldException e) {
            return type.cast(type.getField("MAX_VALUE").get(null));
        }
    }

    /**
     * Get the value of the given numeric type that best represents negative infinity.
     * @throws java.lang.ReflectiveOperationException if this fails, which should not happen with the primitive types
     */
    public static <T extends Number> T negativeInfinity(Class<T> type) throws ReflectiveOperationException {
        try {
            return type.cast(type.getField("NEGATIVE_INFINITY").get(null));
        }
        catch(NoSuchFieldException e) {
            return type.cast(type.getField("MIN_VALUE").get(null));
        }
    }

    /**
     * Try to parse the given text as a number of the given type
     * @param text string representation of a number
     * @param type numeric type to parse
     * @param infinity whether infinities should be allowed
     * @return a parsed number
     * @throws NumberFormatException if a number could not be parsed for whatever reason
     */
    public static <T extends Number> T parse(String text, Class<T> type, boolean infinity) throws NumberFormatException {
        try {
            if(infinity) {
                String trimmed = text.trim();
                if("oo".equals(trimmed) || "+oo".equals(trimmed)) {
                    return positiveInfinity(type);
                } else if("-oo".equals(trimmed)) {
                    return negativeInfinity(type);
                }
            }
            return type.cast(type.getMethod("valueOf", String.class).invoke(null, text));
        } catch(ReflectiveOperationException e) {
            if(e.getCause() instanceof NumberFormatException) {
                throw (NumberFormatException) e.getCause();
            } else {
                throw new IllegalArgumentException("cannot parse type " + type.getName(), e);
            }
        }
    }

    public static <T extends Number> T coerce(Object obj, Class<T> type, boolean infinity) throws NumberFormatException {
        if(type.isInstance(obj)) {
            return type.cast(obj);
        } else if(obj instanceof String) {
            return parse((String) obj, type, infinity);
        } else if(obj instanceof Number) {
            Number n = (Number) obj;
            if(type.equals(Double.class)) {
                return type.cast(n.doubleValue());
            } else if(type.equals(Float.class)) {
                return type.cast(n.floatValue());
            } else if(type.equals(Long.class)) {
                return type.cast(n.longValue());
            } else if(type.equals(Integer.class)) {
                return type.cast(n.intValue());
            } else if(type.equals(Short.class)) {
                return type.cast(n.shortValue());
            } else if(type.equals(Byte.class)) {
                return type.cast(n.byteValue());
            }
        }

        throw new NumberFormatException("Cannot coerce " + obj + " to " + type.getSimpleName());
    }

    public static double clamp(double value, double min, double max) {
        return value < min ? min : (value > max ? max : value);
    }

    public static int clamp(int value, int min, int max) {
        return value < min ? min : (value > max ? max : value);
    }

    public static double clamp(double value, Range<Double> range) {
        return clamp(value,
                     range.hasLowerBound() ? range.lowerEndpoint() : Double.NEGATIVE_INFINITY,
                     range.hasUpperBound() ? range.upperEndpoint() : Double.POSITIVE_INFINITY);
    }

    /**
     * Divide the first argument by the second and round the result up to the next integer.
     * @param numerator     Assumed to be >= 0
     * @param denominator   Assumed to be > 0
     */
    public static int divideRoundingUp(int numerator, int denominator) {
        return (numerator + denominator - 1) / denominator;
    }

    /**
     * Round the first argument up to the next multiple of the second argument
     * @param value         Assumed to be >= 0
     * @param modulus       Assumed to be > 0
     */
    public static int roundUp(int value, int modulus) {
        return divideRoundingUp(value, modulus) * modulus;
    }

    /**
     * Round the first argument up to the next multiple of the second argument
     * @param value         Assumed to be >= 0
     * @param modulus       Assumed to be > 0
     */
    public static int roundDown(int value, int modulus) {
        return (value / modulus) * modulus;
    }

    /**
     * Convert a value in the range 0..1 to a percentage in the range 0..100.
     * The result will only be 0 if the input is exactly 0, and will only be 100
     * if the input is exactly 1.
     */
    public static int percentage(double n) {
        int percent = (int) Math.round(n * 100);
        if(percent == 0 && n != 0) {
            percent = 1;
        } else if(percent == 100 && n != 1) {
            percent = 99;
        }
        return percent;
    }

    public static double square(double n) {
        return n * n;
    }

    public static int ceil(Number n) {
        return (int) Math.ceil(n.doubleValue());
    }

    public static int floor(Number n) {
        return (int) Math.floor(n.doubleValue());
    }
}