Package com.blackrook.expression.struct

Class Utils

java.lang.Object

com.blackrook.expression.struct.Utils

public final class Utils
extends Object

Constructor Summary

Constructors

Constructor	Description
Utils()

Method Summary

Modifier and Type	Method	Description
static <T> void	arraySwap(T[] array, int a, int b)	Swaps the contents of two indices of an array.
static double	clampValue(double val, double lo, double hi)	Coerces a double to the range bounded by lo and hi.
static double	degToRad(double degrees)	Converts degrees to radians.
static byte[]	digest(byte[] bytes, String algorithmName)	Returns a hash of a set of bytes digested by an encryption algorithm.
static boolean	isEmpty(Object obj)	Checks if a value is "empty." The following is considered "empty": Null references.
static double	linearInterpolate(double factor, double x, double y)	Gives a value that is the result of a linear interpolation between two values.
static double	radToDeg(double radians)	Converts radians to degrees.
static byte[]	sha1(byte[] bytes)	Returns a 20-byte SHA-1 hash of a set of bytes.
static <T extends Comparable<T>> int	sortFrom(T[] array, int index)	Shifts an object to an appropriate position according to the object's Comparable.compareTo(Object) function.
static <T> int	sortFrom(T[] array, int index, Comparator<? super T> comparator)	Shifts an object to an appropriate position according to the provided comparator function.
static double	wrapValue(double val, double lo, double hi)	Coerces a double to the range bounded by lo and hi, by "wrapping" the value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Utils

public Utils()

Method Detail

isEmpty

public static boolean isEmpty(Object obj)

Checks if a value is "empty." The following is considered "empty":

• Null references.
• Array objects that have a length of 0.
• Boolean objects that are false.
• Character objects that are the null character ('\0', '').
• Number objects that are zero.
• String objects that are the empty string, or are String.trim()'ed down to the empty string.
• Collection objects where Collection.isEmpty() returns true.

Parameters:

obj - the object to check.

Returns:

true if the provided object is considered "empty", false otherwise.

sortFrom

public static <T extends Comparable<T>> int sortFrom(T[] array,
                                                     int index)

Shifts an object to an appropriate position according to the object's Comparable.compareTo(Object) function.

Type Parameters:

T - the object type stored in the array that extends Comparable.

Parameters:

array - the array to shift the contents of.

index - the index to add it to (the contents are replaced).

Returns:

the final index in the array of the sorted object.

sortFrom

public static <T> int sortFrom(T[] array,
                               int index,
                               Comparator<? super T> comparator)

Shifts an object to an appropriate position according to the provided comparator function.

Type Parameters:

T - the object type stored in the arrays.

Parameters:

array - the array to shift the contents of.

index - the index to add it to (the contents are replaced).

comparator - the comparator to use.

Returns:

the final index in the array of the sorted object.

arraySwap

public static <T> void arraySwap(T[] array,
                                 int a,
                                 int b)

Swaps the contents of two indices of an array.

Type Parameters:

T - the object type stored in the array.

Parameters:

array - the input array.

a - the first index.

b - the second index.

digest

public static byte[] digest(byte[] bytes,
                            String algorithmName)

Returns a hash of a set of bytes digested by an encryption algorithm. Can return null if this Java implementation cannot perform this. Do not use this if you care if the algorithm is provided or not.

Parameters:

bytes - the bytes to encode.

algorithmName - the name to the algorithm to use.

Returns:

the resultant byte digest, or null if the algorithm is not supported.

sha1

public static byte[] sha1(byte[] bytes)

Returns a 20-byte SHA-1 hash of a set of bytes. Can return null if this Java implementation cannot perform this, but it shouldn't, since SHA-1 is mandatorily implemented for all implementations.

Parameters:

bytes - the input bytes.

Returns:

the resultant 20-byte digest.

See Also:

digest(byte[], String)

radToDeg

public static double radToDeg(double radians)

Converts radians to degrees.

Parameters:

radians - the input angle in radians.

Returns:

the resultant angle in degrees.

degToRad

public static double degToRad(double degrees)

Converts degrees to radians.

Parameters:

degrees - the input angle in degrees.

Returns:

the resultant angle in radians.

clampValue

public static double clampValue(double val,
                                double lo,
                                double hi)

Coerces a double to the range bounded by lo and hi.
Example: clampValue(32,-16,16) returns 16.
Example: clampValue(4,-16,16) returns 4.
Example: clampValue(-1000,-16,16) returns -16.

Parameters:

val - the double.

lo - the lower bound.

hi - the upper bound.

Returns:

the value after being "forced" into the range.

wrapValue

public static double wrapValue(double val,
                               double lo,
                               double hi)

Coerces a double to the range bounded by lo and hi, by "wrapping" the value.
Example: wrapValue(32,-16,16) returns 0.
Example: wrapValue(4,-16,16) returns 4.
Example: wrapValue(-1000,-16,16) returns 8.

Parameters:

val - the double.

lo - the lower bound.

hi - the upper bound.

Returns:

the value after being "wrapped" into the range.

linearInterpolate

public static double linearInterpolate(double factor,
                                       double x,
                                       double y)

Gives a value that is the result of a linear interpolation between two values.

Parameters:

factor - the interpolation factor.

x - the first value.

y - the second value.

Returns:

the interpolated value.