/**
* Searches the specified region of chars for the specified value using the binary search
* algorithm. The region <strong>must</strong> be sorted (as by the {@link #sort} method) prior to
* making this call. If it is not sorted, the results are undefined. If the region contains
* multiple elements with the specified value, there is no guarantee which one will be found.
*
* @param a the region to be searched.
* @param key the value to be searched for.
* @return index of the search key, if it is contained in the region; otherwise,
* <tt>(-(<i>insertion point</i>) - 1)</tt>. The <i>insertion point</i> is defined as the
* point at which the key would be inserted into the region: the index of the first element
* greater than the key, or <tt>region.length()</tt>, if all elements in the region are less
* than the specified key. Note that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @see #sort(CharRegion)
*/
public static int binarySearch(CharRegion a, char key) {
char[] arr = a.baseArray();
int low = a.offset();
int high = a.length() - 1;
while (low <= high) {
int mid = (low + high) / 2;
char midVal = arr[mid];
if (midVal < key) low = mid + 1;
else if (midVal > key) high = mid - 1;
else return mid; // key found
}
return -(low + 1); // key not found.
}
/**
* Returns <tt>true</tt> if the two specified regions of chars are <i>equal</i> to one another.
* Two regions are considered equal if both regions contain the same number of elements, and all
* corresponding pairs of elements in the two regions are equal. In other words, two regions are
* equal if they contain the same elements in the same order. Also, two region references are
* considered equal if both are <tt>null</tt>.
*
* <p>
*
* @param a one region to be tested for equality.
* @param a2 the other region to be tested for equality.
* @return <tt>true</tt> if the two regions are equal.
*/
public static boolean equals(CharRegion a, CharRegion a2) {
if (a == a2) return true;
if (a == null || a2 == null) return false;
char[] arr1 = a.baseArray();
char[] arr2 = a2.baseArray();
if (arr1 == arr2) return true;
int length = a.length();
if (a2.length() != length) return false;
for (int i = a.offset(), j = a2.offset(); length-- > 0; i++, j++)
if (arr1[i] != arr2[i]) return false;
return true;
}
/**
* Sorts the specified region of chars into ascending numerical order, using {@link
* Arrays#sort(char[], int, int)} method.
*
* @param a the region to be sorted.
*/
public static void sort(CharRegion a) {
Arrays.sort(a.baseArray(), a.startIdx(), a.endIdx());
}
/**
* Fills the specified region of chars with a specific value, using {@link Arrays#fill(char[],
* int, int, char)} method.
*
* @param a the region to be filled.
*/
public static void fill(CharRegion a, char value) {
Arrays.fill(a.baseArray(), a.startIdx(), a.endIdx(), value);
}
