com.google.ical.iter.IntSet Maven / Gradle / Ivy
// Copyright (C) 2006 Google Inc.
//
// 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 com.google.ical.iter;
import java.util.BitSet;
/**
* a set of integers in a small range.
*
* @author [email protected] (Mike Samuel)
*/
final class IntSet {
BitSet ints = new BitSet();
void add(int n) {
ints.set(encode(n));
}
int encode(int n) {
return n < 0 ? ((-n << 1) + 1) : (n << 1);
}
int decode(int i) {
return (i >>> 1) * (-(i & 1) | 1);
}
boolean contains(int n) {
return ints.get(encode(n));
}
int size() { return ints.cardinality(); }
int[] toIntArray() {
int[] out = new int[ints.cardinality()];
int a = 0, b = out.length;
for (int i = -1; (i = ints.nextSetBit(i + 1)) >= 0;) {
int n = decode(i);
if (n < 0) {
out[a++] = n;
} else {
out[--b] = n;
}
}
// if it contains -3, -1, 0, 1, 2, 4
// Then out will be -1, -3, 4, 2, 1, 0
reverse(out, 0, a);
reverse(out, a, out.length);
return out;
}
private static void reverse(int[] arr, int s, int e) {
for (int i = s, j = e; i < --j; ++i) {
int t = arr[i];
arr[i] = arr[j];
arr[j] = t;
}
}
}