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/**

 * @test

 * @bug 8028267

 * @summary Unit tests for the com.sun.tools.javac.util.Bits class.

 * @run main BitsTest

 */

import java.util.Arrays;

import java.util.HashSet;

import java.util.Set;

import com.sun.tools.javac.util.Bits;

public class BitsTest {

    final static int[] samples = { 0, 1, 7, 16, 19, 31, 32, 33, 63, 64 };

    final static int LENGTH = samples[samples.length - 1] + 50;

    public static void main(String... args) throws Exception {

        testIncl();

        testInclRange();

        testDup();

        testClear();

        testExcl();

        testExcludeFrom();

        testBinOps();

        testNextBit();

    }

    // Test Bits.incl

    static void testIncl() {

        for (int a : samples) {

            for (int b : samples) {

                Bits bits = new Bits();

                bits.incl(a);

                if (a != b)

                    bits.incl(b);

                for (int i = 0; i < LENGTH; i++)

                    assert bits.isMember(i) == (i == a || i == b);

            }

        }

    }

    // Test Bits.excl

    static void testExcl() {

        for (int a : samples) {

            for (int b : samples) {

                Bits bits = new Bits();

                bits.inclRange(0, LENGTH);

                bits.excl(a);

                if (a != b)

                    bits.excl(b);

                for (int i = 0; i < LENGTH; i++)

                    assert !bits.isMember(i) == (i == a || i == b);

            }

        }

    }

    // Test Bits.inclRange with various ranges.

    static void testInclRange() {

        for (int i = 0; i < samples.length; i++) {

            for (int j = i; j < samples.length; j++)

                testInclRangeHelper(samples[i], samples[j]);

        }

    }

    // Tests Bits.inclRange for the given range.

    static void testInclRangeHelper(int from, int to) {

        Bits bits = new Bits();

        bits.inclRange(from, to);

        for (int i = 0; i < LENGTH; i++)

            assert bits.isMember(i) == (from <= i && i < to);

    }

    // Test Bits.dup

    static void testDup() {

        Bits bits = sampleBits();

        Bits dupBits = bits.dup();

        assertEquals(LENGTH, bits, dupBits);

    }

    // Make sure Bits.clear clears all bits.

    static void testClear() {

        Bits bits = sampleBits();

        bits.clear();

        for (int i = 0; i < LENGTH; i++)

            assert !bits.isMember(i);

    }

    // Test Bits.excludeFrom

    static void testExcludeFrom() {

        Bits bits = sampleBits();

        int half = samples.length / 2;

        Set<Integer> expected = new HashSet<Integer>();

        for (int i : Arrays.copyOf(samples, half))

            expected.add(i);

        bits.excludeFrom(samples[half]);

        for (int i = 0; i < LENGTH; i++)

            assert bits.isMember(i) == expected.contains(i);

    }

    // Test andSet, orSet, diffSet, xorSet

    static void testBinOps() {

        int[] a = { 1630757163, -592623705 };

        int[] b = { 1062404889, 1969380693 };

        int[] or   = { a[0] | b[0],  a[1] | b[1] };

        int[] and  = { a[0] & b[0],  a[1] & b[1] };

        int[] xor  = { a[0] ^ b[0],  a[1] ^ b[1] };

        int[] diff = { a[0] & ~b[0], a[1] & ~b[1] };

        assertEquals(64, fromInts(a).orSet  (fromInts(b)), fromInts(or));

        assertEquals(64, fromInts(a).andSet (fromInts(b)), fromInts(and));

        assertEquals(64, fromInts(a).xorSet (fromInts(b)), fromInts(xor));

        assertEquals(64, fromInts(a).diffSet(fromInts(b)), fromInts(diff));

    }

    // Create a Bits-instance based on bits in 'ints' argument.

    static Bits fromInts(int[] ints) {

        Bits bits = new Bits();

        for (int bit = 0; bit < ints.length * 32; bit++)

            if ((ints[bit / 32] & (1 << (bit % 32))) != 0)

                bits.incl(bit);

        return bits;

    }

    // Asserts that two Bits-instances are equal up to first 'len' bits.

    static void assertEquals(int len, Bits a, Bits b) {

        for (int i = 0; i < len; i++)

            assert a.isMember(i) == b.isMember(i);

    }

    // Test Bits.nextBit

    static void testNextBit() {

        Bits bits = sampleBits();

        int index = 0;

        for (int bit = 0; bit < LENGTH; bit++) {

            int expected;

            // Passed last sample index?

            if (index < samples.length) {

                expected = samples[index];

                if (bit == samples[index])

                    index++;

            } else {

                expected = -1;

            }

            assert bits.nextBit(bit) == expected;

        }

    }

    // Convenience method: Generate a Bits-instance based on samples.

    static Bits sampleBits() {

        Bits bits = new Bits();

        for (int i : samples)

            bits.incl(i);

        return bits;

    }

}