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/*
 * @test
 * @bug 8358066
 * @summary Test for bug in Convert.utfNumChars()
 * @modules jdk.compiler/com.sun.tools.javac.util
 * @run main TestUtfNumChars
 */

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

import java.util.function.IntPredicate;
import java.util.stream.IntStream;

public class TestUtfNumChars {

    public static void main(String[] args) {

        // This is the string "ab«cd≤ef🟢gh"
        String s = "ab\u00ABcd\u2264ef\ud83d\udd34gh";

        // This is its modified UTF-8 encoding
        byte[] utf8 = Convert.string2utf(s);    // UTF-8: 61 62 c2 ab 63 64 e2 89 a4 65 66 ed a0 bd ed b4 b4 67 68
                                                // Bytes: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
                                                // Chars: 00 01 02 .. 03 04 05 .. .. 06 07 08 .. .. 09 .. .. 10 11

        // These are the offsets in "utf8" marking the boundaries of encoded Java charcters
        int[] offsets = new int[] {
            0, 1, 2, 4, 5, 6, 9, 10, 11, 14, 17, 18
        };
        IntPredicate boundary = off -> off == utf8.length || IntStream.of(offsets).anyMatch(off2 -> off2 == off);

        // Check Convert.utfNumChars() on every subsequence
        for (int i = 0; i < offsets.length; i++) {
            int i_off = offsets[i];
            if (!boundary.test(i_off))
                continue;
            for (int j = i; j < offsets.length; j++) {
                int j_off = offsets[j];
                if (!boundary.test(j_off))
                    continue;
                int nchars = Convert.utfNumChars(utf8, i_off, j_off - i_off);
                if (nchars != j - i)
                    throw new AssertionError(String.format("nchars %d != %d for [%d, %d)", nchars, j - i, i_off, j_off));
            }
        }
    }
}