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package io.legaldocml.unsafe;

import io.legaldocml.util.Strings;
import sun.misc.Unsafe;

/**
 * @author Jacques Militello
 */
public final class UnsafeString {

    /**
     * Unsafe special object.
     */
    private static final Unsafe UNSAFE = UnsafeHelper.getUnsafe();

    /**
     * Field offset of the inner value var in the String class.
     */
    private static final long VALUE_OFFSET = UnsafeHelper.getFieldOffset(String.class, "value");

    /**
     * Empty char.
     */
    private static final char[] EMPTY = new char[0];

    @SuppressWarnings("all")
    private static final sun.misc.JavaLangAccess JAVA_LANG_ACCESS = sun.misc.SharedSecrets.getJavaLangAccess();

    private UnsafeString() {
    }

    public static String buildUnsafe(char[] chars) {
        if (chars == null || chars.length == 0) {
            return Strings.EMPTY;
        }
        String mutable = new String();// an empty string to hack
        UNSAFE.putObject(mutable, VALUE_OFFSET, chars);
        return mutable;
    }

    public static char[] getChars(String s) {
        if (s == null) {
            return EMPTY;
        }
        return (char[]) UNSAFE.getObject(s, VALUE_OFFSET);
    }

    @SuppressWarnings("all")
    public static String valueOf(char[] chars) {
        if (chars == null || chars.length == 0) {
            return Strings.EMPTY;
        }
        return JAVA_LANG_ACCESS.newStringUnsafe(chars);
    }

}