io.questdb.std.str.DirectCharSequence Maven / Gradle / Ivy

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 *
 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2020 QuestDB
 *
 *  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.
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package io.questdb.std.str;

import io.questdb.std.Mutable;
import io.questdb.std.Unsafe;

public class DirectCharSequence extends AbstractCharSequence implements Mutable {
    private long lo;
    private long hi;
    private int len;

    @Override
    public void clear() {
        hi = lo = 0;
    }

    @Override
    public int hashCode() {
        if (lo == hi) {
            return 0;
        }

        int h = 0;
        for (long p = lo; p < hi; p += 2) {
            h = 31 * h + Unsafe.getUnsafe().getChar(p);
        }
        return h;
    }

    @Override
    public CharSequence subSequence(int start, int end) {
        DirectCharSequence seq = new DirectCharSequence();
        seq.lo = this.lo + start;
        seq.hi = this.lo + end;
        return seq;
    }

    @Override
    public int length() {
        return len;
    }

    @Override
    public char charAt(int index) {
        return Unsafe.getUnsafe().getChar(lo + ((long) index << 1));
    }

    public DirectCharSequence of(long lo, long hi) {
        this.lo = lo;
        this.hi = hi;
        this.len = (int) ((hi - lo) / 2);
        return this;
    }
}