1/*
2 * Copyright (C) 2010, Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#pragma once
26
27namespace WTF {
28
29// An abstract number of element in a sequence. The sequence has a first element.
30// This type should be used instead of integer because 2 contradicting traditions can
31// call a first element '0' or '1' which makes integer type ambiguous.
32class OrdinalNumber {
33public:
34 static OrdinalNumber beforeFirst() { return OrdinalNumber(-1); }
35 static OrdinalNumber fromZeroBasedInt(int zeroBasedInt) { return OrdinalNumber(zeroBasedInt); }
36 static OrdinalNumber fromOneBasedInt(int oneBasedInt) { return OrdinalNumber(oneBasedInt - 1); }
37
38 OrdinalNumber() : m_zeroBasedValue(0) { }
39
40 int zeroBasedInt() const { return m_zeroBasedValue; }
41 int oneBasedInt() const { return m_zeroBasedValue + 1; }
42
43 bool operator==(OrdinalNumber other) const { return m_zeroBasedValue == other.m_zeroBasedValue; }
44 bool operator!=(OrdinalNumber other) const { return !((*this) == other); }
45 bool operator>(OrdinalNumber other) const { return m_zeroBasedValue > other.m_zeroBasedValue; }
46
47private:
48 OrdinalNumber(int zeroBasedInt) : m_zeroBasedValue(zeroBasedInt) { }
49 int m_zeroBasedValue;
50};
51
52}
53
54using WTF::OrdinalNumber;
55