1/*
2 * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public License
15 * along with this library; see the file COPYING.LIB.  If not, write to
16 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
17 * Boston, MA 02110-1301, USA.
18 *
19 */
20
21#include "config.h"
22#include "StepRange.h"
23
24#include "HTMLNames.h"
25#include "HTMLParserIdioms.h"
26#include <wtf/MathExtras.h>
27#include <wtf/text/WTFString.h>
28
29using namespace std;
30
31namespace WebCore {
32
33using namespace HTMLNames;
34
35StepRange::StepRange()
36    : m_maximum(100)
37    , m_minimum(0)
38    , m_step(1)
39    , m_stepBase(0)
40    , m_hasStep(false)
41{
42}
43
44StepRange::StepRange(const StepRange& stepRange)
45    : m_maximum(stepRange.m_maximum)
46    , m_minimum(stepRange.m_minimum)
47    , m_step(stepRange.m_step)
48    , m_stepBase(stepRange.m_stepBase)
49    , m_stepDescription(stepRange.m_stepDescription)
50    , m_hasStep(stepRange.m_hasStep)
51{
52}
53
54StepRange::StepRange(const Decimal& stepBase, const Decimal& minimum, const Decimal& maximum, const Decimal& step, const StepDescription& stepDescription)
55    : m_maximum(maximum)
56    , m_minimum(minimum)
57    , m_step(step.isFinite() ? step : 1)
58    , m_stepBase(stepBase.isFinite() ? stepBase : 1)
59    , m_stepDescription(stepDescription)
60    , m_hasStep(step.isFinite())
61{
62    ASSERT(m_maximum.isFinite());
63    ASSERT(m_minimum.isFinite());
64    ASSERT(m_step.isFinite());
65    ASSERT(m_stepBase.isFinite());
66}
67
68Decimal StepRange::acceptableError() const
69{
70    // FIXME: We should use DBL_MANT_DIG instead of FLT_MANT_DIG regarding to HTML5 specification.
71    DEFINE_STATIC_LOCAL(const Decimal, twoPowerOfFloatMantissaBits, (Decimal::Positive, 0, UINT64_C(1) << FLT_MANT_DIG));
72    return m_stepDescription.stepValueShouldBe == StepValueShouldBeReal ? m_step / twoPowerOfFloatMantissaBits : Decimal(0);
73}
74
75Decimal StepRange::alignValueForStep(const Decimal& currentValue, const Decimal& newValue) const
76{
77    DEFINE_STATIC_LOCAL(const Decimal, tenPowerOf21, (Decimal::Positive, 21, 1));
78    if (newValue >= tenPowerOf21)
79        return newValue;
80
81    return stepMismatch(currentValue) ? newValue : roundByStep(newValue, m_stepBase);
82}
83
84Decimal StepRange::clampValue(const Decimal& value) const
85{
86    const Decimal inRangeValue = max(m_minimum, min(value, m_maximum));
87    if (!m_hasStep)
88        return inRangeValue;
89    // Rounds inRangeValue to minimum + N * step.
90    const Decimal roundedValue = roundByStep(inRangeValue, m_minimum);
91    const Decimal clampedValue = roundedValue > m_maximum ? roundedValue - m_step : roundedValue;
92    ASSERT(clampedValue >= m_minimum);
93    ASSERT(clampedValue <= m_maximum);
94    return clampedValue;
95}
96
97Decimal StepRange::parseStep(AnyStepHandling anyStepHandling, const StepDescription& stepDescription, const String& stepString)
98{
99    if (stepString.isEmpty())
100        return stepDescription.defaultValue();
101
102    if (equalIgnoringCase(stepString, "any")) {
103        switch (anyStepHandling) {
104        case RejectAny:
105            return Decimal::nan();
106        case AnyIsDefaultStep:
107            return stepDescription.defaultValue();
108        default:
109            ASSERT_NOT_REACHED();
110        }
111    }
112
113    Decimal step = parseToDecimalForNumberType(stepString);
114    if (!step.isFinite() || step <= 0)
115        return stepDescription.defaultValue();
116
117    switch (stepDescription.stepValueShouldBe) {
118    case StepValueShouldBeReal:
119        step *= stepDescription.stepScaleFactor;
120        break;
121    case ParsedStepValueShouldBeInteger:
122        // For date, month, and week, the parsed value should be an integer for some types.
123        step = max(step.round(), Decimal(1));
124        step *= stepDescription.stepScaleFactor;
125        break;
126    case ScaledStepValueShouldBeInteger:
127        // For datetime, datetime-local, time, the result should be an integer.
128        step *= stepDescription.stepScaleFactor;
129        step = max(step.round(), Decimal(1));
130        break;
131    default:
132        ASSERT_NOT_REACHED();
133    }
134
135    ASSERT(step > 0);
136    return step;
137}
138
139Decimal StepRange::roundByStep(const Decimal& value, const Decimal& base) const
140{
141    return base + ((value - base) / m_step).round() * m_step;
142}
143
144bool StepRange::stepMismatch(const Decimal& valueForCheck) const
145{
146    if (!m_hasStep)
147        return false;
148    if (!valueForCheck.isFinite())
149        return false;
150    const Decimal value = (valueForCheck - m_stepBase).abs();
151    if (!value.isFinite())
152        return false;
153    // Decimal's fractional part size is DBL_MAN_DIG-bit. If the current value
154    // is greater than step*2^DBL_MANT_DIG, the following computation for
155    // remainder makes no sense.
156    DEFINE_STATIC_LOCAL(const Decimal, twoPowerOfDoubleMantissaBits, (Decimal::Positive, 0, UINT64_C(1) << DBL_MANT_DIG));
157    if (value / twoPowerOfDoubleMantissaBits > m_step)
158        return false;
159    // The computation follows HTML5 4.10.7.2.10 `The step attribute' :
160    // ... that number subtracted from the step base is not an integral multiple
161    // of the allowed value step, the element is suffering from a step mismatch.
162    const Decimal remainder = (value - m_step * (value / m_step).round()).abs();
163    // Accepts erros in lower fractional part which IEEE 754 single-precision
164    // can't represent.
165    const Decimal computedAcceptableError = acceptableError();
166    return computedAcceptableError < remainder && remainder < (m_step - computedAcceptableError);
167}
168
169} // namespace WebCore
170