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 "core/html/forms/StepRange.h"
23
24#include "core/HTMLNames.h"
25#include "core/html/parser/HTMLParserIdioms.h"
26#include "wtf/MathExtras.h"
27#include "wtf/text/WTFString.h"
28#include <float.h>
29
30namespace blink {
31
32using namespace HTMLNames;
33
34StepRange::StepRange()
35    : m_maximum(100)
36    , m_minimum(0)
37    , m_step(1)
38    , m_stepBase(0)
39    , m_hasStep(false)
40{
41}
42
43StepRange::StepRange(const StepRange& stepRange)
44    : m_maximum(stepRange.m_maximum)
45    , m_minimum(stepRange.m_minimum)
46    , m_step(stepRange.m_step)
47    , m_stepBase(stepRange.m_stepBase)
48    , m_stepDescription(stepRange.m_stepDescription)
49    , m_hasStep(stepRange.m_hasStep)
50{
51}
52
53StepRange::StepRange(const Decimal& stepBase, const Decimal& minimum, const Decimal& maximum, const Decimal& step, const StepDescription& stepDescription)
54    : m_maximum(maximum)
55    , m_minimum(minimum)
56    , m_step(step.isFinite() ? step : 1)
57    , m_stepBase(stepBase.isFinite() ? stepBase : 1)
58    , m_stepDescription(stepDescription)
59    , m_hasStep(step.isFinite())
60{
61    ASSERT(m_maximum.isFinite());
62    ASSERT(m_minimum.isFinite());
63    ASSERT(m_step.isFinite());
64    ASSERT(m_stepBase.isFinite());
65}
66
67Decimal StepRange::acceptableError() const
68{
69    // FIXME: We should use DBL_MANT_DIG instead of FLT_MANT_DIG regarding to HTML5 specification.
70    DEFINE_STATIC_LOCAL(const Decimal, twoPowerOfFloatMantissaBits, (Decimal::Positive, 0, UINT64_C(1) << FLT_MANT_DIG));
71    return m_stepDescription.stepValueShouldBe == StepValueShouldBeReal ? m_step / twoPowerOfFloatMantissaBits : Decimal(0);
72}
73
74Decimal StepRange::alignValueForStep(const Decimal& currentValue, const Decimal& newValue) const
75{
76    DEFINE_STATIC_LOCAL(const Decimal, tenPowerOf21, (Decimal::Positive, 21, 1));
77    if (newValue >= tenPowerOf21)
78        return newValue;
79
80    return stepMismatch(currentValue) ? newValue : roundByStep(newValue, m_stepBase);
81}
82
83Decimal StepRange::clampValue(const Decimal& value) const
84{
85    const Decimal inRangeValue = std::max(m_minimum, std::min(value, m_maximum));
86    if (!m_hasStep)
87        return inRangeValue;
88    // Rounds inRangeValue to stepBase + N * step.
89    const Decimal roundedValue = roundByStep(inRangeValue, m_stepBase);
90    const Decimal clampedValue = roundedValue > m_maximum ? roundedValue - m_step : (roundedValue < m_minimum ? roundedValue + m_step : roundedValue);
91    ASSERT(clampedValue >= m_minimum);
92    ASSERT(clampedValue <= m_maximum);
93    return clampedValue;
94}
95
96Decimal StepRange::parseStep(AnyStepHandling anyStepHandling, const StepDescription& stepDescription, const String& stepString)
97{
98    if (stepString.isEmpty())
99        return stepDescription.defaultValue();
100
101    if (equalIgnoringCase(stepString, "any")) {
102        switch (anyStepHandling) {
103        case RejectAny:
104            return Decimal::nan();
105        case AnyIsDefaultStep:
106            return stepDescription.defaultValue();
107        default:
108            ASSERT_NOT_REACHED();
109        }
110    }
111
112    Decimal step = parseToDecimalForNumberType(stepString);
113    if (!step.isFinite() || step <= 0)
114        return stepDescription.defaultValue();
115
116    switch (stepDescription.stepValueShouldBe) {
117    case StepValueShouldBeReal:
118        step *= stepDescription.stepScaleFactor;
119        break;
120    case ParsedStepValueShouldBeInteger:
121        // For date, month, and week, the parsed value should be an integer for some types.
122        step = std::max(step.round(), Decimal(1));
123        step *= stepDescription.stepScaleFactor;
124        break;
125    case ScaledStepValueShouldBeInteger:
126        // For datetime, datetime-local, time, the result should be an integer.
127        step *= stepDescription.stepScaleFactor;
128        step = std::max(step.round(), Decimal(1));
129        break;
130    default:
131        ASSERT_NOT_REACHED();
132    }
133
134    ASSERT(step > 0);
135    return step;
136}
137
138Decimal StepRange::roundByStep(const Decimal& value, const Decimal& base) const
139{
140    return base + ((value - base) / m_step).round() * m_step;
141}
142
143bool StepRange::stepMismatch(const Decimal& valueForCheck) const
144{
145    if (!m_hasStep)
146        return false;
147    if (!valueForCheck.isFinite())
148        return false;
149    const Decimal value = (valueForCheck - m_stepBase).abs();
150    if (!value.isFinite())
151        return false;
152    // Decimal's fractional part size is DBL_MAN_DIG-bit. If the current value
153    // is greater than step*2^DBL_MANT_DIG, the following computation for
154    // remainder makes no sense.
155    DEFINE_STATIC_LOCAL(const Decimal, twoPowerOfDoubleMantissaBits, (Decimal::Positive, 0, UINT64_C(1) << DBL_MANT_DIG));
156    if (value / twoPowerOfDoubleMantissaBits > m_step)
157        return false;
158    // The computation follows HTML5 4.10.7.2.10 `The step attribute' :
159    // ... that number subtracted from the step base is not an integral multiple
160    // of the allowed value step, the element is suffering from a step mismatch.
161    const Decimal remainder = (value - m_step * (value / m_step).round()).abs();
162    // Accepts errors in lower fractional part which IEEE 754 single-precision
163    // can't represent.
164    const Decimal computedAcceptableError = acceptableError();
165    return computedAcceptableError < remainder && remainder < (m_step - computedAcceptableError);
166}
167
168} // namespace blink
169