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/NeverDestroyed.h>
28
29namespace WebCore {
30
31using namespace HTMLNames;
32
33StepRange::StepRange()
34 : m_maximum(100)
35 , m_minimum(0)
36 , m_step(1)
37 , m_stepBase(0)
38 , m_stepDescription()
39{
40}
41
42StepRange::StepRange(const StepRange& stepRange)
43 : m_maximum(stepRange.m_maximum)
44 , m_minimum(stepRange.m_minimum)
45 , m_step(stepRange.m_step)
46 , m_stepBase(stepRange.m_stepBase)
47 , m_stepDescription(stepRange.m_stepDescription)
48 , m_hasRangeLimitations(stepRange.m_hasRangeLimitations)
49 , m_hasStep(stepRange.m_hasStep)
50{
51}
52
53StepRange::StepRange(const Decimal& stepBase, RangeLimitations rangeLimitations, 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_hasRangeLimitations(rangeLimitations == RangeLimitations::Valid)
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 static NeverDestroyed<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 static NeverDestroyed<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 = std::max(m_minimum, std::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 (equalLettersIgnoringASCIICase(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 = std::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 = std::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 static NeverDestroyed<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