Source/WebCore/platform/Length.cpp

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2001 Dirk Mueller ( mueller@kde.org )
 * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2014 Apple Inc. All rights reserved.
 * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "config.h"
#include "Length.h"

#include "CalculationValue.h"
#include <wtf/ASCIICType.h>
#include <wtf/HashMap.h>
#include <wtf/NeverDestroyed.h>
#include <wtf/StdLibExtras.h>
#include <wtf/text/StringBuffer.h>
#include <wtf/text/StringView.h>

using namespace WTF;

namespace WebCore {

static Length parseLength(const UChar* data, unsigned length)
{
    if (length == 0)
        return Length(1, Relative);

    unsigned i = 0;
    while (i < length && isSpaceOrNewline(data[i]))
        ++i;
    if (i < length && (data[i] == '+' || data[i] == '-'))
        ++i;
    while (i < length && isASCIIDigit(data[i]))
        ++i;
    unsigned intLength = i;
    while (i < length && (isASCIIDigit(data[i]) || data[i] == '.'))
        ++i;
    unsigned doubleLength = i;

    // IE quirk: Skip whitespace between the number and the % character (20 % => 20%).
    while (i < length && isSpaceOrNewline(data[i]))
        ++i;

    bool ok;
    UChar next = (i < length) ? data[i] : ' ';
    if (next == '%') {
        // IE quirk: accept decimal fractions for percentages.
        double r = charactersToDouble(data, doubleLength, &ok);
        if (ok)
            return Length(r, Percent);
        return Length(1, Relative);
    }
    int r = charactersToIntStrict(data, intLength, &ok);
    if (next == '*') {
        if (ok)
            return Length(r, Relative);
        return Length(1, Relative);
    }
    if (ok)
        return Length(r, Fixed);
    return Length(0, Relative);
}

static unsigned countCharacter(StringImpl& string, UChar character)
{
    unsigned count = 0;
    unsigned length = string.length();
    for (unsigned i = 0; i < length; ++i)
        count += string[i] == character;
    return count;
}

std::unique_ptr<Length[]> newCoordsArray(const String& string, int& len)
{
    unsigned length = string.length();
    StringBuffer<UChar> spacified(length);
    for (unsigned i = 0; i < length; i++) {
        UChar cc = string[i];
        if (cc > '9' || (cc < '0' && cc != '-' && cc != '*' && cc != '.'))
            spacified[i] = ' ';
        else
            spacified[i] = cc;
    }
    RefPtr<StringImpl> str = StringImpl::adopt(spacified);

    str = str->simplifyWhiteSpace();

    len = countCharacter(*str, ' ') + 1;
    auto r = std::make_unique<Length[]>(len);

    int i = 0;
    unsigned pos = 0;
    size_t pos2;

    auto upconvertedCharacters = StringView(str.get()).upconvertedCharacters();
    while ((pos2 = str->find(' ', pos)) != notFound) {
        r[i++] = parseLength(upconvertedCharacters + pos, pos2 - pos);
        pos = pos2+1;
    }
    r[i] = parseLength(upconvertedCharacters + pos, str->length() - pos);

    ASSERT(i == len - 1);

    return r;
}

std::unique_ptr<Length[]> newLengthArray(const String& string, int& len)
{
    RefPtr<StringImpl> str = string.impl()->simplifyWhiteSpace();
    if (!str->length()) {
        len = 1;
        return nullptr;
    }

    len = countCharacter(*str, ',') + 1;
    auto r = std::make_unique<Length[]>(len);

    int i = 0;
    unsigned pos = 0;
    size_t pos2;

    auto upconvertedCharacters = StringView(str.get()).upconvertedCharacters();
    while ((pos2 = str->find(',', pos)) != notFound) {
        r[i++] = parseLength(upconvertedCharacters + pos, pos2 - pos);
        pos = pos2+1;
    }

    ASSERT(i == len - 1);

    // IE Quirk: If the last comma is the last char skip it and reduce len by one.
    if (str->length()-pos > 0)
        r[i] = parseLength(upconvertedCharacters + pos, str->length() - pos);
    else
        len--;

    return r;
}

class CalculationValueMap {
public:
    CalculationValueMap();

    unsigned insert(PassRef<CalculationValue>);
    void ref(unsigned handle);
    void deref(unsigned handle);

    CalculationValue& get(unsigned handle) const;

private:
    struct Entry {
        uint64_t referenceCountMinusOne;
        CalculationValue* value;
        Entry();
        Entry(CalculationValue&);
    };

    unsigned m_nextAvailableHandle;
    HashMap<unsigned, Entry> m_map;
};

inline CalculationValueMap::Entry::Entry()
    : referenceCountMinusOne(0)
    , value(nullptr)
{
}

inline CalculationValueMap::Entry::Entry(CalculationValue& value)
    : referenceCountMinusOne(0)
    , value(&value)
{
}

inline CalculationValueMap::CalculationValueMap()
    : m_nextAvailableHandle(1)
{
}
    
inline unsigned CalculationValueMap::insert(PassRef<CalculationValue> value)
{
    ASSERT(m_nextAvailableHandle);

    // The leakRef below is balanced by the adoptRef in the deref member function.
    Entry leakedValue = value.leakRef();

    // FIXME: This monotonically increasing handle generation scheme is potentially wasteful
    // of the handle space. Consider reusing empty handles. https://bugs.webkit.org/show_bug.cgi?id=80489
    while (!m_map.isValidKey(m_nextAvailableHandle) || !m_map.add(m_nextAvailableHandle, leakedValue).isNewEntry)
        ++m_nextAvailableHandle;

    return m_nextAvailableHandle++;
}

inline CalculationValue& CalculationValueMap::get(unsigned handle) const
{
    ASSERT(m_map.contains(handle));

    return *m_map.find(handle)->value.value;
}

inline void CalculationValueMap::ref(unsigned handle)
{
    ASSERT(m_map.contains(handle));

    ++m_map.find(handle)->value.referenceCountMinusOne;
}

inline void CalculationValueMap::deref(unsigned handle)
{
    ASSERT(m_map.contains(handle));

    auto it = m_map.find(handle);
    if (it->value.referenceCountMinusOne) {
        --it->value.referenceCountMinusOne;
        return;
    }

    // The adoptRef here is balanced by the leakRef in the insert member function.
    Ref<CalculationValue> value { adoptRef(*it->value.value) };

    m_map.remove(it);
}

static CalculationValueMap& calculationValues()
{
    static NeverDestroyed<CalculationValueMap> map;
    return map;
}

Length::Length(PassRef<CalculationValue> value)
    : m_hasQuirk(false)
    , m_type(Calculated)
    , m_isFloat(false)
{
    m_calculationValueHandle = calculationValues().insert(std::move(value));
}
        
Length Length::blendMixedTypes(const Length& from, double progress) const
{
    if (progress <= 0.0)
        return from;
        
    if (progress >= 1.0)
        return *this;
        
    auto blend = std::make_unique<CalcExpressionBlendLength>(from, *this, progress);
    return Length(CalculationValue::create(std::move(blend), CalculationRangeAll));
}

CalculationValue& Length::calculationValue() const
{
    ASSERT(isCalculated());
    return calculationValues().get(m_calculationValueHandle);
}
    
void Length::ref() const
{
    ASSERT(isCalculated());
    calculationValues().ref(m_calculationValueHandle);
}

void Length::deref() const
{
    ASSERT(isCalculated());
    calculationValues().deref(m_calculationValueHandle);
}

float Length::nonNanCalculatedValue(int maxValue) const
{
    ASSERT(isCalculated());
    float result = calculationValue().evaluate(maxValue);
    if (std::isnan(result))
        return 0;
    return result;
}

bool Length::isCalculatedEqual(const Length& other) const
{
    return calculationValue() == other.calculationValue();
}

struct SameSizeAsLength {
    int32_t value;
    int32_t metaData;
};
COMPILE_ASSERT(sizeof(Length) == sizeof(SameSizeAsLength), length_should_stay_small);

} // namespace WebCore