Source/WebCore/html/track/VTTScanner.cpp

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#include "config.h"
#include "VTTScanner.h"

#include <wtf/text/StringToIntegerConversion.h>

namespace WebCore {

VTTScanner::VTTScanner(const String& line)
    : m_is8Bit(line.is8Bit())
{
    if (m_is8Bit) {
        m_data.characters8 = line.characters8();
        m_end.characters8 = m_data.characters8 + line.length();
    } else {
        m_data.characters16 = line.characters16();
        m_end.characters16 = m_data.characters16 + line.length();
    }
}

bool VTTScanner::scan(char c)
{
    if (!match(c))
        return false;
    advance();
    return true;
}

bool VTTScanner::scan(const LChar* characters, size_t charactersCount)
{
    unsigned matchLength = m_is8Bit ? m_end.characters8 - m_data.characters8 : m_end.characters16 - m_data.characters16;
    if (matchLength < charactersCount)
        return false;
    bool matched;
    if (m_is8Bit)
        matched = WTF::equal(m_data.characters8, characters, charactersCount);
    else
        matched = WTF::equal(m_data.characters16, characters, charactersCount);
    if (matched)
        advance(charactersCount);
    return matched;
}

bool VTTScanner::scanRun(const Run& run, const String& toMatch)
{
    ASSERT(run.start() == position());
    ASSERT(run.start() <= end());
    ASSERT(run.end() >= run.start());
    ASSERT(run.end() <= end());
    size_t matchLength = run.length();
    if (toMatch.length() > matchLength)
        return false;
    bool matched;
    if (m_is8Bit)
        matched = WTF::equal(toMatch.impl(), m_data.characters8, matchLength);
    else
        matched = WTF::equal(toMatch.impl(), m_data.characters16, matchLength);
    if (matched)
        seekTo(run.end());
    return matched;
}

void VTTScanner::skipRun(const Run& run)
{
    ASSERT(run.start() <= end());
    ASSERT(run.end() >= run.start());
    ASSERT(run.end() <= end());
    seekTo(run.end());
}

String VTTScanner::extractString(const Run& run)
{
    ASSERT(run.start() == position());
    ASSERT(run.start() <= end());
    ASSERT(run.end() >= run.start());
    ASSERT(run.end() <= end());
    String s;
    if (m_is8Bit)
        s = String(m_data.characters8, run.length());
    else
        s = String(m_data.characters16, run.length());
    seekTo(run.end());
    return s;
}

String VTTScanner::restOfInputAsString()
{
    Run rest(position(), end(), m_is8Bit);
    return extractString(rest);
}

unsigned VTTScanner::scanDigits(int& number)
{
    Run runOfDigits = collectWhile<isASCIIDigit>();
    if (runOfDigits.isEmpty()) {
        number = 0;
        return 0;
    }

    StringView string;
    unsigned numDigits = runOfDigits.length();
    if (m_is8Bit)
        string = { m_data.characters8, numDigits };
    else
        string = { m_data.characters16, numDigits };

    // Since these are ASCII digits, the only failure mode is overflow, so use the maximum int value.
    number = parseInteger<int>(string).value_or(std::numeric_limits<int>::max());

    // Consume the digits.
    seekTo(runOfDigits.end());
    return numDigits;
}

bool VTTScanner::scanFloat(float& number, bool* isNegative)
{
    bool negative = scan('-');
    Run integerRun = collectWhile<isASCIIDigit>();

    seekTo(integerRun.end());
    Run decimalRun(position(), position(), m_is8Bit);
    if (scan('.')) {
        decimalRun = collectWhile<isASCIIDigit>();
        seekTo(decimalRun.end());
    }

    // At least one digit required.
    if (integerRun.isEmpty() && decimalRun.isEmpty()) {
        // Restore to starting position.
        seekTo(integerRun.start());
        return false;
    }

    size_t lengthOfFloat = Run(integerRun.start(), position(), m_is8Bit).length();
    bool validNumber;
    if (m_is8Bit)
        number = charactersToFloat(integerRun.start(), lengthOfFloat, &validNumber);
    else
        number = charactersToFloat(reinterpret_cast<const UChar*>(integerRun.start()), lengthOfFloat, &validNumber);

    if (!validNumber)
        number = std::numeric_limits<float>::max();
    else if (negative)
        number = -number;

    if (isNegative)
        *isNegative = negative;

    return true;
}

}