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| ** |
| ** Copyright (C) 2016 The Qt Company Ltd. |
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| ** This file is part of the QtXmlPatterns module of the Qt Toolkit. |
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| ****************************************************************************/ |
| |
| #include <QString> |
| |
| #include "qcompressedwhitespace_p.h" |
| |
| QT_BEGIN_NAMESPACE |
| |
| using namespace QPatternist; |
| |
| CompressedWhitespace::CharIdentifier CompressedWhitespace::toIdentifier(const QChar ch) |
| { |
| switch(ch.unicode()) |
| { |
| case ' ': |
| return Space; |
| case '\n': |
| return LF; |
| case '\r': |
| return CR; |
| case '\t': |
| return Tab; |
| default: |
| { |
| Q_ASSERT_X(false, Q_FUNC_INFO, |
| "The caller must guarantee only whitespace is passed."); |
| return Tab; |
| } |
| } |
| } |
| |
| bool CompressedWhitespace::isEven(const int number) |
| { |
| Q_ASSERT(number >= 0); |
| return number % 2 == 0; |
| } |
| |
| quint8 CompressedWhitespace::toCompressedChar(const QChar ch, const int len) |
| { |
| Q_ASSERT(len > 0); |
| Q_ASSERT(len <= MaxCharCount); |
| |
| return len + toIdentifier(ch); |
| } |
| |
| QChar CompressedWhitespace::toChar(const CharIdentifier id) |
| { |
| switch(id) |
| { |
| case Space: return QLatin1Char(' '); |
| case CR: return QLatin1Char('\r'); |
| case LF: return QLatin1Char('\n'); |
| case Tab: return QLatin1Char('\t'); |
| default: |
| { |
| Q_ASSERT_X(false, Q_FUNC_INFO, "Unexpected input"); |
| return QChar(); |
| } |
| } |
| } |
| |
| QString CompressedWhitespace::compress(const QStringRef &input) |
| { |
| Q_ASSERT(!isEven(1) && isEven(0) && isEven(2)); |
| Q_ASSERT(!input.isEmpty()); |
| |
| QString result; |
| const int len = input.length(); |
| |
| /* The amount of compressed characters. For instance, if input is |
| * four spaces followed by one tab, compressedChars will be 2, and the resulting |
| * QString will have a length of 1, two compressedChars stored in one QChar. */ |
| int compressedChars = 0; |
| |
| for(int i = 0; i < len; ++i) |
| { |
| const QChar c(input.at(i)); |
| |
| int start = i; |
| |
| while(true) |
| { |
| if(i + 1 == input.length() || input.at(i + 1) != c) |
| break; |
| else |
| ++i; |
| } |
| |
| /* The length of subsequent whitespace characters in the input. */ |
| int wsLen = (i - start) + 1; |
| |
| /* We might get a sequence of whitespace that is so long, that we can't |
| * store it in one unit/byte. In that case we chop it into as many subsequent |
| * ones that is needed. */ |
| while(true) |
| { |
| const int unitLength = qMin(wsLen, int(MaxCharCount)); |
| wsLen -= unitLength; |
| |
| ushort resultCP = toCompressedChar(c, unitLength); |
| |
| if(isEven(compressedChars)) |
| result += QChar(resultCP); |
| else |
| { |
| resultCP = resultCP << 8; |
| resultCP |= result.at(result.size() - 1).unicode(); |
| result[result.size() - 1] = resultCP; |
| } |
| |
| ++compressedChars; |
| |
| if(wsLen == 0) |
| break; |
| } |
| } |
| |
| return result; |
| } |
| |
| QString CompressedWhitespace::decompress(const QString &input) |
| { |
| Q_ASSERT(!input.isEmpty()); |
| const int len = input.length() * 2; |
| QString retval; |
| |
| for(int i = 0; i < len; ++i) |
| { |
| ushort cp = input.at(i / 2).unicode(); |
| |
| if(isEven(i)) |
| cp &= Lower8Bits; |
| else |
| { |
| cp = cp >> 8; |
| |
| if(cp == 0) |
| return retval; |
| } |
| |
| const quint8 wsLen = cp & Lower6Bits; |
| const quint8 id = cp & UpperTwoBits; |
| |
| /* Resize retval, and fill in on the top. */ |
| const int oldSize = retval.size(); |
| const int newSize = retval.size() + wsLen; |
| retval.resize(newSize); |
| const QChar ch(toChar(CharIdentifier(id))); |
| |
| for(int f = oldSize; f < newSize; ++f) |
| retval[f] = ch; |
| } |
| |
| return retval; |
| } |
| |
| QT_END_NAMESPACE |
| |