qqmldompath.cpp

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// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "qqmldomitem_p.h"
#include "qqmldomerrormessage_p.h"
#include <QtCore/QDebug>
#include <QtCore/QTextStream>
#include <QtCore/QChar>
 
#include <cstdint>
 
QT_BEGIN_NAMESPACE
namespace QQmlJS {
namespace Dom {
class ErrorMessage;
 
namespace PathEls {
 
void Base::dump(Sink sink) const {
    if (hasSquareBrackets())
        sink(u"[");
    sink(name());
    if (hasSquareBrackets())
        sink(u"]");
}
 
Filter::Filter(function<bool(DomItem)> f, QStringView filterDescription): filterFunction(f), filterDescription(filterDescription) {}
 
QString Filter::name() const {
    return QLatin1String("?(%1)").arg(filterDescription); }
 
bool Filter::checkName(QStringView s) const
{
    return s.startsWith(u"?(")
            && s.mid(2, s.size()-3) == filterDescription
            && s.endsWith(u")");
}
 
enum class ParserState{
    Start,
    IndexOrKey,
    End
};
 
PathComponent::~PathComponent(){
}
 
int PathComponent::cmp(const PathComponent &p1, const PathComponent &p2)
{
    int k1 = static_cast<int>(p1.kind());
    int k2 = static_cast<int>(p2.kind());
    if (k1 < k2)
        return -1;
    if (k1 > k2)
        return 1;
    switch (p1.kind()) {
    case Kind::Empty:
        return 0;
    case Kind::Field:
        return p1.data.field.fieldName.compare(p2.data.field.fieldName);
    case Kind::Index:
        if (p1.data.index.indexValue < p2.data.index.indexValue)
            return -1;
        if (p1.data.index.indexValue > p2.data.index.indexValue)
            return 1;
        return 0;
    case Kind::Key:
        return p1.data.key.keyValue.compare(p2.data.key.keyValue);
    case Kind::Root:
    {
        PathRoot k1 = p1.data.root.contextKind;
        PathRoot k2 = p2.data.root.contextKind;
        if (k1 == PathRoot::Env || k1 == PathRoot::Universe)
            k1 = PathRoot::Top;
        if (k2 == PathRoot::Env || k2 == PathRoot::Universe)
            k2 = PathRoot::Top;
        int c = int(k1) - int(k2);
        if (c != 0)
            return c;
        return p1.data.root.contextName.compare(p2.data.root.contextName);
    }
    case Kind::Current:
    {
        int c = int(p1.data.current.contextKind) - int(p2.data.current.contextKind);
        if (c != 0)
            return c;
        return p1.data.current.contextName.compare(p2.data.current.contextName);
    }
    case Kind::Any:
        return 0;
    case Kind::Filter:
    {
        int c = p1.data.filter.filterDescription.compare(p2.data.filter.filterDescription);
        if (c != 0)
            return c;
        if (p1.data.filter.filterDescription.startsWith(u"<")) {
            // assuming non comparable native code (target comparison is not portable)
            auto pp1 = &p1;
            auto pp2 = &p2;
            if (pp1 < pp2)
                return -1;
            if (pp1 > pp2)
                return 1;
        }
        return 0;
    }
    }
    Q_ASSERT(false && "unexpected PathComponent in PathComponent::cmp");
    return 0;
}
 
} // namespace PathEls
 
const PathEls::PathComponent &Path::component(int i) const
{
    static Component emptyComponent;
    if (i < 0)
        i += m_length;
    if (i >= m_length || i < 0) {
        Q_ASSERT(false && "index out of bounds");
        return emptyComponent;
    }
    i = i - m_length - m_endOffset;
    auto data = m_data.get();
    while (data) {
        i += data->components.size();
        if (i >= 0)
            return std::as_const(data)->components[i];
        data = data->parent.get();
    }
    Q_ASSERT(false && "Invalid data reached while resolving a seemengly valid index in Path (inconsisten Path object)");
    return emptyComponent;
}
 
Path Path::operator[](int i) const
{
    return mid(i,1);
}
 
QQmlJS::Dom::Path::operator bool() const
{
    return length() != 0;
}
 
PathIterator Path::begin() const
{
    return PathIterator{*this};
}
 
PathIterator Path::end() const
{
    return PathIterator();
}
 
PathRoot Path::headRoot() const
{
    auto &comp = component(0);
    if (PathEls::Root const * r = comp.base()->asRoot())
        return r->contextKind;
    return PathRoot::Other;
}
 
PathCurrent Path::headCurrent() const
{
    auto comp = component(0);
    if (PathEls::Current const * c = comp.base()->asCurrent())
        return c->contextKind;
    return PathCurrent::Other;
}
 
Path::Kind Path::headKind() const
{
    if (m_length == 0)
        return Path::Kind::Empty;
    return component(0).kind();
}
 
QString Path::headName() const
{
    return component(0).name();
}
 
bool Path::checkHeadName(QStringView name) const
{
    return component(0).checkName(name);
}
 
index_type Path::headIndex(index_type defaultValue) const
{
    return component(0).index(defaultValue);
}
 
function<bool (DomItem)> Path::headFilter() const
{
    auto &comp = component(0);
    if (PathEls::Filter const * f = comp.base()->asFilter()) {
        return f->filterFunction;
    }
    return {};
}
 
Path Path::head() const
{
    return mid(0,1);
}
 
Path Path::last() const
{
    return mid(m_length-1, 1);
}
 
Source Path::split() const
{
    int i = length();
    while (i>0) {
        const PathEls::PathComponent &c=component(--i);
        if (c.kind() == Kind::Field || c.kind() == Kind::Root || c.kind() == Kind::Current) {
            return Source{mid(0, i), mid(i)};
        }
    }
    return Source{Path(), *this};
}
 
bool inQString(QStringView el, QString base)
{
    if (quintptr(base.constData()) > quintptr(el.begin())
        || quintptr(base.constData() + base.size()) < quintptr(el.begin()))
        return false;
    ptrdiff_t diff = base.constData() - el.begin();
    return diff >= 0 && diff < base.size();
}
 
bool inQString(QString el, QString base)
{
    if (quintptr(base.constData()) > quintptr(el.constData())
        || quintptr(base.constData() + base.size()) < quintptr(el.constData()))
        return false;
    ptrdiff_t diff = base.constData() - el.constData();
    return diff >= 0 && diff < base.size() && diff + el.size() < base.size();
}
 
Path Path::fromString(QStringView s, ErrorHandler errorHandler)
{
    if (s.isEmpty())
        return Path();
    int len=1;
    const QChar dot = QChar::fromLatin1('.');
    const QChar lsBrace = QChar::fromLatin1('[');
    const QChar rsBrace = QChar::fromLatin1(']');
    const QChar dollar = QChar::fromLatin1('$');
    const QChar at = QChar::fromLatin1('@');
    const QChar quote = QChar::fromLatin1('"');
    const QChar backslash = QChar::fromLatin1('\\');
    const QChar underscore = QChar::fromLatin1('_');
    const QChar tilda = QChar::fromLatin1('~');
    for (int i=0; i < s.size(); ++i)
        if (s.at(i) == lsBrace || s.at(i) == dot)
            ++len;
    QVector<Component> components;
    components.reserve(len);
    int i = 0;
    int i0 = 0;
    PathEls::ParserState state = PathEls::ParserState::Start;
    QStringList strVals;
    while (i < s.size()) {
        // skip space
        while (i < s.size() && s.at(i).isSpace())
            ++i;
        if (i >= s.size())
            break;
        QChar c = s.at(i++);
        switch (state) {
        case PathEls::ParserState::Start:
            if (c == dollar) {
                i0 = i;
                while (i < s.size() && s.at(i).isLetterOrNumber()){
                    ++i;
                }
                components.append(Component(PathEls::Root(s.mid(i0,i-i0))));
                state = PathEls::ParserState::End;
            } else if (c == at) {
                i0 = i;
                while (i < s.size() && s.at(i).isLetterOrNumber()){
                    ++i;
                }
                components.append(Component(PathEls::Current(s.mid(i0,i-i0))));
                state = PathEls::ParserState::End;
            } else if (c.isLetter()) {
                myErrors().warning(tr("Field expressions should start with a dot, even when at the start of the path %1.")
                                 .arg(s)).handle(errorHandler);
                return Path();
            } else {
                --i;
                state = PathEls::ParserState::End;
            }
            break;
        case PathEls::ParserState::IndexOrKey:
            if (c.isDigit()) {
                i0 = i-1;
                while (i < s.size() && s.at(i).isDigit())
                    ++i;
                bool ok;
                components.append(Component(static_cast<index_type>(s.mid(i0,i-i0).toString()
                                                                    .toLongLong(&ok))));
                if (!ok) {
                    myErrors().warning(tr("Error extracting integer from '%1' at char %2.")
                        .arg(s.mid(i0,i-i0))
                        .arg(QString::number(i0))).handle(errorHandler);
                }
            } else if (c.isLetter() || c == tilda || c == underscore) {
                i0 = i-1;
                while (i < s.size() && (s.at(i).isLetterOrNumber() || s.at(i) == underscore || s.at(i) == tilda))
                    ++i;
                components.append(Component(PathEls::Key(s.mid(i0, i - i0).toString())));
            } else if (c == quote) {
                i0 = i;
                QString strVal;
                bool properEnd = false;
                while (i < s.size()) {
                    c = s.at(i);
                    if (c == quote) {
                        properEnd = true;
                        break;
                    } else if (c == backslash) {
                        strVal.append(s.mid(i0, i - i0).toString());
                        c = s.at(++i);
                        i0 = i + 1;
                        if (c == QChar::fromLatin1('n'))
                            strVal.append(QChar::fromLatin1('\n'));
                        else if (c == QChar::fromLatin1('r'))
                            strVal.append(QChar::fromLatin1('\r'));
                        else if (c == QChar::fromLatin1('t'))
                            strVal.append(QChar::fromLatin1('\t'));
                        else
                            strVal.append(c);
                    }
                    ++i;
                }
                if (properEnd) {
                    strVal.append(s.mid(i0, i - i0).toString());
                    ++i;
                } else {
                    myErrors().error(tr("Unclosed quoted string at char %1.")
                                     .arg(QString::number(i - 1))).handle(errorHandler);
                    return Path();
                }
                components.append(PathEls::Key(strVal));
            } else if (c == QChar::fromLatin1('*')) {
                components.append(Component(PathEls::Any()));
            } else if (c == QChar::fromLatin1('?')) {
                while (i < s.size() && s.at(i).isSpace())
                    ++i;
                if (i >= s.size() || s.at(i) != QChar::fromLatin1('(')) {
                    myErrors().error(tr("Expected a brace in filter after the question mark (at char %1).")
                            .arg(QString::number(i))).handle(errorHandler);
                    return Path();
                }
                i0 = ++i;
                while (i < s.size() && s.at(i) != QChar::fromLatin1(')')) ++i; // check matching braces when skipping??
                if (i >= s.size() || s.at(i) != QChar::fromLatin1(')')) {
                    myErrors().error(tr("Expected a closing brace in filter after the question mark (at char %1).")
                            .arg(QString::number(i))).handle(errorHandler);
                    return Path();
                }
                //auto filterDesc = s.mid(i0,i-i0);
                ++i;
                myErrors().error(tr("Filter from string not yet implemented.")).handle(errorHandler);
                return Path();
            } else {
                myErrors().error(tr("Unexpected character '%1' after square bracket at %2.")
                                 .arg(c).arg(i-1)).handle(errorHandler);
                return Path();
            }
            while (i < s.size() && s.at(i).isSpace()) ++i;
            if (i >= s.size() || s.at(i) != rsBrace) {
                myErrors().error(tr("square braces misses closing brace at char %1.")
                                 .arg(QString::number(i))).handle(errorHandler);
                return Path();
            } else {
                ++i;
            }
            state = PathEls::ParserState::End;
            break;
        case PathEls::ParserState::End:
            if (c == dot) {
                while (i < s.size() && s.at(i).isSpace()) ++i;
                if (i == s.size()) {
                    components.append(Component());
                    state = PathEls::ParserState::End;
                } else if (s.at(i).isLetter() || s.at(i) == underscore || s.at(i) == tilda) {
                    i0 = i;
                    while (i < s.size() && (s.at(i).isLetterOrNumber() || s.at(i) == underscore || s.at(i) == tilda)) {
                        ++i;
                    }
                    components.append(Component(PathEls::Field(s.mid(i0,i-i0))));
                    state = PathEls::ParserState::End;
                } else if (s.at(i).isDigit()) {
                    i0 = i;
                    while (i < s.size() && s.at(i).isDigit()){
                        ++i;
                    }
                    bool ok;
                    components.append(Component(static_cast<index_type>(s.mid(i0,i-i0).toString().toLongLong(&ok))));
                    if (!ok) {
                        myErrors().warning(tr("Error extracting integer from '%1' at char %2.")
                                           .arg(s.mid(i0,i-i0))
                                           .arg(QString::number(i0))).handle(errorHandler);
                        return Path();
                    } else {
                        myErrors().info(tr("Index should use square brackets and not a dot (at char %1).")
                                           .arg(QString::number(i0))).handle(errorHandler);
                    }
                    state = PathEls::ParserState::End;
                } else if (s.at(i) == dot || s.at(i) == lsBrace) {
                    components.append(Component());
                    state = PathEls::ParserState::End;
                } else if (s.at(i) == at) {
                    i0 = ++i;
                    while (i < s.size() && s.at(i).isLetterOrNumber()){
                        ++i;
                    }
                    components.append(Component(PathEls::Current(s.mid(i0,i-i0))));
                    state = PathEls::ParserState::End;
                } else if (s.at(i) == dollar) {
                    i0 = ++i;
                    while (i < s.size() && s.at(i).isLetterOrNumber()){
                        ++i;
                    }
                    components.append(Component(PathEls::Root(s.mid(i0,i-i0))));
                    state = PathEls::ParserState::End;
                } else {
                    c=s.at(i);
                    myErrors().error(tr("Unexpected character '%1' after dot (at char %2).")
                                     .arg(QStringView(&c,1))
                                     .arg(QString::number(i-1))).handle(errorHandler);
                    return Path();
                }
            } else if (c == lsBrace) {
                state = PathEls::ParserState::IndexOrKey;
            } else {
                myErrors().error(tr("Unexpected character '%1' after end of component (char %2).")
                                 .arg(QStringView(&c,1))
                                 .arg(QString::number(i-1))).handle(errorHandler);
                return Path();
            }
            break;
        }
    }
    switch (state) {
    case PathEls::ParserState::Start:
        return Path();
    case PathEls::ParserState::IndexOrKey:
        errorHandler(myErrors().error(tr("unclosed square brace at end.")));
 
        return Path();
    case PathEls::ParserState::End:
        return Path(0, components.size(), std::make_shared<PathEls::PathData>(
                        strVals, components));
    }
    Q_ASSERT(false && "Unexpected state in Path::fromString");
    return Path();
}
 
Path Path::Root(PathRoot s)
{
    return Path(0,1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Root(s)))));
}
 
Path Path::Root(QString s)
{
    return Path(0,1,std::make_shared<PathEls::PathData>(
                    QStringList(s), QVector<Component>(1,Component(PathEls::Root(s)))));
}
 
Path Path::Index(index_type i)
{
    return Path(0,1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Index(i)))));
}
 
Path Path::Root(QStringView s)
{
    return Path(0,1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Root(s)))));
}
 
 
Path Path::Field(QStringView s)
{
    return Path(0,1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Field(s)))));
}
 
Path Path::Field(QString s)
{
    return Path(0,1,std::make_shared<PathEls::PathData>(
                    QStringList(s), QVector<Component>(1,Component(PathEls::Field(s)))));
}
 
Path Path::Key(QStringView s)
{
    return Path(
            0, 1,
            std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1, Component(PathEls::Key(s.toString())))));
}
 
Path Path::Key(QString s)
{
    return Path(0, 1,
                std::make_shared<PathEls::PathData>(
                        QStringList(), QVector<Component>(1, Component(PathEls::Key(s)))));
}
 
Path Path::Current(PathCurrent s)
{
    return Path(0,1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Current(s)))));
}
 
Path Path::Current(QString s)
{
    return Path(0,1,std::make_shared<PathEls::PathData>(
                    QStringList(s), QVector<Component>(1,Component(PathEls::Current(s)))));
}
 
Path Path::Current(QStringView s)
{
    return Path(0,1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Current(s)))));
}
 
Path Path::Empty()
{
    return Path();
}
 
Path Path::empty() const
{
    if (m_endOffset != 0)
        return noEndOffset().empty();
    return Path(0,m_length+1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component()), m_data));
}
 
Path Path::field(QString name) const
{
    auto res = field(QStringView(name));
    res.m_data->strData.append(name);
    return res;
}
 
Path Path::field(QStringView name) const
{
    if (m_endOffset != 0)
        return noEndOffset().field(name);
    return Path(0,m_length+1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Field(name))), m_data));
}
 
Path Path::key(QString name) const
{
    if (m_endOffset != 0)
        return noEndOffset().key(name);
    return Path(0,m_length+1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Key(name))), m_data));
}
 
Path Path::key(QStringView name) const
{
    return key(name.toString());
}
 
Path Path::index(index_type i) const
{
    if (m_endOffset != 0)
        return noEndOffset().index(i);
    return Path(0,m_length+1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(i)), m_data));
}
 
Path Path::any() const
{
    if (m_endOffset != 0)
        return noEndOffset().any();
    return Path(0,m_length+1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Any())), m_data));
}
 
Path Path::filter(function<bool (DomItem)> filterF, QString desc) const
{
    auto res = filter(filterF, QStringView(desc));
    res.m_data->strData.append(desc);
    return res;
}
 
Path Path::filter(function<bool (DomItem)> filter, QStringView desc) const
{
    if (m_endOffset != 0)
        return noEndOffset().filter(filter, desc);
    return Path(0,m_length+1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Filter(filter, desc))), m_data));
}
 
Path Path::current(PathCurrent s) const
{
    return Path(0,m_length+1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Current(s))), m_data));
}
 
Path Path::current(QString s) const
{
    auto res = current(QStringView(s));
    res.m_data->strData.append(s);
    return res;
}
 
Path Path::current(QStringView s) const
{
    if (m_endOffset != 0)
        return noEndOffset().current(s);
    return Path(0,m_length+1,std::make_shared<PathEls::PathData>(
                    QStringList(), QVector<Component>(1,Component(PathEls::Current(s))), m_data));
}
 
Path Path::path(Path toAdd, bool avoidToAddAsBase) const
{
    if (toAdd.length() == 0)
        return *this;
    int resLength = length() + toAdd.length();
    if (m_endOffset != 0) {
        Path thisExtended = this->expandBack();
        if (thisExtended.length() > resLength)
            thisExtended = thisExtended.mid(0, resLength);
        Path added = thisExtended.mid(length(), thisExtended.length() - length());
        if (added == toAdd.mid(0, toAdd.length())) {
            if (resLength == thisExtended.length())
                return thisExtended;
            else
                return thisExtended.path(toAdd.mid(added.length(), resLength - thisExtended.length()));
        }
    }
    if (!avoidToAddAsBase) {
        Path toAddExtended = toAdd.expandFront();
        if (toAddExtended.length() >= resLength) {
            toAddExtended = toAddExtended.mid(toAddExtended.length() - resLength, resLength);
            if (toAddExtended.mid(0,length()) == *this)
                return toAddExtended;
        }
    }
    QVector<Component> components;
    components.reserve(toAdd.length());
    QStringList addedStrs;
    bool addHasStr = false;
    auto data = toAdd.m_data.get();
    while (data) {
        if (!data->strData.isEmpty()) {
            addHasStr = true;
            break;
        }
        data = data->parent.get();
    }
    if (addHasStr) {
        QStringList myStrs;
        data = m_data.get();
        while (data) {
            myStrs.append(data->strData);
            data = data->parent.get();
        }
        data = toAdd.m_data.get();
        while (data) {
            for (int ij = 0; ij < data->strData.size(); ++ij) {
                bool hasAlready = false;
                for (int ii = 0; ii < myStrs.size() && !hasAlready; ++ii)
                    hasAlready = inQString(data->strData[ij], myStrs[ii]);
                if (!hasAlready)
                    addedStrs.append(data->strData[ij]);
            }
            data = data->parent.get();
        }
    }
    QStringList toAddStrs;
    for (int i = 0; i < toAdd.length(); ++i) {
        components.append(toAdd.component(i));
        QStringView compStrView = toAdd.component(i).stringView();
        if (!compStrView.isEmpty()) {
            for (int j = 0; j < addedStrs.size(); ++j) {
                if (inQString(compStrView, addedStrs[j])) {
                    toAddStrs.append(addedStrs[j]);
                    addedStrs.removeAt(j);
                    break;
                }
            }
        }
    }
    return Path(0, m_length + toAdd.length(), std::make_shared<PathEls::PathData>(
                    toAddStrs, components, ((m_endOffset == 0) ? m_data : noEndOffset().m_data)));
}
 
Path Path::expandFront() const
{
    int newLen = 0;
    auto data = m_data.get();
    while (data) {
        newLen += data->components.size();
        data = data->parent.get();
    }
    newLen -= m_endOffset;
    return Path(m_endOffset, newLen, m_data);
}
 
Path Path::expandBack() const
{
    if (m_endOffset > 0)
        return Path(0, m_length + m_endOffset, m_data);
    return *this;
}
 
Path &Path::operator++()
{
    if (m_length > 0)
        m_length -= 1;
    return *this;
}
 
Path Path::operator++(int)
{
    Path res = *this;
    if (m_length > 0)
        m_length -= 1;
    return res;
}
 
int Path::cmp(const Path &p1, const Path &p2)
{
    // lexicographic ordering
    const int lMin = qMin(p1.m_length, p2.m_length);
    if (p1.m_data.get() == p2.m_data.get() && p1.m_endOffset == p2.m_endOffset && p1.m_length == p2.m_length)
        return 0;
    for (int i = 0; i < lMin; ++i) {
        int c = Component::cmp(p1.component(i), p2.component(i));
        if (c != 0)
            return c;
    }
    if (lMin < p2.m_length)
        return -1;
    if (p1.m_length > lMin)
        return 1;
    return 0;
}
 
Path::Path(quint16 endOffset, quint16 length, std::shared_ptr<PathEls::PathData> data)
    :m_endOffset(endOffset), m_length(length), m_data(data)
{
}
 
Path Path::noEndOffset() const
{
    if (m_length == 0)
        return Path();
    if (m_endOffset == 0)
        return *this;
    // peel back
    qint16 endOffset = m_endOffset;
    std::shared_ptr<PathEls::PathData> lastData = m_data;
    while (lastData && endOffset >= lastData->components.size()) {
        endOffset -= lastData->components.size();
        lastData = lastData->parent;
    }
    if (endOffset > 0) {
        Q_ASSERT(lastData && "Internal problem, reference to non existing PathData");
        return Path(0, m_length, std::make_shared<PathEls::PathData>(
                        lastData->strData, lastData->components.mid(0, lastData->components.size() - endOffset), lastData->parent));
    }
    return Path(0, m_length, lastData);
}
 
Path Path::appendComponent(const PathEls::PathComponent &c)
{
    if (m_endOffset != 0) {
        Path newP = noEndOffset();
        return newP.appendComponent(c);
    }
    if (m_data && m_data.use_count() != 1) {
        // create a new path (otherwise paths linking to this will change)
        Path newP(c);
        newP.m_data->parent = m_data;
        newP.m_length = static_cast<quint16>(m_length + 1);
        return newP;
    }
    auto my_data =
            (m_data ? m_data
                    : std::make_shared<PathEls::PathData>(QStringList(),
                                                          QVector<PathEls::PathComponent>()));
    switch (c.kind()) {
    case PathEls::Kind::Any:
    case PathEls::Kind::Empty:
    case PathEls::Kind::Index:
        // no string
    case PathEls::Kind::Field:
        // string assumed to stay valid (Fields::...)
        my_data->components.append(c);
        break;
    case PathEls::Kind::Current:
        if (c.asCurrent()->contextKind == PathCurrent::Other) {
            my_data->strData.append(c.asCurrent()->contextName.toString());
            my_data->components.append(PathEls::Current(my_data->strData.last()));
        } else {
            my_data->components.append(c);
        }
        break;
    case PathEls::Kind::Filter:
        if (!c.base()->asFilter()->filterDescription.isEmpty()) {
            my_data->strData.append(c.base()->asFilter()->filterDescription.toString());
            my_data->components.append(
                    PathEls::Filter(c.base()->asFilter()->filterFunction, my_data->strData.last()));
        } else {
            my_data->components.append(c);
        }
        break;
    case PathEls::Kind::Key:
        my_data->components.append(c);
        break;
    case PathEls::Kind::Root:
        if (c.asRoot()->contextKind == PathRoot::Other) {
            my_data->strData.append(c.asRoot()->contextName.toString());
            my_data->components.append(PathEls::Root(my_data->strData.last()));
        } else {
            my_data->components.append(c);
        }
        break;
    }
    if (m_data)
        m_endOffset = 1;
    return Path { 0, static_cast<quint16>(m_length + 1), my_data };
}
 
ErrorGroups Path::myErrors()
{
    static ErrorGroups res = {{NewErrorGroup("PathParsing")}};
    return res;
}
 
void Path::dump(Sink sink) const
{
    bool first = true;
    for (int i = 0; i < m_length; ++i) {
        auto &c = component(i);
        if (!c.hasSquareBrackets()) {
            if (!first || (c.kind() != Kind::Root && c.kind() != Kind::Current))
                sink(u".");
        }
        c.dump(sink);
        first = false;
    }
}
 
QString Path::toString() const
{
    QString res;
    QTextStream stream(&res);
    dump([&stream](QStringView str){ stream << str; });
    stream.flush();
    return res;
}
 
Path Path::dropFront(int n) const
{
    if (m_length > n && n >= 0)
        return Path(m_endOffset, m_length - n, m_data);
    return Path();
}
 
Path Path::dropTail(int n) const
{
    if (m_length > n && n >= 0)
        return Path(m_endOffset + n, m_length - n, m_data);
    return Path();
}
 
Path Path::mid(int offset, int length) const
{
    length = qMin(m_length - offset, length);
    if (offset < 0 || offset >= m_length || length <= 0 || length > m_length)
        return Path();
    int newEndOffset = m_endOffset + m_length - offset - length;
    return Path(newEndOffset, length, m_data);
}
 
Path Path::mid(int offset) const
{
    return mid(offset, m_length - offset);
}
 
Path Path::fromString(QString s, ErrorHandler errorHandler)
{
    Path res = fromString(QStringView(s), errorHandler);
    if (res.m_data)
        res.m_data->strData.append(s);
    return res;
}
 
} // end namespace Dom
} // end namespace QQmlJS
QT_END_NAMESPACE
 
#include "moc_qqmldompath_p.cpp"