qqmllscompletion.cpp

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// Copyright (C) 2024 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 "qqmllscompletion_p.h"
 
using namespace QLspSpecification;
using namespace QQmlJS::Dom;
using namespace Qt::StringLiterals;
 
QT_BEGIN_NAMESPACE
 
Q_LOGGING_CATEGORY(QQmlLSCompletionLog, "qt.languageserver.completions")
 
 
CompletionItem QQmlLSCompletion::makeSnippet(QUtf8StringView qualifier, QUtf8StringView label,
                                             QUtf8StringView insertText)
{
    CompletionItem res;
    if (!qualifier.isEmpty()) {
        res.label = qualifier.data();
        res.label += '.';
    }
    res.label += label.data();
    res.insertTextFormat = InsertTextFormat::Snippet;
    if (!qualifier.isEmpty()) {
        res.insertText = qualifier.data();
        *res.insertText += '.';
        *res.insertText += insertText.data();
    } else {
        res.insertText = insertText.data();
    }
    res.kind = int(CompletionItemKind::Snippet);
    res.insertTextMode = InsertTextMode::AdjustIndentation;
    return res;
}
 
CompletionItem QQmlLSCompletion::makeSnippet(QUtf8StringView label, QUtf8StringView insertText)
{
    return makeSnippet(QByteArray(), label, insertText);
}
 
bool QQmlLSCompletion::betweenLocations(QQmlJS::SourceLocation left,
                                        const QQmlLSCompletionPosition &positionInfo,
                                        QQmlJS::SourceLocation right) const
{
    if (!left.isValid())
        return false;
    // note: left.end() == ctx.offset() means that the cursor lies exactly after left
    if (!(left.end() <= positionInfo.offset()))
        return false;
    if (!right.isValid())
        return true;
 
    // note: ctx.offset() == right.begin() means that the cursor lies exactly before right
    return positionInfo.offset() <= right.begin();
}
 
bool QQmlLSCompletion::afterLocation(QQmlJS::SourceLocation left,
                                     const QQmlLSCompletionPosition &positionInfo) const
{
    return betweenLocations(left, positionInfo, QQmlJS::SourceLocation{});
}
 
bool QQmlLSCompletion::beforeLocation(const QQmlLSCompletionPosition &ctx,
                                      QQmlJS::SourceLocation right) const
{
    if (!right.isValid())
        return true;
 
    // note: ctx.offset() == right.begin() means that the cursor lies exactly before right
    if (ctx.offset() <= right.begin())
        return true;
 
    return false;
}
 
bool QQmlLSCompletion::ctxBeforeStatement(const QQmlLSCompletionPosition &positionInfo,
                                          const DomItem &parentForContext,
                                          FileLocationRegion firstRegion) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
    const bool result = beforeLocation(positionInfo, regions[firstRegion]);
    return result;
}
 
void
QQmlLSCompletion::suggestBindingCompletion(const DomItem &itemAtPosition, BackInsertIterator it) const
{
    suggestReachableTypes(itemAtPosition, LocalSymbolsType::AttachedType, CompletionItemKind::Class,
                          it);
 
    const QQmlJSScope::ConstPtr scope = [&]() {
        if (!QQmlLSUtils::isFieldMemberAccess(itemAtPosition))
            return itemAtPosition.qmlObject().semanticScope();
 
        const DomItem owner = itemAtPosition.directParent().field(Fields::left);
        auto expressionType = QQmlLSUtils::resolveExpressionType(
                owner, ResolveActualTypeForFieldMemberExpression);
        return expressionType ? expressionType->semanticScope : QQmlJSScope::ConstPtr{};
    }();
 
    if (!scope)
        return;
 
    propertyCompletion(scope, nullptr, it);
    signalHandlerCompletion(scope, nullptr, it);
}
 
void QQmlLSCompletion::insideImportCompletionHelper(const DomItem &file,
                                                    const QQmlLSCompletionPosition &positionInfo,
                                                    BackInsertIterator it) const
{
    // returns completions for import statements, ctx is supposed to be in an import statement
    const CompletionContextStrings &ctx = positionInfo.cursorPosition;
    ImportCompletionType importCompletionType = ImportCompletionType::None;
    QRegularExpression spaceRe(uR"(\W+)"_s);
    QList<QStringView> linePieces = ctx.preLine().split(spaceRe, Qt::SkipEmptyParts);
    qsizetype effectiveLength = linePieces.size()
            + ((!ctx.preLine().isEmpty() && ctx.preLine().last().isSpace()) ? 1 : 0);
    if (effectiveLength < 2) {
        CompletionItem comp;
        comp.label = "import";
        comp.kind = int(CompletionItemKind::Keyword);
        it = comp;
    }
    if (linePieces.isEmpty() || linePieces.first() != u"import")
        return;
    if (effectiveLength == 2) {
        // the cursor is after the import, possibly in a partial module name
        importCompletionType = ImportCompletionType::Module;
    } else if (effectiveLength == 3) {
        if (linePieces.last() != u"as") {
            // the cursor is after the module, possibly in a partial version token (or partial as)
            CompletionItem comp;
            comp.label = "as";
            comp.kind = int(CompletionItemKind::Keyword);
            it = comp;
            importCompletionType = ImportCompletionType::Version;
        }
    }
    DomItem env = file.environment();
    if (std::shared_ptr<DomEnvironment> envPtr = env.ownerAs<DomEnvironment>()) {
        switch (importCompletionType) {
        case ImportCompletionType::None:
            break;
        case ImportCompletionType::Module: {
            QDuplicateTracker<QString> modulesSeen;
            for (const QString &uri : envPtr->moduleIndexUris(env)) {
                QStringView base = ctx.base(); // if we allow spaces we should get rid of them
                if (uri.startsWith(base)) {
                    QStringList rest = uri.mid(base.size()).split(u'.');
                    if (rest.isEmpty())
                        continue;
 
                    const QString label = rest.first();
                    if (!modulesSeen.hasSeen(label)) {
                        CompletionItem comp;
                        comp.label = label.toUtf8();
                        comp.kind = int(CompletionItemKind::Module);
                        it = comp;
                    }
                }
            }
            break;
        }
        case ImportCompletionType::Version:
            if (ctx.base().isEmpty()) {
                for (int majorV :
                     envPtr->moduleIndexMajorVersions(env, linePieces.at(1).toString())) {
                    CompletionItem comp;
                    comp.label = QString::number(majorV).toUtf8();
                    comp.kind = int(CompletionItemKind::Constant);
                    it = comp;
                }
            } else {
                bool hasMajorVersion = ctx.base().endsWith(u'.');
                int majorV = -1;
                if (hasMajorVersion)
                    majorV = ctx.base().mid(0, ctx.base().size() - 1).toInt(&hasMajorVersion);
                if (!hasMajorVersion)
                    break;
                if (std::shared_ptr<ModuleIndex> mIndex =
                            envPtr->moduleIndexWithUri(env, linePieces.at(1).toString(), majorV)) {
                    for (int minorV : mIndex->minorVersions()) {
                        CompletionItem comp;
                        comp.label = QString::number(minorV).toUtf8();
                        comp.kind = int(CompletionItemKind::Constant);
                        it = comp;
                    }
                }
            }
            break;
        }
    }
}
 
void QQmlLSCompletion::idsCompletions(const DomItem &component, BackInsertIterator it) const
{
    qCDebug(QQmlLSCompletionLog) << "adding ids completions";
    for (const QString &k : component.field(Fields::ids).keys()) {
        CompletionItem comp;
        comp.label = k.toUtf8();
        comp.kind = int(CompletionItemKind::Value);
        it = comp;
    }
}
 
static bool testScopeSymbol(const QQmlJSScope::ConstPtr &scope, LocalSymbolsTypes options,
                            CompletionItemKind kind)
{
    const bool currentIsSingleton = scope->isSingleton();
    const bool currentIsAttached = !scope->attachedType().isNull();
    if ((options & LocalSymbolsType::Singleton) && currentIsSingleton) {
        return true;
    }
    if ((options & LocalSymbolsType::AttachedType) && currentIsAttached) {
        return true;
    }
    const bool isObjectType = scope->isReferenceType();
    if (options & LocalSymbolsType::ObjectType && !currentIsSingleton && isObjectType) {
        return kind != CompletionItemKind::Constructor || scope->isCreatable();
    }
    if (options & LocalSymbolsType::ValueType && !currentIsSingleton && !isObjectType) {
        return true;
    }
    return false;
}
 
void QQmlLSCompletion::suggestReachableTypes(const DomItem &el, LocalSymbolsTypes options,
                                             CompletionItemKind kind, BackInsertIterator it) const
{
    auto file = el.containingFile().as<QmlFile>();
    if (!file)
        return;
    auto resolver = file->typeResolver();
    if (!resolver)
        return;
 
    const QString requiredQualifiers = QQmlLSUtils::qualifiersFrom(el);
    const auto keyValueRange = resolver->importedTypes().asKeyValueRange();
    for (const auto &type : keyValueRange) {
        // ignore special QQmlJSImporterMarkers
        const bool isMarkerType = type.first.contains(u"$internal$.")
                || type.first.contains(u"$anonymous$.") || type.first.contains(u"$module$.");
        if (isMarkerType || !type.first.startsWith(requiredQualifiers))
            continue;
 
        auto &scope = type.second.scope;
        if (!scope)
            continue;
 
        if (!testScopeSymbol(scope, options, kind))
            continue;
 
        CompletionItem completion;
        completion.label = QStringView(type.first).sliced(requiredQualifiers.size()).toUtf8();
        completion.kind = int(kind);
        it = completion;
    }
}
 
void QQmlLSCompletion::jsIdentifierCompletion(const QQmlJSScope::ConstPtr &scope,
                                              QDuplicateTracker<QString> *usedNames,
                                              BackInsertIterator it) const
{
    for (const auto &[name, jsIdentifier] : scope->ownJSIdentifiers().asKeyValueRange()) {
        CompletionItem completion;
        if (usedNames && usedNames->hasSeen(name)) {
            continue;
        }
        completion.label = name.toUtf8();
        completion.kind = int(CompletionItemKind::Variable);
        QString detail = u"has type "_s;
        if (jsIdentifier.typeName) {
            if (jsIdentifier.isConst) {
                detail.append(u"const ");
            }
            detail.append(*jsIdentifier.typeName);
        } else {
            detail.append(jsIdentifier.isConst ? u"const"_s : u"var"_s);
        }
        completion.detail = detail.toUtf8();
        it = completion;
    }
}
 
void QQmlLSCompletion::methodCompletion(const QQmlJSScope::ConstPtr &scope,
                                        QDuplicateTracker<QString> *usedNames,
                                        BackInsertIterator it) const
{
    // JS functions in current and base scopes
    for (const auto &[name, method] : scope->methods().asKeyValueRange()) {
        if (method.access() != QQmlJSMetaMethod::Public)
            continue;
        if (usedNames && usedNames->hasSeen(name)) {
            continue;
        }
        CompletionItem completion;
        completion.label = name.toUtf8();
        completion.kind = int(CompletionItemKind::Method);
        it = completion;
        // TODO: QQmlLSUtils::reachableSymbols seems to be able to do documentation and detail
        // and co, it should also be done here if possible.
    }
}
 
void QQmlLSCompletion::propertyCompletion(const QQmlJSScope::ConstPtr &scope,
                                          QDuplicateTracker<QString> *usedNames,
                                          BackInsertIterator it) const
{
    for (const auto &[name, property] : scope->properties().asKeyValueRange()) {
        if (usedNames && usedNames->hasSeen(name)) {
            continue;
        }
        CompletionItem completion;
        completion.label = name.toUtf8();
        completion.kind = int(CompletionItemKind::Property);
        QString detail{ u"has type "_s };
        if (!property.isWritable())
            detail.append(u"readonly "_s);
        detail.append(property.typeName().isEmpty() ? u"var"_s : property.typeName());
        completion.detail = detail.toUtf8();
        it = completion;
    }
}
 
void QQmlLSCompletion::enumerationCompletion(const QQmlJSScope::ConstPtr &scope,
                                             QDuplicateTracker<QString> *usedNames,
                                             BackInsertIterator it) const
{
    for (const QQmlJSMetaEnum &enumerator : scope->enumerations()) {
        if (usedNames && usedNames->hasSeen(enumerator.name())) {
            continue;
        }
        CompletionItem completion;
        completion.label = enumerator.name().toUtf8();
        completion.kind = static_cast<int>(CompletionItemKind::Enum);
        it = completion;
    }
}
 
void QQmlLSCompletion::enumerationValueCompletionHelper(const QStringList &enumeratorKeys,
                                                        BackInsertIterator it) const
{
    for (const QString &enumeratorKey : enumeratorKeys) {
        CompletionItem completion;
        completion.label = enumeratorKey.toUtf8();
        completion.kind = static_cast<int>(CompletionItemKind::EnumMember);
        it = completion;
    }
}
 
void QQmlLSCompletion::enumerationValueCompletion(const QQmlJSScope::ConstPtr &scope,
                                                  const QString &enumeratorName,
                                                  BackInsertIterator result) const
{
    auto enumerator = scope->enumeration(enumeratorName);
    if (enumerator.isValid()) {
        enumerationValueCompletionHelper(enumerator.keys(), result);
        return;
    }
 
    for (const QQmlJSMetaEnum &enumerator : scope->enumerations()) {
        enumerationValueCompletionHelper(enumerator.keys(), result);
    }
}
 
template<typename F>
void collectFromAllJavaScriptParents(const F &&f, const QQmlJSScope::ConstPtr &scope)
{
    for (QQmlJSScope::ConstPtr current = scope; current; current = current->parentScope()) {
        f(current);
        if (current->scopeType() == QQmlSA::ScopeType::QMLScope)
            return;
    }
}
 
void QQmlLSCompletion::suggestJSExpressionCompletion(const DomItem &scriptIdentifier,
                                                     BackInsertIterator result) const
{
    QDuplicateTracker<QString> usedNames;
    QQmlJSScope::ConstPtr nearestScope;
 
    // note: there is an edge case, where the user asks for completion right after the dot
    // of some qualified expression like `root.hello`. In this case, scriptIdentifier is actually
    // the BinaryExpression instead of the left-hand-side that has not be written down yet.
    const bool askForCompletionOnDot = QQmlLSUtils::isFieldMemberExpression(scriptIdentifier);
    const bool hasQualifier =
            QQmlLSUtils::isFieldMemberAccess(scriptIdentifier) || askForCompletionOnDot;
 
    if (!hasQualifier) {
        for (QUtf8StringView view : std::array<QUtf8StringView, 3>{ "null", "false", "true" }) {
            CompletionItem completion;
            completion.label = view.data();
            completion.kind = int(CompletionItemKind::Value);
            result = completion;
        }
        idsCompletions(scriptIdentifier.component(), result);
        suggestReachableTypes(scriptIdentifier,
                              LocalSymbolsType::Singleton | LocalSymbolsType::AttachedType,
                              CompletionItemKind::Class, result);
 
        auto scope = scriptIdentifier.nearestSemanticScope();
        if (!scope)
            return;
        nearestScope = scope;
 
        enumerationCompletion(nearestScope, &usedNames, result);
    } else {
        const DomItem owner =
                (askForCompletionOnDot ? scriptIdentifier : scriptIdentifier.directParent())
                        .field(Fields::left);
        auto expressionType = QQmlLSUtils::resolveExpressionType(
                owner, ResolveActualTypeForFieldMemberExpression);
        if (!expressionType || !expressionType->semanticScope)
            return;
        nearestScope = expressionType->semanticScope;
        // Use root element scope to use find the enumerations
        // This should be changed when we support usages in external files
        if (expressionType->type == QmlComponentIdentifier)
            nearestScope = owner.rootQmlObject(GoTo::MostLikely).semanticScope();
        if (expressionType->name) {
            // note: you only get enumeration values in qualified expressions, never alone
            enumerationValueCompletion(nearestScope, *expressionType->name, result);
 
            // skip enumeration types if already inside an enumeration type
            if (auto enumerator = nearestScope->enumeration(*expressionType->name);
                !enumerator.isValid()) {
                enumerationCompletion(nearestScope, &usedNames, result);
            }
 
            if (expressionType->type == EnumeratorIdentifier)
                return;
        }
    }
 
    Q_ASSERT(nearestScope);
 
    methodCompletion(nearestScope, &usedNames, result);
    propertyCompletion(nearestScope, &usedNames, result);
 
    if (!hasQualifier) {
        // collect all of the stuff from parents
        collectFromAllJavaScriptParents(
                [this, &usedNames, result](const QQmlJSScope::ConstPtr &scope) {
                    jsIdentifierCompletion(scope, &usedNames, result);
                },
                nearestScope);
        collectFromAllJavaScriptParents(
                [this, &usedNames, result](const QQmlJSScope::ConstPtr &scope) {
                    methodCompletion(scope, &usedNames, result);
                },
                nearestScope);
        collectFromAllJavaScriptParents(
                [this, &usedNames, result](const QQmlJSScope::ConstPtr &scope) {
                    propertyCompletion(scope, &usedNames, result);
                },
                nearestScope);
 
        auto file = scriptIdentifier.containingFile().as<QmlFile>();
        if (!file)
            return;
        auto resolver = file->typeResolver();
        if (!resolver)
            return;
 
        const auto globals = resolver->jsGlobalObject();
        methodCompletion(globals, &usedNames, result);
        propertyCompletion(globals, &usedNames, result);
    }
}
 
static const QQmlJSScope *resolve(const QQmlJSScope *current, const QStringList &names)
{
    for (const QString &name : names) {
        if (auto property = current->property(name); property.isValid()) {
            if (auto propertyType = property.type().get()) {
                current = propertyType;
                continue;
            }
        }
        return {};
    }
    return current;
}
 
bool QQmlLSCompletion::cursorInFrontOfItem(const DomItem &parentForContext,
                                           const QQmlLSCompletionPosition &positionInfo)
{
    auto fileLocations = FileLocations::treeOf(parentForContext)->info().fullRegion;
    return positionInfo.offset() <= fileLocations.offset;
}
 
bool QQmlLSCompletion::cursorAfterColon(const DomItem &currentItem,
                                        const QQmlLSCompletionPosition &positionInfo)
{
    auto location = FileLocations::treeOf(currentItem)->info();
    auto region = location.regions.constFind(ColonTokenRegion);
 
    if (region == location.regions.constEnd())
        return false;
 
    if (region.value().isValid() && region.value().offset < positionInfo.offset()) {
        return true;
    }
    return false;
}
 
static const QMap<QString, QList<QString>> valuesForPragmas{
    { u"ComponentBehavior"_s, { u"Unbound"_s, u"Bound"_s } },
    { u"NativeMethodBehavior"_s, { u"AcceptThisObject"_s, u"RejectThisObject"_s } },
    { u"ListPropertyAssignBehavior"_s, { u"Append"_s, u"Replace"_s, u"ReplaceIfNotDefault"_s } },
    { u"Singleton"_s, {} },
    { u"ValueTypeBehavior"_s, { u"Addressable"_s, u"Inaddressable"_s } },
};
 
void QQmlLSCompletion::insidePragmaCompletion(QQmlJS::Dom::DomItem currentItem,
                                              const QQmlLSCompletionPosition &positionInfo,
                                              BackInsertIterator result) const
{
    if (cursorAfterColon(currentItem, positionInfo)) {
        const QString name = currentItem.field(Fields::name).value().toString();
        auto values = valuesForPragmas.constFind(name);
        if (values == valuesForPragmas.constEnd())
            return;
 
        for (const auto &value : *values) {
            CompletionItem comp;
            comp.label = value.toUtf8();
            comp.kind = static_cast<int>(CompletionItemKind::Value);
            result = comp;
        }
        return;
    }
 
    for (const auto &pragma : valuesForPragmas.asKeyValueRange()) {
        CompletionItem comp;
        comp.label = pragma.first.toUtf8();
        if (!pragma.second.isEmpty()) {
            comp.insertText = QString(pragma.first).append(u": ").toUtf8();
        }
        comp.kind = static_cast<int>(CompletionItemKind::Value);
        result = comp;
    }
}
 
void QQmlLSCompletion::insideQmlObjectCompletion(const DomItem &parentForContext,
                                                 const QQmlLSCompletionPosition &positionInfo,
                                                 BackInsertIterator result) const
{
 
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation leftBrace = regions[LeftBraceRegion];
    const QQmlJS::SourceLocation rightBrace = regions[RightBraceRegion];
 
    if (beforeLocation(positionInfo, leftBrace)) {
        LocalSymbolsTypes options;
        options.setFlag(LocalSymbolsType::ObjectType);
        suggestReachableTypes(positionInfo.itemAtPosition, options, CompletionItemKind::Constructor,
                              result);
        suggestSnippetsForLeftHandSideOfBinding(positionInfo.itemAtPosition, result);
 
        if (QQmlLSUtils::isFieldMemberExpression(positionInfo.itemAtPosition)) {
            suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        }
        return;
    }
 
    if (betweenLocations(leftBrace, positionInfo, rightBrace)) {
        // default/required property completion
        for (QUtf8StringView view :
             std::array<QUtf8StringView, 6>{ "", "readonly ", "default ", "default required ",
                                             "required default ", "required " }) {
            // readonly properties require an initializer
            if (view != QUtf8StringView("readonly ")) {
                result = makeSnippet(
                        QByteArray(view.data()).append("property type name;"),
                        QByteArray(view.data()).append("property ${1:type} ${0:name};"));
            }
 
            result = makeSnippet(
                    QByteArray(view.data()).append("property type name: value;"),
                    QByteArray(view.data()).append("property ${1:type} ${2:name}: ${0:value};"));
        }
 
        // signal
        result = makeSnippet("signal name(arg1:type1, ...)", "signal ${1:name}($0)");
 
        // signal without parameters
        result = makeSnippet("signal name;", "signal ${0:name};");
 
        // make already existing property required
        result = makeSnippet("required name;", "required ${0:name};");
 
        // function
        result = makeSnippet("function name(args...): returnType { statements...}",
                             "function ${1:name}($2): ${3:returnType} {\n\t$0\n}");
 
        // enum
        result = makeSnippet("enum name { Values...}", "enum ${1:name} {\n\t${0:values}\n}");
 
        // inline component
        result = makeSnippet("component Name: BaseType { ... }",
                             "component ${1:name}: ${2:baseType} {\n\t$0\n}");
 
        // add bindings
        const DomItem containingObject = parentForContext.qmlObject();
        suggestBindingCompletion(containingObject, result);
 
        // add Qml Types for default binding
        const DomItem containingFile = parentForContext.containingFile();
        suggestReachableTypes(containingFile, LocalSymbolsType::ObjectType,
                              CompletionItemKind::Constructor, result);
        suggestSnippetsForLeftHandSideOfBinding(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insidePropertyDefinitionCompletion(
        const DomItem &currentItem, const QQmlLSCompletionPosition &positionInfo,
        BackInsertIterator result) const
{
    auto info = FileLocations::treeOf(currentItem)->info();
    const QQmlJS::SourceLocation propertyKeyword = info.regions[PropertyKeywordRegion];
 
    // do completions for the keywords
    if (positionInfo.offset() < propertyKeyword.offset + propertyKeyword.length) {
        const QQmlJS::SourceLocation readonlyKeyword = info.regions[ReadonlyKeywordRegion];
        const QQmlJS::SourceLocation defaultKeyword = info.regions[DefaultKeywordRegion];
        const QQmlJS::SourceLocation requiredKeyword = info.regions[RequiredKeywordRegion];
 
        bool completeReadonly = true;
        bool completeRequired = true;
        bool completeDefault = true;
 
        // if there is already a readonly keyword before the cursor: do not auto complete it again
        if (readonlyKeyword.isValid() && readonlyKeyword.offset < positionInfo.offset()) {
            completeReadonly = false;
            // also, required keywords do not like readonly keywords
            completeRequired = false;
        }
 
        // same for required
        if (requiredKeyword.isValid() && requiredKeyword.offset < positionInfo.offset()) {
            completeRequired = false;
            // also, required keywords do not like readonly keywords
            completeReadonly = false;
        }
 
        // same for default
        if (defaultKeyword.isValid() && defaultKeyword.offset < positionInfo.offset()) {
            completeDefault = false;
        }
        auto addCompletionKeyword = [&result](QUtf8StringView view, bool complete) {
            if (!complete)
                return;
            CompletionItem item;
            item.label = view.data();
            item.kind = int(CompletionItemKind::Keyword);
            result = item;
        };
        addCompletionKeyword(u8"readonly", completeReadonly);
        addCompletionKeyword(u8"required", completeRequired);
        addCompletionKeyword(u8"default", completeDefault);
        addCompletionKeyword(u8"property", true);
 
        return;
    }
 
    const QQmlJS::SourceLocation propertyIdentifier = info.regions[IdentifierRegion];
    if (propertyKeyword.end() <= positionInfo.offset()
        && positionInfo.offset() < propertyIdentifier.offset) {
        suggestReachableTypes(currentItem,
                              LocalSymbolsType::ObjectType | LocalSymbolsType::ValueType,
                              CompletionItemKind::Class, result);
    }
    // do not autocomplete the rest
    return;
}
 
void QQmlLSCompletion::insideBindingCompletion(const DomItem &currentItem,
                                               const QQmlLSCompletionPosition &positionInfo,
                                               BackInsertIterator result) const
{
    const DomItem containingBinding = currentItem.filterUp(
            [](DomType type, const QQmlJS::Dom::DomItem &) { return type == DomType::Binding; },
            FilterUpOptions::ReturnOuter);
 
    // do scriptidentifiercompletion after the ':' of a binding
    if (cursorAfterColon(containingBinding, positionInfo)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
 
        if (auto type = QQmlLSUtils::resolveExpressionType(currentItem, ResolveOwnerType)) {
            const QStringList names = currentItem.field(Fields::name).toString().split(u'.');
            const QQmlJSScope *current = resolve(type->semanticScope.get(), names);
            // add type names when binding to an object type or a property with var type
            if (!current || current->accessSemantics() == QQmlSA::AccessSemantics::Reference) {
                LocalSymbolsTypes options;
                options.setFlag(LocalSymbolsType::ObjectType);
                suggestReachableTypes(positionInfo.itemAtPosition, options,
                                      CompletionItemKind::Constructor, result);
                suggestSnippetsForRightHandSideOfBinding(positionInfo.itemAtPosition, result);
            }
        }
        return;
    }
 
    // ignore the binding if asking for completion in front of the binding
    if (cursorInFrontOfItem(containingBinding, positionInfo)) {
        insideQmlObjectCompletion(currentItem.containingObject(), positionInfo, result);
        return;
    }
 
    const DomItem containingObject = currentItem.qmlObject();
 
    suggestBindingCompletion(positionInfo.itemAtPosition, result);
 
    // add Qml Types for default binding
    suggestReachableTypes(positionInfo.itemAtPosition, LocalSymbolsType::ObjectType,
                          CompletionItemKind::Constructor, result);
    suggestSnippetsForLeftHandSideOfBinding(positionInfo.itemAtPosition, result);
}
 
void QQmlLSCompletion::insideImportCompletion(const DomItem &currentItem,
                                              const QQmlLSCompletionPosition &positionInfo,
                                              BackInsertIterator result) const
{
    const DomItem containingFile = currentItem.containingFile();
    insideImportCompletionHelper(containingFile, positionInfo, result);
 
    // when in front of the import statement: propose types for root Qml Object completion
    if (cursorInFrontOfItem(currentItem, positionInfo)) {
        suggestReachableTypes(containingFile, LocalSymbolsType::ObjectType,
                              CompletionItemKind::Constructor, result);
    }
}
 
void QQmlLSCompletion::insideQmlFileCompletion(const DomItem &currentItem,
                                               const QQmlLSCompletionPosition &positionInfo,
                                               BackInsertIterator result) const
{
    const DomItem containingFile = currentItem.containingFile();
    // completions for code outside the root Qml Object
    // global completions
    if (positionInfo.cursorPosition.atLineStart()) {
        if (positionInfo.cursorPosition.base().isEmpty()) {
            for (const QStringView &s : std::array<QStringView, 2>({ u"pragma", u"import" })) {
                CompletionItem comp;
                comp.label = s.toUtf8();
                comp.kind = int(CompletionItemKind::Keyword);
                result = comp;
            }
        }
    }
    // Types for root Qml Object completion
    suggestReachableTypes(containingFile, LocalSymbolsType::ObjectType,
                          CompletionItemKind::Constructor, result);
}
 
void QQmlLSCompletion::suggestVariableDeclarationStatementCompletion(
        BackInsertIterator result, QQmlLSUtilsAppendOption option) const
{
    // let/var/const statement
    for (auto view : std::array<QUtf8StringView, 3>{ "let", "var", "const" }) {
        auto snippet = makeSnippet(QByteArray(view.data()).append(" variable = value"),
                             QByteArray(view.data()).append(" ${1:variable} = $0"));
        if (option == AppendSemicolon) {
            snippet.insertText->append(";");
            snippet.label.append(";");
        }
        result = snippet;
    }
}
 
void QQmlLSCompletion::suggestCaseAndDefaultStatementCompletion(BackInsertIterator result) const
{
    // case snippet
    result = makeSnippet("case value: statements...", "case ${1:value}:\n\t$0");
    // case + brackets snippet
    result = makeSnippet("case value: { statements... }", "case ${1:value}: {\n\t$0\n}");
 
    // default snippet
    result = makeSnippet("default: statements...", "default:\n\t$0");
    // default + brackets snippet
    result = makeSnippet("default: { statements... }", "default: {\n\t$0\n}");
}
 
void QQmlLSCompletion::suggestContinueAndBreakStatementIfNeeded(const DomItem &itemAtPosition,
                                                                BackInsertIterator result) const
{
    bool alreadyInLabel = false;
    bool alreadyInSwitch = false;
    for (DomItem current = itemAtPosition; current; current = current.directParent()) {
        switch (current.internalKind()) {
        case DomType::ScriptExpression:
            // reached end of script expression
            return;
 
        case DomType::ScriptForStatement:
        case DomType::ScriptForEachStatement:
        case DomType::ScriptWhileStatement:
        case DomType::ScriptDoWhileStatement: {
            CompletionItem continueKeyword;
            continueKeyword.label = "continue";
            continueKeyword.kind = int(CompletionItemKind::Keyword);
            result = continueKeyword;
 
            // do not add break twice
            if (!alreadyInSwitch && !alreadyInLabel) {
                CompletionItem breakKeyword;
                breakKeyword.label = "break";
                breakKeyword.kind = int(CompletionItemKind::Keyword);
                result = breakKeyword;
            }
            // early exit: cannot suggest more completions
            return;
        }
        case DomType::ScriptSwitchStatement: {
            // check if break was already inserted
            if (alreadyInSwitch || alreadyInLabel)
                break;
            alreadyInSwitch = true;
 
            CompletionItem breakKeyword;
            breakKeyword.label = "break";
            breakKeyword.kind = int(CompletionItemKind::Keyword);
            result = breakKeyword;
            break;
        }
        case DomType::ScriptLabelledStatement: {
            // check if break was already inserted because of switch or loop
            if (alreadyInSwitch || alreadyInLabel)
                break;
            alreadyInLabel = true;
 
            CompletionItem breakKeyword;
            breakKeyword.label = "break";
            breakKeyword.kind = int(CompletionItemKind::Keyword);
            result = breakKeyword;
            break;
        }
        default:
            break;
        }
    }
}
 
void QQmlLSCompletion::suggestJSStatementCompletion(const DomItem &itemAtPosition,
                                                    BackInsertIterator result) const
{
    suggestJSExpressionCompletion(itemAtPosition, result);
    
    if (QQmlLSUtils::isFieldMemberAccess(itemAtPosition))
        return;
 
    // expression statements
    suggestVariableDeclarationStatementCompletion(result);
    // block statement
    result = makeSnippet("{ statements... }", "{\n\t$0\n}");
 
    // if + brackets statement
    result = makeSnippet("if (condition) { statements }", "if ($1) {\n\t$0\n}");
 
    // do statement
    result = makeSnippet("do { statements } while (condition);", "do {\n\t$1\n} while ($0);");
 
    // while + brackets statement
    result = makeSnippet("while (condition) { statements...}", "while ($1) {\n\t$0\n}");
 
    // for + brackets loop statement
    result = makeSnippet("for (initializer; condition; increment) { statements... }",
                         "for ($1;$2;$3) {\n\t$0\n}");
 
    // for ... in + brackets loop statement
    result = makeSnippet("for (property in object) { statements... }", "for ($1 in $2) {\n\t$0\n}");
 
    // for ... of + brackets loop statement
    result = makeSnippet("for (element of array) { statements... }", "for ($1 of $2) {\n\t$0\n}");
 
    // try + catch statement
    result = makeSnippet("try { statements... } catch(error) { statements... }",
                         "try {\n\t$1\n} catch($2) {\n\t$0\n}");
 
    // try + finally statement
    result = makeSnippet("try { statements... } finally { statements... }",
                         "try {\n\t$1\n} finally {\n\t$0\n}");
 
    // try + catch + finally statement
    result = makeSnippet(
            "try { statements... } catch(error) { statements... } finally { statements... }",
            "try {\n\t$1\n} catch($2) {\n\t$3\n} finally {\n\t$0\n}");
 
    // one can always assume that JS code in QML is inside a function, so always propose `return`
    for (auto &&view : { "return"_ba, "throw"_ba }) {
        CompletionItem item;
        item.label = std::move(view);
        item.kind = int(CompletionItemKind::Keyword);
        result = item;
    }
 
    // rules for case+default statements:
    // 1) when inside a CaseBlock, or
    // 2) inside a CaseClause, as an (non-nested) element of the CaseClause statementlist.
    // 3) inside a DefaultClause, as an (non-nested) element of the DefaultClause statementlist,
    //
    // switch (x) {
    // // (1)
    // case 1:
    //      myProperty = 5;
    //      // (2) -> could be another statement of current case, but also a new case or default!
    // default:
    //      myProperty = 5;
    //      // (3) -> could be another statement of current default, but also a new case or default!
    // }
    const DomType currentKind = itemAtPosition.internalKind();
    const DomType parentKind = itemAtPosition.directParent().internalKind();
    if (currentKind == DomType::ScriptCaseBlock || currentKind == DomType::ScriptCaseClause
        || currentKind == DomType::ScriptDefaultClause
        || (currentKind == DomType::List
            && (parentKind == DomType::ScriptCaseClause
                || parentKind == DomType::ScriptDefaultClause))) {
        suggestCaseAndDefaultStatementCompletion(result);
    }
    suggestContinueAndBreakStatementIfNeeded(itemAtPosition, result);
}
 
void QQmlLSCompletion::insideForStatementCompletion(const DomItem &parentForContext,
                                                    const QQmlLSCompletionPosition &positionInfo,
                                                    BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation leftParenthesis = regions[LeftParenthesisRegion];
    const QQmlJS::SourceLocation firstSemicolon = regions[FirstSemicolonTokenRegion];
    const QQmlJS::SourceLocation secondSemicolon = regions[SecondSemicolonRegion];
    const QQmlJS::SourceLocation rightParenthesis = regions[RightParenthesisRegion];
 
    if (betweenLocations(leftParenthesis, positionInfo, firstSemicolon)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        suggestVariableDeclarationStatementCompletion(result,
                                                      QQmlLSUtilsAppendOption::AppendNothing);
        return;
    }
    if (betweenLocations(firstSemicolon, positionInfo, secondSemicolon)
        || betweenLocations(secondSemicolon, positionInfo, rightParenthesis)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
 
    if (afterLocation(rightParenthesis, positionInfo)) {
        suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideScriptLiteralCompletion(const DomItem &currentItem,
                                                     const QQmlLSCompletionPosition &positionInfo,
                                                     BackInsertIterator result) const
{
    Q_UNUSED(currentItem);
    if (positionInfo.cursorPosition.base().isEmpty()) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideCallExpression(const DomItem &currentItem,
                                            const QQmlLSCompletionPosition &positionInfo,
                                            BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(currentItem)->info().regions;
    const QQmlJS::SourceLocation leftParenthesis = regions[LeftParenthesisRegion];
    const QQmlJS::SourceLocation rightParenthesis = regions[RightParenthesisRegion];
    if (beforeLocation(positionInfo, leftParenthesis)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    if (betweenLocations(leftParenthesis, positionInfo, rightParenthesis)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideIfStatement(const DomItem &currentItem,
                                         const QQmlLSCompletionPosition &positionInfo,
                                         BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(currentItem)->info().regions;
    const QQmlJS::SourceLocation leftParenthesis = regions[LeftParenthesisRegion];
    const QQmlJS::SourceLocation rightParenthesis = regions[RightParenthesisRegion];
    const QQmlJS::SourceLocation elseKeyword = regions[ElseKeywordRegion];
 
    if (betweenLocations(leftParenthesis, positionInfo, rightParenthesis)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    if (betweenLocations(rightParenthesis, positionInfo, elseKeyword)) {
        suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    if (afterLocation(elseKeyword, positionInfo)) {
        suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideReturnStatement(const DomItem &currentItem,
                                             const QQmlLSCompletionPosition &positionInfo,
                                             BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(currentItem)->info().regions;
    const QQmlJS::SourceLocation returnKeyword = regions[ReturnKeywordRegion];
 
    if (afterLocation(returnKeyword, positionInfo)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideWhileStatement(const DomItem &currentItem,
                                            const QQmlLSCompletionPosition &positionInfo,
                                            BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(currentItem)->info().regions;
    const QQmlJS::SourceLocation leftParenthesis = regions[LeftParenthesisRegion];
    const QQmlJS::SourceLocation rightParenthesis = regions[RightParenthesisRegion];
 
    if (betweenLocations(leftParenthesis, positionInfo, rightParenthesis)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    if (afterLocation(rightParenthesis, positionInfo)) {
        suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideDoWhileStatement(const DomItem &parentForContext,
                                              const QQmlLSCompletionPosition &positionInfo,
                                              BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
    const QQmlJS::SourceLocation doKeyword = regions[DoKeywordRegion];
    const QQmlJS::SourceLocation whileKeyword = regions[WhileKeywordRegion];
    const QQmlJS::SourceLocation leftParenthesis = regions[LeftParenthesisRegion];
    const QQmlJS::SourceLocation rightParenthesis = regions[RightParenthesisRegion];
 
    if (betweenLocations(doKeyword, positionInfo, whileKeyword)) {
        suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    if (betweenLocations(leftParenthesis, positionInfo, rightParenthesis)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideForEachStatement(const DomItem &parentForContext,
                                              const QQmlLSCompletionPosition &positionInfo,
                                              BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation inOf = regions[InOfTokenRegion];
    const QQmlJS::SourceLocation leftParenthesis = regions[LeftParenthesisRegion];
    const QQmlJS::SourceLocation rightParenthesis = regions[RightParenthesisRegion];
 
    if (betweenLocations(leftParenthesis, positionInfo, inOf)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        suggestVariableDeclarationStatementCompletion(result);
        return;
    }
    if (betweenLocations(inOf, positionInfo, rightParenthesis)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
 
    if (afterLocation(rightParenthesis, positionInfo)) {
        suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideSwitchStatement(const DomItem &parentForContext,
                                             const QQmlLSCompletionPosition positionInfo,
                                             BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation leftParenthesis = regions[LeftParenthesisRegion];
    const QQmlJS::SourceLocation rightParenthesis = regions[RightParenthesisRegion];
 
    if (betweenLocations(leftParenthesis, positionInfo, rightParenthesis)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideCaseClause(const DomItem &parentForContext,
                                        const QQmlLSCompletionPosition &positionInfo,
                                        BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation caseKeyword = regions[CaseKeywordRegion];
    const QQmlJS::SourceLocation colonToken = regions[ColonTokenRegion];
 
    if (betweenLocations(caseKeyword, positionInfo, colonToken)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    if (afterLocation(colonToken, positionInfo)) {
        suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
        return;
    }
 
}
 
bool QQmlLSCompletion::isCaseOrDefaultBeforeCtx(const DomItem &currentClause,
                                                const QQmlLSCompletionPosition &positionInfo,
                                                FileLocationRegion keywordRegion) const
{
    Q_ASSERT(keywordRegion == QQmlJS::Dom::CaseKeywordRegion
             || keywordRegion == QQmlJS::Dom::DefaultKeywordRegion);
 
    if (!currentClause)
        return false;
 
    const auto token = FileLocations::treeOf(currentClause)->info().regions[keywordRegion];
    if (afterLocation(token, positionInfo))
        return true;
 
    return false;
}
 
DomItem
QQmlLSCompletion::previousCaseOfCaseBlock(const DomItem &parentForContext,
                                          const QQmlLSCompletionPosition &positionInfo) const
{
    const DomItem caseClauses = parentForContext.field(Fields::caseClauses);
    for (int i = 0; i < caseClauses.indexes(); ++i) {
        const DomItem currentClause = caseClauses.index(i);
        if (isCaseOrDefaultBeforeCtx(currentClause, positionInfo, QQmlJS::Dom::CaseKeywordRegion)) {
            return currentClause;
        }
    }
 
    const DomItem defaultClause = parentForContext.field(Fields::defaultClause);
    if (isCaseOrDefaultBeforeCtx(defaultClause, positionInfo, QQmlJS::Dom::DefaultKeywordRegion))
        return parentForContext.field(Fields::defaultClause);
 
    const DomItem moreCaseClauses = parentForContext.field(Fields::moreCaseClauses);
    for (int i = 0; i < moreCaseClauses.indexes(); ++i) {
        const DomItem currentClause = moreCaseClauses.index(i);
        if (isCaseOrDefaultBeforeCtx(currentClause, positionInfo, QQmlJS::Dom::CaseKeywordRegion)) {
            return currentClause;
        }
    }
 
    return {};
}
 
void QQmlLSCompletion::insideCaseBlock(const DomItem &parentForContext,
                                       const QQmlLSCompletionPosition &positionInfo,
                                       BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation leftBrace = regions[LeftBraceRegion];
    const QQmlJS::SourceLocation rightBrace = regions[RightBraceRegion];
 
    if (!betweenLocations(leftBrace, positionInfo, rightBrace))
        return;
 
    // TODO: looks fishy
    // if there is a previous case or default clause, you can still add statements to it
    if (const auto previousCase = previousCaseOfCaseBlock(parentForContext, positionInfo)) {
        suggestJSStatementCompletion(previousCase, result);
        return;
    }
 
    // otherwise, only complete case and default
    suggestCaseAndDefaultStatementCompletion(result);
}
 
void QQmlLSCompletion::insideDefaultClause(const DomItem &parentForContext,
                                           const QQmlLSCompletionPosition &positionInfo,
                                           BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation colonToken = regions[ColonTokenRegion];
 
    if (afterLocation(colonToken, positionInfo)) {
        suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
        return ;
    }
}
 
void QQmlLSCompletion::insideBinaryExpressionCompletion(
        const DomItem &parentForContext, const QQmlLSCompletionPosition &positionInfo,
        BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation operatorLocation = regions[OperatorTokenRegion];
 
    if (beforeLocation(positionInfo, operatorLocation)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    if (afterLocation(operatorLocation, positionInfo)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideScriptPattern(const DomItem &parentForContext,
                                           const QQmlLSCompletionPosition &positionInfo,
                                           BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation equal = regions[EqualTokenRegion];
 
    if (!afterLocation(equal, positionInfo))
        return;
 
    // otherwise, only complete case and default
    suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
}
 
void QQmlLSCompletion::insideVariableDeclarationEntry(const DomItem &parentForContext,
                                                      const QQmlLSCompletionPosition &positionInfo,
                                                      BackInsertIterator result) const
{
    insideScriptPattern(parentForContext, positionInfo, result);
}
 
void QQmlLSCompletion::insideThrowStatement(const DomItem &parentForContext,
                                            const QQmlLSCompletionPosition &positionInfo,
                                            BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation throwKeyword = regions[ThrowKeywordRegion];
 
    if (afterLocation(throwKeyword, positionInfo)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideLabelledStatement(const DomItem &parentForContext,
                                               const QQmlLSCompletionPosition &positionInfo,
                                               BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation colon = regions[ColonTokenRegion];
 
    if (afterLocation(colon, positionInfo)) {
        suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    // note: the case "beforeLocation(ctx, colon)" probably never happens:
    // this is because without the colon, the parser will probably not parse this as a
    // labelledstatement but as a normal expression statement.
    // So this case only happens when the colon already exists, and the user goes back to the
    // label name and requests completion for that label.
}
 
static void collectLabels(const DomItem &context, QQmlLSCompletion::BackInsertIterator result)
{
    for (DomItem current = context; current; current = current.directParent()) {
        if (current.internalKind() == DomType::ScriptLabelledStatement) {
            const QString label = current.field(Fields::label).value().toString();
            if (label.isEmpty())
                continue;
            CompletionItem item;
            item.label = label.toUtf8();
            item.kind = int(CompletionItemKind::Value); // variable?
            // TODO: more stuff here?
            result = item;
        } else if (current.internalKind() == DomType::ScriptExpression) {
            // quick exit when leaving the JS part
            return;
        }
    }
    return;
}
 
void QQmlLSCompletion::insideContinueStatement(const DomItem &parentForContext,
                                               const QQmlLSCompletionPosition &positionInfo,
                                               BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation continueKeyword = regions[ContinueKeywordRegion];
 
    if (afterLocation(continueKeyword, positionInfo)) {
        collectLabels(parentForContext, result);
        return;
    }
}
 
void QQmlLSCompletion::insideBreakStatement(const DomItem &parentForContext,
                                            const QQmlLSCompletionPosition &positionInfo,
                                            BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation breakKeyword = regions[BreakKeywordRegion];
 
    if (afterLocation(breakKeyword, positionInfo)) {
        collectLabels(parentForContext, result);
        return;
    }
}
 
void QQmlLSCompletion::insideConditionalExpression(const DomItem &parentForContext,
                                                   const QQmlLSCompletionPosition &positionInfo,
                                                   BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation questionMark = regions[QuestionMarkTokenRegion];
    const QQmlJS::SourceLocation colon = regions[ColonTokenRegion];
 
    if (beforeLocation(positionInfo, questionMark)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    if (betweenLocations(questionMark, positionInfo, colon)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
    if (afterLocation(colon, positionInfo)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideUnaryExpression(const DomItem &parentForContext,
                                             const QQmlLSCompletionPosition &positionInfo,
                                             BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation operatorToken = regions[OperatorTokenRegion];
 
    if (afterLocation(operatorToken, positionInfo)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insidePostExpression(const DomItem &parentForContext,
                                            const QQmlLSCompletionPosition &positionInfo,
                                            BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation operatorToken = regions[OperatorTokenRegion];
 
    if (beforeLocation(positionInfo, operatorToken)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::insideParenthesizedExpression(const DomItem &parentForContext,
                                                     const QQmlLSCompletionPosition &positionInfo,
                                                     BackInsertIterator result) const
{
    const auto regions = FileLocations::treeOf(parentForContext)->info().regions;
 
    const QQmlJS::SourceLocation leftParenthesis = regions[LeftParenthesisRegion];
    const QQmlJS::SourceLocation rightParenthesis = regions[RightParenthesisRegion];
 
    if (betweenLocations(leftParenthesis, positionInfo, rightParenthesis)) {
        suggestJSExpressionCompletion(positionInfo.itemAtPosition, result);
        return;
    }
}
 
void QQmlLSCompletion::signalHandlerCompletion(const QQmlJSScope::ConstPtr &scope,
                                               QDuplicateTracker<QString> *usedNames,
                                               BackInsertIterator result) const
{
    const auto keyValues = scope->methods().asKeyValueRange();
    for (const auto &[name, method] : keyValues) {
        if (method.access() != QQmlJSMetaMethod::Public
            || method.methodType() != QQmlJSMetaMethodType::Signal) {
            continue;
        }
        if (usedNames && usedNames->hasSeen(name)) {
            continue;
        }
 
        CompletionItem completion;
        completion.label = QQmlSignalNames::signalNameToHandlerName(name).toUtf8();
        completion.kind = int(CompletionItemKind::Method);
        result = completion;
    }
}
 
QList<CompletionItem>
QQmlLSCompletion::completions(const DomItem &currentItem,
                              const CompletionContextStrings &contextStrings) const
{
    QList<CompletionItem> result;
    collectCompletions(currentItem, contextStrings, std::back_inserter(result));
    return result;
}
 
void QQmlLSCompletion::collectCompletions(const DomItem &currentItem,
                                          const CompletionContextStrings &contextStrings,
                                          BackInsertIterator result) const
{
    const QQmlLSCompletionPosition positionInfo{ currentItem, contextStrings };
    for (DomItem currentParent = currentItem; currentParent;
         currentParent = currentParent.directParent()) {
        const DomType currentType = currentParent.internalKind();
 
        switch (currentType) {
        case DomType::Id:
            // suppress completions for ids
            return;
        case DomType::Pragma:
            insidePragmaCompletion(currentParent, positionInfo, result);
            return;
        case DomType::ScriptType: {
            if (currentParent.directParent().internalKind() == DomType::QmlObject) {
                insideQmlObjectCompletion(currentParent.directParent(), positionInfo, result);
                return;
            }
 
            LocalSymbolsTypes options;
            options.setFlag(LocalSymbolsType::ObjectType);
            options.setFlag(LocalSymbolsType::ValueType);
            suggestReachableTypes(currentItem, options, CompletionItemKind::Class, result);
            return;
        }
        case DomType::ScriptFormalParameter:
            // no autocompletion inside of function parameter definition
            return;
        case DomType::Binding:
            insideBindingCompletion(currentParent, positionInfo, result);
            return;
        case DomType::Import:
            insideImportCompletion(currentParent, positionInfo, result);
            return;
        case DomType::ScriptForStatement:
            insideForStatementCompletion(currentParent, positionInfo, result);
            return;
        case DomType::ScriptBlockStatement:
            suggestJSStatementCompletion(positionInfo.itemAtPosition, result);
            return;
        case DomType::QmlFile:
            insideQmlFileCompletion(currentParent, positionInfo, result);
            return;
        case DomType::QmlObject:
            insideQmlObjectCompletion(currentParent, positionInfo, result);
            return;
        case DomType::MethodInfo:
            // suppress completions
            return;
        case DomType::PropertyDefinition:
            insidePropertyDefinitionCompletion(currentParent, positionInfo, result);
            return;
        case DomType::ScriptBinaryExpression:
            // ignore field member expressions: these need additional context from its parents
            if (QQmlLSUtils::isFieldMemberExpression(currentParent))
                continue;
            insideBinaryExpressionCompletion(currentParent, positionInfo, result);
            return;
        case DomType::ScriptLiteral:
            insideScriptLiteralCompletion(currentParent, positionInfo, result);
            return;
        case DomType::ScriptCallExpression:
            insideCallExpression(currentParent, positionInfo, result);
            return;
        case DomType::ScriptIfStatement:
            insideIfStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptReturnStatement:
            insideReturnStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptWhileStatement:
            insideWhileStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptDoWhileStatement:
            insideDoWhileStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptForEachStatement:
            insideForEachStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptTryCatchStatement:
            return;
        case DomType::ScriptSwitchStatement:
            insideSwitchStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptCaseClause:
            insideCaseClause(currentParent, positionInfo, result);
            return;
        case DomType::ScriptDefaultClause:
            if (ctxBeforeStatement(positionInfo, currentParent, QQmlJS::Dom::DefaultKeywordRegion))
                continue;
            insideDefaultClause(currentParent, positionInfo, result);
            return;
        case DomType::ScriptCaseBlock:
            insideCaseBlock(currentParent, positionInfo, result);
            return;
        case DomType::ScriptVariableDeclaration:
            // not needed: thats a list of ScriptVariableDeclarationEntry, and those entries cannot
            // be suggested because they all start with `{`, `[` or an identifier that should not be
            // in use yet.
            return;
        case DomType::ScriptVariableDeclarationEntry:
            insideVariableDeclarationEntry(currentParent, positionInfo, result);
            return;
        case DomType::ScriptProperty:
            // fallthrough: a ScriptProperty is a ScriptPattern but inside a JS Object. It gets the
            // same completions as a ScriptPattern.
        case DomType::ScriptPattern:
            insideScriptPattern(currentParent, positionInfo, result);
            return;
        case DomType::ScriptThrowStatement:
            insideThrowStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptLabelledStatement:
            insideLabelledStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptContinueStatement:
            insideContinueStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptBreakStatement:
            insideBreakStatement(currentParent, positionInfo, result);
            return;
        case DomType::ScriptConditionalExpression:
            insideConditionalExpression(currentParent, positionInfo, result);
            return;
        case DomType::ScriptUnaryExpression:
            insideUnaryExpression(currentParent, positionInfo, result);
            return;
        case DomType::ScriptPostExpression:
            insidePostExpression(currentParent, positionInfo, result);
            return;
        case DomType::ScriptParenthesizedExpression:
            insideParenthesizedExpression(currentParent, positionInfo, result);
            return;
 
        // TODO: Implement those statements.
        // In the meanwhile, suppress completions to avoid weird behaviors.
        case DomType::ScriptArray:
        case DomType::ScriptObject:
        case DomType::ScriptElision:
        case DomType::ScriptArrayEntry:
            return;
 
        default:
            continue;
        }
        Q_UNREACHABLE();
    }
 
    // no completion could be found
    qCDebug(QQmlLSUtilsLog) << "No completion was found for current request.";
    return;
}
 
QQmlLSCompletion::QQmlLSCompletion(const QFactoryLoader &pluginLoader)
{
    const auto keys = pluginLoader.metaDataKeys();
    for (qsizetype i = 0; i < keys.size(); ++i) {
        auto instance = std::unique_ptr<QQmlLSPlugin>(
                qobject_cast<QQmlLSPlugin *>(pluginLoader.instance(i)));
        if (!instance)
            continue;
        if (auto completionInstance = instance->createCompletionPlugin())
            m_plugins.push_back(std::move(completionInstance));
    }
}
 
void QQmlLSCompletion::collectFromPlugins(qxp::function_ref<CompletionFromPluginFunction> f,
                                          BackInsertIterator result) const
{
    for (const auto &plugin : m_plugins) {
        Q_ASSERT(plugin);
        f(plugin.get(), result);
    }
}
 
void QQmlLSCompletion::suggestSnippetsForLeftHandSideOfBinding(const DomItem &itemAtPosition,
                                                               BackInsertIterator result) const
{
    collectFromPlugins(
            [&itemAtPosition](QQmlLSCompletionPlugin *p, BackInsertIterator result) {
                p->suggestSnippetsForLeftHandSideOfBinding(itemAtPosition, result);
            },
            result);
}
 
void QQmlLSCompletion::suggestSnippetsForRightHandSideOfBinding(const DomItem &itemAtPosition,
                                                                BackInsertIterator result) const
{
    collectFromPlugins(
            [&itemAtPosition](QQmlLSCompletionPlugin *p, BackInsertIterator result) {
                p->suggestSnippetsForRightHandSideOfBinding(itemAtPosition, result);
            },
            result);
}
 
QT_END_NAMESPACE