blame: src/fsdirmodel.h

#pragma once

#include <QAbstractItemModel>

#include <QByteArray>

#include <QIcon>

#include <QList>

// A directory-tree model that uses std::filesystem for enumeration so that

// directory entries with non-UTF-8 filenames (e.g. Latin-1 encoded names on

// a UTF-8 locale) are listed correctly instead of being silently dropped or

// mangled by QDir / QFileSystemModel.

//

// The model is lazily populated: child directories are enumerated only when

// the view first expands a node (via canFetchMore / fetchMore).

class FsDirModel : public QAbstractItemModel

{

    Q_OBJECT

public:

    explicit FsDirModel(QObject *parent = nullptr);

    ~FsDirModel() override;

    // Set the directory shown as the tree root.  Call rootIndex() afterwards

    // and pass the result to QTreeView::setRootIndex() so the root node itself

    // is hidden and only its children are displayed as top-level items.

    void setRootPath(const QByteArray &nativePath);

    void setRootPath(const QString &path);   // convenience: converts via QFile::encodeName

    // Model index of the root-path node (the one whose *children* are shown

    // as top-level items when passed to QTreeView::setRootIndex).

    QModelIndex rootIndex() const;

    // Raw native OS byte path for the node at index.

    QByteArray filePath(const QModelIndex &index) const;

    // Walk the tree to find (and lazily populate) the node for nativePath.

    // Returns an invalid index if the path is not under the current root.

    QModelIndex indexForPath(const QByteArray &nativePath);

    // QAbstractItemModel interface

    QModelIndex index(int row, int column,

                      const QModelIndex &parent = QModelIndex()) const override;

    QModelIndex parent(const QModelIndex &index) const override;

    int rowCount(const QModelIndex &parent = QModelIndex()) const override;

    int columnCount(const QModelIndex &parent = QModelIndex()) const override;

    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;

    bool hasChildren(const QModelIndex &parent = QModelIndex()) const override;

    bool canFetchMore(const QModelIndex &parent) const override;

    void fetchMore(const QModelIndex &parent) override;

private:

    struct Node {

        QByteArray  nativePath;

        QString     displayName;

        Node       *parent   = nullptr;

        QList<Node *> children;

        bool        populated = false;

    };

    // Synchronously populate node->children from the filesystem.

    // Only call this inside fetchMore (with proper begin/endInsertRows around it).

    static QList<Node *> listSubdirs(Node *parent);

    Node *nodeForIndex(const QModelIndex &index) const;

    QModelIndex indexForNode(Node *node) const;

    static void destroyChildren(Node *node);

    Node   m_virtualRoot;   // hidden root; always has exactly 0 or 1 child

    QIcon  m_folderIcon;

};