Create a CellTable class that stores cells with QHash

QMap is too slow to use as storage for cells, with
QHash I was able cut writeBool() & friends time by half.

Author: dantti

QXlsx/header/xlsxcellreference.h

@@ -9,11 +9,22 @@
 
 QT_BEGIN_NAMESPACE_XLSX
 
+const int XLSX_ROW_MAX    = 1048576;
+const int XLSX_COLUMN_MAX = 16384;
+const int XLSX_STRING_MAX = 32767;
+
 class QXLSX_EXPORT CellReference
 {
 public:
     CellReference();
-    CellReference(int row, int column);
+    /*!
+        Constructs the Reference from the given \a row, and \a column.
+    */
+    constexpr CellReference(int row, int column)
+        : _row(row)
+        , _column(column)
+    {
+    }
     CellReference(const QString &cell);
     CellReference(const char *cell);
     CellReference(const CellReference &other);
@@ -36,9 +47,15 @@ class QXLSX_EXPORT CellReference
         return _row != other._row || _column != other._column;
     }
 
+    inline bool operator>(const CellReference &other) const
+    {
+        return _row > other._row ||  _column != other._column;
+    }
+
 private:
     void init(const QString &cell);
-    int _row, _column;
+    int _row{-1};
+    int _column{-1};
 };
 
 QT_END_NAMESPACE_XLSX

QXlsx/header/xlsxworksheet_p.h

@@ -16,17 +16,13 @@
 #include <QSharedPointer>
 #include <QString>
 #include <QVector>
-#include <QtGlobal>
+#include <QHash>
 
 class QXmlStreamWriter;
 class QXmlStreamReader;
 
 QT_BEGIN_NAMESPACE_XLSX
 
-const int XLSX_ROW_MAX    = 1048576;
-const int XLSX_COLUMN_MAX = 16384;
-const int XLSX_STRING_MAX = 32767;
-
 class SharedStrings;
 
 struct XlsxHyperlinkData {
@@ -137,6 +133,53 @@ struct XlsxColumnInfo {
     bool collapsed;
 };
 
+class CellTable
+{
+public:
+    static QList<int> sorteIntList(QList<int> &&keys) {
+        std::sort(keys.begin(), keys.end());
+        return keys;
+    }
+
+    inline QList<int> sortedRows() const {
+        QList<int> keys = cells.keys();
+        std::sort(keys.begin(), keys.end());
+        return keys;
+    }
+
+    void setValue(int row, int column, const std::shared_ptr<Cell> &cell) {
+        cells[row].emplace(column, cell);
+        firstRow = qMin(firstRow, row);
+        firstColumn = qMin(firstColumn, column);
+        lastRow = qMin(lastRow, row);
+        lastColumn = qMin(lastColumn, column);
+    }
+
+    std::shared_ptr<Cell> cellAt(int row, int column) const{
+        return cells.value(row).value(column);
+    }
+
+    bool contains(int row, int column) const{
+        auto it = cells.find(row);
+        if (it != cells.end()) {
+            return it->contains(column);
+        }
+        return false;
+    }
+
+    bool isEmpty() const {
+        return cells.isEmpty();
+    }
+
+    // It's faster with a single QHash, but in Qt5 it's capacity limits
+    // how much cells we can hold
+    QHash<int, QHash<int, std::shared_ptr<Cell>>> cells;
+    int firstRow = -1;
+    int firstColumn = -1;
+    int lastRow = -1;
+    int lastColumn = -1;
+};
+
 class WorksheetPrivate : public AbstractSheetPrivate
 {
     Q_DECLARE_PUBLIC(Worksheet)
@@ -182,7 +225,7 @@ class WorksheetPrivate : public AbstractSheetPrivate
     SharedStrings *sharedStrings() const;
 
 public:
-    QMap<int, QMap<int, std::shared_ptr<Cell>>> cellTable;
+    CellTable cellTable;
 
     QMap<int, QMap<int, QString>> comments;
     QMap<int, QMap<int, QSharedPointer<XlsxHyperlinkData>>> urlTable;

QXlsx/source/xlsxcellreference.cpp

@@ -1,6 +1,7 @@
 // xlsxcellreference.cpp
 
 #include "xlsxcellreference.h"
+#include "xlsxworksheet_p.h"
 
 #include <QMap>
 #include <QRegularExpression>
@@ -69,20 +70,7 @@ int col_from_name(const QString &col_str)
 /*!
     Constructs an invalid Cell Reference
 */
-CellReference::CellReference()
-    : _row(-1)
-    , _column(-1)
-{
-}
-
-/*!
-    Constructs the Reference from the given \a row, and \a column.
-*/
-CellReference::CellReference(int row, int column)
-    : _row(row)
-    , _column(column)
-{
-}
+CellReference::CellReference() = default;
 
 /*!
     \overload