QItemSelectionModel: replace a QPair with a dedicated struct

Pairs are easy to use, but they have no semantics attached: Two
QPair<int, int> compare equal, e.g., even though one is used as a
coordinate and the other as, say, a fraction. It also carries no
information for the reader of the code, as exemplified by the urge to
comment on the content of the pairs in both functions that use them.

So, write a minimal struct with equality and qHash() instead. The
comments are now no longer needed.

Change-Id: I51f6ff049a5f8fa61c51856376ac2fcbfb8dd506
Reviewed-by: David Faure <david.faure@kdab.com>

1 files changed, 23 insertions, 8 deletions

diff --git a/src/corelib/itemmodels/qitemselectionmodel.cpp b/src/corelib/itemmodels/qitemselectionmodel.cpp
index 27442fb2fa..7327b5deee 100644
--- a/src/corelib/itemmodels/qitemselectionmodel.cpp
+++ b/src/corelib/itemmodels/qitemselectionmodel.cpp
@@ -1721,6 +1721,23 @@ QModelIndexList QItemSelectionModel::selectedIndexes() const
     return selected.indexes();
 }
 
+struct RowOrColumnDefinition {
+    QModelIndex parent;
+    int rowOrColumn;
+
+    friend bool operator==(const RowOrColumnDefinition &lhs, const RowOrColumnDefinition &rhs) noexcept
+    { return lhs.parent == rhs.parent && lhs.rowOrColumn == rhs.rowOrColumn; }
+    friend bool operator!=(const RowOrColumnDefinition &lhs, const RowOrColumnDefinition &rhs) noexcept
+    { return !operator==(lhs, rhs); }
+};
+size_t qHash(const RowOrColumnDefinition &key, size_t seed = 0) noexcept
+{
+    QtPrivate::QHashCombine hash;
+    seed = hash(seed, key.parent);
+    seed = hash(seed, key.rowOrColumn);
+    return seed;
+}
+
 /*!
     \since 4.2
     Returns the indexes in the given \a column for the rows where all columns are selected.
@@ -1731,16 +1748,15 @@ QModelIndexList QItemSelectionModel::selectedIndexes() const
 QModelIndexList QItemSelectionModel::selectedRows(int column) const
 {
     QModelIndexList indexes;
-    //the QSet contains pairs of parent modelIndex
-    //and row number
-    QSet< QPair<QModelIndex, int> > rowsSeen;
+
+    QSet<RowOrColumnDefinition> rowsSeen;
 
     const QItemSelection ranges = selection();
     for (int i = 0; i < ranges.count(); ++i) {
         const QItemSelectionRange &range = ranges.at(i);
         QModelIndex parent = range.parent();
         for (int row = range.top(); row <= range.bottom(); row++) {
-            QPair<QModelIndex, int> rowDef = qMakePair(parent, row);
+            RowOrColumnDefinition rowDef = {parent, row};
             if (!rowsSeen.contains(rowDef)) {
                 rowsSeen << rowDef;
                 if (isRowSelected(row, parent)) {
@@ -1763,16 +1779,15 @@ QModelIndexList QItemSelectionModel::selectedRows(int column) const
 QModelIndexList QItemSelectionModel::selectedColumns(int row) const
 {
     QModelIndexList indexes;
-    //the QSet contains pairs of parent modelIndex
-    //and column number
-    QSet< QPair<QModelIndex, int> > columnsSeen;
+
+    QSet<RowOrColumnDefinition> columnsSeen;
 
     const QItemSelection ranges = selection();
     for (int i = 0; i < ranges.count(); ++i) {
         const QItemSelectionRange &range = ranges.at(i);
         QModelIndex parent = range.parent();
         for (int column = range.left(); column <= range.right(); column++) {
-            QPair<QModelIndex, int> columnDef = qMakePair(parent, column);
+            RowOrColumnDefinition columnDef = {parent, column};
             if (!columnsSeen.contains(columnDef)) {
                 columnsSeen << columnDef;
                 if (isColumnSelected(column, parent)) {