core/scriptmodel: add expression model for unique lists

src/core/scriptmodel.cpp

@@ -0,0 +1,133 @@
+#include "scriptmodel.hpp"
+#include <algorithm>
+#include <iterator>
+
+#include <qabstractitemmodel.h>
+#include <qcontainerfwd.h>
+#include <qlist.h>
+#include <qnamespace.h>
+#include <qtmetamacros.h>
+#include <qtversionchecks.h>
+#include <qtypes.h>
+#include <qvariant.h>
+
+void ScriptModel::updateValuesUnique(const QVariantList& newValues) {
+	this->mValues.reserve(newValues.size());
+
+	auto iter = this->mValues.begin();
+	auto newIter = newValues.begin();
+
+	while (true) {
+		if (newIter == newValues.end()) {
+			if (iter == this->mValues.end()) break;
+
+			auto startIndex = static_cast<qint32>(newValues.length());
+			auto endIndex = static_cast<qint32>(this->mValues.length() - 1);
+
+			this->beginRemoveRows(QModelIndex(), startIndex, endIndex);
+			this->mValues.erase(iter, this->mValues.end());
+			this->endRemoveRows();
+
+			break;
+		} else if (iter == this->mValues.end()) {
+			// Prior branch ensures length is at least 1.
+			auto startIndex = static_cast<qint32>(this->mValues.length());
+			auto endIndex = static_cast<qint32>(newValues.length() - 1);
+
+			this->beginInsertRows(QModelIndex(), startIndex, endIndex);
+			this->mValues.append(newValues.sliced(startIndex));
+			this->endInsertRows();
+
+			break;
+		} else if (*newIter != *iter) {
+			auto oldIter = std::find(iter, this->mValues.end(), *newIter);
+
+			if (oldIter != this->mValues.end()) {
+				if (std::find(newIter, newValues.end(), *iter) == newValues.end()) {
+					// Remove any entries we would otherwise move around that aren't in the new list.
+					auto startIter = iter;
+
+					do {
+						++iter;
+					} while (iter != this->mValues.end()
+					         && std::find(newIter, newValues.end(), *iter) == newValues.end());
+
+					auto index = static_cast<qint32>(std::distance(this->mValues.begin(), iter));
+					auto startIndex = static_cast<qint32>(std::distance(this->mValues.begin(), startIter));
+
+					this->beginRemoveRows(QModelIndex(), startIndex, index - 1);
+					iter = this->mValues.erase(startIter, iter);
+					this->endRemoveRows();
+				} else {
+					// Advance iters to capture a whole move sequence as a single operation if possible.
+					auto oldStartIter = oldIter;
+					do {
+						++oldIter;
+						++newIter;
+					} while (oldIter != this->mValues.end() && newIter != newValues.end()
+					         && *oldIter == *newIter);
+
+					auto index = static_cast<qint32>(std::distance(this->mValues.begin(), iter));
+					auto oldStartIndex =
+					    static_cast<qint32>(std::distance(this->mValues.begin(), oldStartIter));
+					auto oldIndex = static_cast<qint32>(std::distance(this->mValues.begin(), oldIter));
+					auto len = oldIndex - oldStartIndex;
+
+					this->beginMoveRows(QModelIndex(), oldStartIndex, oldIndex - 1, QModelIndex(), index);
+
+					// While it is possible to optimize this further, it is currently not worth the time.
+					for (auto i = 0; i != len; i++) {
+						this->mValues.move(oldStartIndex + i, index + i);
+					}
+
+					iter = this->mValues.begin() + (index + len);
+					this->endMoveRows();
+				}
+			} else {
+				auto startNewIter = newIter;
+
+				do {
+					newIter++;
+				} while (newIter != newValues.end()
+				         && std::find(iter, this->mValues.end(), *newIter) == this->mValues.end());
+
+				auto index = static_cast<qint32>(std::distance(this->mValues.begin(), iter));
+				auto newIndex = static_cast<qint32>(std::distance(newValues.begin(), newIter));
+				auto startNewIndex = static_cast<qint32>(std::distance(newValues.begin(), startNewIter));
+				auto len = newIndex - startNewIndex;
+
+				this->beginInsertRows(QModelIndex(), index, index + len - 1);
+#if QT_VERSION <= QT_VERSION_CHECK(6, 8, 0)
+				this->mValues.resize(this->mValues.length() + len);
+#else
+				this->mValues.resizeForOverwrite(this->mValues.length() + len);
+#endif
+				iter = this->mValues.begin() + index; // invalidated
+				std::move_backward(iter, this->mValues.end() - len, this->mValues.end());
+				iter = std::copy(startNewIter, newIter, iter);
+				this->endInsertRows();
+			}
+		} else {
+			++iter;
+			++newIter;
+		}
+	}
+}
+
+void ScriptModel::setValues(const QVariantList& newValues) {
+	if (newValues == this->mValues) return;
+	this->updateValuesUnique(newValues);
+	emit this->valuesChanged();
+}
+
+qint32 ScriptModel::rowCount(const QModelIndex& parent) const {
+	if (parent != QModelIndex()) return 0;
+	return static_cast<qint32>(this->mValues.length());
+}
+
+QVariant ScriptModel::data(const QModelIndex& index, qint32 role) const {
+	if (role != Qt::UserRole) return QVariant();
+	return this->mValues.at(index.row());
+}
+
+QHash<int, QByteArray> ScriptModel::roleNames() const { return {{Qt::UserRole, "modelData"}}; }