Reduce SessionItem signaling

• reduce SessionItem signaling regarding sample items
• cleanup/simplify code
• fix warning

GUI/Model/To/DomainObjectBuilder.cpp

-//  ************************************************************************************************
-//
-//  BornAgain: simulate and fit reflection and scattering
-//
-//! @file      GUI/Model/To/DomainObjectBuilder.cpp
-//! @brief     Implements DomainObjectBuilder namespace
-//!
-//! @homepage  http://www.bornagainproject.org
-//! @license   GNU General Public License v3 or higher (see COPYING)
-//! @copyright Forschungszentrum Jülich GmbH 2018
-//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
-//
-//  ************************************************************************************************
-
-#include "GUI/Model/To/DomainObjectBuilder.h"
-#include "GUI/Model/Instrument/InstrumentItems.h"
-#include "GUI/Model/Sample/InterferenceItems.h"
-#include "GUI/Model/Sample/LayerItem.h"
-#include "GUI/Model/Sample/MultiLayerItem.h"
-#include "GUI/Model/Sample/ParticleLayoutItem.h"
-#include "GUI/Model/To/ToDomain.h"
-#include "GUI/Util/Error.h"
-
-std::unique_ptr<MultiLayer>
-GUI::Model::DomainObjectBuilder::buildMultiLayer(const MultiLayerItem& multiLayerItem)
-{
-    auto P_multilayer = GUI::Transform::ToDomain::createMultiLayer(multiLayerItem);
-    for (auto* layerItem : multiLayerItem.layers()) {
-        const bool isFirstLayer = layerItem == multiLayerItem.layers().first();
-        const bool isLastLayer = layerItem == multiLayerItem.layers().last();
-        auto P_layer = buildLayer(*layerItem, isFirstLayer || isLastLayer);
-        if (P_layer) {
-            const auto roughness = layerItem->roughness().currentItem();
-            auto P_roughness = GUI::Transform::ToDomain::createLayerRoughness(roughness);
-            if (P_roughness && !isLastLayer)
-                P_multilayer->addLayerWithTopRoughness(*P_layer, *P_roughness);
-            else
-                P_multilayer->addLayer(*P_layer);
-        }
-    }
-    return P_multilayer;
-}
-
-std::unique_ptr<Layer> GUI::Model::DomainObjectBuilder::buildLayer(const LayerItem& item,
-                                                                   bool isFirstOrLastLayer)
-{
-    auto P_layer = GUI::Transform::ToDomain::createLayer(item, isFirstOrLastLayer);
-    for (ParticleLayoutItem* layout : item.layouts()) {
-        auto P_layout = buildParticleLayout(*layout);
-        if (P_layout)
-            P_layer->addLayout(*P_layout);
-    }
-    return P_layer;
-}
-
-std::unique_ptr<ParticleLayout>
-GUI::Model::DomainObjectBuilder::buildParticleLayout(const ParticleLayoutItem& item)
-{
-    auto P_layout = GUI::Transform::ToDomain::createParticleLayout(item);
-    QVector<SessionItem*> children = item.getItems();
-    for (int i = 0; i < children.size(); ++i) {
-        auto P_particle = GUI::Transform::ToDomain::createIParticle(*children[i]);
-        if (P_particle) {
-            P_layout->addParticle(*P_particle);
-            continue;
-        }
-
-        throw Error("GUI::Model::DomainObjectBuilder::buildParticleLayout()"
-                    " -> Error! Not implemented");
-    }
-    InterferenceItem* interference = item.interference().currentItem();
-    if (interference) {
-        auto P_interference = interference->createInterference();
-        if (P_interference)
-            P_layout->setInterference(*P_interference);
-    }
-    return P_layout;
-}