Move BuildGraphLoader into its own set of files.

Change-Id: Icd11a83337a34d3544bfd59c1ab93c9d2ccb4dea
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

5 files changed, 637 insertions, 547 deletions

diff --git a/src/lib/buildgraph/buildgraph.cpp b/src/lib/buildgraph/buildgraph.cpp
index 8fa790bf2..95330f962 100644
--- a/src/lib/buildgraph/buildgraph.cpp
+++ b/src/lib/buildgraph/buildgraph.cpp
@@ -31,25 +31,16 @@
 #include "artifact.h"
 #include "projectbuilddata.h"
 #include "productbuilddata.h"
-#include "cycledetector.h"
-#include "rulesevaluationcontext.h"
-#include "transformer.h"
 
 #include <jsextensions/moduleproperties.h>
-#include <language/loader.h>
 #include <language/language.h>
 #include <language/scriptengine.h>
 #include <logging/logger.h>
 #include <logging/translator.h>
 #include <tools/error.h>
-#include <tools/fileinfo.h>
-#include <tools/propertyfinder.h>
 #include <tools/qbsassert.h>
-#include <tools/setupprojectparameters.h>
 
-#include <QDir>
 #include <QFile>
-#include <QFileInfo>
 
 namespace qbs {
 namespace Internal {
@@ -436,503 +427,5 @@ void dumpProductBuildData(const ResolvedProductConstPtr &product)
             dumpProductBuildDataInternal(product, artifact, QByteArray());
 }
 
-
-BuildGraphLoader::BuildGraphLoader(const QProcessEnvironment &env, const Logger &logger) :
-    m_logger(logger), m_environment(env)
-{
-}
-
-static bool isConfigCompatible(const QVariantMap &userCfg, const QVariantMap &projectCfg)
-{
-    QVariantMap::const_iterator it = userCfg.begin();
-    for (; it != userCfg.end(); ++it) {
-        if (it.value().type() == QVariant::Map) {
-            if (!isConfigCompatible(it.value().toMap(), projectCfg.value(it.key()).toMap()))
-                return false;
-        } else {
-            QVariant value = projectCfg.value(it.key());
-            if (!value.isNull() && value != it.value()) {
-                return false;
-            }
-        }
-    }
-    return true;
-}
-
-void restoreBackPointers(const ResolvedProjectPtr &project)
-{
-    foreach (const ResolvedProductPtr &product, project->products) {
-        product->project = project;
-        if (!product->buildData)
-            continue;
-        foreach (Artifact * const a, product->buildData->artifacts) {
-            a->project = project;
-            project->topLevelProject()->buildData->insertIntoArtifactLookupTable(a);
-        }
-    }
-
-    foreach (const ResolvedProjectPtr &subProject, project->subProjects) {
-        subProject->parentProject = project;
-        restoreBackPointers(subProject);
-    }
-}
-
-BuildGraphLoadResult BuildGraphLoader::load(const SetupProjectParameters &parameters,
-        const RulesEvaluationContextPtr &evalContext)
-{
-    m_result = BuildGraphLoadResult();
-    m_evalContext = evalContext;
-
-    const QString projectId = TopLevelProject::deriveId(parameters.buildConfigurationTree());
-    const QString buildDir
-            = TopLevelProject::deriveBuildDirectory(parameters.buildRoot(), projectId);
-    const QString buildGraphFilePath
-            = ProjectBuildData::deriveBuildGraphFilePath(buildDir, projectId);
-
-    PersistentPool pool(m_logger);
-    m_logger.qbsDebug() << "[BG] trying to load: " << buildGraphFilePath;
-    try {
-        pool.load(buildGraphFilePath);
-    } catch (const ErrorInfo &loadError) {
-        if (parameters.restoreBehavior() == SetupProjectParameters::RestoreOnly)
-            throw loadError;
-        m_logger.qbsInfo() << loadError.toString();
-        return m_result;
-    }
-
-    if (!isConfigCompatible(parameters.buildConfigurationTree(), pool.headData().projectConfig)) {
-        const QString message = Tr::tr("Cannot use stored build graph at '%1':"
-                "Incompatible project configuration.").arg(buildGraphFilePath);
-        if (parameters.restoreBehavior() == SetupProjectParameters::RestoreOnly)
-            throw ErrorInfo(message);
-        m_logger.qbsInfo() << message;
-        return m_result;
-    }
-
-    const TopLevelProjectPtr project = TopLevelProject::create();
-
-    // TODO: Store some meta data that will enable us to show actual progress (e.g. number of products).
-    evalContext->initializeObserver(Tr::tr("Restoring build graph from disk"), 1);
-
-    project->load(pool);
-    project->buildData->evaluationContext = evalContext;
-
-    if (QFileInfo(project->location.fileName()) != QFileInfo(parameters.projectFilePath())) {
-        QString errorMessage = Tr::tr("Stored build graph is for project file '%1', but "
-                                      "input file is '%2'. ")
-                .arg(QDir::toNativeSeparators(project->location.fileName()),
-                     QDir::toNativeSeparators(parameters.projectFilePath()));
-        if (!parameters.ignoreDifferentProjectFilePath()) {
-            errorMessage += Tr::tr("Aborting.");
-            throw ErrorInfo(errorMessage);
-        }
-
-        // Okay, let's assume it's the same project anyway (the source dir might have moved).
-        errorMessage += Tr::tr("Ignoring.");
-        m_logger.qbsWarning() << errorMessage;
-    }
-
-    restoreBackPointers(project);
-    foreach (Artifact * const a, project->buildData->dependencyArtifacts)
-        a->project = project;
-
-    project->location = CodeLocation(parameters.projectFilePath(), project->location.line(),
-                                     project->location.column());
-    project->setBuildConfiguration(pool.headData().projectConfig);
-    project->buildDirectory = buildDir;
-    m_result.loadedProject = project;
-    evalContext->incrementProgressValue();
-
-    if (parameters.restoreBehavior() == SetupProjectParameters::RestoreOnly)
-        return m_result;
-    QBS_CHECK(parameters.restoreBehavior() == SetupProjectParameters::RestoreAndTrackChanges);
-
-    trackProjectChanges(parameters, buildGraphFilePath, project);
-    return m_result;
-}
-
-static void exchangeDependencies(const ResolvedProductPtr &newProduct,
-                                 const QList<ResolvedProductPtr> &allRestoredProducts,
-                                 const QList<ResolvedProductPtr> &addedProducts)
-{
-    QSet<ResolvedProductPtr> newDependencies;
-    foreach (const ResolvedProductPtr &dependency, newProduct->dependencies) {
-        if (addedProducts.contains(dependency)) {
-            newDependencies << dependency;
-            exchangeDependencies(dependency, allRestoredProducts, addedProducts);
-            continue;
-        }
-        bool counterPartFound = false;
-        foreach (const ResolvedProductPtr &restoredProduct, allRestoredProducts) {
-            if (restoredProduct->name == dependency->name) {
-                newDependencies << restoredProduct;
-                counterPartFound = true;
-                break;
-            }
-        }
-        QBS_CHECK(counterPartFound);
-    }
-    newProduct->dependencies = newDependencies;
-}
-
-static void manipulateAddedProducts(const QList<ResolvedProjectPtr> &allRestoredProjects,
-                                    const QList<ResolvedProductPtr> &allRestoredProducts,
-                                    const QList<ResolvedProductPtr> &addedProducts)
-{
-    foreach (const ResolvedProductPtr &product, addedProducts) {
-        // Find the right existing (sub-)project to put the new product into.
-        bool projectFound = false;
-        foreach (const ResolvedProjectPtr &project, allRestoredProjects) {
-            if (project->location != product->project->location)
-                continue;
-            product->project = project;
-            project->products.append(product);
-            projectFound = true;
-            break;
-        }
-        QBS_CHECK(projectFound);
-
-        // Exchange dependencies that are not new with their counterparts from the restored project.
-        exchangeDependencies(product, allRestoredProducts, addedProducts);
-    }
-}
-
-// TODO: Pay more attention to project metadata such as name and location. If these change,
-// we must transfer them over to the old build graph.
-void BuildGraphLoader::trackProjectChanges(const SetupProjectParameters &parameters,
-        const QString &buildGraphFilePath, const TopLevelProjectPtr &restoredProject)
-{
-    const FileInfo bgfi(buildGraphFilePath);
-    const QList<ResolvedProjectPtr> allRestoredProjects
-            = restoredProject->allSubProjects() << restoredProject;
-    bool projectFileChanged = false;
-    bool subProjectRemoved = false;
-    foreach (const ResolvedProjectConstPtr &p, allRestoredProjects) {
-        FileInfo fi(p->location.fileName());
-        if (!fi.exists()) {
-            subProjectRemoved = true;
-            break;
-        }
-        if (bgfi.lastModified() < fi.lastModified()) {
-            projectFileChanged = true;
-            break;
-        }
-    }
-    if (subProjectRemoved)
-        m_logger.qbsTrace() << "A sub-project was removed, must re-resolve project";
-    if (projectFileChanged)
-        m_logger.qbsTrace() << "A project file changed, must re-resolve project.";
-
-    bool environmentChanged = false;
-    for (QHash<QString, QString>::ConstIterator it = restoredProject->usedEnvironment.constBegin();
-         !environmentChanged && it != restoredProject->usedEnvironment.constEnd(); ++it) {
-        environmentChanged = m_environment.value(it.key()) != it.value();
-    }
-    if (environmentChanged)
-        m_logger.qbsTrace() << "A relevant environment variable changed, must re-resolve project.";
-
-    bool productRemoved = false;
-    const QList<ResolvedProductPtr> allRestoredProducts = restoredProject->allProducts();
-    QList<ResolvedProductPtr> changedProducts;
-    foreach (const ResolvedProductPtr &product, allRestoredProducts) {
-        const FileInfo pfi(product->location.fileName());
-        if (!pfi.exists()) {
-            productRemoved = true;
-        } else if (bgfi.lastModified() < pfi.lastModified()) {
-            changedProducts += product;
-        } else {
-            foreach (const GroupPtr &group, product->groups) {
-                if (!group->wildcards)
-                    continue;
-                const QSet<QString> files
-                        = group->wildcards->expandPatterns(group, product->sourceDirectory);
-                QSet<QString> wcFiles;
-                foreach (const SourceArtifactConstPtr &sourceArtifact, group->wildcards->files)
-                    wcFiles += sourceArtifact->absoluteFilePath;
-                if (files == wcFiles)
-                    continue;
-                changedProducts += product;
-                break;
-            }
-        }
-    }
-
-    if (!environmentChanged && !projectFileChanged && !subProjectRemoved && !productRemoved
-            && changedProducts.isEmpty()) {
-        return;
-    }
-
-    Loader ldr(m_evalContext->engine(), m_logger);
-    ldr.setSearchPaths(parameters.searchPaths());
-    m_result.newlyResolvedProject = ldr.loadProject(parameters);
-
-    QMap<QString, ResolvedProductPtr> freshProductsByName;
-    const QList<ResolvedProductPtr> allNewlyResolvedProducts
-            = m_result.newlyResolvedProject->allProducts();
-    foreach (const ResolvedProductPtr &cp, allNewlyResolvedProducts)
-        freshProductsByName.insert(cp->name, cp);
-
-    QSet<TransformerPtr> seenTransformers;
-    foreach (const ResolvedProductPtr &product, allRestoredProducts) {
-        if (!product->buildData)
-            continue;
-        foreach (Artifact *artifact, product->buildData->artifacts) {
-            if (!artifact->transformer || seenTransformers.contains(artifact->transformer))
-                continue;
-            seenTransformers.insert(artifact->transformer);
-            ResolvedProductPtr freshProduct = freshProductsByName.value(product->name);
-            if (freshProduct && checkForPropertyChanges(artifact->transformer, freshProduct)) {
-                m_result.discardLoadedProject = true;
-                return;
-            }
-        }
-    }
-
-    foreach (const ResolvedProductPtr &product, changedProducts) {
-        ResolvedProductPtr freshProduct = freshProductsByName.value(product->name);
-        if (!freshProduct)
-            continue;
-        onProductChanged(product, freshProduct);
-        if (m_result.discardLoadedProject)
-            return;
-    }
-
-    QSet<QString> oldProductNames, newProductNames;
-    foreach (const ResolvedProductConstPtr &product, allRestoredProducts)
-        oldProductNames += product->name;
-    foreach (const ResolvedProductConstPtr &product, allNewlyResolvedProducts)
-        newProductNames += product->name;
-
-    const QSet<QString> removedProductsNames = oldProductNames - newProductNames;
-    if (!removedProductsNames.isEmpty()) {
-        foreach (const ResolvedProductPtr &product, allRestoredProducts) {
-            if (removedProductsNames.contains(product->name))
-                onProductRemoved(product);
-        }
-    }
-
-    const QSet<QString> addedProductNames = newProductNames - oldProductNames;
-    QList<ResolvedProductPtr> addedProducts;
-    foreach (const QString &productName, addedProductNames) {
-        const ResolvedProductPtr &freshProduct = freshProductsByName.value(productName);
-        QBS_ASSERT(freshProduct, continue);
-        addedProducts.append(freshProduct);
-    }
-    if (!addedProducts.isEmpty()) {
-        manipulateAddedProducts(allRestoredProjects, allRestoredProducts, addedProducts);
-        BuildDataResolver bpr(m_logger);
-        bpr.resolveProductBuildDataForExistingProject(restoredProject, addedProducts);
-    }
-
-    CycleDetector(m_logger).visitProject(restoredProject);
-}
-
-void BuildGraphLoader::onProductRemoved(const ResolvedProductPtr &product)
-{
-    m_logger.qbsDebug() << "[BG] product '" << product->name << "' removed.";
-
-    product->topLevelProject()->buildData->isDirty = true;
-    product->project->products.removeOne(product);
-
-    // delete all removed artifacts physically from the disk
-    if (product->buildData) {
-        foreach (Artifact *artifact, product->buildData->artifacts) {
-            artifact->disconnectAll(m_logger);
-            removeGeneratedArtifactFromDisk(artifact, m_logger);
-        }
-    }
-}
-
-void BuildGraphLoader::onProductChanged(const ResolvedProductPtr &product,
-                                        const ResolvedProductPtr &changedProduct)
-{
-    m_logger.qbsDebug() << "[BG] product '" << product->name << "' changed.";
-
-    ArtifactsPerFileTagMap artifactsPerFileTag;
-    QList<Artifact *> addedArtifacts;
-    ArtifactList artifactsToRemove;
-    QHash<QString, SourceArtifactConstPtr> oldArtifacts, newArtifacts;
-
-    const QList<SourceArtifactPtr> oldProductAllFiles = product->allEnabledFiles();
-    foreach (const SourceArtifactConstPtr &a, oldProductAllFiles)
-        oldArtifacts.insert(a->absoluteFilePath, a);
-    foreach (const SourceArtifactPtr &a, changedProduct->allEnabledFiles()) {
-        newArtifacts.insert(a->absoluteFilePath, a);
-        if (!oldArtifacts.contains(a->absoluteFilePath)) {
-            // artifact added
-            m_logger.qbsDebug() << "[BG] artifact '" << a->absoluteFilePath
-                                << "' added to product " << product->name;
-            Artifact *newArtifact = lookupArtifact(product, a->absoluteFilePath);
-            if (newArtifact) {
-                // User added a source file that was a generated artifact in the previous
-                // build, e.g. a C++ source file that was generated and now is a non-generated
-                // source file.
-                newArtifact->artifactType = Artifact::SourceFile;
-            } else {
-                newArtifact = createArtifact(product, a, m_logger);
-                foreach (Artifact *oldArtifact,
-                         product->topLevelProject()->buildData->lookupArtifacts(newArtifact->filePath())) {
-                    if (oldArtifact == newArtifact
-                            || oldArtifact->artifactType != Artifact::FileDependency) {
-                        // The source file already exists in another product.
-                        continue;
-                    }
-                    // User added a source file that was recognized as file dependency in the
-                    // previous build, e.g. a C++ header file.
-                    replaceFileDependencyWithArtifact(oldArtifact, newArtifact);
-                }
-            }
-            addedArtifacts += newArtifact;
-        }
-    }
-
-    foreach (const SourceArtifactPtr &a, oldProductAllFiles) {
-        const SourceArtifactConstPtr changedArtifact = newArtifacts.value(a->absoluteFilePath);
-        if (!changedArtifact) {
-            // artifact removed
-            m_logger.qbsDebug() << "[BG] artifact '" << a->absoluteFilePath
-                                << "' removed from product " << product->name;
-            Artifact *artifact = lookupArtifact(product, a->absoluteFilePath);
-            QBS_CHECK(artifact);
-            removeArtifactAndExclusiveDependents(artifact, &artifactsToRemove);
-            continue;
-        }
-        if (changedArtifact->fileTags != a->fileTags) {
-            // artifact's filetags have changed
-            m_logger.qbsDebug() << "[BG] filetags have changed for artifact '"
-                    << a->absoluteFilePath << "' from " << a->fileTags << " to "
-                    << changedArtifact->fileTags;
-            Artifact *artifact = lookupArtifact(product, a->absoluteFilePath);
-            QBS_CHECK(artifact);
-
-            // handle added filetags
-            foreach (const FileTag &addedFileTag, changedArtifact->fileTags - a->fileTags)
-                artifactsPerFileTag[addedFileTag] += artifact;
-
-            // handle removed filetags
-            foreach (const FileTag &removedFileTag, a->fileTags - changedArtifact->fileTags) {
-                artifact->fileTags -= removedFileTag;
-                foreach (Artifact *parent, artifact->parents) {
-                    if (parent->transformer && parent->transformer->rule->inputs.contains(removedFileTag)) {
-                        // this parent has been created because of the removed filetag
-                        removeArtifactAndExclusiveDependents(parent, &artifactsToRemove);
-                    }
-                }
-            }
-        }
-    }
-
-    // Discard groups of the old product. Use the groups of the new one.
-    product->groups = changedProduct->groups;
-    product->properties = changedProduct->properties;
-
-    // apply rules for new artifacts
-    foreach (Artifact *artifact, addedArtifacts)
-        foreach (const FileTag &ft, artifact->fileTags)
-            artifactsPerFileTag[ft] += artifact;
-    RulesApplicator(product, artifactsPerFileTag, m_logger).applyAllRules();
-
-    addTargetArtifacts(product, artifactsPerFileTag, m_logger);
-
-    // parents of removed artifacts must update their transformers
-    foreach (Artifact *removedArtifact, artifactsToRemove)
-        foreach (Artifact *parent, removedArtifact->parents)
-            product->topLevelProject()->buildData->artifactsThatMustGetNewTransformers += parent;
-    product->topLevelProject()->buildData->updateNodesThatMustGetNewTransformer(m_logger);
-
-    // delete all removed artifacts physically from the disk
-    foreach (Artifact *artifact, artifactsToRemove) {
-        removeGeneratedArtifactFromDisk(artifact, m_logger);
-        delete artifact;
-    }
-}
-
-/**
-  * Removes the artifact and all the artifacts that depend exclusively on it.
-  * Example: if you remove a cpp artifact then the obj artifact is removed but
-  * not the resulting application (if there's more then one cpp artifact).
-  */
-void BuildGraphLoader::removeArtifactAndExclusiveDependents(Artifact *artifact,
-        ArtifactList *removedArtifacts)
-{
-    if (removedArtifacts)
-        removedArtifacts->insert(artifact);
-    foreach (Artifact *parent, artifact->parents) {
-        bool removeParent = false;
-        disconnect(parent, artifact, m_logger);
-        if (parent->children.isEmpty()) {
-            removeParent = true;
-        } else if (parent->transformer) {
-            artifact->topLevelProject()->buildData->artifactsThatMustGetNewTransformers += parent;
-            parent->transformer->inputs.remove(artifact);
-            removeParent = parent->transformer->inputs.isEmpty();
-        }
-        if (removeParent)
-            removeArtifactAndExclusiveDependents(parent, removedArtifacts);
-    }
-    artifact->topLevelProject()->buildData->removeArtifact(artifact, m_logger);
-}
-
-bool BuildGraphLoader::checkForPropertyChanges(const TransformerPtr &restoredTrafo,
-                                               const ResolvedProductPtr &freshProduct)
-{
-    PropertyFinder finder;
-    foreach (const Property &property, restoredTrafo->modulePropertiesUsedInPrepareScript) {
-        QVariant v;
-        if (property.kind == Property::PropertyInProduct) {
-            v = freshProduct->properties->value().value(property.propertyName);
-        } else if (property.value.type() == QVariant::List) {
-            v = finder.propertyValues(freshProduct->properties->value(), property.moduleName,
-                                      property.propertyName);
-        } else {
-            v = finder.propertyValue(freshProduct->properties->value(), property.moduleName,
-                                     property.propertyName);
-        }
-        if (property.value != v)
-            return true;
-    }
-    return false;
-}
-
-void BuildGraphLoader::replaceFileDependencyWithArtifact(Artifact *filedep, Artifact *artifact)
-{
-    QBS_ASSERT(filedep->project == artifact->project, return);
-    if (m_logger.traceEnabled()) {
-        m_logger.qbsTrace()
-            << QString::fromLocal8Bit("[BG] replace file dependency '%1' "
-                                      "with artifact of type '%2'")
-                             .arg(relativeArtifactFileName(filedep)).arg(artifact->artifactType);
-    }
-    foreach (const ResolvedProductPtr &product, filedep->project->products) {
-        if (!product->buildData)
-            continue;
-        foreach (Artifact *artifactInProduct, product->buildData->artifacts) {
-            if (artifactInProduct->children.contains(filedep)) {
-                disconnect(artifactInProduct, filedep, m_logger);
-                loggedConnect(artifactInProduct, artifact, m_logger);
-            }
-            artifactInProduct->fileDependencies.remove(filedep);
-        }
-    }
-    filedep->topLevelProject()->buildData->dependencyArtifacts.remove(filedep);
-    filedep->topLevelProject()->buildData->removeFromArtifactLookupTable(filedep);
-    delete filedep;
-}
-
-void addTargetArtifacts(const ResolvedProductPtr &product,
-                        ArtifactsPerFileTagMap &artifactsPerFileTag, const Logger &logger)
-{
-    foreach (const FileTag &fileTag, product->fileTags) {
-        foreach (Artifact * const artifact, artifactsPerFileTag.value(fileTag)) {
-            if (artifact->artifactType == Artifact::Generated)
-                product->buildData->targetArtifacts += artifact;
-        }
-    }
-    if (product->buildData->targetArtifacts.isEmpty()) {
-        const QString msg = QString::fromLocal8Bit("No artifacts generated for product '%1'.");
-        logger.qbsDebug() << msg.arg(product->name);
-    }
-}
-
 } // namespace Internal
 } // namespace qbs
diff --git a/src/lib/buildgraph/buildgraph.h b/src/lib/buildgraph/buildgraph.h
index b5712de7f..14df4e44e 100644
--- a/src/lib/buildgraph/buildgraph.h
+++ b/src/lib/buildgraph/buildgraph.h
@@ -33,14 +33,11 @@
 #include "rulesapplicator.h"
 
 #include <language/forward_decls.h>
-#include <logging/logger.h>
 
-#include <QProcessEnvironment>
 #include <QScriptValue>
 #include <QStringList>
 
 namespace qbs {
-class SetupProjectParameters;
 namespace Internal {
 class Logger;
 class ScriptEngine;
@@ -80,43 +77,6 @@ QStringList toStringList(const T &artifactContainer)
     return l;
 }
 
-class BuildGraphLoadResult
-{
-public:
-    BuildGraphLoadResult() : discardLoadedProject(false) {}
-
-    TopLevelProjectPtr newlyResolvedProject;
-    TopLevelProjectPtr loadedProject;
-    bool discardLoadedProject;
-};
-
-
-class BuildGraphLoader
-{
-public:
-    BuildGraphLoader(const QProcessEnvironment &env, const Logger &logger);
-
-    BuildGraphLoadResult load(const SetupProjectParameters &parameters,
-                              const RulesEvaluationContextPtr &evalContext);
-
-private:
-    void trackProjectChanges(const SetupProjectParameters &parameters,
-                             const QString &buildGraphFilePath,
-                             const TopLevelProjectPtr &restoredProject);
-    void onProductRemoved(const ResolvedProductPtr &product);
-    void onProductChanged(const ResolvedProductPtr &product,
-                          const ResolvedProductPtr &changedProduct);
-    void removeArtifactAndExclusiveDependents(Artifact *artifact,
-            ArtifactList *removedArtifacts = 0);
-    bool checkForPropertyChanges(const TransformerPtr &restoredTrafo, const ResolvedProductPtr &freshProduct);
-    void replaceFileDependencyWithArtifact(Artifact *filedep, Artifact *artifact);
-
-    RulesEvaluationContextPtr m_evalContext;
-    BuildGraphLoadResult m_result;
-    Logger m_logger;
-    QProcessEnvironment m_environment;
-};
-
 } // namespace Internal
 } // namespace qbs
 
diff --git a/src/lib/buildgraph/buildgraph.pri b/src/lib/buildgraph/buildgraph.pri
index d33e53861..ad4aa0349 100644
--- a/src/lib/buildgraph/buildgraph.pri
+++ b/src/lib/buildgraph/buildgraph.pri
@@ -1,6 +1,7 @@
 SOURCES += \
     $$PWD/automoc.cpp\
     $$PWD/buildgraph.cpp\
+    $$PWD/buildgraphloader.cpp \
     $$PWD/executor.cpp\
     $$PWD/executorjob.cpp\
     $$PWD/rulegraph.cpp\
@@ -26,6 +27,7 @@ SOURCES += \
 HEADERS += \
     $$PWD/automoc.h\
     $$PWD/buildgraph.h\
+    $$PWD/buildgraphloader.h \
     $$PWD/executor.h\
     $$PWD/executorjob.h\
     $$PWD/rulegraph.h\
diff --git a/src/lib/buildgraph/buildgraphloader.cpp b/src/lib/buildgraph/buildgraphloader.cpp
new file mode 100644
index 000000000..eea9bbd73
--- /dev/null
+++ b/src/lib/buildgraph/buildgraphloader.cpp
@@ -0,0 +1,550 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt Build Suite.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+#include "buildgraphloader.h"
+
+#include "artifact.h"
+#include "artifactlist.h"
+#include "buildgraph.h"
+#include "cycledetector.h"
+#include "productbuilddata.h"
+#include "projectbuilddata.h"
+#include "rulesevaluationcontext.h"
+#include "transformer.h"
+#include <language/language.h>
+#include <language/loader.h>
+#include <logging/translator.h>
+#include <tools/propertyfinder.h>
+#include <tools/qbsassert.h>
+#include <tools/setupprojectparameters.h>
+
+#include <QDir>
+#include <QFileInfo>
+
+namespace qbs {
+namespace Internal {
+
+BuildGraphLoader::BuildGraphLoader(const QProcessEnvironment &env, const Logger &logger) :
+    m_logger(logger), m_environment(env)
+{
+}
+
+static bool isConfigCompatible(const QVariantMap &userCfg, const QVariantMap &projectCfg)
+{
+    QVariantMap::const_iterator it = userCfg.begin();
+    for (; it != userCfg.end(); ++it) {
+        if (it.value().type() == QVariant::Map) {
+            if (!isConfigCompatible(it.value().toMap(), projectCfg.value(it.key()).toMap()))
+                return false;
+        } else {
+            QVariant value = projectCfg.value(it.key());
+            if (!value.isNull() && value != it.value()) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+static void restoreBackPointers(const ResolvedProjectPtr &project)
+{
+    foreach (const ResolvedProductPtr &product, project->products) {
+        product->project = project;
+        if (!product->buildData)
+            continue;
+        foreach (Artifact * const a, product->buildData->artifacts) {
+            a->project = project;
+            project->topLevelProject()->buildData->insertIntoArtifactLookupTable(a);
+        }
+    }
+
+    foreach (const ResolvedProjectPtr &subProject, project->subProjects) {
+        subProject->parentProject = project;
+        restoreBackPointers(subProject);
+    }
+}
+
+BuildGraphLoadResult BuildGraphLoader::load(const SetupProjectParameters &parameters,
+        const RulesEvaluationContextPtr &evalContext)
+{
+    m_result = BuildGraphLoadResult();
+    m_evalContext = evalContext;
+
+    const QString projectId = TopLevelProject::deriveId(parameters.buildConfigurationTree());
+    const QString buildDir
+            = TopLevelProject::deriveBuildDirectory(parameters.buildRoot(), projectId);
+    const QString buildGraphFilePath
+            = ProjectBuildData::deriveBuildGraphFilePath(buildDir, projectId);
+
+    PersistentPool pool(m_logger);
+    m_logger.qbsDebug() << "[BG] trying to load: " << buildGraphFilePath;
+    try {
+        pool.load(buildGraphFilePath);
+    } catch (const ErrorInfo &loadError) {
+        if (parameters.restoreBehavior() == SetupProjectParameters::RestoreOnly)
+            throw loadError;
+        m_logger.qbsInfo() << loadError.toString();
+        return m_result;
+    }
+
+    if (!isConfigCompatible(parameters.buildConfigurationTree(), pool.headData().projectConfig)) {
+        const QString message = Tr::tr("Cannot use stored build graph at '%1':"
+                "Incompatible project configuration.").arg(buildGraphFilePath);
+        if (parameters.restoreBehavior() == SetupProjectParameters::RestoreOnly)
+            throw ErrorInfo(message);
+        m_logger.qbsInfo() << message;
+        return m_result;
+    }
+
+    const TopLevelProjectPtr project = TopLevelProject::create();
+
+    // TODO: Store some meta data that will enable us to show actual progress (e.g. number of products).
+    evalContext->initializeObserver(Tr::tr("Restoring build graph from disk"), 1);
+
+    project->load(pool);
+    project->buildData->evaluationContext = evalContext;
+
+    if (QFileInfo(project->location.fileName()) != QFileInfo(parameters.projectFilePath())) {
+        QString errorMessage = Tr::tr("Stored build graph is for project file '%1', but "
+                                      "input file is '%2'. ")
+                .arg(QDir::toNativeSeparators(project->location.fileName()),
+                     QDir::toNativeSeparators(parameters.projectFilePath()));
+        if (!parameters.ignoreDifferentProjectFilePath()) {
+            errorMessage += Tr::tr("Aborting.");
+            throw ErrorInfo(errorMessage);
+        }
+
+        // Okay, let's assume it's the same project anyway (the source dir might have moved).
+        errorMessage += Tr::tr("Ignoring.");
+        m_logger.qbsWarning() << errorMessage;
+    }
+
+    restoreBackPointers(project);
+    foreach (Artifact * const a, project->buildData->dependencyArtifacts)
+        a->project = project;
+
+    project->location = CodeLocation(parameters.projectFilePath(), project->location.line(),
+                                     project->location.column());
+    project->setBuildConfiguration(pool.headData().projectConfig);
+    project->buildDirectory = buildDir;
+    m_result.loadedProject = project;
+    evalContext->incrementProgressValue();
+
+    if (parameters.restoreBehavior() == SetupProjectParameters::RestoreOnly)
+        return m_result;
+    QBS_CHECK(parameters.restoreBehavior() == SetupProjectParameters::RestoreAndTrackChanges);
+
+    trackProjectChanges(parameters, buildGraphFilePath, project);
+    return m_result;
+}
+
+static void exchangeDependencies(const ResolvedProductPtr &newProduct,
+                                 const QList<ResolvedProductPtr> &allRestoredProducts,
+                                 const QList<ResolvedProductPtr> &addedProducts)
+{
+    QSet<ResolvedProductPtr> newDependencies;
+    foreach (const ResolvedProductPtr &dependency, newProduct->dependencies) {
+        if (addedProducts.contains(dependency)) {
+            newDependencies << dependency;
+            exchangeDependencies(dependency, allRestoredProducts, addedProducts);
+            continue;
+        }
+        bool counterPartFound = false;
+        foreach (const ResolvedProductPtr &restoredProduct, allRestoredProducts) {
+            if (restoredProduct->name == dependency->name) {
+                newDependencies << restoredProduct;
+                counterPartFound = true;
+                break;
+            }
+        }
+        QBS_CHECK(counterPartFound);
+    }
+    newProduct->dependencies = newDependencies;
+}
+
+static void manipulateAddedProducts(const QList<ResolvedProjectPtr> &allRestoredProjects,
+                                    const QList<ResolvedProductPtr> &allRestoredProducts,
+                                    const QList<ResolvedProductPtr> &addedProducts)
+{
+    foreach (const ResolvedProductPtr &product, addedProducts) {
+        // Find the right existing (sub-)project to put the new product into.
+        bool projectFound = false;
+        foreach (const ResolvedProjectPtr &project, allRestoredProjects) {
+            if (project->location != product->project->location)
+                continue;
+            product->project = project;
+            project->products.append(product);
+            projectFound = true;
+            break;
+        }
+        QBS_CHECK(projectFound);
+
+        // Exchange dependencies that are not new with their counterparts from the restored project.
+        exchangeDependencies(product, allRestoredProducts, addedProducts);
+    }
+}
+
+// TODO: Pay more attention to project metadata such as name and location. If these change,
+// we must transfer them over to the old build graph.
+void BuildGraphLoader::trackProjectChanges(const SetupProjectParameters &parameters,
+        const QString &buildGraphFilePath, const TopLevelProjectPtr &restoredProject)
+{
+    const FileInfo bgfi(buildGraphFilePath);
+    const QList<ResolvedProjectPtr> allRestoredProjects
+            = restoredProject->allSubProjects() << restoredProject;
+    bool projectFileChanged = false;
+    bool subProjectRemoved = false;
+    foreach (const ResolvedProjectConstPtr &p, allRestoredProjects) {
+        FileInfo fi(p->location.fileName());
+        if (!fi.exists()) {
+            subProjectRemoved = true;
+            break;
+        }
+        if (bgfi.lastModified() < fi.lastModified()) {
+            projectFileChanged = true;
+            break;
+        }
+    }
+    if (subProjectRemoved)
+        m_logger.qbsTrace() << "A sub-project was removed, must re-resolve project";
+    if (projectFileChanged)
+        m_logger.qbsTrace() << "A project file changed, must re-resolve project.";
+
+    bool environmentChanged = false;
+    for (QHash<QString, QString>::ConstIterator it = restoredProject->usedEnvironment.constBegin();
+         !environmentChanged && it != restoredProject->usedEnvironment.constEnd(); ++it) {
+        environmentChanged = m_environment.value(it.key()) != it.value();
+    }
+    if (environmentChanged)
+        m_logger.qbsTrace() << "A relevant environment variable changed, must re-resolve project.";
+
+    bool productRemoved = false;
+    const QList<ResolvedProductPtr> allRestoredProducts = restoredProject->allProducts();
+    QList<ResolvedProductPtr> changedProducts;
+    foreach (const ResolvedProductPtr &product, allRestoredProducts) {
+        const FileInfo pfi(product->location.fileName());
+        if (!pfi.exists()) {
+            productRemoved = true;
+        } else if (bgfi.lastModified() < pfi.lastModified()) {
+            changedProducts += product;
+        } else {
+            foreach (const GroupPtr &group, product->groups) {
+                if (!group->wildcards)
+                    continue;
+                const QSet<QString> files
+                        = group->wildcards->expandPatterns(group, product->sourceDirectory);
+                QSet<QString> wcFiles;
+                foreach (const SourceArtifactConstPtr &sourceArtifact, group->wildcards->files)
+                    wcFiles += sourceArtifact->absoluteFilePath;
+                if (files == wcFiles)
+                    continue;
+                changedProducts += product;
+                break;
+            }
+        }
+    }
+
+    if (!environmentChanged && !projectFileChanged && !subProjectRemoved && !productRemoved
+            && changedProducts.isEmpty()) {
+        return;
+    }
+
+    Loader ldr(m_evalContext->engine(), m_logger);
+    ldr.setSearchPaths(parameters.searchPaths());
+    m_result.newlyResolvedProject = ldr.loadProject(parameters);
+
+    QMap<QString, ResolvedProductPtr> freshProductsByName;
+    const QList<ResolvedProductPtr> allNewlyResolvedProducts
+            = m_result.newlyResolvedProject->allProducts();
+    foreach (const ResolvedProductPtr &cp, allNewlyResolvedProducts)
+        freshProductsByName.insert(cp->name, cp);
+
+    QSet<TransformerPtr> seenTransformers;
+    foreach (const ResolvedProductPtr &product, allRestoredProducts) {
+        if (!product->buildData)
+            continue;
+        foreach (Artifact *artifact, product->buildData->artifacts) {
+            if (!artifact->transformer || seenTransformers.contains(artifact->transformer))
+                continue;
+            seenTransformers.insert(artifact->transformer);
+            ResolvedProductPtr freshProduct = freshProductsByName.value(product->name);
+            if (freshProduct && checkForPropertyChanges(artifact->transformer, freshProduct)) {
+                m_result.discardLoadedProject = true;
+                return;
+            }
+        }
+    }
+
+    foreach (const ResolvedProductPtr &product, changedProducts) {
+        ResolvedProductPtr freshProduct = freshProductsByName.value(product->name);
+        if (!freshProduct)
+            continue;
+        onProductChanged(product, freshProduct);
+        if (m_result.discardLoadedProject)
+            return;
+    }
+
+    QSet<QString> oldProductNames, newProductNames;
+    foreach (const ResolvedProductConstPtr &product, allRestoredProducts)
+        oldProductNames += product->name;
+    foreach (const ResolvedProductConstPtr &product, allNewlyResolvedProducts)
+        newProductNames += product->name;
+
+    const QSet<QString> removedProductsNames = oldProductNames - newProductNames;
+    if (!removedProductsNames.isEmpty()) {
+        foreach (const ResolvedProductPtr &product, allRestoredProducts) {
+            if (removedProductsNames.contains(product->name))
+                onProductRemoved(product);
+        }
+    }
+
+    const QSet<QString> addedProductNames = newProductNames - oldProductNames;
+    QList<ResolvedProductPtr> addedProducts;
+    foreach (const QString &productName, addedProductNames) {
+        const ResolvedProductPtr &freshProduct = freshProductsByName.value(productName);
+        QBS_ASSERT(freshProduct, continue);
+        addedProducts.append(freshProduct);
+    }
+    if (!addedProducts.isEmpty()) {
+        manipulateAddedProducts(allRestoredProjects, allRestoredProducts, addedProducts);
+        BuildDataResolver bpr(m_logger);
+        bpr.resolveProductBuildDataForExistingProject(restoredProject, addedProducts);
+    }
+
+    CycleDetector(m_logger).visitProject(restoredProject);
+}
+
+void BuildGraphLoader::onProductRemoved(const ResolvedProductPtr &product)
+{
+    m_logger.qbsDebug() << "[BG] product '" << product->name << "' removed.";
+
+    product->topLevelProject()->buildData->isDirty = true;
+    product->project->products.removeOne(product);
+
+    // delete all removed artifacts physically from the disk
+    if (product->buildData) {
+        foreach (Artifact *artifact, product->buildData->artifacts) {
+            artifact->disconnectAll(m_logger);
+            removeGeneratedArtifactFromDisk(artifact, m_logger);
+        }
+    }
+}
+
+void BuildGraphLoader::onProductChanged(const ResolvedProductPtr &product,
+                                        const ResolvedProductPtr &changedProduct)
+{
+    m_logger.qbsDebug() << "[BG] product '" << product->name << "' changed.";
+
+    ArtifactsPerFileTagMap artifactsPerFileTag;
+    QList<Artifact *> addedArtifacts;
+    ArtifactList artifactsToRemove;
+    QHash<QString, SourceArtifactConstPtr> oldArtifacts, newArtifacts;
+
+    const QList<SourceArtifactPtr> oldProductAllFiles = product->allEnabledFiles();
+    foreach (const SourceArtifactConstPtr &a, oldProductAllFiles)
+        oldArtifacts.insert(a->absoluteFilePath, a);
+    foreach (const SourceArtifactPtr &a, changedProduct->allEnabledFiles()) {
+        newArtifacts.insert(a->absoluteFilePath, a);
+        if (!oldArtifacts.contains(a->absoluteFilePath)) {
+            // artifact added
+            m_logger.qbsDebug() << "[BG] artifact '" << a->absoluteFilePath
+                                << "' added to product " << product->name;
+            Artifact *newArtifact = lookupArtifact(product, a->absoluteFilePath);
+            if (newArtifact) {
+                // User added a source file that was a generated artifact in the previous
+                // build, e.g. a C++ source file that was generated and now is a non-generated
+                // source file.
+                newArtifact->artifactType = Artifact::SourceFile;
+            } else {
+                newArtifact = createArtifact(product, a, m_logger);
+                foreach (Artifact *oldArtifact,
+                         product->topLevelProject()->buildData->lookupArtifacts(newArtifact->filePath())) {
+                    if (oldArtifact == newArtifact
+                            || oldArtifact->artifactType != Artifact::FileDependency) {
+                        // The source file already exists in another product.
+                        continue;
+                    }
+                    // User added a source file that was recognized as file dependency in the
+                    // previous build, e.g. a C++ header file.
+                    replaceFileDependencyWithArtifact(oldArtifact, newArtifact);
+                }
+            }
+            addedArtifacts += newArtifact;
+        }
+    }
+
+    foreach (const SourceArtifactPtr &a, oldProductAllFiles) {
+        const SourceArtifactConstPtr changedArtifact = newArtifacts.value(a->absoluteFilePath);
+        if (!changedArtifact) {
+            // artifact removed
+            m_logger.qbsDebug() << "[BG] artifact '" << a->absoluteFilePath
+                                << "' removed from product " << product->name;
+            Artifact *artifact = lookupArtifact(product, a->absoluteFilePath);
+            QBS_CHECK(artifact);
+            removeArtifactAndExclusiveDependents(artifact, &artifactsToRemove);
+            continue;
+        }
+        if (changedArtifact->fileTags != a->fileTags) {
+            // artifact's filetags have changed
+            m_logger.qbsDebug() << "[BG] filetags have changed for artifact '"
+                    << a->absoluteFilePath << "' from " << a->fileTags << " to "
+                    << changedArtifact->fileTags;
+            Artifact *artifact = lookupArtifact(product, a->absoluteFilePath);
+            QBS_CHECK(artifact);
+
+            // handle added filetags
+            foreach (const FileTag &addedFileTag, changedArtifact->fileTags - a->fileTags)
+                artifactsPerFileTag[addedFileTag] += artifact;
+
+            // handle removed filetags
+            foreach (const FileTag &removedFileTag, a->fileTags - changedArtifact->fileTags) {
+                artifact->fileTags -= removedFileTag;
+                foreach (Artifact *parent, artifact->parents) {
+                    if (parent->transformer && parent->transformer->rule->inputs.contains(removedFileTag)) {
+                        // this parent has been created because of the removed filetag
+                        removeArtifactAndExclusiveDependents(parent, &artifactsToRemove);
+                    }
+                }
+            }
+        }
+    }
+
+    // Discard groups of the old product. Use the groups of the new one.
+    product->groups = changedProduct->groups;
+    product->properties = changedProduct->properties;
+
+    // apply rules for new artifacts
+    foreach (Artifact *artifact, addedArtifacts)
+        foreach (const FileTag &ft, artifact->fileTags)
+            artifactsPerFileTag[ft] += artifact;
+    RulesApplicator(product, artifactsPerFileTag, m_logger).applyAllRules();
+
+    addTargetArtifacts(product, artifactsPerFileTag, m_logger);
+
+    // parents of removed artifacts must update their transformers
+    foreach (Artifact *removedArtifact, artifactsToRemove)
+        foreach (Artifact *parent, removedArtifact->parents)
+            product->topLevelProject()->buildData->artifactsThatMustGetNewTransformers += parent;
+    product->topLevelProject()->buildData->updateNodesThatMustGetNewTransformer(m_logger);
+
+    // delete all removed artifacts physically from the disk
+    foreach (Artifact *artifact, artifactsToRemove) {
+        removeGeneratedArtifactFromDisk(artifact, m_logger);
+        delete artifact;
+    }
+}
+
+/**
+  * Removes the artifact and all the artifacts that depend exclusively on it.
+  * Example: if you remove a cpp artifact then the obj artifact is removed but
+  * not the resulting application (if there's more then one cpp artifact).
+  */
+void BuildGraphLoader::removeArtifactAndExclusiveDependents(Artifact *artifact,
+        ArtifactList *removedArtifacts)
+{
+    if (removedArtifacts)
+        removedArtifacts->insert(artifact);
+    foreach (Artifact *parent, artifact->parents) {
+        bool removeParent = false;
+        disconnect(parent, artifact, m_logger);
+        if (parent->children.isEmpty()) {
+            removeParent = true;
+        } else if (parent->transformer) {
+            artifact->topLevelProject()->buildData->artifactsThatMustGetNewTransformers += parent;
+            parent->transformer->inputs.remove(artifact);
+            removeParent = parent->transformer->inputs.isEmpty();
+        }
+        if (removeParent)
+            removeArtifactAndExclusiveDependents(parent, removedArtifacts);
+    }
+    artifact->topLevelProject()->buildData->removeArtifact(artifact, m_logger);
+}
+
+bool BuildGraphLoader::checkForPropertyChanges(const TransformerPtr &restoredTrafo,
+                                               const ResolvedProductPtr &freshProduct)
+{
+    PropertyFinder finder;
+    foreach (const Property &property, restoredTrafo->modulePropertiesUsedInPrepareScript) {
+        QVariant v;
+        if (property.kind == Property::PropertyInProduct) {
+            v = freshProduct->properties->value().value(property.propertyName);
+        } else if (property.value.type() == QVariant::List) {
+            v = finder.propertyValues(freshProduct->properties->value(), property.moduleName,
+                                      property.propertyName);
+        } else {
+            v = finder.propertyValue(freshProduct->properties->value(), property.moduleName,
+                                     property.propertyName);
+        }
+        if (property.value != v)
+            return true;
+    }
+    return false;
+}
+
+void BuildGraphLoader::replaceFileDependencyWithArtifact(Artifact *filedep, Artifact *artifact)
+{
+    QBS_ASSERT(filedep->project == artifact->project, return);
+    if (m_logger.traceEnabled()) {
+        m_logger.qbsTrace()
+            << QString::fromLocal8Bit("[BG] replace file dependency '%1' "
+                                      "with artifact of type '%2'")
+                             .arg(relativeArtifactFileName(filedep)).arg(artifact->artifactType);
+    }
+    foreach (const ResolvedProductPtr &product, filedep->project->products) {
+        if (!product->buildData)
+            continue;
+        foreach (Artifact *artifactInProduct, product->buildData->artifacts) {
+            if (artifactInProduct->children.contains(filedep)) {
+                disconnect(artifactInProduct, filedep, m_logger);
+                loggedConnect(artifactInProduct, artifact, m_logger);
+            }
+            artifactInProduct->fileDependencies.remove(filedep);
+        }
+    }
+    filedep->topLevelProject()->buildData->dependencyArtifacts.remove(filedep);
+    filedep->topLevelProject()->buildData->removeFromArtifactLookupTable(filedep);
+    delete filedep;
+}
+
+void addTargetArtifacts(const ResolvedProductPtr &product,
+                        ArtifactsPerFileTagMap &artifactsPerFileTag, const Logger &logger)
+{
+    foreach (const FileTag &fileTag, product->fileTags) {
+        foreach (Artifact * const artifact, artifactsPerFileTag.value(fileTag)) {
+            if (artifact->artifactType == Artifact::Generated)
+                product->buildData->targetArtifacts += artifact;
+        }
+    }
+    if (product->buildData->targetArtifacts.isEmpty()) {
+        const QString msg = QString::fromLocal8Bit("No artifacts generated for product '%1'.");
+        logger.qbsDebug() << msg.arg(product->name);
+    }
+}
+
+} // namespace Internal
+} // namespace qbs
diff --git a/src/lib/buildgraph/buildgraphloader.h b/src/lib/buildgraph/buildgraphloader.h
new file mode 100644
index 000000000..6bc0b625b
--- /dev/null
+++ b/src/lib/buildgraph/buildgraphloader.h
@@ -0,0 +1,85 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt Build Suite.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+#ifndef QBS_BUILDGRAPHLOADER_H
+#define QBS_BUILDGRAPHLOADER_H
+
+#include "forward_decls.h"
+
+#include <language/forward_decls.h>
+#include <logging/logger.h>
+
+#include <QProcessEnvironment>
+
+namespace qbs {
+class SetupProjectParameters;
+
+namespace Internal {
+class ArtifactList;
+
+class BuildGraphLoadResult
+{
+public:
+    BuildGraphLoadResult() : discardLoadedProject(false) {}
+
+    TopLevelProjectPtr newlyResolvedProject;
+    TopLevelProjectPtr loadedProject;
+    bool discardLoadedProject;
+};
+
+
+class BuildGraphLoader
+{
+public:
+    BuildGraphLoader(const QProcessEnvironment &env, const Logger &logger);
+
+    BuildGraphLoadResult load(const SetupProjectParameters &parameters,
+                              const RulesEvaluationContextPtr &evalContext);
+
+private:
+    void trackProjectChanges(const SetupProjectParameters &parameters,
+                             const QString &buildGraphFilePath,
+                             const TopLevelProjectPtr &restoredProject);
+    void onProductRemoved(const ResolvedProductPtr &product);
+    void onProductChanged(const ResolvedProductPtr &product,
+                          const ResolvedProductPtr &changedProduct);
+    void removeArtifactAndExclusiveDependents(Artifact *artifact,
+            ArtifactList *removedArtifacts = 0);
+    bool checkForPropertyChanges(const TransformerPtr &restoredTrafo, const ResolvedProductPtr &freshProduct);
+    void replaceFileDependencyWithArtifact(Artifact *filedep, Artifact *artifact);
+
+    RulesEvaluationContextPtr m_evalContext;
+    BuildGraphLoadResult m_result;
+    Logger m_logger;
+    QProcessEnvironment m_environment;
+};
+
+} // namespace Internal
+} // namespace qbs
+
+#endif // Include guard.