ProjectExplorer: Add FolderNode::compress

Add a method to FolderNode that compresses a tree of folders like
A/B/C/file.txt into one FolderNode (A/B/C) and a FileNode (file.txt)

Change-Id: I5efa038c33b91ea01017269daa048ba101085d01
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/cmakeprojectmanager/servermodereader.cpp

@@ -226,6 +226,8 @@ static void addCMakeVFolder(FolderNode *base, const Utils::FileName &basePath, i
     folder->setDisplayName(displayName);
     base->addNode(folder);
     folder->buildTree(files);
+    for (FolderNode *fn : folder->folderNodes())
+        fn->compress();
 }
 
 static void addCMakeInputs(CMakeListsNode *root,

src/plugins/projectexplorer/projectnodes.cpp

@@ -459,6 +459,33 @@ void FolderNode::buildTree(QList<FileNode *> &files, const Utils::FileName &over
     emitTreeChanged();
 }
 
+// "Compress" a tree of foldernodes such that foldernodes with exactly one foldernode as a child
+// are merged into one. This e.g. turns a sequence of FolderNodes "foo" "bar" "baz" into one
+// FolderNode named "foo/bar/baz", saving a lot of clicks in the Project View to get to the actual
+// files.
+void FolderNode::compress()
+{
+    QList<Node *> children = nodes();
+    if (auto subFolder = children.count() == 1 ? children.at(0)->asFolderNode() : nullptr) {
+        // Only one subfolder: Compress!
+        setDisplayName(QDir::toNativeSeparators(displayName() + "/" + subFolder->displayName()));
+        for (Node *n : subFolder->nodes()) {
+            subFolder->removeNode(n);
+            n->setParentFolderNode(nullptr);
+            addNode(n);
+        }
+        setAbsoluteFilePathAndLine(subFolder->filePath(), -1);
+
+        removeNode(subFolder);
+        delete subFolder;
+
+        compress();
+    } else {
+        for (FolderNode *fn : folderNodes())
+            fn->compress();
+    }
+}
+
 void FolderNode::accept(NodesVisitor *visitor)
 {
     visitor->visitFolderNode(this);

src/plugins/projectexplorer/projectnodes.h

@@ -204,6 +204,7 @@ public:
     FolderNode *recursiveFindOrCreateFolderNode(const Utils::FileName &directory,
                                                 const Utils::FileName &overrideBaseDir = Utils::FileName());
     void buildTree(QList<FileNode *> &files, const Utils::FileName &overrideBaseDir = Utils::FileName());
+    void compress();
 
     virtual void accept(NodesVisitor *visitor);