logic: reduce access to filesystem while indexing

* use canonical filepath cache in cxx indexer
* made constructors of FilePath explicit
* use FilePath at more places instead of string
* forward declares FilePath wherever possible

src/lib_gui/utility/path_detector/CombinedPathDetector.cpp

@@ -1,5 +1,7 @@
 #include "utility/path_detector/CombinedPathDetector.h"
 
+#include "utility/file/FilePath.h"
+
 CombinedPathDetector::CombinedPathDetector()
 	: PathDetector("combined")
 {

src/lib_gui/utility/path_detector/PathDetector.cpp

@@ -1,5 +1,7 @@
 #include "utility/path_detector/PathDetector.h"
 
+#include "utility/file/FilePath.h"
+
 PathDetector::PathDetector(const std::string& name)
 	: m_name(name)
 {

src/lib_gui/utility/path_detector/PathDetector.h

@@ -4,7 +4,7 @@
 #include <string>
 #include <vector>
 
-#include "utility/file/FilePath.h"
+class FilePath;
 
 class PathDetector
 {

src/lib_gui/utility/path_detector/cxx_header/CxxFrameworkPathDetector.cpp

@@ -1,5 +1,6 @@
 #include "utility/path_detector/cxx_header/CxxFrameworkPathDetector.h"
 
+#include "utility/file/FilePath.h"
 #include "utility/path_detector/cxx_header/utilityCxxHeaderDetection.h"
 #include "utility/utilityApp.h"
 #include "utility/utilityString.h"

src/lib_gui/utility/path_detector/cxx_header/CxxHeaderPathDetector.cpp

@@ -1,5 +1,6 @@
 #include "utility/path_detector/cxx_header/CxxHeaderPathDetector.h"
 
+#include "utility/file/FilePath.h"
 #include "utility/path_detector/cxx_header/utilityCxxHeaderDetection.h"
 #include "utility/utilityApp.h"
 #include "utility/utilityString.h"

src/lib_gui/utility/path_detector/cxx_header/CxxVsHeaderPathDetector.cpp

@@ -34,10 +34,10 @@ std::vector<FilePath> CxxVsHeaderPathDetector::getPaths() const
 
 		for (size_t i = 0; i < subdirectories.size(); i++)
 		{
-			FilePath headerSearchPath = vsInstallPath.concat(subdirectories[i]);
+			FilePath headerSearchPath = vsInstallPath.concat(FilePath(subdirectories[i]));
 			if (headerSearchPath.exists())
 			{
-				headerPaths.push_back(headerSearchPath.canonical().str());
+				headerPaths.push_back(headerSearchPath.canonical());
 			}
 		}
 	}
@@ -56,7 +56,7 @@ std::vector<FilePath> CxxVsHeaderPathDetector::getPaths() const
 			FilePath sdkPath = getWindowsSdkPathUsingRegistry(windowsSdkVersions[i]);
 			if (sdkPath.exists())
 			{
-				FilePath sdkIncludePath = sdkPath.concat("include/");
+				FilePath sdkIncludePath = sdkPath.concat(FilePath("include/"));
 				if (sdkIncludePath.exists())
 				{
 					std::vector<std::string> subdirectories;
@@ -67,7 +67,7 @@ std::vector<FilePath> CxxVsHeaderPathDetector::getPaths() const
 					bool usingSubdirectories = false;
 					for (size_t j = 0; j < subdirectories.size(); j++)
 					{
-						FilePath sdkSubdirectory = sdkPath.concat(subdirectories[j]);
+						FilePath sdkSubdirectory = sdkPath.concat(FilePath(subdirectories[j]));
 						if (sdkSubdirectory.exists())
 						{
 							headerPaths.push_back(sdkSubdirectory);

src/lib_gui/utility/path_detector/java_runtime/JavaPathDetector.h

@@ -2,7 +2,6 @@
 #define JAVA_PATH_DETECTOR_H
 
 #include "utility/path_detector/PathDetector.h"
-#include "utility/file/FilePath.h"
 
 class JavaPathDetector: public PathDetector
 {

src/lib_gui/utility/path_detector/java_runtime/JavaPathDetectorLinux.cpp

@@ -1,5 +1,6 @@
 #include "utility/path_detector/java_runtime/JavaPathDetectorLinux.h"
 
+#include "utility/file/FilePath.h"
 #include "utility/utilityApp.h"
 #include "utility/utilityString.h"
 
@@ -43,7 +44,7 @@ FilePath JavaPathDetectorLinux::readLink(const FilePath& path) const
 {
 	std::string command = "readlink -f " + path.str();
 	FilePath javaPath( utility::executeProcess(command.c_str()));
-	if ( !javaPath.empty() )
+	if (!javaPath.empty())
 	{
 		return javaPath;
 	}

src/lib_gui/utility/path_detector/java_runtime/JavaPathDetectorMac.cpp

@@ -1,5 +1,6 @@
 #include "utility/path_detector/java_runtime/JavaPathDetectorMac.h"
 
+#include "utility/file/FilePath.h"
 #include "utility/utilityApp.h"
 #include "utility/utilityString.h"
 

src/lib_gui/utility/path_detector/java_runtime/JavaPathDetectorWindows.cpp

@@ -3,6 +3,7 @@
 #include <QSettings>
 #include <QSysInfo>
 
+#include "utility/file/FilePath.h"
 #include "utility/utilityApp.h"
 
 JavaPathDetectorWindows::JavaPathDetectorWindows(const std::string javaVersion)

src/lib_gui/utility/path_detector/maven_executable/MavenPathDetectorUnix.cpp

@@ -1,5 +1,6 @@
 #include "utility/path_detector/maven_executable/MavenPathDetectorUnix.h"
 
+#include "utility/file/FilePath.h"
 #include "utility/utilityApp.h"
 
 MavenPathDetectorUnix::MavenPathDetectorUnix()

src/lib_gui/utility/path_detector/maven_executable/MavenPathDetectorWindows.cpp

@@ -1,5 +1,6 @@
 #include "utility/path_detector/maven_executable/MavenPathDetectorWindows.h"
 
+#include "utility/file/FilePath.h"
 #include "utility/utilityApp.h"
 
 MavenPathDetectorWindows::MavenPathDetectorWindows()