Clang: Don't index already indexed symbols

We don't index system headers any more and introduce a first step to
decrease double indexing. For that we introduces the SourcesManager which
so far tells you only if a file was already indexed for a certain time
stamp.

Change-Id: Icde54465693ca84a622764c595635cac365c0111
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/tools/clangrefactoringbackend/source/symbolsvisitorbase.h

@@ -26,6 +26,8 @@
 #pragma once
 
 #include "sourcelocationsutils.h"
+#include "sourcesmanager.h"
+#include "symbolentry.h"
 
 #include <filepathcachinginterface.h>
 
@@ -43,9 +45,11 @@ class SymbolsVisitorBase
 {
 public:
     SymbolsVisitorBase(FilePathCachingInterface &filePathCache,
-                       const clang::SourceManager *sourceManager)
+                       const clang::SourceManager *sourceManager,
+                       SourcesManager &sourcesManager)
         : m_filePathCache(filePathCache),
-          m_sourceManager(sourceManager)
+          m_sourceManager(sourceManager),
+          m_sourcesManager(sourcesManager)
     {}
 
     FilePathId filePathId(clang::SourceLocation sourceLocation)
@@ -56,6 +60,19 @@ public:
         return filePathId(fileEntry);
     }
 
+    bool alreadyParsed(clang::FileID fileId)
+    {
+        const clang::FileEntry *fileEntry = m_sourceManager->getFileEntryForID(fileId);
+
+        return m_sourcesManager.alreadyParsed(filePathId(fileEntry),
+                                              fileEntry->getModificationTime());
+    }
+
+    bool alreadyParsed(clang::SourceLocation sourceLocation)
+    {
+        return alreadyParsed(m_sourceManager->getFileID(sourceLocation));
+    }
+
     FilePathId filePathId(const clang::FileEntry *fileEntry)
     {
         if (fileEntry) {
@@ -128,10 +145,17 @@ public:
         m_sourceManager = sourceManager;
     }
 
+    bool isInSystemHeader(clang::FileID fileId) const
+    {
+        return clang::SrcMgr::isSystem(
+                    m_sourceManager->getSLocEntry(fileId).getFile().getFileCharacteristic());
+    }
+
 protected:
     std::vector<FilePathId> m_filePathIndices;
     FilePathCachingInterface &m_filePathCache;
     const clang::SourceManager *m_sourceManager = nullptr;
+    SourcesManager &m_sourcesManager;
 };
 
 } // namespace ClangBackend