Clang: Add file cache

The database is using file path integer ids to handle file paths because
otherwise we would save many redundant data. This patch is improving it
further with the introduction of a database based file path cache. The
entries are now divided in a directory path and file name. This is quite
handy for directory based file watching.

Change-Id: I03f2e388e43f3d521d6bf8e39dfb95eb2309dc73
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/tools/clangrefactoringbackend/source/sourcelocationentry.h

@@ -25,11 +25,10 @@
 
 #pragma once
 
-#include <stringcachefwd.h>
+#include <filepathid.h>
 
 #include <limits>
 #include <vector>
-#include <iosfwd>
 
 using uint = unsigned int;
 
@@ -59,18 +58,18 @@ class SourceLocationEntry
 {
 public:
     SourceLocationEntry(SymbolIndex symbolId,
-                        FilePathIndex fileId,
+                        FilePathId filePathId,
                         LineColumn lineColumn,
                         SymbolType symbolType)
         : symbolId(symbolId),
-          fileId(fileId),
+          filePathId(filePathId),
           line(lineColumn.line),
           column(lineColumn.column),
           symbolType(symbolType)
     {}
 
     SymbolIndex symbolId = 0;
-    FilePathIndex fileId = std::numeric_limits<uint>::max();
+    FilePathId filePathId;
     uint line =  0;
     uint column = 0;
     SymbolType symbolType;
@@ -78,7 +77,7 @@ public:
     friend bool operator==(const SourceLocationEntry &first, const SourceLocationEntry &second)
     {
         return first.symbolId == second.symbolId
-            && first.fileId == second.fileId
+            && first.filePathId == second.filePathId
             && first.line == second.line
             && first.column == second.column
             && first.symbolType == second.symbolType;
@@ -87,6 +86,4 @@ public:
 
 using SourceLocationEntries = std::vector<SourceLocationEntry>;
 
-std::ostream &operator<<(std::ostream &out, const SourceLocationEntry &entry);
-
 } // namespace ClangBackEnd