Clang: Add clang query

Clang query is mechanism to use AST matcher to search for code. Think
about regular expression but in the context of AST. So you get a semantic
search tool for C++.

Change-Id: I72e882c5b53a0c52f352a3664847c4c3e4f6fc2e
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/libs/clangbackendipc/sourcefilepathcontainerbase.h

@@ -0,0 +1,66 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** 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 The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#pragma once
+
+#include "filepath.h"
+
+#include <unordered_map>
+
+namespace ClangBackEnd {
+
+using FilePathDict = std::unordered_map<uint, FilePath>;
+
+class SourceFilePathContainerBase
+{
+public:
+    SourceFilePathContainerBase() = default;
+    SourceFilePathContainerBase(std::unordered_map<uint, FilePath> &&filePathHash)
+        : filePathHash(std::move(filePathHash))
+    {
+    }
+
+    void insertFilePath(uint fileId, Utils::SmallString &&fileDirectory, Utils::SmallString &&fileName)
+    {
+        filePathHash.emplace(std::piecewise_construct,
+                             std::forward_as_tuple(fileId),
+                             std::forward_as_tuple(std::move(fileDirectory), std::move(fileName)));
+    }
+
+    void reserve(std::size_t size)
+    {
+        filePathHash.reserve(size / 3);
+    }
+
+    const FilePathDict &filePaths() const
+    {
+        return filePathHash;
+    }
+
+protected:
+    FilePathDict filePathHash;
+};
+
+} // namespace ClangBackEnd