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/tools/clangrefactoringbackend/source/clangtool.cpp

@@ -0,0 +1,72 @@
+/****************************************************************************
+**
+** 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.
+**
+****************************************************************************/
+
+#include "clangtool.h"
+
+namespace ClangBackEnd {
+
+namespace {
+
+// use std::filesystem::path if it is supported by all compilers
+
+std::string toNativePath(std::string &&path)
+{
+#ifdef WIN32
+    std::replace(path.begin(), path.end(), '/', '\\');
+#endif
+
+    return std::move(path);
+}
+}
+
+void ClangTool::addFile(std::string &&directory,
+                           std::string &&fileName,
+                           std::string &&content,
+                           std::vector<std::string> &&commandLine)
+{
+    fileContents.emplace_back(toNativePath(std::move(directory)),
+                              std::move(fileName),
+                              std::move(content),
+                              std::move(commandLine));
+
+    const auto &fileContent = fileContents.back();
+
+    compilationDatabase.addFile(fileContent.directory, fileContent.fileName, fileContent.commandLine);
+    sourceFilePaths.push_back(fileContent.filePath);
+}
+
+clang::tooling::ClangTool ClangTool::createTool() const
+{
+    clang::tooling::ClangTool tool(compilationDatabase, sourceFilePaths);
+
+    for (auto &&fileContent : fileContents) {
+        if (!fileContent.content.empty())
+            tool.mapVirtualFile(fileContent.filePath, fileContent.content);
+    }
+
+    return tool;
+}
+
+} // namespace ClangBackEnd