LSP: add a convenient function returning a TextDocument

...for a Utils::FileName

Change-Id: If490eba29a50f20c2f19f741e60f09244ee73cb6
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/languageclient/languageclientutils.cpp

@@ -0,0 +1,38 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 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 "languageclientutils.h"
+
+#include <texteditor/textdocument.h>
+#include <coreplugin/editormanager/documentmodel.h>
+
+using namespace LanguageClient;
+using namespace LanguageServerProtocol;
+
+TextEditor::TextDocument *LanguageClient::textDocumentForFileName(const Utils::FileName &fileName)
+{
+    return qobject_cast<TextEditor::TextDocument *>(
+        Core::DocumentModel::documentForFilePath(fileName.toString()));
+}