LanguageClient: add signature help provider

Change-Id: Ia89c28b574c92802bbfda280115a50f5955f0854
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/languageclient/languageclientfunctionhint.h

@@ -0,0 +1,53 @@
+/****************************************************************************
+**
+** 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.
+**
+****************************************************************************/
+
+#pragma once
+
+#include <texteditor/codeassist/completionassistprovider.h>
+
+namespace LanguageClient {
+
+class Client;
+
+class FunctionHintAssistProvider : public TextEditor::CompletionAssistProvider
+{
+public:
+    explicit FunctionHintAssistProvider(Client *client);
+
+    TextEditor::IAssistProcessor *createProcessor() const override;
+    RunType runType() const override;
+
+    int activationCharSequenceLength() const override;
+    bool isActivationCharSequence(const QString &sequence) const override;
+    bool isContinuationChar(const QChar &c) const override;
+
+    void setTriggerCharacters(QList<QString> triggerChars);
+private:
+    QList<QString> m_triggerChars;
+    int m_activationCharSequenceLength = 0;
+    Client *m_client = nullptr; // not owned
+};
+
+} // namespace LanguageClient