LanguageClient: add signature help provider

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

src/plugins/languageclient/languageclientfunctionhint.cpp

@@ -0,0 +1,144 @@
+/****************************************************************************
+**
+** 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 "languageclientfunctionhint.h"
+#include "client.h"
+
+#include <languageserverprotocol/languagefeatures.h>
+#include <texteditor/codeassist/assistinterface.h>
+#include <texteditor/codeassist/functionhintproposal.h>
+#include <texteditor/codeassist/iassistprocessor.h>
+#include <texteditor/codeassist/ifunctionhintproposalmodel.h>
+
+using namespace TextEditor;
+using namespace LanguageServerProtocol;
+
+namespace LanguageClient {
+
+class FunctionHintProposalModel : public IFunctionHintProposalModel
+{
+public:
+    explicit FunctionHintProposalModel(SignatureHelp signature)
+        : m_sigis(signature)
+    {}
+    void reset() override {}
+    int size() const override
+    { return m_sigis.signatures().size(); }
+    QString text(int index) const override;
+
+    int activeArgument(const QString &/*prefix*/) const override
+    { return m_sigis.activeParameter().value_or(0); }
+
+private:
+    LanguageServerProtocol::SignatureHelp m_sigis;
+};
+
+QString FunctionHintProposalModel::text(int index) const
+{
+    return m_sigis.signatures().size() > index ? m_sigis.signatures().at(index).label() : QString();
+}
+
+class FunctionHintProcessor : public IAssistProcessor
+{
+public:
+    explicit FunctionHintProcessor(Client *client) : m_client(client) {}
+    IAssistProposal *perform(const AssistInterface *interface) override;
+    bool running() override { return m_running; }
+    bool needsRestart() const override { return true; }
+
+private:
+    void handleSignatureResponse(const SignatureHelpRequest::Response &response);
+
+    QPointer<Client> m_client;
+    bool m_running = false;
+    int m_pos = -1;
+};
+
+IAssistProposal *FunctionHintProcessor::perform(const AssistInterface *interface)
+{
+    QTC_ASSERT(m_client, return nullptr);
+    m_pos = interface->position();
+    QTextCursor cursor(interface->textDocument());
+    cursor.setPosition(m_pos);
+    auto uri = DocumentUri::fromFileName(Utils::FileName::fromString(interface->fileName()));
+    SignatureHelpRequest request;
+    request.setParams(TextDocumentPositionParams(TextDocumentIdentifier(uri), Position(cursor)));
+    request.setResponseCallback([this](auto response) { this->handleSignatureResponse(response); });
+    m_client->sendContent(request);
+    m_running = true;
+    return nullptr;
+}
+
+void FunctionHintProcessor::handleSignatureResponse(const SignatureHelpRequest::Response &response)
+{
+    m_running = false;
+    if (auto error = response.error())
+        m_client->log(error.value());
+    FunctionHintProposalModelPtr model(
+        new FunctionHintProposalModel(response.result().value().value()));
+    setAsyncProposalAvailable(new FunctionHintProposal(m_pos, model));
+}
+
+FunctionHintAssistProvider::FunctionHintAssistProvider(Client *client)
+    : m_client(client)
+{}
+
+TextEditor::IAssistProcessor *FunctionHintAssistProvider::createProcessor() const
+{
+    return new FunctionHintProcessor(m_client);
+}
+
+IAssistProvider::RunType FunctionHintAssistProvider::runType() const
+{
+    return Asynchronous;
+}
+
+int FunctionHintAssistProvider::activationCharSequenceLength() const
+{
+    return m_activationCharSequenceLength;
+}
+
+bool FunctionHintAssistProvider::isActivationCharSequence(
+    const QString &sequence) const
+{
+    return Utils::anyOf(m_triggerChars,
+                        [sequence](const QString &trigger) { return trigger.endsWith(sequence); });
+}
+
+bool FunctionHintAssistProvider::isContinuationChar(const QChar &/*c*/) const
+{
+    return true;
+}
+
+void FunctionHintAssistProvider::setTriggerCharacters(QList<QString> triggerChars)
+{
+    m_triggerChars = triggerChars;
+    for (const QString &trigger : triggerChars) {
+        if (trigger.length() > m_activationCharSequenceLength)
+            m_activationCharSequenceLength = trigger.length();
+    }
+}
+
+} // namespace LanguageClient