/****************************************************************************
**
** Copyright (C) 2022 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Creator documentation.
**
** 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 Free Documentation License Usage
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
**
****************************************************************************/

/*!
    \previouspage creator-editor-fakevim.html
    \page creator-language-servers.html
    \nextpage creator-mime-types.html

    \title Using Language Servers

    For several programming languages, a \e {language server} is available
    that provides information about the code to IDEs as long as they support
    communication via the \l{Language Server Protocol}
    {language server protocol (LSP)}. This enables the
    IDE to provide the following services:

    \list
        \li \l{Completing Code}{Code completion}
        \li Sending document formatting requests to the language server to
            automatically format documents using the settings specified in
            \uicontrol Tools > \uicontrol Options > \uicontrol {Text Editor}
            > \uicontrol Behavior
        \li Highlighting the symbol under cursor
        \li \l{Viewing Function Tooltips}{Viewing function tooltips}
        \li \l{Semantic Highlighting}{Semantic highlighting}, as defined in
            \l{https://github.com/microsoft/vscode-languageserver-node/pull/367}
            {Proposal of the semantic highlighting protocol extension}
        \li Navigating in the code by using the \l{Searching with the Locator}
            {locator} or \l{Moving to Symbol Definition or Declaration}
            {moving to the symbol definition}
        \li Inspecting code by viewing the document outline in the
            \l{Viewing Defined Types and Symbols}{Outline} view or
            in the \uicontrol Symbols list on the \l{Using the Editor Toolbar}
            {editor toolbar}
        \li \l{Finding Symbols}{Finding references to symbols}
        \li \l{Renaming Symbols}{Renaming the symbol under cursor}
        \li Code actions
        \li Displaying diagnostics from the language server as tooltips. You can
            also select a code range to display diagnostics for.
    \endlist

    By providing a client for the language server protocol, \QC can support
    the above features for several other programming languages besides C++.
    However, the client does not support language servers that require special
    handling.

    \section1 Adding MIME Types for Language Servers

    \QC uses the \l{https://www.iana.org/assignments/media-types/media-types.xhtml}
    {MIME type} of the file to determine which language server to request
    information from when you open a file for editing. Add new MIME types or
    file patterns to match language servers. If you do not set at least one MIME
    type or file pattern, no files will be sent to the language server. This is
    done to avoid unnecessary traffic and inaccurate information, as files are
    only sent to the languge server if they are known to be handled by it. For
    more information about how \QC uses MIME types, see \l {Editing MIME Types}.

    \section1 Specifying Settings for Language Clients

    You can add a generic generic stdIO language server for Python, for example.
    For \l{Connecting Android Devices}{Android development}, you can add a Java
    language server.

    \section2 Adding Language Servers

    To view a list of language servers, select \uicontrol Tools >
    \uicontrol Options > \uicontrol {Language Client} (or
    \uicontrol {Qt Creator} > \uicontrol Preferences >
    \uicontrol {Language Client} > on \macos).

    \image qtcreator-language-client-options.png "Language client options page"

    To enable a language server, select the check box next to the language
    server name and specify settings for the server.

    To remove language servers from the list, select \uicontrol Delete.

    \section2 Specifying Generic Settings

    To add a generic language server:

    \list 1
        \li Select \uicontrol Tools > \uicontrol Options >
            \uicontrol {Language Client} > \uicontrol Add >
            \uicontrol {New Generic StdIO Language Server}
            to add a generic language server.
        \li In the \uicontrol Name field, enter a name for the language server.
            Select the \inlineimage icons/replace.png
            (\uicontrol {Variables}) button to use a variable for the server
            name. For more information, see \l{Using Qt Creator Variables}.
        \li In the \uicontrol {Language} field, select
            \uicontrol {Set MIME Types} to select the MIME types of the files to
            send to the language server. In the field below, you can enter file
            patterns to extend the MIME types, separated by semicolons.
        \li In the \uicontrol {Startup behavior} field, select whether the
            language server is started when \QC starts or when a project or file
            with a matching MIME type is opened. The
            \uicontrol {General Messages} \l{Viewing Output}{output pane}
            displays information about the connection to the language server.
        \li In the \uicontrol Initialization field, you can add language server
            specific JSON attributes to pass to an \c initialize request.
        \li In the \uicontrol Executable field, enter the path to the language
            server executable.
        \li In the \uicontrol Arguments field, enter any required command line
            arguments. Select \uicontrol Variables to use variables as
            arguments.
    \endlist

    \section2 Specifying Java Language Server Settings

    To add a Java language server:

    \list 1
        \li Select \uicontrol Tools > \uicontrol Options >
            \uicontrol {Language Client} > \uicontrol Add >
            \uicontrol {New Java Language Server} to add a Java language server.
            \image qtcreator-language-client-options-java.png "Java language server options"
        \li In the \uicontrol Name field, enter a name for the language server.
            Select the \inlineimage icons/replace.png
            (\uicontrol {Variables}) button to use a variable for the server
            name. For more information, see \l{Using Qt Creator Variables}.
        \li In the \uicontrol Java field, enter the path to the Java executable.
        \li In the \uicontrol {Java Language Server} field, enter the path to
            the Java language server \c .jar file.
    \endlist


    \section1 Supported Locator Filters

    The locator enables you to browse not only files, but any items defined by
    \e {locator filters}. The language client plugin supports the following
    locator filters:

    \list
            \li Locating symbols in the current project (\c {:})
            \li Locating symbols in the current document (\c {.})
            \li Locating class (\c {c}), enum, and function (\c {m})
                definitions in your project
    \endlist

    \section1 Inspecting Language Clients

    \QC sends messages (\e Requests) to the language server and receives
    responses that contain the requested information if the language server is
    capable of handling the requests. To inspect the communication between \QC
    and language servers and view server capabilities, select \uicontrol Tools
    > \uicontrol {Debug \QC} > \uicontrol {Inspect Language Client}.

    \image qtcreator-language-client-inspector-log.png "Language Client Inspector dialog"

    The dialog shows a list of running language servers. The value of the
    \uicontrol {Startup behavior} field in the language server options
    determines when the server is started. The information displayed depends on
    the language server.

    \uicontrol Log displays additional information about the selected log entry.
    You can see the \uicontrol {Content length} and \uicontrol {MIME type} of
    a \uicontrol {Client Message} and \uicontrol {Server Message}, as well as
    inspect the data sent between \QC and the language server.

    To remove old entries, select \uicontrol Clear.

    \section2 Capabilities

    In \uicontrol Capabilities, you can check whether a language server is
    capable of a specific task. You cannot modify the server capabilities
    in this dialog.

    You can view the \uicontrol Name, \uicontrol Value, and \uicontrol Type
    of the capability.

    \image qtcreator-language-client-inspector-capabilities.png "Language Client Inspector Capabilities tab"

    For some language servers, \uicontrol {Dynamic Capabilities} lists the
    \uicontrol Methods and \uicontrol Options available.

    \section2 Memory Usage

    For a clangd server, you can inspect the total amount of memory used by a
    particular component in \uicontrol {Memory Usage}.

    \image qtcreator-language-client-inspector-capabilities.png "Language Client Inspector Capabilities tab"

    \section1 Reporting Issues

    The language service client has been mostly tested with Python and Java.
    If problems arise when you try them or some other language, please select
    \uicontrol Help > \uicontrol {Report Bug} to report them in the
    \l{https://bugreports.qt.io/}{Qt Project Bug Tracker}. The reports
    should include \QC console output with the environment
    variable \c {QT_LOGGING_RULES=qtc.languageclient.*=true} set.
*/
