darkragnara / dls

A D Language Server implementation

D Language Server

LSP compliance: 3.7.0

This is a work in progress. There might will be bugs and crashes...

DLS implements the server side of the Language Server Protocol (LSP) for the D programming language. It does not contain any language feature itself (yet), but uses already available components, and provides an interface to work with the LSP. Current features include:

• Code completion
• Go to definition
• Error checking
• Formatting
• Symbol searching
• Symbol highlighting
• Documentation on hover
• Random crashes

Libraries used (the stuff doing the actual hard work):

• arsd
• DCD
• DFMT
• D-Scanner
• DSymbol
• Dub
• emsi_containers
• inifiled
• libddoc
• libdparse
• msgpack-d
• stdx-allocator

Installing

You can run dub fetch dls and then dub run dls:bootstrap to install dls. The second command will output a path to a symbolic link that will always point to the latest DLS executable. DLS will propose updates as they come, and update the symbolic link upon upgrading.

Client side configuration

All these keys should be formatted as d.dls.[section].[key] (e.g. d.dls.format.endOfLine).

Section: symbol	Type	Default value
importPaths	string[]	[]

Section: analysis	Type	Default value
configFile	string	"dscanner.ini"

Section: format	Type	Default value
endOfLine	"lf" or "cr" or "crlf"	"lf"
maxLineLength	number	120
dfmtAlignSwitchStatements	boolean	true
dfmtBraceStyle	"allman" or "otbs" or "stroustrup"	"allman"
dfmtOutdentAttributes	boolean	true
dfmtSoftMaxLineLength	number	80
dfmtSpaceAfterCast	boolean	true
dfmtSpaceAfterKeywords	boolean	true
dfmtSpaceBeforeFunctionParameters	boolean	false
dfmtSplitOperatorAtLineEnd	boolean	false
dfmtSelectiveImportSpace	boolean	true
dfmtCompactLabeledStatements	boolean	true
dfmtTemplateConstraintStyle	"conditionalNewlineIndent" or "conditionalNewline" or "alwaysNewline" or "alwaysNewlineIndent"	"conditionalNewlineIndent"
dfmtSingleTemplateConstraintIndent	boolean	false

The bootstrap subpackage and the update system

In order to simplify the process of updating DLS, an update system is implemented. However, the extension will need to locate a first version of DLS; this is where dls:bootstrap comes in. The steps are:

• dub fetch dls will fetch the latest version of DLS
• dub run --quiet dls:bootstrap will output the path to a symlink pointing to the latest DLS executable

Nothing specific is required on the client's part regarding updates: the server will send notifications to the user when an update is available, and download/build the new version (in parallel to responding to requests). Binary downloads are available and should be picked up automatically for Windows, macOS and Linux in both x86 and x86_64 flavors.

Caveats

The server may delegate a few operations to the client-side extension depending on the language client's capabilities. The client should watch these files for the server to work properly:

• dub.selections.json
• dub.json
• dub.sdl
• *.ini

If the client supports dynamic registration of the workspace/didChangeWatchedFiles method, then the server will automatically register file watching. If the client doesn't support dynamic registration however, the client-side extension will need to manually do it. The server needs to know at least when dub.selections.json files change to properly provide completion support. If dub.json and dub.sdl are also watched, dub.selections.json will automatically be regenerated and then it will be used for completion support. Watching *.ini allows DLS to monitor D-Scanner config files, even if the name is changed in the config and isn't precisly dscanner.ini.

Custom messages

The LSP defines messages with methods starting in $/ to be implementation dependant. DLS uses $/dls as a prefix for some custom messages.

Message	Type	Parameter	Description
$/dls.upgradeDls.start	Notification	null	Sent when the upgrade process starts
$/dls.upgradeDls.stop	Notification	null	Sent when the upgrade process stops
$/dls.upgradeDls.totalSize	Notification	number	Sent during the download, with the total size of the upgrade download
$/dls.upgradeDls.chunkSize	Notification	number	Sent during the download, with the size of a chunk that was just downloaded
$/dls.upgradeDls.extract	Notification	null	Sent when the download is finished and the contents are written on the disk
$/dls.upgradeSelections.start	Notification	number	Sent when DLS starts upgrading dub.selections.json
$/dls.upgradeSelections.stop	Notification	null	Sent when DLS has finished upgrading dub.selections.json

Example usage

I made a VSCode extension and an Atom package using DLS:

• https://github.com/LaurentTreguier/vscode-dls
• https://github.com/LaurentTreguier/ide-dlang