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160 lines
5.8 KiB
Markdown
160 lines
5.8 KiB
Markdown
# Deno Language Server
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The Deno Language Server provides a server implementation of the
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[Language Server Protocol](https://microsoft.github.io/language-server-protocol/)
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which is specifically tailored to provide a _Deno_ view of code. It is
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integrated into the command line and can be started via the `lsp` sub-command.
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> :warning: The Language Server is experimental and not feature complete. This
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> document gives an overview of the structure of the language server.
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## Structure
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When the language server is started, a `LanguageServer` instance is created
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which holds all of the state of the language server. It also defines all of the
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methods that the client calls via the Language Server RPC protocol.
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## Settings
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There are several settings that the language server supports for a workspace:
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- `deno.enable`
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- `deno.config`
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- `deno.importMap`
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- `deno.codeLens.implementations`
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- `deno.codeLens.references`
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- `deno.codeLens.referencesAllFunctions`
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- `deno.codeLens.test`
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- `deno.suggest.completeFunctionCalls`
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- `deno.suggest.names`
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- `deno.suggest.paths`
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- `deno.suggest.autoImports`
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- `deno.suggest.imports.autoDiscover`
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- `deno.suggest.imports.hosts`
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- `deno.lint`
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- `deno.unstable`
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There are settings that are supported on a per resource basis by the language
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server:
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- `deno.enable`
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- `deno.codeLens.test`
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There are several points in the process where Deno analyzes these settings.
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First, when the `initialize` request from the client, the
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`initializationOptions` will be assumed to be an object that represents the
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`deno` namespace of options. For example, the following value:
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```json
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{
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"enable": true,
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"unstable": true
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}
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```
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Would enable Deno with the unstable APIs for this instance of the language
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server.
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When the language server receives a `workspace/didChangeConfiguration`
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notification, it will assess if the client has indicated if it has a
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`workspaceConfiguration` capability. If it does, it will send a
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`workspace/configuration` request which will include a request for the workspace
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configuration as well as the configuration of all URIs that the language server
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is currently tracking.
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If the client has the `workspaceConfiguration` capability, the language server
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will send a configuration request for the URI when it received the
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`textDocument/didOpen` notification in order to get the resources specific
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settings.
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If the client does not have the `workspaceConfiguration` capability, the
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language server will assume the workspace setting applies to all resources.
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## Commands
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There are several commands that might be issued by the language server to the
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client, which the client is expected to implement:
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- `deno.cache` - This is sent as a resolution code action when there is an
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un-cached module specifier that is being imported into a module. It will be
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sent with and argument that contains the resolved specifier as a string to be
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cached.
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- `deno.showReferences` - This is sent as the command on some code lenses to
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show locations of references. The arguments contain the specifier that is the
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subject of the command, the start position of the target and the locations of
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the references to show.
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- `deno.test` - This is sent as part of a test code lens to, of which the client
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is expected to run a test based on the arguments, which are the specifier the
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test is contained in and the name of the test to filter the tests on.
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## Requests
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The LSP currently supports the following custom requests. A client should
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implement these in order to have a fully functioning client that integrates well
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with Deno:
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- `deno/cache` - This command will instruct Deno to attempt to cache a module
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and all of its dependencies. If a `referrer` only is passed, then all
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dependencies for the module specifier will be loaded. If there are values in
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the `uris`, then only those `uris` will be cached.
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It expects parameters of:
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```ts
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interface CacheParams {
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referrer: TextDocumentIdentifier;
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uris: TextDocumentIdentifier[];
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}
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```
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- `deno/performance` - Requests the return of the timing averages for the
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internal instrumentation of Deno.
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It does not expect any parameters.
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- `deno/reloadImportRegistries` - Reloads any cached responses from import
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registries.
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It does not expect any parameters.
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- `deno/virtualTextDocument` - Requests a virtual text document from the LSP,
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which is a read only document that can be displayed in the client. This allows
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clients to access documents in the Deno cache, like remote modules and
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TypeScript library files built into Deno. The Deno language server will encode
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all internal files under the custom schema `deno:`, so clients should route
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all requests for the `deno:` schema back to the `deno/virtualTextDocument`
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API.
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It also supports a special URL of `deno:/status.md` which provides a markdown
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formatted text document that contains details about the status of the LSP for
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display to a user.
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It expects parameters of:
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```ts
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interface VirtualTextDocumentParams {
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textDocument: TextDocumentIdentifier;
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}
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```
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## Notifications
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There is currently one custom notification that is sent from the server to the
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client:
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- `deno/registryStatus` - when `deno.suggest.imports.autoDiscover` is `true` and
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an origin for an import being added to a document is not explicitly set in
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`deno.suggest.imports.hosts`, the origin will be checked and the notification
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will be sent to the client of the status.
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When receiving the notification, if the param `suggestion` is `true`, the
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client should offer the user the choice to enable the origin and add it to the
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configuration for `deno.suggest.imports.hosts`. If `suggestion` is `false` the
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client should add it to the configuration of as `false` to stop the language
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server from attempting to detect if suggestions are supported.
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The params for the notification are:
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```ts
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interface RegistryStatusNotificationParams {
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origin: string;
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suggestions: boolean;
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}
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```
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