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46 lines
2.1 KiB
Markdown
46 lines
2.1 KiB
Markdown
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# waspls Architecture
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waspls uses the [lsp](https://hackage.haskell.org/package/lsp) library for
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interacting with the Language Server Protocol.
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The main entry point is `serve` in `Wasp/LSP/Server.hs`. This function sets up
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the LSP server, the reactor thread, and starts everything.
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The handlers to LSP notifications and requests are defined in `Wasp/LSP/Handlers.hs`
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and imported by `Wasp/LSP/Server.hs` so that the `lsp` package can be told about
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them. Mostly, these handlers are small functions to call out to the actual
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implementation in another source file.
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There are two types of handlers in waspls:
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1. "Analysis handlers" that extract some syntactic or semantic information from
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source code and store it in the server state.
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2. "Request handlers" that use the information stored in the server state to
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provide LSP features, such as autocompletion and goto definition.
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Request handlers have read-only access to the server state, while analysis
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handlers can write to the state.
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## Multithreading
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By default, the `lsp` package is single-threaded. Because waspls sometimes
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needs to do time-intensive work, such as getting the list of exported symbols
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from TypeScript files, there is a mechanism for running code on a separate
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thread. The purpose of this is to avoid blocking the main thread for long periods
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of time, which would make the language server feel unresponsive in the editor.
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This mechanism is the "reactor thread," which continuously looks for new actions
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to run on a separate thread. For details, see the documentation in `Wasp/LSP/Reactor.hs`.
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# Testing Development Versions of waspls
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Set the wasp executable path in the Wasp VSCode extension to `wasp-cli`. To
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build the LSP, run `cabal install`. Then, restart the language server in VSCode
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by running the `Wasp: Restart Wasp LSP Server` command. By default, you can
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press <kbd>Ctrl+Shift+P</kbd> to open the command palette to search for the
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command.
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Note that, after changing the executable path in the extension settings, you
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have to reload the VSCode window. You can do this either by closing and reopening
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the window or by running the command `Developer: Reload Window`.
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