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patch 8.2.4648: handling LSP messages is a bit slow
Problem: Handling LSP messages is a bit slow. Solution: Included support for LSP messages. (Yegappan Lakshmanan, closes #10025)
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‎runtime/doc/channel.txt‎

Lines changed: 92 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -53,6 +53,7 @@ RAW nothing known, Vim cannot tell where a message ends
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NL every message ends in a NL (newline) character
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JSON JSON encoding |json_encode()|
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JS JavaScript style JSON-like encoding |js_encode()|
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LSP Language Server Protocol encoding |language-server-protocol|
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Common combination are:
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- Using a job connected through pipes in NL mode. E.g., to run a style
@@ -130,6 +131,7 @@ When using an IPv6 address, enclose it within square brackets. E.g.,
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"js" - Use JS (JavaScript) encoding, more efficient than JSON.
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"nl" - Use messages that end in a NL character
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"raw" - Use raw messages
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"lsp" - Use language server protocol encoding
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*channel-callback* *E921*
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"callback" A function that is called when a message is received that is
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not handled otherwise (e.g. a JSON message with ID zero). It
@@ -140,8 +142,8 @@ When using an IPv6 address, enclose it within square brackets. E.g.,
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endfunc
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let channel = ch_open("localhost:8765", {"callback": "Handle"})
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<
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When "mode" is "json" or "js" the "msg" argument is the body
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of the received message, converted to Vim types.
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When "mode" is "json" or "js" or "lsp" the "msg" argument is
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the body of the received message, converted to Vim types.
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When "mode" is "nl" the "msg" argument is one message,
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excluding the NL.
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When "mode" is "raw" the "msg" argument is the whole message
@@ -165,7 +167,19 @@ When using an IPv6 address, enclose it within square brackets. E.g.,
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to check for messages, the close_cb may be invoked while still
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in the callback. The plugin must handle this somehow, it can
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be useful to know that no more data is coming.
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*channel-drop*
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If it is not known if there is a message to be read, use a
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try/catch block: >
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try
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let msg = ch_readraw(a:channel)
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catch
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let msg = 'no message'
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endtry
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try
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let err = ch_readraw(a:channel, #{part: 'err'})
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catch
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let err = 'no error'
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endtry
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< *channel-drop*
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"drop" Specifies when to drop messages:
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"auto" When there is no callback to handle a message.
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The "close_cb" is also considered for this.
@@ -443,7 +457,7 @@ to check if there is something to read.
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Note that when there is no callback, messages are dropped. To avoid that add
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a close callback to the channel.
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To read all output from a RAW channel that is available: >
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To read all normal output from a RAW channel that is available: >
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let output = ch_readraw(channel)
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To read the error output: >
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let output = ch_readraw(channel, {"part": "err"})
@@ -503,6 +517,7 @@ ch_evalexpr({handle}, {expr} [, {options}]) *ch_evalexpr()*
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according to the type of channel. The function cannot be used
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with a raw channel. See |channel-use|.
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{handle} can be a Channel or a Job that has a Channel.
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When using the "lsp" channel mode, {expr} must be a |Dict|.
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*E917*
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{options} must be a Dictionary. It must not have a "callback"
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entry. It can have a "timeout" entry to specify the timeout
@@ -578,7 +593,7 @@ ch_info({handle}) *ch_info()*
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"err_io" "out", "null", "pipe", "file" or "buffer"
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"err_timeout" timeout in msec
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"in_status" "open" or "closed"
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"in_mode" "NL", "RAW", "JSON" or "JS"
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"in_mode" "NL", "RAW", "JSON", "JS" or "LSP"
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"in_io" "null", "pipe", "file" or "buffer"
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"in_timeout" timeout in msec
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@@ -674,6 +689,7 @@ ch_sendexpr({handle}, {expr} [, {options}]) *ch_sendexpr()*
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with a raw channel.
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See |channel-use|. *E912*
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{handle} can be a Channel or a Job that has a Channel.
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When using the "lsp" channel mode, {expr} must be a |Dict|.
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Can also be used as a |method|: >
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GetChannel()->ch_sendexpr(expr)
@@ -1361,5 +1377,76 @@ The same in |Vim9| script: >
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# start accepting shell commands
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startinsert
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==============================================================================
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14. Language Server Protocol *language-server-protocol*
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The language server protocol specification is available at:
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https://microsoft.github.io/language-server-protocol/specification
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Each LSP protocol message starts with a simple HTTP header followed by the
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payload encoded in JSON-RPC format. This is described in:
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https://www.jsonrpc.org/specification
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For messages received on a channel with mode set to "lsp", Vim will process
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the HTTP header and decode the payload into a Vim |Dict| type and call the
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channel callback or the specified callback function. When sending messages on
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a channel using |ch_evalexpr()| or |ch_sendexpr()|, Vim will add the HTTP
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header and encode the Vim expression into JSON-RPC.
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To open a channel using the 'lsp' mode, set the 'mode' item in the |ch_open()|
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{options} argument to 'lsp'. Example: >
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let ch = ch_open(..., #{mode: 'lsp'})
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To open a channel using the 'lsp' mode with a job, set the 'in_mode' and
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'out_mode' items in the |job_start()| {options} argument to 'lsp'. Example: >
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let job = job_start(...., #{in_mode: 'lsp', out_mode: 'lsp'})
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To synchronously send a JSON-RPC request to the server, use the |ch_evalexpr()|
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function. This function will return the response from the server. You can use
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the 'timeout' field in the {options} argument to control the response wait
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time. Example: >
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let req = {}
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let req.method = 'textDocument/definition'
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let req.params = {}
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let req.params.textDocument = #{uri: 'a.c'}
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let req.params.position = #{line: 10, character: 3}
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let resp = ch_evalexpr(ch, req, #{timeout: 100})
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Note that in the request message the 'id' field should not be specified. If it
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is specified, then Vim will overwrite the value with an internally generated
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identifier. Vim currently supports only a number type for the 'id' field.
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To send a JSON-RPC request to the server and asynchronously process the
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response, use the |ch_sendexpr()| function and supply a callback function.
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Example: >
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let req = {}
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let req.method = 'textDocument/hover'
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let req.params = {}
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let req.params.textDocument = #{uri: 'a.c'}
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let req.params.position = #{line: 10, character: 3}
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let resp = ch_sendexpr(ch, req, #{callback: 'MyFn'})
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To send a JSON-RPC notification message to the server, use the |ch_sendexpr()|
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function. Example: >
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call ch_sendexpr(ch, #{method: 'initialized'})
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To respond to a JSON-RPC request message from the server, use the
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|ch_sendexpr()| function. In the response message, copy the 'id' field value
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from the server request message. Example: >
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let resp = {}
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let resp.id = req.id
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let resp.result = 1
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call ch_sendexpr(ch, resp)
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The JSON-RPC notification messages from the server are delivered through the
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|channel-callback| function.
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vim:tw=78:ts=8:noet:ft=help:norl:

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