refactor(lsp): avoid using coroutine when parsing frames

runtime/lua/vim/net/_transport.lua

@@ -1,5 +1,6 @@
 local uv = vim.uv
 local log = require('vim.lsp.log')
+local strbuffer = require('vim._core.stringbuffer')
 
 --- Interface for transport implementations.
 ---
@@ -182,34 +183,36 @@ function TransportConnect:terminate()
   end
 end
 
---- Create a message stream from a coroutine decoder.
+--- Create a message stream from a decoder.
 ---
---- The decoder receives transport data from `coroutine.yield()`
---- and may yield a message body when a full message is available.
---- A nil yield means it needs more transport data.
---- Decoder errors are reported through `on_error`.
+--- The decoder consumes from the given string buffer
+--- and returns a message body when a full message is available.
+--- `nil` means it needs more transport data.
+--- decoder errors are reported through `on_error`.
 ---
 ---@class (private, exact) vim.MessageStream
----@field private co thread
----@field private decode fun()
+---@field private strbuf string.buffer
+---@field private decode fun(strbuf: string.buffer): string?
 ---@field private on_read fun(err: string?, data: string?)
 ---@field private on_error fun(err: any)
 ---@field feed fun(self: vim.MessageStream, err: string?, data: string?)
 ---@field encode fun(msg: string): string
----@field new fun(decode: fun(), encode: (fun(msg: string): string), on_read: fun(err: string?, data: string?), on_error: fun(err: any)): vim.MessageStream
+---@field new fun(decode: (fun(strbuf: string.buffer): string?), encode: (fun(msg: string): string), on_read: fun(err: string?, data: string?), on_error: fun(err: any)): vim.MessageStream
 local MessageStream = {}
 
+---@param decode fun(strbuf: string.buffer): string?
+---@param encode fun(msg: string): string
+---@param on_read fun(err: string?, data: string?)
+---@param on_error fun(err: any)
+---@return vim.MessageStream
 function MessageStream.new(decode, encode, on_read, on_error)
-  local self = setmetatable({
-    co = coroutine.create(decode),
+  return setmetatable({
+    strbuf = strbuffer.new(),
     decode = decode,
     on_read = on_read,
     on_error = on_error,
     encode = encode,
   }, { __index = MessageStream })
-
-  coroutine.resume(self.co)
-  return self
 end
 
 ---@param err string?
@@ -223,8 +226,10 @@ function MessageStream:feed(err, data)
     return
   end
 
+  self.strbuf:put(data)
+
   while true do
-    local ok, body = coroutine.resume(self.co, data)
+    local ok, body = pcall(self.decode, self.strbuf)
     if not ok then
       self.on_error(body)
       return
@@ -232,7 +237,6 @@ function MessageStream:feed(err, data)
       break
     end
     self.on_read(nil, body)
-    data = ''
   end
 end