vis-config

parser.lua

(1873B)

 --- Stateful parser for the data send by a language server.
 -- Note the chunks received may not end with the end of a message.
 -- In the worst case a data chunk contains two partial messages one
 -- at the beginning and one at the end.
 -- @module parser
 -- @author Florian Fischer
 -- @license GPL-3
 -- @copyright Florian Fischer 2021-2024
 local parser = {}
 
 local Parser = {}
 
 function parser.new()
   local self = {exp_len = nil, data = '', msgs = {}}
 
   setmetatable(self, {__index = Parser})
   return self
 end
 
 function Parser:add(data)
   self.data = self.data .. data
 
   -- we have not seen a complete header in data yet
   if not self.exp_len then
     -- search for the end of a header
     -- LSP message format: 'header\r\n\r\nbody'
     local header_end, content_start = self.data:find('\r\n\r\n')
 
     -- header is not complete yet -> save data and wait for more
     if not header_end then
       return
     end
 
     -- got a complete header
     local header = self.data:sub(1, header_end)
 
     -- extract content length from the header
     self.exp_len = tonumber(header:match('%d+'))
     if not self.exp_len then
       return 'invalid header in data: ' .. self.data
     end
 
     -- consume header from data
     self.data = self.data:sub(content_start + 1)
   end
 
   local data_avail = string.len(self.data)
   -- we have no complete message yet -> await more data
   if self.exp_len > data_avail then
     return
   end
 
   local complete_msg = self.data:sub(1, self.exp_len)
   table.insert(self.msgs, complete_msg)
 
   -- consume complete_msg from data
   self.data = self.data:sub(self.exp_len + 1)
 
   local leftover = data_avail - self.exp_len
 
   -- reset exp_len to search for a new header
   self.exp_len = nil
 
   if leftover > 0 then
     return self:add('')
   end
 end
 
 function Parser:get_msgs()
   local msgs = self.msgs
   self.msgs = {}
   return msgs
 end
 
 return parser