code / nomsu

   1 -- This file contains the logic for making nicer error messages
   2 debug_getinfo = debug.getinfo
   3 Files = require "files"
   4 C = require "colors"
   5 pretty_error = require("pretty_errors")
   6 export SOURCE_MAP
   7 
   8 ok, to_lua = pcall -> require('moonscript.base').to_lua
   9 if not ok then to_lua = -> nil
  10 MOON_SOURCE_MAP = setmetatable {},
  11     __index: (file)=>
  12         _, line_table = to_lua(file)
  13         self[file] = line_table or false
  14         return line_table or false
  15 
  16 -- Make a better version of debug.getinfo that provides info about the original source
  17 -- where the error came from, even if that's in another language.
  18 debug.getinfo = (thread,f,what)->
  19     if what == nil
  20         f,what,thread = thread,f,nil
  21     if type(f) == 'number' then f += 1 -- Account for this wrapper function
  22     info = if thread == nil
  23         debug_getinfo(f,what)
  24     else debug_getinfo(thread,f,what)
  25     if not info or not info.func then return info
  26     if info.short_src or info.source or info.linedefine or info.currentline
  27         -- TODO: reduce duplicate code
  28         if map = SOURCE_MAP[info.source]
  29             if info.currentline
  30                 info.currentline = assert(map[info.currentline])
  31             if info.linedefined
  32                 info.linedefined = assert(map[info.linedefined])
  33             if info.lastlinedefined
  34                 info.lastlinedefined = assert(map[info.lastlinedefined])
  35             info.short_src = info.source\match('@([^[]*)') or info.short_src
  36             info.name = if info.name
  37                 "action '#{info.name\from_lua_id!}'"
  38             else "main chunk"
  39     return info
  40 
  41 -- This uses a slightly modified Damerau-Levenshtein distance:
  42 strdist = (a,b,cache={})->
  43     if a == b then return 0
  44     if #a < #b then a,b = b,a
  45     if b == "" then return #a
  46     k = a..'\003'..b
  47     unless cache[k]
  48         -- Insert, delete, substitute (given weight 1.1 as a heuristic)
  49         cache[k] = math.min(
  50             strdist(a\sub(1,-2),b,cache) + 1,
  51             strdist(a,b\sub(1,-2),cache) + 1,
  52             strdist(a\sub(1,-2),b\sub(1,-2),cache) + (a\sub(-1) ~= b\sub(-1) and 1.1 or 0)
  53         )
  54         -- Transposition:
  55         if #a >= 2 and #b >= 2 and a\sub(-1,-1) == b\sub(-2,-2) and a\sub(-2,-2) == b\sub(-1,-1)
  56             cache[k] = math.min(cache[k], strdist(a\sub(1,-3),b\sub(1,-3),cache) + 1)
  57     return cache[k]
  58 
  59 enhance_error = (error_message)->
  60     -- Hacky: detect the line numbering
  61     unless error_message and error_message\match("%d|")
  62         error_message or= ""
  63         -- When calling 'nil' actions, make a better error message
  64         if fn_name = error_message\match("attempt to call a nil value %(method '(.*)'%)")
  65             action_name = fn_name\from_lua_id!
  66             error_message = "This object does not have the method '#{action_name}'."
  67         elseif fn_name = (error_message\match("attempt to call a nil value %(global '(.*)'%)") or
  68             error_message\match("attempt to call global '(.*)' %(a nil value%)"))
  69 
  70             action_name = fn_name\from_lua_id!
  71             error_message = "The action '#{action_name}' is not defined."
  72 
  73             -- Look for simple misspellings:
  74 
  75             -- This check is necessary for handling both top-level code and code inside a fn
  76             func = debug.getinfo(2,'f').func
  77             local env
  78             if _VERSION == "Lua 5.1"
  79                 env = getfenv(func)
  80             else
  81                 ename,env = debug.getupvalue(func, 1)
  82                 unless ename == "_ENV" or ename == "_G"
  83                     func = debug.getinfo(3,'f').func
  84                     ename,env = debug.getupvalue(func, 1)
  85 
  86             THRESHOLD = math.min(4.5, .9*#action_name) -- Ignore matches with strdist > THRESHOLD
  87             candidates = {}
  88             cache = {}
  89 
  90             -- Locals:
  91             for i=1,99
  92                 k, v = debug.getlocal(2, i)
  93                 break if k == nil
  94                 unless k\sub(1,1) == "(" or type(v) != 'function'
  95                     k = k\from_lua_id!
  96                     if strdist(k, action_name, cache) <= THRESHOLD and k != ""
  97                         table.insert candidates, k
  98 
  99             -- Upvalues:
 100             for i=1,debug.getinfo(func, 'u').nups
 101                 k, v = debug.getupvalue(func, i)
 102                 unless k\sub(1,1) == "(" or type(v) != 'function'
 103                     k = k\from_lua_id!
 104                     if strdist(k, action_name, cache) <= THRESHOLD and k != ""
 105                         table.insert candidates, k
 106 
 107             -- Globals and global compile rules:
 108             scan = (t, is_lua_id)->
 109                 return unless t
 110                 for k,v in pairs(t)
 111                     if type(k) == 'string' and type(v) == 'function'
 112                         k = k\from_lua_id! unless is_lua_id
 113                         if strdist(k, action_name, cache) <= THRESHOLD and k != ""
 114                             table.insert candidates, k
 115             scan env.COMPILE_RULES, true
 116             scan env.COMPILE_RULES._IMPORTS, true
 117             scan env
 118             scan env._IMPORTS
 119 
 120             if #candidates > 0
 121                 for c in *candidates do THRESHOLD = math.min(THRESHOLD, strdist(c, action_name, cache))
 122                 candidates = [c for c in *candidates when strdist(c, action_name, cache) <= THRESHOLD]
 123                 --candidates = ["#{c}[#{strdist(c,action_name,cache)}/#{THRESHOLD}]" for c in *candidates]
 124                 if #candidates == 1
 125                     error_message ..= "\n\x1b[3mSuggestion: Maybe you meant '#{candidates[1]}'? "
 126                 elseif #candidates > 0
 127                     last = table.remove(candidates)
 128                     error_message ..= "\n"..C('italic', "Suggestion: Maybe you meant '#{table.concat candidates, "', '"}'#{#candidates > 1 and ',' or ''} or '#{last}'? ")
 129 
 130         level = 2
 131         while true
 132             -- TODO: reduce duplicate code
 133             calling_fn = debug_getinfo(level)
 134             if not calling_fn then break
 135             level += 1
 136             local filename, file, line_num
 137             if map = SOURCE_MAP and SOURCE_MAP[calling_fn.source]
 138                 if calling_fn.currentline
 139                     line_num = assert(map[calling_fn.currentline])
 140                 filename,start,stop = calling_fn.source\match('@([^[]*)%[([0-9]+):([0-9]+)]')
 141                 if not filename
 142                     filename,start = calling_fn.source\match('@([^[]*)%[([0-9]+)]')
 143                 assert(filename)
 144                 file = Files.read(filename)
 145             else
 146                 filename = calling_fn.short_src
 147                 file = Files.read(filename)
 148                 if calling_fn.short_src\match("%.moon$") and type(MOON_SOURCE_MAP[file]) == 'table'
 149                     char = MOON_SOURCE_MAP[file][calling_fn.currentline]
 150                     line_num = file\line_number_at(char)
 151                 else
 152                     line_num = calling_fn.currentline
 153 
 154             if file and filename and line_num
 155                 start = 1
 156                 lines = file\lines!
 157                 for i=1,line_num-1 do start += #lines[i] + 1
 158                 stop = start + #lines[line_num]
 159                 start += #lines[line_num]\match("^ *")
 160                 error_message = pretty_error{
 161                     title:"Error"
 162                     error:error_message, source:file
 163                     start:start, stop:stop, filename:filename
 164                 }
 165                 break
 166             if calling_fn.func == xpcall then break
 167 
 168 
 169     ret = {
 170         C('bold red', error_message or "Error")
 171         "stack traceback:"
 172     }
 173 
 174     level = 2
 175     while true
 176         -- TODO: reduce duplicate code
 177         calling_fn = debug_getinfo(level)
 178         if not calling_fn then break
 179         if calling_fn.func == xpcall then break
 180         level += 1
 181         name = calling_fn.name and "function '#{calling_fn.name}'" or nil
 182         if calling_fn.linedefined == 0 then name = "main chunk"
 183         if name == "function 'run_lua_fn'" then continue
 184         line = nil
 185         if map = SOURCE_MAP and SOURCE_MAP[calling_fn.source]
 186             if calling_fn.currentline
 187                 calling_fn.currentline = assert(map[calling_fn.currentline])
 188             if calling_fn.linedefined
 189                 calling_fn.linedefined = assert(map[calling_fn.linedefined])
 190             if calling_fn.lastlinedefined
 191                 calling_fn.lastlinedefined = assert(map[calling_fn.lastlinedefined])
 192             --calling_fn.short_src = calling_fn.source\match('"([^[]*)')
 193             filename,start,stop = calling_fn.source\match('@([^[]*)%[([0-9]+):([0-9]+)]')
 194             if not filename
 195                 filename,start = calling_fn.source\match('@([^[]*)%[([0-9]+)]')
 196             assert(filename)
 197             name = if calling_fn.name
 198                 "action '#{calling_fn.name\from_lua_id!}'"
 199             else "main chunk"
 200 
 201             file = Files.read(filename)
 202             lines = file and file\lines! or {}
 203             if err_line = lines[calling_fn.currentline]
 204                 offending_statement = C('bright red', err_line\match("^[ ]*(.*)"))
 205                 line = C('yellow', "#{filename}:#{calling_fn.currentline} in #{name}\n        #{offending_statement}")
 206             else
 207                 line = C('yellow', "#{filename}:#{calling_fn.currentline} in #{name}")
 208         else
 209             local line_num
 210             if name == nil
 211                 search_level = level
 212                 _info = debug.getinfo(search_level)
 213                 while true
 214                     search_level += 1
 215                     _info = debug.getinfo(search_level)
 216                     break unless _info
 217                     for i=1,999
 218                         varname, val = debug.getlocal(search_level, i)
 219                         if not varname then break
 220                         if val == calling_fn.func
 221                             name = "local '#{varname}'"
 222                             if not varname\match("%(")
 223                                 break
 224                     unless name
 225                         for i=1,_info.nups
 226                             varname, val = debug.getupvalue(_info.func, i)
 227                             if not varname then break
 228                             if val == calling_fn.func
 229                                 name = "upvalue '#{varname}'"
 230                                 if not varname\match("%(")
 231                                     break
 232 
 233             local file, lines
 234             if file = Files.read(calling_fn.short_src)
 235                 lines = file\lines!
 236             
 237             if file and (calling_fn.short_src\match("%.moon$") or file\match("^#![^\n]*moon\n")) and type(MOON_SOURCE_MAP[file]) == 'table'
 238                 char = MOON_SOURCE_MAP[file][calling_fn.currentline]
 239                 line_num = file\line_number_at(char)
 240                 line = C('cyan', "#{calling_fn.short_src}:#{line_num} in #{name or '?'}")
 241             else
 242                 line_num = calling_fn.currentline
 243                 if calling_fn.short_src == '[C]'
 244                     line = C('green', "#{calling_fn.short_src} in #{name or '?'}")
 245                 else
 246                     line = C('blue', "#{calling_fn.short_src}:#{calling_fn.currentline} in #{name or '?'}")
 247 
 248             if file
 249                 if err_line = lines[line_num]
 250                     offending_statement = C('bright red', "#{err_line\match("^[ ]*(.*)$")}")
 251                     line ..= "\n        "..offending_statement
 252         table.insert ret, line
 253         if calling_fn.istailcall
 254             table.insert ret, C('dim', "      (...tail calls...)")
 255 
 256     return table.concat(ret, "\n")
 257 
 258 guard = (fn)->
 259     ok, err = xpcall(fn, enhance_error)
 260     if not ok
 261         io.stderr\write err
 262         io.stderr\flush!
 263         os.exit 1
 264 
 265 return {:guard, :enhance_error, :print_error}