webmcp
annotate libraries/nihil/nihil.lua @ 0:9fdfb27f8e67
Version 1.0.0
| author | jbe/bsw |
|---|---|
| date | Sun Oct 25 12:00:00 2009 +0100 (2009-10-25) |
| parents | |
| children | 3d43a5cf17c1 |
| rev | line source |
|---|---|
| jbe/bsw@0 | 1 #!/usr/bin/env lua |
| jbe/bsw@0 | 2 |
| jbe/bsw@0 | 3 local error = error |
| jbe/bsw@0 | 4 local getmetatable = getmetatable |
| jbe/bsw@0 | 5 local module = module |
| jbe/bsw@0 | 6 local rawset = rawset |
| jbe/bsw@0 | 7 local setmetatable = setmetatable |
| jbe/bsw@0 | 8 |
| jbe/bsw@0 | 9 module(...) |
| jbe/bsw@0 | 10 |
| jbe/bsw@0 | 11 metatable = { |
| jbe/bsw@0 | 12 __tostring = function(self) |
| jbe/bsw@0 | 13 return "nil" .. self[1] |
| jbe/bsw@0 | 14 end, |
| jbe/bsw@0 | 15 __newindex = function() |
| jbe/bsw@0 | 16 error("Objects representing nil are immutable.") |
| jbe/bsw@0 | 17 end |
| jbe/bsw@0 | 18 } |
| jbe/bsw@0 | 19 |
| jbe/bsw@0 | 20 nils = setmetatable({}, { |
| jbe/bsw@0 | 21 __mode = "v", |
| jbe/bsw@0 | 22 __index = function(self, level) |
| jbe/bsw@0 | 23 if level > 0 then |
| jbe/bsw@0 | 24 local result = setmetatable({ level }, metatable) |
| jbe/bsw@0 | 25 rawset(self, level, result) |
| jbe/bsw@0 | 26 return result |
| jbe/bsw@0 | 27 end |
| jbe/bsw@0 | 28 end, |
| jbe/bsw@0 | 29 __newindex = function() |
| jbe/bsw@0 | 30 error("Table is immutable.") |
| jbe/bsw@0 | 31 end |
| jbe/bsw@0 | 32 }) |
| jbe/bsw@0 | 33 |
| jbe/bsw@0 | 34 function lift(value) |
| jbe/bsw@0 | 35 if value == nil then |
| jbe/bsw@0 | 36 return nils[1] |
| jbe/bsw@0 | 37 elseif getmetatable(value) == metatable then |
| jbe/bsw@0 | 38 return nils[value[1]+1] |
| jbe/bsw@0 | 39 else |
| jbe/bsw@0 | 40 return value |
| jbe/bsw@0 | 41 end |
| jbe/bsw@0 | 42 end |
| jbe/bsw@0 | 43 |
| jbe/bsw@0 | 44 function lower(value) |
| jbe/bsw@0 | 45 if value == nil then |
| jbe/bsw@0 | 46 error("Cannot lower nil.") |
| jbe/bsw@0 | 47 elseif getmetatable(value) == metatable then |
| jbe/bsw@0 | 48 return nils[value[1]-1] |
| jbe/bsw@0 | 49 else |
| jbe/bsw@0 | 50 return value |
| jbe/bsw@0 | 51 end |
| jbe/bsw@0 | 52 end |