comparison: compat_env.lua
compat_env.lua
- changeset 5
- 7667b101cb1e
equal
deleted
inserted
replaced
| 4:4cb0d1dbc65b | 5:7667b101cb1e |
|---|---|
| 1 --[[ | |
| 2 compat_env - see README for details. | |
| 3 (c) 2012 David Manura. Licensed under Lua 5.1/5.2 terms (MIT license). | |
| 4 --]] | |
| 5 | |
| 6 local M = {_TYPE='module', _NAME='compat_env', _VERSION='0.2.2.20120406'} | |
| 7 | |
| 8 local function check_chunk_type(s, mode) | |
| 9 local nmode = mode or 'bt' | |
| 10 local is_binary = s and #s > 0 and s:byte(1) == 27 | |
| 11 if is_binary and not nmode:match'b' then | |
| 12 return nil, ("attempt to load a binary chunk (mode is '%s')"):format(mode) | |
| 13 elseif not is_binary and not nmode:match't' then | |
| 14 return nil, ("attempt to load a text chunk (mode is '%s')"):format(mode) | |
| 15 end | |
| 16 return true | |
| 17 end | |
| 18 | |
| 19 local IS_52_LOAD = pcall(load, '') | |
| 20 if IS_52_LOAD then | |
| 21 M.load = _G.load | |
| 22 M.loadfile = _G.loadfile | |
| 23 else | |
| 24 -- 5.2 style `load` implemented in 5.1 | |
| 25 function M.load(ld, source, mode, env) | |
| 26 local f | |
| 27 if type(ld) == 'string' then | |
| 28 local s = ld | |
| 29 local ok, err = check_chunk_type(s, mode) | |
| 30 if not ok then return ok, err end | |
| 31 local err; f, err = loadstring(s, source) | |
| 32 if not f then return f, err end | |
| 33 elseif type(ld) == 'function' then | |
| 34 local ld2 = ld | |
| 35 if (mode or 'bt') ~= 'bt' then | |
| 36 local first = ld() | |
| 37 local ok, err = check_chunk_type(first, mode) | |
| 38 if not ok then return ok, err end | |
| 39 ld2 = function() | |
| 40 if first then | |
| 41 local chunk=first; first=nil; return chunk | |
| 42 else return ld() end | |
| 43 end | |
| 44 end | |
| 45 local err; f, err = load(ld2, source); if not f then return f, err end | |
| 46 else | |
| 47 error(("bad argument #1 to 'load' (function expected, got %s)") | |
| 48 :format(type(ld)), 2) | |
| 49 end | |
| 50 if env then setfenv(f, env) end | |
| 51 return f | |
| 52 end | |
| 53 | |
| 54 -- 5.2 style `loadfile` implemented in 5.1 | |
| 55 function M.loadfile(filename, mode, env) | |
| 56 if (mode or 'bt') ~= 'bt' then | |
| 57 local ioerr | |
| 58 local fh, err = io.open(filename, 'rb'); if not fh then return fh,err end | |
| 59 local function ld() | |
| 60 local chunk; chunk,ioerr = fh:read(4096); return chunk | |
| 61 end | |
| 62 local f, err = M.load(ld, filename and '@'..filename, mode, env) | |
| 63 fh:close() | |
| 64 if not f then return f, err end | |
| 65 if ioerr then return nil, ioerr end | |
| 66 return f | |
| 67 else | |
| 68 local f, err = loadfile(filename); if not f then return f, err end | |
| 69 if env then setfenv(f, env) end | |
| 70 return f | |
| 71 end | |
| 72 end | |
| 73 end | |
| 74 | |
| 75 if _G.setfenv then -- Lua 5.1 | |
| 76 M.setfenv = _G.setfenv | |
| 77 M.getfenv = _G.getfenv | |
| 78 else -- >= Lua 5.2 | |
| 79 -- helper function for `getfenv`/`setfenv` | |
| 80 local function envlookup(f) | |
| 81 local name, val | |
| 82 local up = 0 | |
| 83 local unknown | |
| 84 repeat | |
| 85 up=up+1; name, val = debug.getupvalue(f, up) | |
| 86 if name == '' then unknown = true end | |
| 87 until name == '_ENV' or name == nil | |
| 88 if name ~= '_ENV' then | |
| 89 up = nil | |
| 90 if unknown then | |
| 91 error("upvalues not readable in Lua 5.2 when debug info missing", 3) | |
| 92 end | |
| 93 end | |
| 94 return (name == '_ENV') and up, val, unknown | |
| 95 end | |
| 96 | |
| 97 -- helper function for `getfenv`/`setfenv` | |
| 98 local function envhelper(f, name) | |
| 99 if type(f) == 'number' then | |
| 100 if f < 0 then | |
| 101 error(("bad argument #1 to '%s' (level must be non-negative)") | |
| 102 :format(name), 3) | |
| 103 elseif f < 1 then | |
| 104 error("thread environments unsupported in Lua 5.2", 3) --[*] | |
| 105 end | |
| 106 f = debug.getinfo(f+2, 'f').func | |
| 107 elseif type(f) ~= 'function' then | |
| 108 error(("bad argument #1 to '%s' (number expected, got %s)") | |
| 109 :format(type(name, f)), 2) | |
| 110 end | |
| 111 return f | |
| 112 end | |
| 113 -- [*] might simulate with table keyed by coroutine.running() | |
| 114 | |
| 115 -- 5.1 style `setfenv` implemented in 5.2 | |
| 116 function M.setfenv(f, t) | |
| 117 local f = envhelper(f, 'setfenv') | |
| 118 local up, val, unknown = envlookup(f) | |
| 119 if up then | |
| 120 debug.upvaluejoin(f, up, function() return up end, 1) --unique upval[*] | |
| 121 debug.setupvalue(f, up, t) | |
| 122 else | |
| 123 local what = debug.getinfo(f, 'S').what | |
| 124 if what ~= 'Lua' and what ~= 'main' then -- not Lua func | |
| 125 error("'setfenv' cannot change environment of given object", 2) | |
| 126 end -- else ignore no _ENV upvalue (warning: incompatible with 5.1) | |
| 127 end | |
| 128 return f -- invariant: original f ~= 0 | |
| 129 end | |
| 130 -- [*] http://lua-users.org/lists/lua-l/2010-06/msg00313.html | |
| 131 | |
| 132 -- 5.1 style `getfenv` implemented in 5.2 | |
| 133 function M.getfenv(f) | |
| 134 if f == 0 or f == nil then return _G end -- simulated behavior | |
| 135 local f = envhelper(f, 'setfenv') | |
| 136 local up, val = envlookup(f) | |
| 137 if not up then return _G end -- simulated behavior [**] | |
| 138 return val | |
| 139 end | |
| 140 -- [**] possible reasons: no _ENV upvalue, C function | |
| 141 end | |
| 142 | |
| 143 | |
| 144 return M |
