AstrolabeQH/DongleStub.lua

   1 --[[-------------------------------------------------------------------------
   2   James Whitehead II grants anyone the right to use this work for any purpose,
   3   without any conditions, unless such conditions are required by law.
   4 ---------------------------------------------------------------------------]]
   5
   6 local major = "DongleStub"
   7 local minor = tonumber(string.match("$Revision: 313 $", "(%d+)") or 1)
   8
   9 local g = getfenv(0)
  10
  11 if not g.DongleStub or g.DongleStub:IsNewerVersion(major, minor) then
  12         local lib = setmetatable({}, {
  13                 __call = function(t,k)
  14                         if type(t.versions) == "table" and t.versions[k] then
  15                                 return t.versions[k].instance
  16                         else
  17                                 error("Cannot find a library with name '"..tostring(k).."'", 2)
  18                         end
  19                 end
  20         })
  21
  22         function lib:IsNewerVersion(major, minor)
  23                 local versionData = self.versions and self.versions[major]
  24
  25                 -- If DongleStub versions have differing major version names
  26                 -- such as DongleStub-Beta0 and DongleStub-1.0-RC2 then a second
  27                 -- instance will be loaded, with older logic.  This code attempts
  28                 -- to compensate for that by matching the major version against
  29                 -- "^DongleStub", and handling the version check correctly.
  30
  31                 if major:match("^DongleStub") then
  32                         local oldmajor,oldminor = self:GetVersion()
  33                         if self.versions and self.versions[oldmajor] then
  34                                 return minor > oldminor
  35                         else
  36                                 return true
  37                         end
  38                 end
  39
  40                 if not versionData then return true end
  41                 local oldmajor,oldminor = versionData.instance:GetVersion()
  42                 return minor > oldminor
  43         end
  44
  45         local function NilCopyTable(src, dest)
  46                 for k,v in pairs(dest) do dest[k] = nil end
  47                 for k,v in pairs(src) do dest[k] = v end
  48         end
  49
  50         function lib:Register(newInstance, activate, deactivate)
  51                 assert(type(newInstance.GetVersion) == "function",
  52                         "Attempt to register a library with DongleStub that does not have a 'GetVersion' method.")
  53
  54                 local major,minor = newInstance:GetVersion()
  55                 assert(type(major) == "string",
  56                         "Attempt to register a library with DongleStub that does not have a proper major version.")
  57                 assert(type(minor) == "number",
  58                         "Attempt to register a library with DongleStub that does not have a proper minor version.")
  59
  60                 -- Generate a log of all library registrations
  61                 if not self.log then self.log = {} end
  62                 table.insert(self.log, string.format("Register: %s, %s", major, minor))
  63
  64                 if not self:IsNewerVersion(major, minor) then return false end
  65                 if not self.versions then self.versions = {} end
  66
  67                 local versionData = self.versions[major]
  68                 if not versionData then
  69                         -- New major version
  70                         versionData = {
  71                                 ["instance"] = newInstance,
  72                                 ["deactivate"] = deactivate,
  73                         }
  74
  75                         self.versions[major] = versionData
  76                         if type(activate) == "function" then
  77                                 table.insert(self.log, string.format("Activate: %s, %s", major, minor))
  78                                 activate(newInstance)
  79                         end
  80                         return newInstance
  81                 end
  82
  83                 local oldDeactivate = versionData.deactivate
  84                 local oldInstance = versionData.instance
  85
  86                 versionData.deactivate = deactivate
  87
  88                 local skipCopy
  89                 if type(activate) == "function" then
  90                         table.insert(self.log, string.format("Activate: %s, %s", major, minor))
  91                         skipCopy = activate(newInstance, oldInstance)
  92                 end
  93
  94                 -- Deactivate the old libary if necessary
  95                 if type(oldDeactivate) == "function" then
  96                         local major, minor = oldInstance:GetVersion()
  97                         table.insert(self.log, string.format("Deactivate: %s, %s", major, minor))
  98                         oldDeactivate(oldInstance, newInstance)
  99                 end
 100
 101                 -- Re-use the old table, and discard the new one
 102                 if not skipCopy then
 103                         NilCopyTable(newInstance, oldInstance)
 104                 end
 105                 return oldInstance
 106         end
 107
 108         function lib:GetVersion() return major,minor end
 109
 110         local function Activate(new, old)
 111                 -- This code ensures that we'll move the versions table even
 112                 -- if the major version names are different, in the case of
 113                 -- DongleStub
 114                 if not old then old = g.DongleStub end
 115
 116                 if old then
 117                         new.versions = old.versions
 118                         new.log = old.log
 119                 end
 120                 g.DongleStub = new
 121         end
 122
 123         -- Actually trigger libary activation here
 124         local stub = g.DongleStub or lib
 125         lib = stub:Register(lib, Activate)
 126 end