table library (except table.sort for now) respects metamethods

1 files changed, 147 insertions, 11 deletions

diff --git a/compat53.lua b/compat53.lua
index 8bf6bd8..761d554 100644
--- a/compat53.lua
+++ b/compat53.lua
@@ -1,12 +1,31 @@
 local lua_version = _VERSION:sub(-3)
 
-if lua_version ~= "5.3" then
-   local _type = type
+if lua_version < "5.3" then
+   -- local aliases for commonly used functions
+   local type, select, error = type, select, error
+
    -- select the most powerful getmetatable function available
-   local gmt = _type(debug) == "table" and debug.getmetatable or
+   local gmt = type(debug) == "table" and debug.getmetatable or
                getmetatable or function() return false end
+
+   -- type checking functions
    local checkinteger -- forward declararation
 
+   local function argcheck(cond, i, f, extra)
+      if not cond then
+         error("bad argument #"..i.." to '"..f.."' ("..extra..")", 0)
+      end
+   end
+
+   local function checktype(x, t, i, f)
+      local xt = type(x)
+      if xt ~= t then
+         error("bad argument #"..i.." to '"..f.."' ("..t..
+               " expected, got "..xt..")", 0)
+      end
+   end
+
+
    -- load utf8 library
    local ok, utf8lib = pcall(require, "compat53.utf8")
    if ok then
@@ -17,6 +36,7 @@ if lua_version ~= "5.3" then
       end
    end
 
+
    -- use Roberto's struct module for string packing/unpacking for now
    -- maybe we'll later extract the functions from the 5.3 string
    -- library for greater compatiblity, but it uses the 5.3 buffer API
@@ -47,14 +67,14 @@ if lua_version ~= "5.3" then
       math.mininteger = minint
 
       function math.tointeger(n)
-         if _type(n) == "number" and n <= maxint and n >= minint and n % 1 == 0 then
+         if type(n) == "number" and n <= maxint and n >= minint and n % 1 == 0 then
             return n
          end
          return nil
       end
 
       function math.type(n)
-         if _type(n) == "number" then
+         if type(n) == "number" then
             if n <= maxint and n >= minint and n % 1 == 0 then
                return "integer"
             else
@@ -65,15 +85,14 @@ if lua_version ~= "5.3" then
          end
       end
 
-      local _error = error
       function checkinteger(x, i, f)
-         local t = _type(x)
+         local t = type(x)
          if t ~= "number" then
-            _error("bad argument #"..i.." to '"..f..
-                   "' (number expected, got "..t..")", 0)
+            error("bad argument #"..i.." to '"..f..
+                  "' (number expected, got "..t..")", 0)
          elseif x > maxint or x < minint or x % 1 ~= 0 then
-            _error("bad argument #"..i.." to '"..f..
-                   "' (number has no integer representation)", 0)
+            error("bad argument #"..i.." to '"..f..
+                  "' (number has no integer representation)", 0)
          else
             return x
          end
@@ -112,6 +131,123 @@ if lua_version ~= "5.3" then
       end
    end
 
+
+   -- update table library
+   do
+      local table_concat = table.concat
+      function table.concat(list, sep, i, j)
+         local mt = gmt(list)
+         if type(mt) == "table" and type(mt.__len) == "function" then
+            local src = list
+            list, i, j  = {}, i or 1, j or mt.__len(src)
+            for k = i, j do
+               list[k] = src[k]
+            end
+         end
+         return table_concat(list, sep, i, j)
+      end
+
+      local table_insert = table.insert
+      function table.insert(list, ...)
+         local mt = gmt(list)
+         local has_mt = type(mt) == "table"
+         local has_len = has_mt and type(mt.__len) == "function"
+         if has_mt and (has_len or mt.__index or mt.__newindex) then
+            local e = (has_len and mt.__len(list) or #list)+1
+            local nargs, pos, value = select('#', ...), ...
+            if nargs == 1 then
+               pos, value = e, pos
+            elseif nargs == 2 then
+               pos = checkinteger(pos, "2", "table.insert")
+               argcheck(1 <= pos and pos <= e, "2", "table.insert",
+                        "position out of bounds" )
+            else
+               error("wrong number of arguments to 'insert'", 0)
+            end
+            for i = e-1, pos, -1 do
+               list[i+1] = list[i]
+            end
+            list[pos] = value
+         else
+            return table_insert(list, ...)
+         end
+      end
+
+      function table.move(a1, f, e, t, a2)
+         a2 = a2 or a1
+         f = checkinteger(f, "2", "table.move")
+         argcheck(f > 0, "2", "table.move",
+                  "initial position must be positive")
+         e = checkinteger(e, "3", "table.move")
+         t = checkinteger(t, "4", "table.move")
+         if e >= f then
+            local m, n, d = 0, e-f, 1
+            if t > f then m, n, d = n, m, -1 end
+            for i = m, n, d do
+               a2[t+i] = a1[f+i]
+            end
+         end
+         return a2
+      end
+
+      local table_remove = table.remove
+      function table.remove(list, pos)
+         local mt = gmt(list)
+         local has_mt = type(mt) == "table"
+         local has_len = has_mt and type(mt.__len) == "function"
+         if has_mt and (has_len or mt.__index or mt.__newindex) then
+            local e = (has_len and mt.__len(list) or #list)
+            pos = pos ~= nil and checkinteger(pos, "2", "table.remove") or e
+            if pos ~= e then
+               argcheck(1 <= pos and pos <= e+1, "2", "table.remove",
+                        "position out of bounds" )
+            end
+            local result = list[pos]
+            while pos < e do
+               list[pos] = list[pos+1]
+               pos = pos + 1
+            end
+            list[pos] = nil
+            return result
+         else
+            return table_remove(list, pos)
+         end
+      end
+
+      -- TODO: table.sort
+
+      local table_unpack = lua_version == "5.1" and unpack or table.unpack
+      local function unpack_helper(list, i, j, ...)
+         if j < i then
+            return ...
+         else
+            return unpack_helper(list, i, j-1, list[j], ...)
+         end
+      end
+      function table.unpack(list, i, j)
+         local mt = gmt(list)
+         local has_mt = type(mt) == "table"
+         local has_len = has_mt and type(mt.__len) == "function"
+         if has_mt and (has_len or mt.__index) then
+            i, j = i or 1, j or (has_len and mt.__len(list)) or #list
+            return unpack_helper(list, i, j)
+         else
+            return table_unpack(list, i, j)
+         end
+      end
+   end
+
+
+   if lua_version == "5.1" then
+      -- detect LuaJIT (including LUAJIT_ENABLE_LUA52COMPAT compilation flag)
+      local is_luajit = (string.dump(function() end) or ""):sub(1, 3) == "\027LJ"
+      local is_luajit52 = is_luajit and
+        #setmetatable({}, { __len = function() return 1 end }) == 1
+
+      -- TODO: add functions from lua-compat-5.2
+
+   end
+
 end
 
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