1 files changed, 78 insertions, 0 deletions

diff --git a/testes/bwcoercion.lua b/testes/bwcoercion.lua
new file mode 100644
index 00000000..cd735ab0
--- /dev/null
+++ b/testes/bwcoercion.lua
@@ -0,0 +1,78 @@
+local tonumber, tointeger = tonumber, math.tointeger
+local type, getmetatable, rawget, error = type, getmetatable, rawget, error
+local strsub = string.sub
+
+local print = print
+
+_ENV = nil
+
+-- Try to convert a value to an integer, without assuming any coercion.
+local function toint (x)
+  x = tonumber(x)   -- handle numerical strings
+  if not x then
+    return false    -- not coercible to a number
+  end
+  return tointeger(x)
+end
+
+
+-- If operation fails, maybe second operand has a metamethod that should
+-- have been called if not for this string metamethod, so try to
+-- call it.
+local function trymt (x, y, mtname)
+  if type(y) ~= "string" then    -- avoid recalling original metamethod
+    local mt = getmetatable(y)
+    local mm = mt and rawget(mt, mtname)
+    if mm then
+      return mm(x, y)
+    end
+  end
+  -- if any test fails, there is no other metamethod to be called
+  error("attempt to '" .. strsub(mtname, 3) ..
+        "' a " .. type(x) .. " with a " .. type(y), 4)
+end
+
+
+local function checkargs (x, y, mtname)
+  local xi = toint(x)
+  local yi = toint(y)
+  if xi and yi then
+    return xi, yi
+  else
+    return trymt(x, y, mtname), nil
+  end
+end
+
+
+local smt = getmetatable("")
+
+smt.__band = function (x, y)
+  local x, y = checkargs(x, y, "__band")
+  return y and x & y or x
+end
+
+smt.__bor = function (x, y)
+  local x, y = checkargs(x, y, "__bor")
+  return y and x | y or x
+end
+
+smt.__bxor = function (x, y)
+  local x, y = checkargs(x, y, "__bxor")
+  return y and x ~ y or x
+end
+
+smt.__shl = function (x, y)
+  local x, y = checkargs(x, y, "__shl")
+  return y and x << y or x
+end
+
+smt.__shr = function (x, y)
+  local x, y = checkargs(x, y, "__shr")
+  return y and x >> y or x
+end
+
+smt.__bnot = function (x)
+  local x, y = checkargs(x, x, "__bnot")
+  return y and ~x or x
+end
+