diff options
Diffstat (limited to 'tests/bwcoercion.lua')
-rw-r--r-- | tests/bwcoercion.lua | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/tests/bwcoercion.lua b/tests/bwcoercion.lua new file mode 100644 index 0000000..cd735ab --- /dev/null +++ b/tests/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 + |