+
+function compare_versions(ver1, comp, ver2)
+ if not ver1 or not ver2
+ or not comp or not (#comp > 0) then
+ error("Invalid parameters")
+ return nil
+ end
+ -- correct compare string
+ if comp == "<>" or comp == "><" or comp == "!=" or comp == "~=" then comp = "~="
+ elseif comp == "<=" or comp == "<" or comp == "=<" then comp = "<="
+ elseif comp == ">=" or comp == ">" or comp == "=>" then comp = ">="
+ elseif comp == "=" or comp == "==" then comp = "=="
+ elseif comp == "<<" then comp = "<"
+ elseif comp == ">>" then comp = ">"
+ else
+ error("Invalid compare string")
+ return nil
+ end
+
+ local av1 = util.split(ver1, "[%.%-]", nil, true)
+ local av2 = util.split(ver2, "[%.%-]", nil, true)
+
+ local max = table.getn(av1)
+ if (table.getn(av1) < table.getn(av2)) then
+ max = table.getn(av2)
+ end
+
+ for i = 1, max, 1 do
+ local s1 = av1[i] or ""
+ local s2 = av2[i] or ""
+
+ -- first "not equal" found return true
+ if comp == "~=" and (s1 ~= s2) then return true end
+ -- first "lower" found return true
+ if (comp == "<" or comp == "<=") and (s1 < s2) then return true end
+ -- first "greater" found return true
+ if (comp == ">" or comp == ">=") and (s1 > s2) then return true end
+ -- not equal then return false
+ if (s1 ~= s2) then return false end
+ end
+
+ -- all equal and not compare greater or lower then true
+ return not (comp == "<" or comp == ">")
+end