Lua 仿PHP的strtotime

--[[
获取时间戳
--]]
function strtotimestamp(timeToConvert)

    local ymdhis = "(%d+)-(%d+)-(%d+) (%d+):(%d+):(%d+)"

    local runyear,runmonth,runday = getymd(timeToConvert);
    local runhour,runminute,runseconds = gethis(timeToConvert);
    local convertedTimestamp = os.time({
                                           year = runyear,
                                           month = runmonth,
                                           day = runday,
                                           hour = runhour,
                                           min = runminute,
                                           sec = runseconds
                                       });
    return convertedTimestamp;
end

--[[
获取年、月、日
--]]
function getymd(str)
    local ymd =  "(%d+)-(%d+)-(%d+)"
    local md =  "(%d+)-(%d+)"
    local runyear, runmonth, runday = str:match(ymd);

    if runyear then
        return runyear, runmonth, runday;
    else
        local runmonth, runday = str:match(md);
        if runmonth then
             return nil,runmonth, runday;
        else
            return nil,nil,nil;
        end
    end

end

--[[
获取时、分、秒
--]]
function gethis(str)
    local his = "(%d+):(%d+):(%d+)"
    local hi = "(%d+):(%d+)"

    local runhour, runminute, runseconds = str:match(his);
    if runhour then
        return runhour, runminute, runseconds;
    else
        local runhour, runminute = str:match(hi);
        if runhour then
             return runhour, runminute, nil;
        else
            return nil,nil, nil;
        end
    end

end