[String] string.equal

--Creator: Bolodefchoco
--Made in: 21/12/2015
--Last update: 22/05/2016
--[[ Notes:
    Does:
        Verifica a similaridade entre a string 1 e a string 2, retornando-a numa escala de 0-1
                            ---------> PODE HAVER BUGS <---------
    Args:
        str1 --> String 1
        str2 --> String 2
]]--

string.equal=function(str1,str2)
    local equal2=function(str1,str2)
        local len = #str1
        local dif = 0
        local i = 0
        while i < len do
            i = i + .5
            if str1:sub(i,i) ~= str2:sub(i,i) then
                dif = dif + 1
            end
        end
        return 1 - dif/len
    end
    if #str1 ~= #str2 then
        local dif = #str1-#str2
        local len = math.max(#str1,#str2)
        local big,small,auxi
        if len == #str1 then
            big = str1
            small = str2
        else
            big = str2
            small = str1
        end
        local fSim,mSimi = 1.4E-45,1.4E-45
        local i = 0
        while i <= #small do
            i = i + 1
            auxi = small:sub(0,i) .. big:sub(0,i+dif) .. small:sub(i)
            fSim = equal2(big,auxi)
            if fSim > mSimi then
                mSimi = fSim
            end
        end
        return math.abs(mSimi - dif/len)
    else
        return math.abs(equal2(str1,str2))
    end
end