-- Frac library (movie script)

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-- Shortcut for creating 'frac' values
-- @param {integer} numerator
-- @param {integer} denominator
-- @return {instance}
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on frac (numerator, denominator)
  return script("Frac").new(numerator, denominator)
end

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-- All functions below this comment only support 'fracs', i.e. instances
-- of the Frac Class, as arguments. An integer n is casted to frac via frac(n).
----------------------------------------

-- Optionally supports more than 2 arguments
on fAdd (a, b) -- ...
  res = a
  repeat with i = 2 to the paramCount
    p = param(i)
    num = res.num * p.denom + res.denom * p.num
    denom = res.denom * p.denom
    res = frac(num, denom)
  end repeat
  return res
end

on fSub (a, b)
  return frac(a.num * b.den - a.den * b.num, a.den * b.den)
end

-- Optionally supports more than 2 arguments
on fMul (a, b) -- ...
  res = a
  repeat with i = 2 to the paramCount
    p = param(i)
    res = frac(res.num * p.num, res.denom * p.denom)
  end repeat
  return res
end

on fDiv (a, b)
  return frac(a.num * b.denom, a.denom * b.num)
end

on fAbs (f)
  return frac(abs(f.num), f.denom)
end

on fNeg (f)
  return frac(-f.num, f.denom)
end

on fEQ (a, b)
  diff = fSub(a, b)
  return diff.num=0
end

on fNE (a, b)
  return not fEQ (a, b)
end

on fGT (a, b)
  diff = fSub(a, b)
  return diff.num>0
end

on fLT (a, b)
  diff = fSub(a, b)
  return diff.num<0
end

on fGE (a, b)
  diff = fSub(a, b)
  return diff.num>=0
end

on fLE (a, b)
  diff = fSub(a, b)
  return diff.num<=0
end