lume/lume.lua

--
-- lume
--
-- Copyright (c) 2014, rxi
--
-- This library is free software; you can redistribute it and/or modify it
-- under the terms of the MIT license. See LICENSE for details.
--

local lume = { _version = "1.0.1" }


function lume.clamp(x, min, max)
  return math.max(math.min(x, max), min)
end


function lume.round(x)
  return x > 0 and math.floor(x + .5) or math.ceil(x - .5)
end


function lume.sign(x)
  return x < 0 and -1 or 1
end


function lume.lerp(a, b, amount)
  return a + (b - a) * lume.clamp(amount, 0, 1)
end


function lume.smooth(a, b, amount)
  local m = (1 - math.cos(lume.clamp(amount, 0, 1) * math.pi)) / 2
  return a + (b - a) * m
end


function lume.pingpong(x, len)
  return (1 - math.abs(1 - x % 2)) * (len or 1)
end


function lume.distance(x1, y1, x2, y2)
  return math.sqrt((x1 - x2) ^ 2 + (y1 - y2) ^ 2)
end


function lume.angle(x1, y1, x2, y2)
  return math.atan2(x1 - x2, y1 - y2)
end


function lume.random(a, b)
  if not a then a, b = 0, 1 end
  if not b then b = 0 end
  return a + math.random() * (b - a)
end


function lume.randomchoice(t)
  return t[math.random(#t)]
end


function lume.shuffle(t)
  for i = 1, #t do
    local r = math.random(#t)
    t[i], t[r] = t[r], t[i]
  end
  return t
end


function lume.array(...)
  local t = {}
  for x in unpack({...}) do t[#t + 1] = x end
  return t
end


function lume.map(t, fn)
  local rtn = {} 
  for k, v in pairs(t) do rtn[k] = fn(v) end
  return rtn
end


function lume.all(t, fn)
  for k, v in pairs(t) do
    if not fn(v) then return false end
  end
  return true
end


function lume.any(t, fn)
  for k, v in pairs(t) do
    if fn(v) then return true end
  end
  return false
end


function lume.reduce(t, fn, first)
  local acc = first
  if acc == nil then acc = 0 end
  for i = 1, #t do acc = fn(acc, t[i]) end
  return acc
end


function lume.set(t, retainkeys)
  local tmp = {}
  for k, v in pairs(t) do tmp[v] = k end
  local rtn = {}
  for k, v in pairs(tmp) do rtn[retainkeys and v or (#rtn + 1)] = k end
  return rtn
end


function lume.filter(t, fn, retainkeys)
  local rtn = {}
  for k, v in pairs(t) do
    if fn(v) then rtn[retainkeys and k or (#rtn + 1)] = v end
  end
  return rtn
end


function lume.merge(t, t2, retainkeys)
  for k, v in pairs(t2) do
    t[retainkeys and k or (#t + 1)] = v
  end
  return t
end


function lume.find(t, value)
  for k, v in pairs(t) do
    if v == value then return k end
  end
  return nil
end


function lume.once(fn, ...)
  local arg = {...}
  return function()
    if arg == nil then return end
    fn(unpack(arg))
    arg = nil
  end
end


function lume.slice(t, i, j)
  i = i or 1
  j = j and (j < 0 and (#t + j) or j) or (#t - i + 1)
  local rtn = {}
  for i = math.max(i, 1), math.min(j, #t) do
    rtn[#rtn + 1] = t[i]
  end
  return rtn
end


function lume.clone(t)
  local rtn = {}
  for k, v in pairs(t) do rtn[k] = v end
  return rtn
end


function lume.fn(fn, ...)
  local arg = {...}
  return function() fn(unpack(arg)) end
end


function lume.serialize(x)
  local f = { string = function(v) return string.format("%q", v) end,
              number = tostring, boolean = tostring }
  f.table = function(t)
    local rtn = {}
    for k, v in pairs(t) do
      rtn[#rtn + 1] = "[" .. f[type(k)](k) .. "]=" .. f[type(v)](v) .. ","
    end
    return "{" .. table.concat(rtn) .. "}"
  end
  return f[type(x)](x)
end


function lume.deserialize(str)
  return lume.dostring("return " .. str)
end


function lume.split(str, sep)
  return lume.array(str:gmatch("([^" .. (sep or "%s") .. "]+)"))
end


function lume.trim(str, chars)
  chars = chars or "%s"
  return str:match("^[" .. chars .. "]*(.-)[" .. chars .. "]*$")
end


function lume.format(str, vars)
  local f = function(x) return tostring(vars[x]) or "{" .. x .. "}" end
  return (str:gsub("{(.-)}", f))
end


function lume.dostring(str)
  return assert(loadstring(str))()
end


function lume.rgba(color)
  local floor = math.floor
  local a = floor((color / 2 ^ 24) % 256)
  local r = floor((color / 2 ^ 16) % 256)
  local g = floor((color / 2 ^ 08) % 256)
  local b = floor((color) % 256)
  return r, g, b, a
end


return lume