lume.lua

--
-- lume
--
-- Copyright (c) 2015 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 = "2.2.3" }

local pairs, ipairs = pairs, ipairs
local type, assert, unpack = type, assert, unpack or table.unpack
local tostring, tonumber = tostring, tonumber
local math_floor = math.floor
local math_ceil = math.ceil
local math_random = math.random
local math_atan2 = math.atan2 or math.atan
local math_sqrt = math.sqrt
local math_abs = math.abs
local math_mod = math.mod

local noop = function()
end

local identity = function(x)
  return x
end

local patternescape = function(str)
  return str:gsub("[%(%)%.%%%+%-%*%?%[%]%^%$]", "%%%1")
end

local absindex = function(len, i)
  return i < 0 and (len + i + 1) or i
end

local iscallable = function(x)
  if type(x) == "function" then return true end
  local mt = getmetatable(x)
  return mt and mt.__call ~= nil
end

local getiter = function(x)
  if lume.isarray(x) then
    return ipairs
  elseif type(x) == "table" then
    return pairs
  end
  error("expected table", 3)
end

local iteratee = function(x)
  if x == nil then return identity end
  if iscallable(x) then return x end
  if type(x) == "table" then
    return function(z)
      for k, v in pairs(x) do
        if z[k] ~= v then return false end
      end
      return true
    end
  end
  return function(z) return z[x] end
end



function lume.clamp(x, min, max)
  return x < min and min or (x > max and max or x)
end


function lume.round(x, increment)
  if increment then return lume.round(x / increment) * increment end
  return x >= 0 and math_floor(x + .5) or math_ceil(x - .5)
end


local gcd2 = function(m, n)
  while m ~= 0 do
      m, n = math_mod(n, m), m
  end
  return n
end

function lume.gcd(...)
  local args = {...}
  if #args == 1 then return unpack(args)
  elseif #args == 2 then return gcd2(unpack(args))
  else return lume.reduce(args, gcd2) end
end


local lcm2 = function(m, n)
  return (m ~= 0 and n ~= 0) and math_abs(m * n / lume.gcd(m, n)) or 0
end

function lume.lcm(...)
  local args = {...}
  if #args == 1 then return unpack(args)
  elseif #args == 2 then return lcm2(unpack(args))
  else return lume.reduce(args, lcm2) end
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 t = lume.clamp(amount, 0, 1)
  local m = t * t * (3 - 2 * t)
  return a + (b - a) * m
end

function lume.remap(amount, minA, maxA, minB, maxB, strategy)
  local n = minB + (amount - minA) * (maxB - minB) / (maxA - minA)
  if strategy == 'clamp' then
    local min = math.min(minB, maxB)
    local max = math.max(minB, maxB)
    n = math.max(min, math.min(max, n))
  end
  return n
end

function lume.pingpong(x)
  return 1 - math_abs(1 - x % 2)
end

function lume.bell(x, center, spread)
  return math.exp(-(x - center)^2 / (2 * spread^2))
end

function lume.distance(x1, y1, x2, y2, squared)
  local dx = x1 - x2
  local dy = y1 - y2
  local s = dx * dx + dy * dy
  return squared and s or math_sqrt(s)
end


function lume.angle(x1, y1, x2, y2)
  return math_atan2(y2 - y1, x2 - x1)
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.weightedchoice(t)
  local sum = 0
  for _, v in pairs(t) do
    assert(v >= 0, "weight value less than zero")
    sum = sum + v
  end
  assert(sum ~= 0, "all weights are zero")
  local rnd = lume.random(sum)
  for k, v in pairs(t) do
    if rnd < v then return k end
    rnd = rnd - v
  end
end


function lume.isarray(x)
  return (type(x) == "table" and x[1] ~= nil) and true or false
end


function lume.push(t, ...)
  local n = select("#", ...)
  for i = 1, n do
    t[#t + 1] = select(i, ...)
  end
  return ...
end


function lume.remove(t, x)
  local iter = getiter(t)
  for i, v in iter(t) do
    if v == x then
      if lume.isarray(t) then
        table.remove(t, i)
        break
      else
        t[i] = nil
        break
      end
    end
  end
  return x
end


function lume.clear(t)
  local iter = getiter(t)
  for k in iter(t) do
    t[k] = nil
  end
  return t
end


function lume.extend(t, ...)
  for i = 1, select("#", ...) do
    local x = select(i, ...)
    if x then
      for k, v in pairs(x) do
        t[k] = v
      end
    end
  end
  return t
end


function lume.shuffle(t)
  local rtn = {}
  for i = 1, #t do
    local r = math_random(i)
    if r ~= i then
      rtn[i] = rtn[r]
    end
    rtn[r] = t[i]
  end
  return rtn
end


function lume.sort(t, comp)
  local rtn = lume.clone(t)
  if comp then
    if type(comp) == "string" then
      table.sort(rtn, function(a, b) return a[comp] < b[comp] end)
    else
      table.sort(rtn, comp)
    end
  else
    table.sort(rtn)
  end
  return rtn
end


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


function lume.each(t, fn, ...)
  local iter = getiter(t)
  if type(fn) == "string" then
    for _, v in iter(t) do v[fn](v, ...) end
  else
    for _, v in iter(t) do fn(v, ...) end
  end
  return t
end


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


function lume.all(t, fn)
  fn = iteratee(fn)
  local iter = getiter(t)
  for _, v in iter(t) do
    if not fn(v) then return false end
  end
  return true
end


function lume.any(t, fn)
  fn = iteratee(fn)
  local iter = getiter(t)
  for _, v in iter(t) do
    if fn(v) then return true end
  end
  return false
end


function lume.reduce(t, fn, first)
  local acc = first
  local started = first and true or false
  local iter = getiter(t)
  for _, v in iter(t) do
    if started then
      acc = fn(acc, v)
    else
      acc = v
      started = true
    end
  end
  assert(started, "reduce of an empty table with no first value")
  return acc
end


function lume.set(t)
  local rtn = {}
  for k in pairs(lume.invert(t)) do
    rtn[#rtn + 1] = k
  end
  return rtn
end


function lume.filter(t, fn, retainkeys)
  fn = iteratee(fn)
  local iter = getiter(t)
  local rtn = {}
  if retainkeys then
    for k, v in iter(t) do
      if fn(v) then rtn[k] = v end
    end
  else
    for _, v in iter(t) do
      if fn(v) then rtn[#rtn + 1] = v end
    end
  end
  return rtn
end


function lume.reject(t, fn, retainkeys)
  fn = iteratee(fn)
  local iter = getiter(t)
  local rtn = {}
  if retainkeys then
    for k, v in iter(t) do
      if not fn(v) then rtn[k] = v end
    end
  else
    for _, v in iter(t) do
      if not fn(v) then rtn[#rtn + 1] = v end
    end
  end
  return rtn
end


function lume.merge(...)
  local rtn = {}
  for i = 1, select("#", ...) do
    local t = select(i, ...)
    local iter = getiter(t)
    for k, v in iter(t) do
      rtn[k] = v
    end
  end
  return rtn
end


function lume.concat(...)
  local rtn = {}
  for i = 1, select("#", ...) do
    local t = select(i, ...)
    if t ~= nil then
      local iter = getiter(t)
      for _, v in iter(t) do
        rtn[#rtn + 1] = v
      end
    end
  end
  return rtn
end


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


function lume.match(t, fn)
  fn = iteratee(fn)
  local iter = getiter(t)
  for k, v in iter(t) do
    if fn(v) then return v, k end
  end
  return nil
end


function lume.count(t, fn)
  local count = 0
  local iter = getiter(t)
  if fn then
    fn = iteratee(fn)
    for _, v in iter(t) do
      if fn(v) then count = count + 1 end
    end
  else
    if lume.isarray(t) then
      return #t
    end
    for _ in iter(t) do count = count + 1 end
  end
  return count
end


function lume.slice(t, i, j)
  i = i and absindex(#t, i) or 1
  j = j and absindex(#t, j) or #t
  local rtn = {}
  for x = i < 1 and 1 or i, j > #t and #t or j do
    rtn[#rtn + 1] = t[x]
  end
  return rtn
end


function lume.first(t, n)
  if not n then return t[1] end
  return lume.slice(t, 1, n)
end


function lume.last(t, n)
  if not n then return t[#t] end
  return lume.slice(t, -n, -1)
end


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


function lume.pick(t, ...)
  local rtn = {}
  for i = 1, select("#", ...) do
    local k = select(i, ...)
    rtn[k] = t[k]
  end
  return rtn
end


function lume.keys(t)
  local rtn = {}
  local iter = getiter(t)
  for k in iter(t) do rtn[#rtn + 1] = k 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, ...)
  assert(iscallable(fn), "expected a function as the first argument")
  local args = { ... }
  return function(...)
    local a = lume.concat(args, { ... })
    return fn(unpack(a))
  end
end


function lume.once(fn, ...)
  local f = lume.fn(fn, ...)
  local done = false
  return function(...)
    if done then return end
    done = true
    return f(...)
  end
end


local memoize_fnkey = {}
local memoize_nil = {}

function lume.memoize(fn)
  local cache = {}
  return function(...)
    local c = cache
    for i = 1, select("#", ...) do
      local a = select(i, ...) or memoize_nil
      c[a] = c[a] or {}
      c = c[a]
    end
    c[memoize_fnkey] = c[memoize_fnkey] or {fn(...)}
    return unpack(c[memoize_fnkey])
  end
end


function lume.combine(...)
  local n = select('#', ...)
  if n == 0 then return noop end
  if n == 1 then
    local fn = select(1, ...)
    if not fn then return noop end
    assert(iscallable(fn), "expected a function or nil")
    return fn
  end
  local funcs = {}
  for i = 1, n do
    local fn = select(i, ...)
    if fn ~= nil then
      assert(iscallable(fn), "expected a function or nil")
      funcs[#funcs + 1] = fn
    end
  end
  return function(...)
    for _, f in ipairs(funcs) do f(...) end
  end
end


function lume.call(fn, ...)
  if fn then
    return fn(...)
  end
end


function lume.time(fn, ...)
  local start = os.clock()
  local rtn = {fn(...)}
  return (os.clock() - start), unpack(rtn)
end


local lambda_cache = {}

function lume.lambda(str)
  if not lambda_cache[str] then
    local args, body = str:match([[^([%w,_ ]-)%->(.-)$]])
    assert(args and body, "bad string lambda")
    local s = "return function(" .. args .. ")\nreturn " .. body .. "\nend"
    lambda_cache[str] = lume.dostring(s)
  end
  return lambda_cache[str]
end


local serialize

local serialize_map = {
  [ "boolean" ] = tostring,
  [ "nil"     ] = tostring,
  [ "string"  ] = function(v) return string.format("%q", v) end,
  [ "number"  ] = function(v)
    if      v ~=  v     then return  "0/0"      --  nan
    elseif  v ==  1 / 0 then return  "1/0"      --  inf
    elseif  v == -1 / 0 then return "-1/0" end  -- -inf
    return tostring(v)
  end,
  [ "table"   ] = function(t, stk)
    stk = stk or {}
    if stk[t] then error("circular reference") end
    local rtn = {}
    stk[t] = true
    for k, v in pairs(t) do
      rtn[#rtn + 1] = "[" .. serialize(k, stk) .. "]=" .. serialize(v, stk)
    end
    stk[t] = nil
    return "{" .. table.concat(rtn, ",") .. "}"
  end
}

setmetatable(serialize_map, {
  __index = function(_, k) error("unsupported serialize type: " .. k) end
})

serialize = function(x, stk)
  return serialize_map[type(x)](x, stk)
end

function lume.serialize(x)
  return serialize(x)
end


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


function lume.split(str, sep)
  if not sep then
    return lume.array(str:gmatch("([%S]+)"))
  else
    assert(sep ~= "", "empty separator")
    local psep = patternescape(sep)
    return lume.array((str..sep):gmatch("(.-)("..psep..")"))
  end
end


function lume.trim(str, chars)
  if not chars then return str:match("^[%s]*(.-)[%s]*$") end
  chars = patternescape(chars)
  return str:match("^[" .. chars .. "]*(.-)[" .. chars .. "]*$")
end


function lume.wordwrap(str, limit)
  limit = limit or 72
  local check
  if type(limit) == "number" then
    check = function(s) return #s >= limit end
  else
    check = limit
  end
  local rtn = {}
  local line = ""
  for word, spaces in str:gmatch("(%S+)(%s*)") do
    local s = line .. word
    if check(s) then
      table.insert(rtn, line .. "\n")
      line = word
    else
      line = s
    end
    for c in spaces:gmatch(".") do
      if c == "\n" then
        table.insert(rtn, line .. "\n")
        line = ""
      else
        line = line .. c
      end
    end
  end
  table.insert(rtn, line)
  return table.concat(rtn)
end


function lume.format(str, vars)
  if not vars then return str end
  local f = function(x)
    return tostring(vars[x] or vars[tonumber(x)] or "{" .. x .. "}")
  end
  return (str:gsub("{(.-)}", f))
end


function lume.trace(...)
  local info = debug.getinfo(2, "Sl")
  local t = { info.short_src .. ":" .. info.currentline .. ":" }
  for i = 1, select("#", ...) do
    local x = select(i, ...)
    if type(x) == "number" then
      x = string.format("%g", lume.round(x, .01))
    end
    t[#t + 1] = tostring(x)
  end
  print(table.concat(t, " "))
end


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


function lume.uuid()
  local fn = function(x)
    local r = math_random(16) - 1
    r = (x == "x") and (r + 1) or (r % 4) + 9
    return ("0123456789abcdef"):sub(r, r)
  end
  return (("xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx"):gsub("[xy]", fn))
end


function lume.hotswap(modname)
  local oldglobal = lume.clone(_G)
  local updated = {}
  local function update(old, new)
    if updated[old] then return end
    updated[old] = true
    local oldmt, newmt = getmetatable(old), getmetatable(new)
    if oldmt and newmt then update(oldmt, newmt) end
    for k, v in pairs(new) do
      if type(v) == "table" then update(old[k], v) else old[k] = v end
    end
  end
  local err = nil
  local function onerror(e)
    for k in pairs(_G) do _G[k] = oldglobal[k] end
    err = lume.trim(e)
  end
  local ok, oldmod = pcall(require, modname)
  oldmod = ok and oldmod or nil
  xpcall(function()
    package.loaded[modname] = nil
    local newmod = require(modname)
    if type(oldmod) == "table" then update(oldmod, newmod) end
    for k, v in pairs(oldglobal) do
      if v ~= _G[k] and type(v) == "table" then
        update(v, _G[k])
        _G[k] = v
      end
    end
  end, onerror)
  package.loaded[modname] = oldmod
  if err then return nil, err end
  return oldmod
end


local ripairs_iter = function(t, i)
  i = i - 1
  local v = t[i]
  if v then return i, v end
end

function lume.ripairs(t)
  return ripairs_iter, t, (#t + 1)
end


function lume.color(str, mul)
  mul = mul or 1
  local r, g, b, a
  r, g, b = str:match("#(%x%x)(%x%x)(%x%x)")
  if r then
    r = tonumber(r, 16) / 0xff
    g = tonumber(g, 16) / 0xff
    b = tonumber(b, 16) / 0xff
    a = 1
  elseif str:match("rgba?%s*%([%d%s%.,]+%)") then
    local f = str:gmatch("[%d.]+")
    r = (f() or 0) / 0xff
    g = (f() or 0) / 0xff
    b = (f() or 0) / 0xff
    a = f() or 1
  else
    error(("bad color string '%s'"):format(str))
  end
  return r * mul, g * mul, b * mul, a * mul
end

function lume.rgba(color, mul)
  mul = mul or 1
  local r = math_floor((color / 16777216) % 256) / 256
  local g = math_floor((color /    65536) % 256) / 256
  local b = math_floor((color /      256) % 256) / 256
  local a = math_floor((color) % 256) / 256
  return r, g, b, a
end


function lume.argb(color, mul)
  mul = mul or 1
  local a = math_floor((color / 16777216) % 256)
  local r = math_floor((color /    65536) % 256)
  local g = math_floor((color /      256) % 256)
  local b = math_floor((color) % 256)
  return r, g, b, a
end

function lume.hsl(h, s, l, a)
  a = a or 1
  -- hsl to rgb, input and output range: 0 - 1
  if s<=0 then
    return l,l,l
  end
  h = h * 6
  local c = (1-math.abs(2*l-1))*s
  local x = (1-math.abs(h%2-1))*c
  local m,r,g,b = (l-.5*c), 0,0,0
  if     h < 1 then r,g,b = c,x,0
  elseif h < 2 then r,g,b = x,c,0
  elseif h < 3 then r,g,b = 0,c,x
  elseif h < 4 then r,g,b = 0,x,c
  elseif h < 5 then r,g,b = x,0,c
  else              r,g,b = c,0,x
  end
  return r+m, g+m, b+m, a
end

function lume.colortohex(c)
  -- rgba [0,1] to #rrggbbaa
  local a = c[4] and math.floor(c[4] * 255) or 255
  return string.format('#%2x%2x%2x%2x',
      math.floor(c[1] * 255),
      math.floor(c[2] * 255),
      math.floor(c[3] * 255),
      a)
end

local chain_mt = {}
chain_mt.__index = lume.map(lume.filter(lume, iscallable, true),
  function(fn)
    return function(self, ...)
      self._value = fn(self._value, ...)
      return self
    end
  end)
chain_mt.__index.result = function(x) return x._value end

function lume.chain(value)
  return setmetatable({ _value = value }, chain_mt)
end

setmetatable(lume,  {
  __call = function(_, ...)
    return lume.chain(...)
  end
})

function lume.createIIR(a, b)
  -- according to IIR direct form II
  assert(#a == #b)
  local z = {} -- history data
  for i = 1, (#a - 1) do
    z[i] = 0
  end
  local filtering = function(xn)
      local v1
      -- A coefficients block
      local s1 = xn
      for i=2, #a do
        v1 = v1 + z[i - 1] * a[i]
      end
      -- B coefficients block
      local s2 = s1 * a[1]
      for i=2, #b do
        s2 = s2 + z[i - 1] * b[i]
      end
      -- delays
      table.insert(z, 1, s1 * a[1])
      z[#a] = nil
      return s2
    end
  return filtering
end

return lume