--[[

List.lua

Copyright © 2017 Albert Krewinkel

Permission to use, copy, modify, and/or distribute this software for any purpose

with or without fee is hereby granted, provided that the above copyright notice

and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH

REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND

FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,

INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS

OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER

TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF

THIS SOFTWARE.

]]

--- Pandoc's List type and helper methods

-- @classmod pandoc.List

-- @author Albert Krewinkel

-- @copyright © 2017 Albert Krewinkel

-- @license MIT

local List = {

  _VERSION = "0.1.0"

}

function List:new (o)

  o = o or {}

  setmetatable(o, self)

  self.__index = self

  return o

end

function List:__call (o)

  return self:new(o)

end

--- Concatenates two lists.

-- @param list second list concatenated to the first

-- @return a new list containing all elements from list1 and list2

function List:__concat (list)

  local res = List.clone(self)

  List.extend(res, list)

  return res

end

--- Returns a (shallow) copy of the list.

function List:clone ()

  local lst = setmetatable({}, getmetatable(self))

  List.extend(lst, self)

  return lst

end

--- Checks if the list has an item equal to the given needle.

-- @param needle item to search for

-- @param init index at which the search is started

-- @return true if a list item is equal to the needle, false otherwise

function List:includes (needle, init)

  return not (List.find(self, needle, init) == nil)

end

--- Returns the value and index of the first occurrence of the given item.

-- @param needle item to search for

-- @param init index at which the search is started

-- @return first item equal to the needle, or nil if no such item exists.

-- @return index of that element

function List:find (needle, init)

  return List.find_if(self, function(x) return x == needle end, init)

end

--- Returns the value and index of the first element for which the predicate

--- holds true.

-- @param pred the predicate function

-- @param init index at which the search is started

-- @return first item for which `test` succeeds, or nil if no such item exists.

-- @return index of that element

function List:find_if (pred, init)

  init = (init == nil and 1) or (init < 0 and #self - init) or init

  for i = init, #self do

    if pred(self[i], i) then

      return self[i], i

    end

  end

  return nil

end

--- Adds the given list to the end of this list.

-- @param list list to appended

function List:extend (list)

  for i = 1, #list do

    self[#self + 1] = list[i]

  end

end

--- Returns a copy of the current list by applying the given function to all

-- elements.

-- @param fn function which is applied to all list items.

function List:map (fn)

  local res = setmetatable({}, getmetatable(self))

  for i = 1, #self do

    res[i] = fn(self[i], i)

  end

  return res

end

--- Returns a new list containing all items satisfying a given condition.

-- @param pred condition items must satisfy.

-- @return a new list containing all items for which `test` was true.

function List:filter (pred)

  local res = setmetatable({}, getmetatable(self))

  for i = 1, #self do

    if pred(self[i], i) then

      res[#res + 1] = self[i]

    end

  end

  return res

end

return List