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--!A cross-platform build utility based on Lua
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
-- http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
-- Copyright (C) 2015-present, Xmake Open Source Community.
--
-- @author ruki
-- @file list.lua
--
-- load modules
local object = require("base/object")
-- define module
local list = list or object { _init = {"_length"} } {0}
-- clear list
function list:clear()
self._length = 0
self._first = nil
self._last = nil
end
-- insert item after the given item
function list:insert(t, after)
if not after then
return self:insert_last(t)
end
assert(t ~= after)
if after._next then
after._next._prev = t
t._next = after._next
else
self._last = t
end
t._prev = after
after._next = t
self._length = self._length + 1
end
-- insert the first item in head
function list:insert_first(t)
if self._first then
self._first._prev = t
t._next = self._first
self._first = t
else
self._first = t
self._last = t
end
self._length = self._length + 1
end
-- insert the last item in tail
function list:insert_last(t)
if self._last then
self._last._next = t
t._prev = self._last
self._last = t
else
self._first = t
self._last = t
end
self._length = self._length + 1
end
-- remove item
function list:remove(t)
if t._next then
if t._prev then
t._next._prev = t._prev
t._prev._next = t._next
else
assert(t == self._first)
t._next._prev = nil
self._first = t._next
end
elseif t._prev then
assert(t == self._last)
t._prev._next = nil
self._last = t._prev
else
assert(t == self._first and t == self._last)
self._first = nil
self._last = nil
end
t._next = nil
t._prev = nil
self._length = self._length - 1
return t
end
-- remove the first item
function list:remove_first()
if not self._first then
return
end
local t = self._first
if t._next then
t._next._prev = nil
self._first = t._next
t._next = nil
else
self._first = nil
self._last = nil
end
self._length = self._length - 1
return t
end
-- remove last item
function list:remove_last()
if not self._last then
return
end
local t = self._last
if t._prev then
t._prev._next = nil
self._last = t._prev
t._prev = nil
else
self._first = nil
self._last = nil
end
self._length = self._length - 1
return t
end
-- push item to tail
function list:push(t)
self:insert_last(t)
end
-- pop item from tail
function list:pop()
self:remove_last()
end
-- shift item: 1 2 3 <- 2 3
function list:shift()
self:remove_first()
end
-- unshift item: 1 2 -> t 1 2
function list:unshift(t)
self:insert_first(t)
end
-- get first item
function list:first()
return self._first
end
-- get last item
function list:last()
return self._last
end
-- get next item
function list:next(last)
if last then
return last._next
else
return self._first
end
end
-- get the previous item
function list:prev(last)
if last then
return last._prev
else
return self._last
end
end
-- get list size
function list:size()
return self._length
end
-- is empty?
function list:empty()
return self:size() == 0
end
-- get items
--
-- e.g.
--
-- for item in list:items() do
-- print(item)
-- end
--
function list:items()
local iter = function (list, item)
return list:next(item)
end
return iter, self, nil
end
-- get reverse items
function list:ritems()
local iter = function (list, item)
return list:prev(item)
end
return iter, self, nil
end
-- new list
function list.new()
return list()
end
-- return module: list
return list
|
