Add deque.lua (thanks Pierre Chapuis)

mumbledj/deque.lua

@@ -0,0 +1,156 @@
+--Copyright (C) 2013-2014 by Pierre Chapuis
+--
+--Permission is hereby granted, free of charge, to any person obtaining a copy
+--of this software and associated documentation files (the "Software"), to deal
+--in the Software without restriction, including without limitation the rights
+--to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+--copies of the Software, and to permit persons to whom the Software is
+--furnished to do so, subject to the following conditions:
+--
+--The above copyright notice and this permission notice shall be included in
+--all copies or substantial portions of the Software.
+--
+--THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+--IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+--FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+--AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+--LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+--OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+--THE SOFTWARE.
+
+local push_right = function(self, x)
+  assert(x ~= nil)
+  self.tail = self.tail + 1
+  self[self.tail] = x
+end
+
+local push_left = function(self, x)
+  assert(x ~= nil)
+  self[self.head] = x
+  self.head = self.head - 1
+end
+
+local peek_right = function(self)
+  return self[self.tail]
+end
+
+local peek_left = function(self)
+  return self[self.head+1]
+end
+
+local pop_right = function(self)
+  if self:is_empty() then return nil end
+  local r = self[self.tail]
+  self[self.tail] = nil
+  self.tail = self.tail - 1
+  return r
+end
+
+local pop_left = function(self)
+  if self:is_empty() then return nil end
+  local r = self[self.head+1]
+  self.head = self.head + 1
+  local r = self[self.head]
+  self[self.head] = nil
+  return r
+end
+
+local rotate_right = function(self, n)
+  n = n or 1
+  if self:is_empty() then return nil end
+  for i=1,n do self:push_left(self:pop_right()) end
+end
+
+local rotate_left = function(self, n)
+  n = n or 1
+  if self:is_empty() then return nil end
+  for i=1,n do self:push_right(self:pop_left()) end
+end
+
+local _remove_at_internal = function(self, idx)
+  for i=idx, self.tail do self[i] = self[i+1] end
+  self.tail = self.tail - 1
+end
+
+local remove_right = function(self, x)
+  for i=self.tail,self.head+1,-1 do
+    if self[i] == x then
+      _remove_at_internal(self, i)
+      return true
+    end
+  end
+  return false
+end
+
+local remove_left = function(self, x)
+  for i=self.head+1,self.tail do
+    if self[i] == x then
+      _remove_at_internal(self, i)
+      return true
+    end
+  end
+  return false
+end
+
+local length = function(self)
+  return self.tail - self.head
+end
+
+local is_empty = function(self)
+  return self:length() == 0
+end
+
+local contents = function(self)
+  local r = {}
+  for i=self.head+1,self.tail do
+    r[i-self.head] = self[i]
+  end
+  return r
+end
+
+local iter_right = function(self)
+  local i = self.tail+1
+  return function()
+    if i > self.head+1 then
+      i = i-1
+      return self[i]
+    end
+  end
+end
+
+local iter_left = function(self)
+  local i = self.head
+  return function()
+    if i < self.tail then
+      i = i+1
+      return self[i]
+    end
+  end
+end
+
+local methods = {
+  push_right = push_right,
+  push_left = push_left,
+  peek_right = peek_right,
+  peek_left = peek_left,
+  pop_right = pop_right,
+  pop_left = pop_left,
+  rotate_right = rotate_right,
+  rotate_left = rotate_left,
+  remove_right = remove_right,
+  remove_left = remove_left,
+  iter_right = iter_right,
+  iter_left = iter_left,
+  length = length,
+  is_empty = is_empty,
+  contents = contents,
+}
+
+local new = function()
+  local r = {head = 0, tail = 0}
+  return setmetatable(r, {__index = methods})
+end
+
+return {
+  new = new,
+}