/ld28

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bzr branch http://9ix.org/bzr/ld28
2 by Josh C
basic delayed movement
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-- deque from https://github.com/catwell/cw-lua/tree/master/deque
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-- under MIT license
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local push_right = function(self, x)
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  assert(x ~= nil)
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  self.tail = self.tail + 1
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  self[self.tail] = x
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end
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local push_left = function(self, x)
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  assert(x ~= nil)
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  self[self.head] = x
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  self.head = self.head - 1
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end
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local peek_right = function(self)
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  return self[self.tail]
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end
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local peek_left = function(self)
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  return self[self.head+1]
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end
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local pop_right = function(self)
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  if self:is_empty() then return nil end
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  local r = self[self.tail]
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  self[self.tail] = nil
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  self.tail = self.tail - 1
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  return r
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end
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local pop_left = function(self)
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  if self:is_empty() then return nil end
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  local r = self[self.head+1]
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  self.head = self.head + 1
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  local r = self[self.head]
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  self[self.head] = nil
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  return r
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end
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local rotate_right = function(self, n)
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  n = n or 1
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  if self:is_empty() then return nil end
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  for i=1,n do self:push_left(self:pop_right()) end
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end
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local rotate_left = function(self, n)
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  n = n or 1
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  if self:is_empty() then return nil end
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  for i=1,n do self:push_right(self:pop_left()) end
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end
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local _remove_at_internal = function(self, idx)
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  for i=idx, self.tail do self[i] = self[i+1] end
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  self.tail = self.tail - 1
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end
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local remove_right = function(self, x)
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  for i=self.tail,self.head+1,-1 do
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    if self[i] == x then
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      _remove_at_internal(self, i)
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      return true
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    end
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  end
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  return false
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end
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local remove_left = function(self, x)
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  for i=self.head+1,self.tail do
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    if self[i] == x then
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      _remove_at_internal(self, i)
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      return true
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    end
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  end
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  return false
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end
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local length = function(self)
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  return self.tail - self.head
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end
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local is_empty = function(self)
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  return self:length() == 0
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end
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local contents = function(self)
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  local r = {}
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  for i=self.head+1,self.tail do
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    r[i-self.head] = self[i]
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  end
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  return r
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end
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local iter_right = function(self)
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  local i = self.tail+1
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  return function()
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    if i > self.head+1 then
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      i = i-1
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      return self[i]
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    end
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  end
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end
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local iter_left = function(self)
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  local i = self.head
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  return function()
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    if i < self.tail then
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      i = i+1
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      return self[i]
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    end
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  end
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end
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local methods = {
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  push_right = push_right,
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  push_left = push_left,
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  peek_right = peek_right,
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  peek_left = peek_left,
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  pop_right = pop_right,
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  pop_left = pop_left,
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  rotate_right = rotate_right,
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  rotate_left = rotate_left,
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  remove_right = remove_right,
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  remove_left = remove_left,
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  iter_right = iter_right,
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  iter_left = iter_left,
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  length = length,
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  is_empty = is_empty,
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  contents = contents,
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}
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local new = function()
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  local r = {head=0,tail=0}
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  return setmetatable(r, {__index=methods})
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end
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return {
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  new = new,
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}