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  1.  
  2. local function iter(lst, elem)
  3.     if not elem then elem = lst.first
  4.     else elem = elem.next end
  5.     return elem
  6. end
  7.  
  8. local list_mt = {}
  9. list_mt.__index = list_mt
  10. list_mt.push_back = function(self, val) 
  11.     if self.last == nil then
  12.         self.first = {value = val, prev = nil, next = nil}
  13.         self.last = self.first
  14.     else
  15.         self.last.next = {value = val, prev = self.last, next = nil}
  16.         self.last = self.last.next
  17.     end
  18. end
  19.  
  20. list_mt.remove = function(self, elem)     
  21.     if elem.next then elem.next.prev = elem.prev end
  22.     if elem.prev then elem.prev.next = elem.next end
  23.     if self.last == elem then self.last = elem.prev end
  24.     if self.first == elem then self.first = elem.next end
  25.     elem = nil
  26. end
  27.  
  28. -- Iterator for List
  29. function ilist(lst)
  30.     return iter, lst, nil
  31. end
  32.  
  33. -- Create new List
  34. function NewList()
  35.     local self = {
  36.         first = nil,
  37.         last = nil
  38.     }
  39.     setmetatable(self, list_mt)
  40.     return self
  41. end
  42.  
  43. lst = NewList()
  44. lst:push_back(123)
  45. lst:push_back(456)
  46. lst:push_back(789)    
  47. lst:push_back(456)
  48. lst:push_back(789)
  49.  
  50. local cnt = 0
  51. for elem in ilist(lst) do
  52.     if elem.value == 456 then
  53.         lst:remove(elem)
  54.     end
  55.     cnt = cnt + 1
  56.     print(cnt, elem.value)        
  57. end
  58.  
  59. print("-----")
  60.  
  61. cnt = 0
  62. for elem in ilist(lst) do
  63.     cnt = cnt + 1
  64.     print(cnt, elem.value)                
  65. end
Success #stdin #stdout 0s 4380KB
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stdin
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Standard input is empty
stdout
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1	123
2	456
3	789
4	456
5	789
-----
1	123
2	789
3	789
https://ideone.com/V2Div4
language:
Lua (luac 5.3.3)
created:
4 years ago
visibility:
public

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