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Posted By

kergoth on 12/18/06


Tagged

object oop tables iteration lua classes traversal functables metatables


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lenn0x


Lua: Descending Table Traversal Round 2: Iterator Object

Published in: Lua 

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  1. traverse = {}
  2. function traverse:new(tname)
  3. 	local o = {}
  4. 	o.names = {}
  5. 	o.queue = {}
  6. 	o.cur = {
  7. 		tbl = nil,
  8. 		path = nil,
  9. 		state = nil,
  10. 	}
  11.  
  12. 	local mt = {}
  13. 	function mt:__call(tn)
  14. 		return o:iter(tn)
  15. 	end
  16. 	mt.__index = self
  17. 	setmetatable(o, mt)
  18.  
  19. 	if tname then
  20. 		o:enqueue(tname)
  21. 	end
  22. 	return o
  23. end
  24. function traverse:next()
  25. 	local v
  26. 	local names, queue, cur = self.names, self.queue, self.cur
  27.  
  28. 	local function _poptbl()
  29. 		if cur.tbl then
  30. 			names[cur.tbl] = nil
  31. 		end
  32. 		cur.tbl = table.remove(queue, 1)
  33. 		cur.path = names[cur.tbl]
  34. 		cur.state = nil
  35. 	end
  36.  
  37. 	repeat
  38. 		-- Find something to return to the user...
  39. 		if not cur.state then
  40. 			-- Pop a new table off the stack
  41. 			_poptbl()
  42. 			if not cur.tbl then
  43. 				-- No more tables to process
  44. 				return nil
  45. 			end
  46. 		end
  47. 		cur.state,v = next(cur.tbl, cur.state)
  48. 	until cur.state
  49.  
  50. 	if type(v) == "table" then
  51. 		local path = cur.path.."."..cur.state
  52. 		names[v] = path
  53. 		table.insert(queue, v)
  54. 	end
  55. 	return cur.path,cur.tbl,cur.state,v
  56. end
  57. function traverse:iter(tname)
  58. 	if tname then
  59. 		self:enqueue(tname)
  60. 	end
  61. 	return function(...) return self:next(unpack(arg)) end, nil, nil
  62. end
  63. function traverse:enqueue(tname)
  64. 	local v = _G[tname]
  65. 	table.insert(self.queue, v)
  66. 	self.names[v] = tname
  67. end
  68. function traverse:reset()
  69. 	self.names = {}
  70. 	self.queue = {}
  71. end
  72. local traverse_mt = {
  73.     __call = function(self, tname)
  74.              	if tname then
  75.              		return self:new(tname):iter()
  76.              	else
  77.              		return self:new()
  78.              	end
  79.              end
  80. }
  81. setmetatable(traverse, traverse_mt)
  82. foo = {a={},b={},c={"bar"},d={e={},f={"moo"}},1,2,3,4,5}
  83. bar = {"alpha", "beta", "theta", omega = {}}
  84.  
  85. local mytraverser = traverse()
  86. mytraverser:enqueue("bar")
  87. mytraverser:enqueue("foo")
  88. for p,t,k,v in mytraverser() do
  89. --for p,t,k,v in traverse('foo') do
  90. 	print(string.format("%s[%s] = %s",tostring(p),tostring(k),tostring(v)))
  91. end
  92. bar[1] = alpha
  93. bar[2] = beta
  94. bar[3] = theta
  95. bar[omega] = table: 0x510650
  96. foo[1] = 1
  97. foo[2] = 2
  98. foo[3] = 3
  99. foo[4] = 4
  100. foo[5] = 5
  101. foo[a] = table: 0x5102d0
  102. foo[c] = table: 0x510370
  103. foo[b] = table: 0x510320
  104. foo[d] = table: 0x5103c0
  105. foo.c[1] = bar
  106. foo.d[e] = table: 0x5104c0
  107. foo.d[f] = table: 0x510510
  108. foo.d.f[1] = moo

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