--[[
訪問一個聚合對象的內容而無需暴露它的內部表示
支持對聚合對象的多種遍歷
爲遍歷不同的聚合結構提供一個統一的接口
應用:
最經典莫過於C++ STL了
]]--
Iterator = {}
function Iterator:new(o)
o = o or {}
setmetatable(o,self)
self.__index = self
return o;
end
ConcreteIterator = Iterator:new()
function ConcreteIterator:new(d)
o = o or {}
setmetatable(o,self)
self.__index = self
o.data = d
o.index = 1; --初始化索引
o.size = table.getn(d)
return o;
end
function ConcreteIterator:Next()
self.index = self.index + 1
end
function ConcreteIterator:IsDone()
if self.index > self.size then
return true
end
return false
end
function ConcreteIterator:GetItem()
return self.data[self.index]
end
Aggregate = {}
function Aggregate:new(o)
o = o or {}
setmetatable(o,self)
self.__index = self
return o;
end
ConcreteAggregate = Aggregate:new()
function ConcreteAggregate:new(o)
o = o or {}
setmetatable(o,self)
self.__index = self
o.data = {}
return o;
end
function ConcreteAggregate:CreateIterator()
return ConcreteIterator:new(self.data)
end
function ConcreteAggregate:PushBack(d)
table.insert(self.data,d)
end
function ConcreteAggregate:Remove(d)
for k,v in pairs(self.data) do
if v == d then
table.remove(self.data,k)
end
end
end
aggregate = ConcreteAggregate:new()
aggregate:PushBack(true)
aggregate:PushBack("QQ羣:")
aggregate:PushBack(315249378)
it = aggregate:CreateIterator()
while it:IsDone() == false do
print(it:GetItem())
it:Next()
end
輸出結果:
true
QQ羣:
315249378