83 lines
1.5 KiB
Plaintext
83 lines
1.5 KiB
Plaintext
local type InputStream = record
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str: string
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offset: number
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refill: function(): string
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new: function(InputStream, function(): string): InputStream
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setRefill: function(InputStream, function(): string)
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readCurrentCharacter: function(): string
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advanceOffset: function(): string
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end
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local istream_mt = {__index = InputStream}
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function InputStream:_manageBuffer()
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if not self.str then
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self.str = self.refill()
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self.offset = 1
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end
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if self.offset > #self.str then
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self.str = self.refill()
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self.offset = 1
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end
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end
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local function initial_stream(): string
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return "DUMMY"
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end
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-- constructors
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function InputStream:new(): InputStream
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local mt = setmetatable(
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{
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string = "",
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offset = 1,
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refill = initial_stream
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} as InputStream,
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istream_mt)
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mt:setRefill(initial_stream)
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return mt
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end
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function InputStream:new(refill: function(): string): InputStream
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refill = refill or initial_stream
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local mt = setmetatable(
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{
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string = "",
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offset = 1,
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refill = function(): string return "DUMMY" end
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} as InputStream,
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istream_mt)
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mt:setRefill(refill)
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return mt
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end
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-- setters/getters
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function InputStream:setRefill(func: function(): string)
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self.refill = func
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self:_manageBuffer()
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end
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--
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function InputStream:readCurrentCharacter(): string
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self:_manageBuffer()
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return self.str:sub(self.offset, self.offset)
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end
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function InputStream:advanceOffset(): string
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self:_manageBuffer()
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local current_char = self.str:sub(self.offset, self.offset)
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self.offset = self.offset + 1
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return current_char
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end
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return InputStream
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