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# coding: ascii-8bit
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class RbMysql
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  class Packet
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    # convert Numeric to LengthCodedBinary
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    def self.lcb(num)
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      return "\xfb" if num.nil?
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      return [num].pack("C") if num < 251
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      return [252, num].pack("Cv") if num < 65536
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      return [253, num&0xffff, num>>16].pack("CvC") if num < 16777216
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      return [254, num&0xffffffff, num>>32].pack("CVV")
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    end
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    # convert String to LengthCodedString
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    def self.lcs(str)
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      str = Charset.to_binary str.dup
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      lcb(str.length)+str
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    end
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    def initialize(data)
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      @data = data
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    end
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    def lcb
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      return nil if @data.empty?
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      case v = utiny
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      when 0xfb
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        return nil
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      when 0xfc
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        return ushort
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      when 0xfd
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        c, v = utiny, ushort
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        return (v << 8)+c
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      when 0xfe
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        v1, v2 = ulong, ulong
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        return (v2 << 32)+v1
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      else
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        return v
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      end
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    end
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    def lcs
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      len = self.lcb
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      return nil unless len
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      @data.slice!(0, len)
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    end
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    def read(len)
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      @data.slice!(0, len)
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    end
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    def string
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      str = @data.unpack('Z*').first
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      @data.slice!(0, str.length+1)
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      str
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    end
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    def utiny
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      @data.slice!(0, 1).unpack('C').first
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    end
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    def ushort
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      @data.slice!(0, 2).unpack('v').first
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    end
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    def ulong
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      @data.slice!(0, 4).unpack('V').first
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    end
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    def eof?
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      @data[0] == ?\xfe && @data.length == 5
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    end
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    def to_s
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      @data
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    end
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  end
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end
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