Class: CharDet::JapaneseContextAnalysis

Inherits:
Object
  • Object
show all
Defined in:
lib/tmail/vendor/rchardet-1.3/lib/rchardet/jpcntx.rb

Direct Known Subclasses

EUCJPContextAnalysis, SJISContextAnalysis

Instance Method Summary collapse

Constructor Details

#initializeJapaneseContextAnalysis

Returns a new instance of JapaneseContextAnalysis.


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# File 'lib/tmail/vendor/rchardet-1.3/lib/rchardet/jpcntx.rb', line 124

def initialize
  reset()
end

Instance Method Details

#feed(aBuf, aLen) ⇒ Object


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# File 'lib/tmail/vendor/rchardet-1.3/lib/rchardet/jpcntx.rb', line 136

def feed(aBuf, aLen)
  return if @_mDone

  # The buffer we got is byte oriented, and a character may span in more than one
  # buffers. In case the last one or two byte in last buffer is not complete, we 
  # record how many byte needed to complete that character and skip these bytes here.
  # We can choose to record those bytes as well and analyse the character once it 
  # is complete, but since a character will not make much difference, by simply skipping
  # this character will simply our logic and improve performance.
  i = @_mNeedToSkipCharNum
  while i < aLen
    order, charLen = get_order(aBuf[i...i+2])
    i += charLen
    if i > aLen
      @_mNeedToSkipCharNum = i - aLen
      @_mLastCharOrder = -1
    else
      if (order != -1) and (@_mLastCharOrder != -1)
        @_mTotalRel += 1
        if @_mTotalRel > MAX_REL_THRESHOLD
          @_mDone = true
          break
        end
        @_mRelSample[jp2CharContext[@_mLastCharOrder][order]] += 1
      end
      @_mLastCharOrder = order
    end
  end
end

#get_confidenceObject


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# File 'lib/tmail/vendor/rchardet-1.3/lib/rchardet/jpcntx.rb', line 170

def get_confidence
  # This is just one way to calculate confidence. It works well for me.
  if @_mTotalRel > MINIMUM_DATA_THRESHOLD
    return (@_mTotalRel - @_mRelSample[0]) / @_mTotalRel
  else
    return DONT_KNOW
  end
end

#get_order(aStr) ⇒ Object


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# File 'lib/tmail/vendor/rchardet-1.3/lib/rchardet/jpcntx.rb', line 179

def get_order(aStr)
  return -1, 1
end

#got_enough_dataObject


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# File 'lib/tmail/vendor/rchardet-1.3/lib/rchardet/jpcntx.rb', line 166

def got_enough_data
  return @_mTotalRel > ENOUGH_REL_THRESHOLD
end

#resetObject


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# File 'lib/tmail/vendor/rchardet-1.3/lib/rchardet/jpcntx.rb', line 128

def reset
  @_mTotalRel = 0 # total sequence received
  @_mRelSample = [0] * NUM_OF_CATEGORY # category counters, each interger counts sequence in its category
  @_mNeedToSkipCharNum = 0 # if last byte in current buffer is not the last byte of a character, we need to know how many bytes to skip in next buffer
  @_mLastCharOrder = -1 # The order of previous char
  @_mDone = false # If this flag is set to constants.True, detection is done and conclusion has been made
end