239 lines
7.5 KiB
Ruby
Executable File
239 lines
7.5 KiB
Ruby
Executable File
######################## BEGIN LICENSE BLOCK ########################
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# The Original Code is Mozilla Communicator client code.
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#
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# The Initial Developer of the Original Code is
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# Netscape Communications Corporation.
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# Portions created by the Initial Developer are Copyright (C) 1998
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# the Initial Developer. All Rights Reserved.
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#
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# Contributor(s)
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# Jeff Hodges
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# Mark Pilgrim - port to Python
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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# 02110-1301 USA
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######################### END LICENSE BLOCK #########################
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module CharDet
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ENOUGH_DATA_THRESHOLD = 1024
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SURE_YES = 0.99
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SURE_NO = 0.01
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class CharDistributionAnalysis
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def initialize
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@_mCharToFreqOrder = nil # Mapping table to get frequency order from char order (get from GetOrder())
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@_mTableSize = nil # Size of above table
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@_mTypicalDistributionRatio = nil # This is a constant value which varies from language to language, used in calculating confidence. See http://www.mozilla.org/projects/intl/UniversalCharsetDetection.html for further detail.
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reset()
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end
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def reset
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# # """reset analyser, clear any state"""
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@_mDone = false # If this flag is set to constants.True, detection is done and conclusion has been made
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@_mTotalChars = 0 # Total characters encountered
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@_mFreqChars = 0 # The number of characters whose frequency order is less than 512
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end
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def feed(aStr, aCharLen)
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# # """feed a character with known length"""
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if aCharLen == 2
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# we only care about 2-bytes character in our distribution analysis
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order = get_order(aStr)
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else
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order = -1
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end
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if order >= 0
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@_mTotalChars += 1
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# order is valid
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if order < @_mTableSize
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if 512 > @_mCharToFreqOrder[order]
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@_mFreqChars += 1
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end
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end
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end
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end
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def get_confidence
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# """return confidence based on existing data"""
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# if we didn't receive any character in our consideration range, return negative answer
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if @_mTotalChars <= 0
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return SURE_NO
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end
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if @_mTotalChars != @_mFreqChars
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r = @_mFreqChars / ((@_mTotalChars - @_mFreqChars) * @_mTypicalDistributionRatio)
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if r < SURE_YES
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return r
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end
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end
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# normalize confidence (we don't want to be 100% sure)
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return SURE_YES
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end
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def got_enough_data
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# It is not necessary to receive all data to draw conclusion. For charset detection,
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# certain amount of data is enough
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return @_mTotalChars > ENOUGH_DATA_THRESHOLD
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end
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def get_order(aStr)
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# We do not handle characters based on the original encoding string, but
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# convert this encoding string to a number, here called order.
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# This allows multiple encodings of a language to share one frequency table.
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return -1
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end
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end
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class EUCTWDistributionAnalysis < CharDistributionAnalysis
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def initialize
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super()
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@_mCharToFreqOrder = EUCTWCharToFreqOrder
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@_mTableSize = EUCTW_TABLE_SIZE
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@_mTypicalDistributionRatio = EUCTW_TYPICAL_DISTRIBUTION_RATIO
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end
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def get_order(aStr)
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# for euc-TW encoding, we are interested
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# first byte range: 0xc4 -- 0xfe
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# second byte range: 0xa1 -- 0xfe
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# no validation needed here. State machine has done that
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if aStr[0..0] >= "\xC4"
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return 94 * (aStr[0] - 0xC4) + aStr[1] - 0xA1
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else
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return -1
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end
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end
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end
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class EUCKRDistributionAnalysis < CharDistributionAnalysis
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def initialize
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super()
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@_mCharToFreqOrder = EUCKRCharToFreqOrder
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@_mTableSize = EUCKR_TABLE_SIZE
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@_mTypicalDistributionRatio = EUCKR_TYPICAL_DISTRIBUTION_RATIO
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end
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def get_order(aStr)
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# for euc-KR encoding, we are interested
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# first byte range: 0xb0 -- 0xfe
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# second byte range: 0xa1 -- 0xfe
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# no validation needed here. State machine has done that
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if aStr[0..0] >= "\xB0"
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return 94 * (aStr[0] - 0xB0) + aStr[1] - 0xA1
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else
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return -1
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end
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end
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end
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class GB2312DistributionAnalysis < CharDistributionAnalysis
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def initialize
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super()
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@_mCharToFreqOrder = GB2312CharToFreqOrder
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@_mTableSize = GB2312_TABLE_SIZE
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@_mTypicalDistributionRatio = GB2312_TYPICAL_DISTRIBUTION_RATIO
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end
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def get_order(aStr)
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# for GB2312 encoding, we are interested
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# first byte range: 0xb0 -- 0xfe
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# second byte range: 0xa1 -- 0xfe
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# no validation needed here. State machine has done that
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if (aStr[0..0] >= "\xB0") and (aStr[1..1] >= "\xA1")
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return 94 * (aStr[0] - 0xB0) + aStr[1] - 0xA1
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else
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return -1
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end
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end
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end
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class Big5DistributionAnalysis < CharDistributionAnalysis
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def initialize
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super
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@_mCharToFreqOrder = Big5CharToFreqOrder
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@_mTableSize = BIG5_TABLE_SIZE
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@_mTypicalDistributionRatio = BIG5_TYPICAL_DISTRIBUTION_RATIO
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end
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def get_order(aStr)
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# for big5 encoding, we are interested
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# first byte range: 0xa4 -- 0xfe
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# second byte range: 0x40 -- 0x7e , 0xa1 -- 0xfe
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# no validation needed here. State machine has done that
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if aStr[0..0] >= "\xA4"
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if aStr[1..1] >= "\xA1"
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return 157 * (aStr[0] - 0xA4) + aStr[1] - 0xA1 + 63
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else
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return 157 * (aStr[0] - 0xA4) + aStr[1] - 0x40
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end
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else
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return -1
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end
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end
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end
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class SJISDistributionAnalysis < CharDistributionAnalysis
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def initialize
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super()
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@_mCharToFreqOrder = JISCharToFreqOrder
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@_mTableSize = JIS_TABLE_SIZE
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@_mTypicalDistributionRatio = JIS_TYPICAL_DISTRIBUTION_RATIO
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end
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def get_order(aStr)
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# for sjis encoding, we are interested
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# first byte range: 0x81 -- 0x9f , 0xe0 -- 0xfe
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# second byte range: 0x40 -- 0x7e, 0x81 -- oxfe
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# no validation needed here. State machine has done that
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aStr = aStr[0..1].join if aStr.class == Array
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if (aStr[0..0] >= "\x81") and (aStr[0..0] <= "\x9F")
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order = 188 * (aStr[0] - 0x81)
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elsif (aStr[0..0] >= "\xE0") and (aStr[0..0] <= "\xEF")
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order = 188 * (aStr[0] - 0xE0 + 31)
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else
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return -1
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end
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order = order + aStr[1] - 0x40
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if aStr[1..1] > "\x7F"
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order =- 1
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end
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return order
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end
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end
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class EUCJPDistributionAnalysis < CharDistributionAnalysis
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def initialize
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super()
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@_mCharToFreqOrder = JISCharToFreqOrder
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@_mTableSize = JIS_TABLE_SIZE
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@_mTypicalDistributionRatio = JIS_TYPICAL_DISTRIBUTION_RATIO
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end
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def get_order(aStr)
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# for euc-JP encoding, we are interested
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# first byte range: 0xa0 -- 0xfe
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# second byte range: 0xa1 -- 0xfe
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# no validation needed here. State machine has done that
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if aStr[0..0] >= "\xA0"
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return 94 * (aStr[0] - 0xA1) + aStr[1] - 0xa1
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else
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return -1
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end
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end
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end
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end
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