Adding new version of chardet

This commit is contained in:
Miroslav Stampar
2015-10-09 13:35:48 +02:00
parent d424d4cdc7
commit 439d003753
39 changed files with 1499 additions and 1148 deletions

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@@ -13,20 +13,21 @@
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
# 02110-1301 USA
######################### END LICENSE BLOCK #########################
from charsetprober import CharSetProber
import constants
from .charsetprober import CharSetProber
from .constants import eNotMe, eDetecting
from .compat import wrap_ord
# This prober doesn't actually recognize a language or a charset.
# It is a helper prober for the use of the Hebrew model probers
@@ -35,40 +36,40 @@ import constants
#
# Four main charsets exist in Hebrew:
# "ISO-8859-8" - Visual Hebrew
# "windows-1255" - Logical Hebrew
# "windows-1255" - Logical Hebrew
# "ISO-8859-8-I" - Logical Hebrew
# "x-mac-hebrew" - ?? Logical Hebrew ??
#
# Both "ISO" charsets use a completely identical set of code points, whereas
# "windows-1255" and "x-mac-hebrew" are two different proper supersets of
# "windows-1255" and "x-mac-hebrew" are two different proper supersets of
# these code points. windows-1255 defines additional characters in the range
# 0x80-0x9F as some misc punctuation marks as well as some Hebrew-specific
# 0x80-0x9F as some misc punctuation marks as well as some Hebrew-specific
# diacritics and additional 'Yiddish' ligature letters in the range 0xc0-0xd6.
# x-mac-hebrew defines similar additional code points but with a different
# x-mac-hebrew defines similar additional code points but with a different
# mapping.
#
# As far as an average Hebrew text with no diacritics is concerned, all four
# charsets are identical with respect to code points. Meaning that for the
# main Hebrew alphabet, all four map the same values to all 27 Hebrew letters
# As far as an average Hebrew text with no diacritics is concerned, all four
# charsets are identical with respect to code points. Meaning that for the
# main Hebrew alphabet, all four map the same values to all 27 Hebrew letters
# (including final letters).
#
# The dominant difference between these charsets is their directionality.
# "Visual" directionality means that the text is ordered as if the renderer is
# not aware of a BIDI rendering algorithm. The renderer sees the text and
# draws it from left to right. The text itself when ordered naturally is read
# not aware of a BIDI rendering algorithm. The renderer sees the text and
# draws it from left to right. The text itself when ordered naturally is read
# backwards. A buffer of Visual Hebrew generally looks like so:
# "[last word of first line spelled backwards] [whole line ordered backwards
# and spelled backwards] [first word of first line spelled backwards]
# and spelled backwards] [first word of first line spelled backwards]
# [end of line] [last word of second line] ... etc' "
# adding punctuation marks, numbers and English text to visual text is
# naturally also "visual" and from left to right.
#
#
# "Logical" directionality means the text is ordered "naturally" according to
# the order it is read. It is the responsibility of the renderer to display
# the text from right to left. A BIDI algorithm is used to place general
# the order it is read. It is the responsibility of the renderer to display
# the text from right to left. A BIDI algorithm is used to place general
# punctuation marks, numbers and English text in the text.
#
# Texts in x-mac-hebrew are almost impossible to find on the Internet. From
# Texts in x-mac-hebrew are almost impossible to find on the Internet. From
# what little evidence I could find, it seems that its general directionality
# is Logical.
#
@@ -76,17 +77,17 @@ import constants
# charsets:
# Visual Hebrew - "ISO-8859-8" - backwards text - Words and sentences are
# backwards while line order is natural. For charset recognition purposes
# the line order is unimportant (In fact, for this implementation, even
# the line order is unimportant (In fact, for this implementation, even
# word order is unimportant).
# Logical Hebrew - "windows-1255" - normal, naturally ordered text.
#
# "ISO-8859-8-I" is a subset of windows-1255 and doesn't need to be
# "ISO-8859-8-I" is a subset of windows-1255 and doesn't need to be
# specifically identified.
# "x-mac-hebrew" is also identified as windows-1255. A text in x-mac-hebrew
# that contain special punctuation marks or diacritics is displayed with
# some unconverted characters showing as question marks. This problem might
# be corrected using another model prober for x-mac-hebrew. Due to the fact
# that x-mac-hebrew texts are so rare, writing another model prober isn't
# that x-mac-hebrew texts are so rare, writing another model prober isn't
# worth the effort and performance hit.
#
#### The Prober ####
@@ -126,28 +127,31 @@ import constants
# charset identified, either "windows-1255" or "ISO-8859-8".
# windows-1255 / ISO-8859-8 code points of interest
FINAL_KAF = '\xea'
NORMAL_KAF = '\xeb'
FINAL_MEM = '\xed'
NORMAL_MEM = '\xee'
FINAL_NUN = '\xef'
NORMAL_NUN = '\xf0'
FINAL_PE = '\xf3'
NORMAL_PE = '\xf4'
FINAL_TSADI = '\xf5'
NORMAL_TSADI = '\xf6'
FINAL_KAF = 0xea
NORMAL_KAF = 0xeb
FINAL_MEM = 0xed
NORMAL_MEM = 0xee
FINAL_NUN = 0xef
NORMAL_NUN = 0xf0
FINAL_PE = 0xf3
NORMAL_PE = 0xf4
FINAL_TSADI = 0xf5
NORMAL_TSADI = 0xf6
# Minimum Visual vs Logical final letter score difference.
# If the difference is below this, don't rely solely on the final letter score distance.
# If the difference is below this, don't rely solely on the final letter score
# distance.
MIN_FINAL_CHAR_DISTANCE = 5
# Minimum Visual vs Logical model score difference.
# If the difference is below this, don't rely at all on the model score distance.
# If the difference is below this, don't rely at all on the model score
# distance.
MIN_MODEL_DISTANCE = 0.01
VISUAL_HEBREW_NAME = "ISO-8859-8"
LOGICAL_HEBREW_NAME = "windows-1255"
class HebrewProber(CharSetProber):
def __init__(self):
CharSetProber.__init__(self)
@@ -159,8 +163,8 @@ class HebrewProber(CharSetProber):
self._mFinalCharLogicalScore = 0
self._mFinalCharVisualScore = 0
# The two last characters seen in the previous buffer,
# mPrev and mBeforePrev are initialized to space in order to simulate a word
# delimiter at the beginning of the data
# mPrev and mBeforePrev are initialized to space in order to simulate
# a word delimiter at the beginning of the data
self._mPrev = ' '
self._mBeforePrev = ' '
# These probers are owned by the group prober.
@@ -170,49 +174,52 @@ class HebrewProber(CharSetProber):
self._mVisualProber = visualProber
def is_final(self, c):
return c in [FINAL_KAF, FINAL_MEM, FINAL_NUN, FINAL_PE, FINAL_TSADI]
return wrap_ord(c) in [FINAL_KAF, FINAL_MEM, FINAL_NUN, FINAL_PE,
FINAL_TSADI]
def is_non_final(self, c):
# The normal Tsadi is not a good Non-Final letter due to words like
# 'lechotet' (to chat) containing an apostrophe after the tsadi. This
# apostrophe is converted to a space in FilterWithoutEnglishLetters causing
# the Non-Final tsadi to appear at an end of a word even though this is not
# the case in the original text.
# The letters Pe and Kaf rarely display a related behavior of not being a
# good Non-Final letter. Words like 'Pop', 'Winamp' and 'Mubarak' for
# example legally end with a Non-Final Pe or Kaf. However, the benefit of
# these letters as Non-Final letters outweighs the damage since these words
# are quite rare.
return c in [NORMAL_KAF, NORMAL_MEM, NORMAL_NUN, NORMAL_PE]
# The normal Tsadi is not a good Non-Final letter due to words like
# 'lechotet' (to chat) containing an apostrophe after the tsadi. This
# apostrophe is converted to a space in FilterWithoutEnglishLetters
# causing the Non-Final tsadi to appear at an end of a word even
# though this is not the case in the original text.
# The letters Pe and Kaf rarely display a related behavior of not being
# a good Non-Final letter. Words like 'Pop', 'Winamp' and 'Mubarak'
# for example legally end with a Non-Final Pe or Kaf. However, the
# benefit of these letters as Non-Final letters outweighs the damage
# since these words are quite rare.
return wrap_ord(c) in [NORMAL_KAF, NORMAL_MEM, NORMAL_NUN, NORMAL_PE]
def feed(self, aBuf):
# Final letter analysis for logical-visual decision.
# Look for evidence that the received buffer is either logical Hebrew or
# visual Hebrew.
# Look for evidence that the received buffer is either logical Hebrew
# or visual Hebrew.
# The following cases are checked:
# 1) A word longer than 1 letter, ending with a final letter. This is an
# indication that the text is laid out "naturally" since the final letter
# really appears at the end. +1 for logical score.
# 2) A word longer than 1 letter, ending with a Non-Final letter. In normal
# Hebrew, words ending with Kaf, Mem, Nun, Pe or Tsadi, should not end with
# the Non-Final form of that letter. Exceptions to this rule are mentioned
# above in isNonFinal(). This is an indication that the text is laid out
# backwards. +1 for visual score
# 3) A word longer than 1 letter, starting with a final letter. Final letters
# should not appear at the beginning of a word. This is an indication that
# the text is laid out backwards. +1 for visual score.
#
# The visual score and logical score are accumulated throughout the text and
# are finally checked against each other in GetCharSetName().
# No checking for final letters in the middle of words is done since that case
# is not an indication for either Logical or Visual text.
#
# We automatically filter out all 7-bit characters (replace them with spaces)
# so the word boundary detection works properly. [MAP]
# 1) A word longer than 1 letter, ending with a final letter. This is
# an indication that the text is laid out "naturally" since the
# final letter really appears at the end. +1 for logical score.
# 2) A word longer than 1 letter, ending with a Non-Final letter. In
# normal Hebrew, words ending with Kaf, Mem, Nun, Pe or Tsadi,
# should not end with the Non-Final form of that letter. Exceptions
# to this rule are mentioned above in isNonFinal(). This is an
# indication that the text is laid out backwards. +1 for visual
# score
# 3) A word longer than 1 letter, starting with a final letter. Final
# letters should not appear at the beginning of a word. This is an
# indication that the text is laid out backwards. +1 for visual
# score.
#
# The visual score and logical score are accumulated throughout the
# text and are finally checked against each other in GetCharSetName().
# No checking for final letters in the middle of words is done since
# that case is not an indication for either Logical or Visual text.
#
# We automatically filter out all 7-bit characters (replace them with
# spaces) so the word boundary detection works properly. [MAP]
if self.get_state() == constants.eNotMe:
if self.get_state() == eNotMe:
# Both model probers say it's not them. No reason to continue.
return constants.eNotMe
return eNotMe
aBuf = self.filter_high_bit_only(aBuf)
@@ -220,23 +227,27 @@ class HebrewProber(CharSetProber):
if cur == ' ':
# We stand on a space - a word just ended
if self._mBeforePrev != ' ':
# next-to-last char was not a space so self._mPrev is not a 1 letter word
# next-to-last char was not a space so self._mPrev is not a
# 1 letter word
if self.is_final(self._mPrev):
# case (1) [-2:not space][-1:final letter][cur:space]
self._mFinalCharLogicalScore += 1
elif self.is_non_final(self._mPrev):
# case (2) [-2:not space][-1:Non-Final letter][cur:space]
# case (2) [-2:not space][-1:Non-Final letter][
# cur:space]
self._mFinalCharVisualScore += 1
else:
# Not standing on a space
if (self._mBeforePrev == ' ') and (self.is_final(self._mPrev)) and (cur != ' '):
if ((self._mBeforePrev == ' ') and
(self.is_final(self._mPrev)) and (cur != ' ')):
# case (3) [-2:space][-1:final letter][cur:not space]
self._mFinalCharVisualScore += 1
self._mBeforePrev = self._mPrev
self._mPrev = cur
# Forever detecting, till the end or until both model probers return eNotMe (handled above)
return constants.eDetecting
# Forever detecting, till the end or until both model probers return
# eNotMe (handled above)
return eDetecting
def get_charset_name(self):
# Make the decision: is it Logical or Visual?
@@ -248,22 +259,25 @@ class HebrewProber(CharSetProber):
return VISUAL_HEBREW_NAME
# It's not dominant enough, try to rely on the model scores instead.
modelsub = self._mLogicalProber.get_confidence() - self._mVisualProber.get_confidence()
modelsub = (self._mLogicalProber.get_confidence()
- self._mVisualProber.get_confidence())
if modelsub > MIN_MODEL_DISTANCE:
return LOGICAL_HEBREW_NAME
if modelsub < -MIN_MODEL_DISTANCE:
return VISUAL_HEBREW_NAME
# Still no good, back to final letter distance, maybe it'll save the day.
# Still no good, back to final letter distance, maybe it'll save the
# day.
if finalsub < 0.0:
return VISUAL_HEBREW_NAME
# (finalsub > 0 - Logical) or (don't know what to do) default to Logical.
# (finalsub > 0 - Logical) or (don't know what to do) default to
# Logical.
return LOGICAL_HEBREW_NAME
def get_state(self):
# Remain active as long as any of the model probers are active.
if (self._mLogicalProber.get_state() == constants.eNotMe) and \
(self._mVisualProber.get_state() == constants.eNotMe):
return constants.eNotMe
return constants.eDetecting
if (self._mLogicalProber.get_state() == eNotMe) and \
(self._mVisualProber.get_state() == eNotMe):
return eNotMe
return eDetecting