The Tor Browser: browser/components/translation/cld2/internal/compact_lang_det

browser/components/translation/cld2/internal/compact_lang_det_impl.h@6474c204b198 (annotated)

browser/components/translation/cld2/internal/compact_lang_det_impl.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 // Copyright 2013 Google Inc. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 //
 // Author: dsites@google.com (Dick Sites)
 //
 #ifndef I18N_ENCODINGS_COMPACT_LANG_DET_COMPACT_LANG_DET_IMPL_H_
 #define I18N_ENCODINGS_COMPACT_LANG_DET_COMPACT_LANG_DET_IMPL_H_
 #include <vector>
 #include "../public/compact_lang_det.h"   // For CLDHints, ResultChunkVector
 #include "integral_types.h"
 #include "lang_script.h"
 namespace CLD2 {
 // Internal use flags
 static const int kCLDFlagFinish = 1;
 static const int kCLDFlagSqueeze = 2;
 static const int kCLDFlagRepeats = 4;
 static const int kCLDFlagTop40 = 8;
 static const int kCLDFlagShort = 16;
 static const int kCLDFlagHint = 32;
 static const int kCLDFlagUseWords = 64;
 static const int kCLDFlagUNUSED = 128;
 // Public use flags, debug output controls, defined in compact_lang_det.h
 // 0x0100 and above
 /***
 Flag meanings:
 Flags are used in the context of a recursive call from Detect to itself,
 trying to deal in a more restrictive way with input that was not reliably
 identified in the top-level call.
 Finish -- Do not further recurse; return whatever result ensues, even if it is
           unreliable. Typically set in any recursive call to take a second try
           on unreliable text.
 Squeeze -- For each text run, do an inplace cheapsqueeze to remove chunks of
           highly repetitive text and chunks of text with too many 1- and
 -letter words. This avoids scoring repetitive or useless non-text
           crap in large files such bogus JPEGs within an HTML file.
 Repeats -- When scoring a text run, do a cheap prediction of each character
           and do not score a unigram/quadgram if the last character of same is
           correctly predicted. This is a slower, finer-grained form of
           cheapsqueeze, typically used when the first pass got unreliable
           results.
 Top40 -- Restrict the set of scored languages to the Google "Top 40", which is
           actually 38 languages. This gets rid of about 110 languages that
           represent about 0.7% of the web. Typically used when the first pass
           got unreliable results.
 Short -- DEPRICATED, unused
 Hint -- EXPERIMENTAL flag for compact_lang_det_test.cc to indicate a language
           hint supplied in parameter plus_one.
 UseWords -- In additon to scoring quad/uni/nil-grams, score complete words
 Tentative decision logic:
 In the middle of first pass -- After 4KB of text, look at the front 256 bytes
           of every full 4KB buffer. If it compresses very well (say 3:1) or has
           lots of spaces (say 1 of every 4 bytes), assume that the input is
           large and contains lots of bogus non-text. Recurse, passing the
           Squeeze flag to strip out chunks of this non-text.
 At the end of the first pass --
           If the top language is reliable and >= 70% of the document, return.
           Else if the top language is reliable and top+2nd >= say 94%, return.
           Else, either the top language is not reliable or there is a lot of
           other crap.
 ***/
   // Scan interchange-valid UTF-8 bytes and detect most likely language,
   // or set of languages.
   //
   // Design goals:
   //   Skip over big stretches of HTML tags
   //   Able to return ranges of different languages
   //   Relatively small tables and relatively fast processing
   //   Thread safe
   //
   typedef struct {
     int perscript_count;
     const Language* perscript_lang;
   } PerScriptPair;
   typedef struct {
     // Constants for hashing 4-7 byte quadgram to 32 bits
     const int kQuadHashB4Shift;
     const int kQuadHashB4bShift;
     const int kQuadHashB5Shift;
     const int kQuadHashB5bShift;
     // Constants for hashing 32 bits to kQuadKeyTable subscript/key
     const int kHashvalToSubShift;
     const uint32 kHashvalToSubMask;
     const int kHashvalToKeyShift;
     const uint32 kHashvalToKeyMask;
     const int kHashvalAssociativity;
     // Pointers to the actual tables
     const PerScriptPair* kPerScriptPair;
     const uint16* kQuadKeyTable;
     const uint32* kQuadValueTable;
   } LangDetObj;
   // For HTML documents, tags are skipped, along with <script> ... </script>
   // and <style> ... </style> sequences, and entities are expanded.
   //
   // We distinguish between bytes of the raw input buffer and bytes of non-tag
   // text letters. Since tags can be over 50% of the bytes of an HTML Page,
   // and are nearly all seven-bit ASCII English, we prefer to distinguish
   // language mixture fractions based on just the non-tag text.
   //
   // Inputs: text and text_length
   //  is_plain_text if true says to NOT parse/skip HTML tags nor entities
   // Outputs:
   //  language3 is an array of the top 3 languages or UNKNOWN_LANGUAGE
   //  percent3 is an array of the text percentages 0..100 of the top 3 languages
   //  normalized_score3 is an array of internal scores, normalized to the
   //    average score for each language over a body of training text. A
   //    normalized score significantly away from 1.0 indicates very skewed text
   //    or gibberish.
   //
   //  text_bytes is the amount of non-tag/letters-only text found
   //  is_reliable set true if the returned Language is at least 2**30 times more
   //  probable then the second-best Language
   //
   // Return value: the most likely Language for the majority of the input text
   //  Length 0 input and text with no reliable letter sequences returns
   //  UNKNOWN_LANGUAGE
   //
   // Subsetting: For fast detection over large documents, these routines will
   // only scan up to a fixed limit (currently 160KB of non-tag letters).
   //
   Language DetectLanguageSummaryV2(
                         const char* buffer,
                         int buffer_length,
                         bool is_plain_text,
                         const CLDHints* cld_hints,
                         bool allow_extended_lang,
                         int flags,
                         Language plus_one,
                         Language* language3,
                         int* percent3,
                         double* normalized_score3,
                         ResultChunkVector* resultchunkvector,
                         int* text_bytes,
                         bool* is_reliable);
   // For unit testing:
   // Remove portions of text that have a high density of spaces, or that are
   // overly repetitive, squeezing the remaining text in-place to the front
   // of the input buffer.
   // Return the new, possibly-shorter length
   int CheapSqueezeInplace(char* isrc, int srclen, int ichunksize);
 }       // End namespace CLD2
 #endif  // I18N_ENCODINGS_COMPACT_LANG_DET_COMPACT_LANG_DET_IMPL_H_

The Tor Browser / annotate

browser/components/translation/cld2/internal/compact_lang_det_impl.h@6474c204b198 (annotated)

browser/components/translation/cld2/internal/compact_lang_det_impl.h