| // 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. |
| |
| // |
| // File: lang_script.h |
| // ================ |
| // |
| // Author: dsites@google.com (Dick Sites) |
| // |
| // This file declares language and script numbers and names for CLD2, |
| // plus routines that access side tables based on these |
| // |
| |
| #ifndef I18N_ENCODINGS_CLD2_LANG_SCRIPT_H__ |
| #define I18N_ENCODINGS_CLD2_LANG_SCRIPT_H__ |
| |
| #include "generated_language.h" |
| #include "generated_ulscript.h" |
| #include "integral_types.h" |
| |
| |
| // NOTE: The script numbers and language numbers here are not guaranteed to be |
| // stable. If you want to record a result for posterity, save the |
| // ULScriptCode(ULScript ulscript) result as character strings. |
| // |
| // The Unicode scripts recognized by CLD2 are numbered almost arbitrarily, |
| // specified in an enum. Each script has human-readable script name and a |
| // 4-letter ISO 15924 script code. Each has a C name (largely for use by |
| // programs that generate declarations in cld2_generated_scripts.h). Each |
| // also has a recognition type |
| // r_type: 0 script-only, 1 nilgrams, 2 quadgrams, 3 CJK |
| // |
| // The declarations for a particular version of Unicode are machine-generated in |
| // generated_scripts.h |
| // |
| // This file includes that one and declares the access routines. The type |
| // involved is called "ULScript" to signify Unicode Letters-Marks Scripts, |
| // which are not quite Unicode Scripts. In particular, the CJK scripts are |
| // merged into a single number because CLD2 recognizes the CJK languages from |
| // four scripts intermixed: Hani (both Hans and Hant), Hangul, Hiragana, and |
| // Katakana. |
| |
| // Each script has one of these four recognition types. |
| // RTypeNone: There is no language associated with this script. In extended |
| // language recognition calls, return a fake language number that maps to |
| // xx-Cham, with literally "xx" for the language code,and with the script |
| // code instead of "Cham". In non-extended calls, return UNKNOWN_LANGUAGE. |
| // RTypeOne: The script maps 1:1 to a single language. No letters are examined |
| // during recognition and no lookups done. |
| // RTypeMany: The usual quadgram + delta-octagram + distinctive-words scoring |
| // is done to determine the languages involved. |
| // RTypeCJK: The CJK unigram + delta-bigram scoring is done to determine the |
| // languages involved. |
| // |
| // Note that the choice of recognition type is a function of script, not |
| // language. In particular, some languges are recognized in multiple scripts |
| // and those have different recognition types (Mongolian mn-Latn vs. mn-Mong |
| // for example). |
| |
| namespace CLD2 { |
| |
| //----------------------------------------------------------------------------// |
| // Functions of ULScript // |
| //----------------------------------------------------------------------------// |
| |
| // If the input is out of range or otherwise unrecognized, it is treated |
| // as ULScript_Common (which never participates in language recognition) |
| const char* ULScriptName(ULScript ulscript); |
| const char* ULScriptCode(ULScript ulscript); |
| const char* ULScriptDeclaredName(ULScript ulscript); |
| ULScriptRType ULScriptRecognitionType(ULScript ulscript); |
| |
| // Name can be either full name or ISO code, or can be ISO code embedded in |
| // a language-script combination such as "en-Latn-GB" |
| ULScript GetULScriptFromName(const char* src); |
| |
| // Map script into Latin, Cyrillic, Arabic, Other |
| int LScript4(ULScript ulscript); |
| |
| //----------------------------------------------------------------------------// |
| // Functions of Language // |
| //----------------------------------------------------------------------------// |
| |
| // The languages recognized by CLD2 are numbered almost arbitrarily, |
| // specified in an enum. Each language has human-readable language name and a |
| // 2- or 3-letter ISO 639 language code. Each has a C name (largely for use by |
| // programs that generate declarations in cld2_generated_languagess.h). |
| // Each has a list of up to four scripts in which it is currently recognized. |
| // |
| // The declarations for a particular set of recognized languages are |
| // machine-generated in |
| // generated_languages.h |
| // |
| // The Language enum is intended to match the internal Google Language enum |
| // in i18n/languages/proto/languages.proto up to NUM_LANGUAGES, with additional |
| // languages assigned above that. Over time, some languages may be renumbered |
| // if they are moved into the Language enum. |
| // |
| // The Language enum includes the fake language numbers for RTypeNone above. |
| // |
| |
| |
| // If the input is out of range or otherwise unrecognized, it is treated |
| // as UNKNOWN_LANGUAGE |
| // |
| // LanguageCode |
| // ------------ |
| // Given the Language, return the language code, e.g. "ko" |
| // This is determined by |
| // the following (in order of preference): |
| // - ISO-639-1 two-letter language code |
| // (all except those mentioned below) |
| // - ISO-639-2 three-letter bibliographic language code |
| // (Tibetan, Dhivehi, Cherokee, Syriac) |
| // - Google-specific language code |
| // (ChineseT ("zh-TW"), Teragram Unknown, Unknown, |
| // Portuguese-Portugal, Portuguese-Brazil, Limbu) |
| // - Fake RTypeNone names. |
| |
| const char* LanguageName(Language lang); |
| const char* LanguageCode(Language lang); |
| const char* LanguageShortCode(Language lang); |
| const char* LanguageDeclaredName(Language lang); |
| |
| // n is in 0..3. Trailing entries are filled with |
| // ULScript_Common (which never participates in language recognition) |
| ULScript LanguageRecognizedScript(Language lang, int n); |
| |
| // Name can be either full name or ISO code, or can be ISO code embedded in |
| // a language-script combination such as "en-Latn-GB" |
| Language GetLanguageFromName(const char* src); |
| |
| // Returns which set of statistically-close languages lang is in. 0 means none. |
| int LanguageCloseSet(Language lang); |
| |
| //----------------------------------------------------------------------------// |
| // Functions of ULScript and Language // |
| //----------------------------------------------------------------------------// |
| |
| // Most common language in each script |
| Language DefaultLanguage(ULScript ulscript); |
| |
| // For RTypeMany recognition, |
| // the CLD2 lookup tables are kept small by encoding a language into one byte. |
| // To avoid limiting CLD2 to at most 256 languages, a larger range of external |
| // Language numbers is mapped to a smaller range of per-script numbers. At |
| // the moment (January 2013) the Latin script has about 90 languages to be |
| // recognized, while all the other scripts total about 50 more languages. In |
| // addition, the RTypeNone scripts map to about 100 fake languages. |
| // So we map all Latin-script languages to one range of 1..255 per-script |
| // numbers and map all the other RTypeMany languages to an overlapping range |
| // 1..255 of per-script numbers. |
| |
| uint8 PerScriptNumber(ULScript ulscript, Language lang); |
| Language FromPerScriptNumber(ULScript ulscript, uint8 perscript_number); |
| |
| // While the speed-sensitive processing deals with per-script language numbers, |
| // there is a need for low-performance dealing with original language numbers |
| // and unknown scripts, mostly for processing language hints. |
| // These routines let one derive a script class from a bare language. |
| // For languages written in multiple scripts, both of these can return true. |
| |
| bool IsLatnLanguage(Language lang); |
| bool IsOthrLanguage(Language lang); |
| |
| |
| //----------------------------------------------------------------------------// |
| // Other // |
| //----------------------------------------------------------------------------// |
| |
| // Utility routine to search alphabetical tables |
| int BinarySearch(const char* key, int lo, int hi, const CharIntPair* cipair); |
| |
| } // namespace CLD2 |
| |
| #endif // I18N_ENCODINGS_CLD2_LANG_SCRIPT_H__ |
