1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_I18N_CASE_CONVERSION_H_ 6 #define BASE_I18N_CASE_CONVERSION_H_ 7 8 #include "base/i18n/base_i18n_export.h" 9 #include "base/strings/string16.h" 10 #include "base/strings/string_piece.h" 11 12 namespace base { 13 namespace i18n { 14 15 // UNICODE CASE-HANDLING ADVICE 16 // 17 // In English it's always safe to convert to upper-case or lower-case text 18 // and get a good answer. But some languages have rules specific to those 19 // locales. One example is the Turkish I: 20 // http://www.i18nguy.com/unicode/turkish-i18n.html 21 // 22 // ToLower/ToUpper use the current ICU locale which will take into account 23 // the user language preference. Use this when dealing with user typing. 24 // 25 // FoldCase canonicalizes to a standardized form independent of the current 26 // locale. Use this when comparing general Unicode strings that don't 27 // necessarily belong in the user's current locale (like commands, protocol 28 // names, other strings from the web) for case-insensitive equality. 29 // 30 // Note that case conversions will change the length of the string in some 31 // not-uncommon cases. Never assume that the output is the same length as 32 // the input. 33 34 // Returns the lower case equivalent of string. Uses ICU's current locale. 35 BASE_I18N_EXPORT string16 ToLower(StringPiece16 string); 36 37 // Returns the upper case equivalent of string. Uses ICU's current locale. 38 BASE_I18N_EXPORT string16 ToUpper(StringPiece16 string); 39 40 // Convert the given string to a canonical case, independent of the current 41 // locale. For ASCII the canonical form is lower case. 42 // See http://unicode.org/faq/casemap_charprop.html#2 43 BASE_I18N_EXPORT string16 FoldCase(StringPiece16 string); 44 45 } // namespace i18n 46 } // namespace base 47 48 #endif // BASE_I18N_CASE_CONVERSION_H_ 49