1 /* 2 ******************************************************************************* 3 * 4 * Copyright (C) 1999-2010, International Business Machines 5 * Corporation and others. All Rights Reserved. 6 * 7 ******************************************************************************* 8 * file name: utf.h 9 * encoding: US-ASCII 10 * tab size: 8 (not used) 11 * indentation:4 12 * 13 * created on: 1999sep09 14 * created by: Markus W. Scherer 15 */ 16 17 /** 18 * \file 19 * \brief C API: Code point macros 20 * 21 * This file defines macros for checking whether a code point is 22 * a surrogate or a non-character etc. 23 * 24 * The UChar and UChar32 data types for Unicode code units and code points 25 * are defined in umachines.h because they can be machine-dependent. 26 * 27 * utf.h is included by utypes.h and itself includes utf8.h and utf16.h after some 28 * common definitions. Those files define macros for efficiently getting code points 29 * in and out of UTF-8/16 strings. 30 * utf16.h macros have "U16_" prefixes. 31 * utf8.h defines similar macros with "U8_" prefixes for UTF-8 string handling. 32 * 33 * ICU processes 16-bit Unicode strings. 34 * Most of the time, such strings are well-formed UTF-16. 35 * Single, unpaired surrogates must be handled as well, and are treated in ICU 36 * like regular code points where possible. 37 * (Pairs of surrogate code points are indistinguishable from supplementary 38 * code points encoded as pairs of supplementary code units.) 39 * 40 * In fact, almost all Unicode code points in normal text (>99%) 41 * are on the BMP (<=U+ffff) and even <=U+d7ff. 42 * ICU functions handle supplementary code points (U+10000..U+10ffff) 43 * but are optimized for the much more frequently occurring BMP code points. 44 * 45 * utf.h defines UChar to be an unsigned 16-bit integer. If this matches wchar_t, then 46 * UChar is defined to be exactly wchar_t, otherwise uint16_t. 47 * 48 * UChar32 is defined to be a signed 32-bit integer (int32_t), large enough for a 21-bit 49 * Unicode code point (Unicode scalar value, 0..0x10ffff). 50 * Before ICU 2.4, the definition of UChar32 was similarly platform-dependent as 51 * the definition of UChar. For details see the documentation for UChar32 itself. 52 * 53 * utf.h also defines a small number of C macros for single Unicode code points. 54 * These are simple checks for surrogates and non-characters. 55 * For actual Unicode character properties see uchar.h. 56 * 57 * By default, string operations must be done with error checking in case 58 * a string is not well-formed UTF-16. 59 * The macros will detect if a surrogate code unit is unpaired 60 * (lead unit without trail unit or vice versa) and just return the unit itself 61 * as the code point. 62 * (It is an accidental property of Unicode and UTF-16 that all 63 * malformed sequences can be expressed unambiguously with a distinct subrange 64 * of Unicode code points.) 65 * 66 * The regular "safe" macros require that the initial, passed-in string index 67 * is within bounds. They only check the index when they read more than one 68 * code unit. This is usually done with code similar to the following loop: 69 * <pre>while(i<length) { 70 * U16_NEXT(s, i, length, c); 71 * // use c 72 * }</pre> 73 * 74 * When it is safe to assume that text is well-formed UTF-16 75 * (does not contain single, unpaired surrogates), then one can use 76 * U16_..._UNSAFE macros. 77 * These do not check for proper code unit sequences or truncated text and may 78 * yield wrong results or even cause a crash if they are used with "malformed" 79 * text. 80 * In practice, U16_..._UNSAFE macros will produce slightly less code but 81 * should not be faster because the processing is only different when a 82 * surrogate code unit is detected, which will be rare. 83 * 84 * Similarly for UTF-8, there are "safe" macros without a suffix, 85 * and U8_..._UNSAFE versions. 86 * The performance differences are much larger here because UTF-8 provides so 87 * many opportunities for malformed sequences. 88 * The unsafe UTF-8 macros are entirely implemented inside the macro definitions 89 * and are fast, while the safe UTF-8 macros call functions for all but the 90 * trivial (ASCII) cases. 91 * (ICU 3.6 optimizes U8_NEXT() and U8_APPEND() to handle most other common 92 * characters inline as well.) 93 * 94 * Unlike with UTF-16, malformed sequences cannot be expressed with distinct 95 * code point values (0..U+10ffff). They are indicated with negative values instead. 96 * 97 * For more information see the ICU User Guide Strings chapter 98 * (http://icu-project.org/userguide/strings.html). 99 * 100 * <em>Usage:</em> 101 * ICU coding guidelines for if() statements should be followed when using these macros. 102 * Compound statements (curly braces {}) must be used for if-else-while... 103 * bodies and all macro statements should be terminated with semicolon. 104 * 105 * @stable ICU 2.4 106 */ 107 108 #ifndef __UTF_H__ 109 #define __UTF_H__ 110 111 #include "unicode/utypes.h" 112 /* include the utfXX.h after the following definitions */ 113 114 /* single-code point definitions -------------------------------------------- */ 115 116 /** 117 * This value is intended for sentinel values for APIs that 118 * (take or) return single code points (UChar32). 119 * It is outside of the Unicode code point range 0..0x10ffff. 120 * 121 * For example, a "done" or "error" value in a new API 122 * could be indicated with U_SENTINEL. 123 * 124 * ICU APIs designed before ICU 2.4 usually define service-specific "done" 125 * values, mostly 0xffff. 126 * Those may need to be distinguished from 127 * actual U+ffff text contents by calling functions like 128 * CharacterIterator::hasNext() or UnicodeString::length(). 129 * 130 * @return -1 131 * @see UChar32 132 * @stable ICU 2.4 133 */ 134 #define U_SENTINEL (-1) 135 136 /** 137 * Is this code point a Unicode noncharacter? 138 * @param c 32-bit code point 139 * @return TRUE or FALSE 140 * @stable ICU 2.4 141 */ 142 #define U_IS_UNICODE_NONCHAR(c) \ 143 ((c)>=0xfdd0 && \ 144 ((uint32_t)(c)<=0xfdef || ((c)&0xfffe)==0xfffe) && \ 145 (uint32_t)(c)<=0x10ffff) 146 147 /** 148 * Is c a Unicode code point value (0..U+10ffff) 149 * that can be assigned a character? 150 * 151 * Code points that are not characters include: 152 * - single surrogate code points (U+d800..U+dfff, 2048 code points) 153 * - the last two code points on each plane (U+__fffe and U+__ffff, 34 code points) 154 * - U+fdd0..U+fdef (new with Unicode 3.1, 32 code points) 155 * - the highest Unicode code point value is U+10ffff 156 * 157 * This means that all code points below U+d800 are character code points, 158 * and that boundary is tested first for performance. 159 * 160 * @param c 32-bit code point 161 * @return TRUE or FALSE 162 * @stable ICU 2.4 163 */ 164 #define U_IS_UNICODE_CHAR(c) \ 165 ((uint32_t)(c)<0xd800 || \ 166 ((uint32_t)(c)>0xdfff && \ 167 (uint32_t)(c)<=0x10ffff && \ 168 !U_IS_UNICODE_NONCHAR(c))) 169 170 /** 171 * Is this code point a BMP code point (U+0000..U+ffff)? 172 * @param c 32-bit code point 173 * @return TRUE or FALSE 174 * @stable ICU 2.8 175 */ 176 #define U_IS_BMP(c) ((uint32_t)(c)<=0xffff) 177 178 /** 179 * Is this code point a supplementary code point (U+10000..U+10ffff)? 180 * @param c 32-bit code point 181 * @return TRUE or FALSE 182 * @stable ICU 2.8 183 */ 184 #define U_IS_SUPPLEMENTARY(c) ((uint32_t)((c)-0x10000)<=0xfffff) 185 186 /** 187 * Is this code point a lead surrogate (U+d800..U+dbff)? 188 * @param c 32-bit code point 189 * @return TRUE or FALSE 190 * @stable ICU 2.4 191 */ 192 #define U_IS_LEAD(c) (((c)&0xfffffc00)==0xd800) 193 194 /** 195 * Is this code point a trail surrogate (U+dc00..U+dfff)? 196 * @param c 32-bit code point 197 * @return TRUE or FALSE 198 * @stable ICU 2.4 199 */ 200 #define U_IS_TRAIL(c) (((c)&0xfffffc00)==0xdc00) 201 202 /** 203 * Is this code point a surrogate (U+d800..U+dfff)? 204 * @param c 32-bit code point 205 * @return TRUE or FALSE 206 * @stable ICU 2.4 207 */ 208 #define U_IS_SURROGATE(c) (((c)&0xfffff800)==0xd800) 209 210 /** 211 * Assuming c is a surrogate code point (U_IS_SURROGATE(c)), 212 * is it a lead surrogate? 213 * @param c 32-bit code point 214 * @return TRUE or FALSE 215 * @stable ICU 2.4 216 */ 217 #define U_IS_SURROGATE_LEAD(c) (((c)&0x400)==0) 218 219 /** 220 * Assuming c is a surrogate code point (U_IS_SURROGATE(c)), 221 * is it a trail surrogate? 222 * @param c 32-bit code point 223 * @return TRUE or FALSE 224 * @stable ICU 4.2 225 */ 226 #define U_IS_SURROGATE_TRAIL(c) (((c)&0x400)!=0) 227 228 /* include the utfXX.h ------------------------------------------------------ */ 229 230 #include "unicode/utf8.h" 231 #include "unicode/utf16.h" 232 233 /* utf_old.h contains deprecated, pre-ICU 2.4 definitions */ 234 #include "unicode/utf_old.h" 235 236 #endif 237
