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/* ******************************************************************************* * * Copyright (C) 1999-2010, International Business Machines * Corporation and others. All Rights Reserved. * ******************************************************************************* * file name: utf.h * encoding: US-ASCII * tab size: 8 (not used) * indentation:4 * * created on: 1999sep09 * created by: Markus W. Scherer */ /** * \file * \brief C API: Code point macros * * This file defines macros for checking whether a code point is * a surrogate or a non-character etc. * * The UChar and UChar32 data types for Unicode code units and code points * are defined in umachines.h because they can be machine-dependent. * * utf.h is included by utypes.h and itself includes utf8.h and utf16.h after some * common definitions. Those files define macros for efficiently getting code points * in and out of UTF-8/16 strings. * utf16.h macros have "U16_" prefixes. * utf8.h defines similar macros with "U8_" prefixes for UTF-8 string handling. * * ICU processes 16-bit Unicode strings. * Most of the time, such strings are well-formed UTF-16. * Single, unpaired surrogates must be handled as well, and are treated in ICU * like regular code points where possible. * (Pairs of surrogate code points are indistinguishable from supplementary * code points encoded as pairs of supplementary code units.) * * In fact, almost all Unicode code points in normal text (>99%) * are on the BMP (<=U+ffff) and even <=U+d7ff. * ICU functions handle supplementary code points (U+10000..U+10ffff) * but are optimized for the much more frequently occurring BMP code points. * * utf.h defines UChar to be an unsigned 16-bit integer. If this matches wchar_t, then * UChar is defined to be exactly wchar_t, otherwise uint16_t. * * UChar32 is defined to be a signed 32-bit integer (int32_t), large enough for a 21-bit * Unicode code point (Unicode scalar value, 0..0x10ffff). * Before ICU 2.4, the definition of UChar32 was similarly platform-dependent as * the definition of UChar. For details see the documentation for UChar32 itself. * * utf.h also defines a small number of C macros for single Unicode code points. * These are simple checks for surrogates and non-characters. * For actual Unicode character properties see uchar.h. * * By default, string operations must be done with error checking in case * a string is not well-formed UTF-16. * The macros will detect if a surrogate code unit is unpaired * (lead unit without trail unit or vice versa) and just return the unit itself * as the code point. * (It is an accidental property of Unicode and UTF-16 that all * malformed sequences can be expressed unambiguously with a distinct subrange * of Unicode code points.) * * The regular "safe" macros require that the initial, passed-in string index * is within bounds. They only check the index when they read more than one * code unit. This is usually done with code similar to the following loop: * <pre>while(i<length) { * U16_NEXT(s, i, length, c); * // use c * }</pre> * * When it is safe to assume that text is well-formed UTF-16 * (does not contain single, unpaired surrogates), then one can use * U16_..._UNSAFE macros. * These do not check for proper code unit sequences or truncated text and may * yield wrong results or even cause a crash if they are used with "malformed" * text. * In practice, U16_..._UNSAFE macros will produce slightly less code but * should not be faster because the processing is only different when a * surrogate code unit is detected, which will be rare. * * Similarly for UTF-8, there are "safe" macros without a suffix, * and U8_..._UNSAFE versions. * The performance differences are much larger here because UTF-8 provides so * many opportunities for malformed sequences. * The unsafe UTF-8 macros are entirely implemented inside the macro definitions * and are fast, while the safe UTF-8 macros call functions for all but the * trivial (ASCII) cases. * (ICU 3.6 optimizes U8_NEXT() and U8_APPEND() to handle most other common * characters inline as well.) * * Unlike with UTF-16, malformed sequences cannot be expressed with distinct * code point values (0..U+10ffff). They are indicated with negative values instead. * * For more information see the ICU User Guide Strings chapter * (http://icu-project.org/userguide/strings.html). * * <em>Usage:</em> * ICU coding guidelines for if() statements should be followed when using these macros. * Compound statements (curly braces {}) must be used for if-else-while... * bodies and all macro statements should be terminated with semicolon. * * @stable ICU 2.4 */ #ifndef __UTF_H__ #define __UTF_H__ #include "unicode/utypes.h" /* include the utfXX.h after the following definitions */ /* single-code point definitions -------------------------------------------- */ /** * This value is intended for sentinel values for APIs that * (take or) return single code points (UChar32). * It is outside of the Unicode code point range 0..0x10ffff. * * For example, a "done" or "error" value in a new API * could be indicated with U_SENTINEL. * * ICU APIs designed before ICU 2.4 usually define service-specific "done" * values, mostly 0xffff. * Those may need to be distinguished from * actual U+ffff text contents by calling functions like * CharacterIterator::hasNext() or UnicodeString::length(). * * @return -1 * @see UChar32 * @stable ICU 2.4 */ #define U_SENTINEL (-1) /** * Is this code point a Unicode noncharacter? * @param c 32-bit code point * @return TRUE or FALSE * @stable ICU 2.4 */ #define U_IS_UNICODE_NONCHAR(c) \ ((c)>=0xfdd0 && \ ((uint32_t)(c)<=0xfdef || ((c)&0xfffe)==0xfffe) && \ (uint32_t)(c)<=0x10ffff) /** * Is c a Unicode code point value (0..U+10ffff) * that can be assigned a character? * * Code points that are not characters include: * - single surrogate code points (U+d800..U+dfff, 2048 code points) * - the last two code points on each plane (U+__fffe and U+__ffff, 34 code points) * - U+fdd0..U+fdef (new with Unicode 3.1, 32 code points) * - the highest Unicode code point value is U+10ffff * * This means that all code points below U+d800 are character code points, * and that boundary is tested first for performance. * * @param c 32-bit code point * @return TRUE or FALSE * @stable ICU 2.4 */ #define U_IS_UNICODE_CHAR(c) \ ((uint32_t)(c)<0xd800 || \ ((uint32_t)(c)>0xdfff && \ (uint32_t)(c)<=0x10ffff && \ !U_IS_UNICODE_NONCHAR(c))) /** * Is this code point a BMP code point (U+0000..U+ffff)? * @param c 32-bit code point * @return TRUE or FALSE * @stable ICU 2.8 */ #define U_IS_BMP(c) ((uint32_t)(c)<=0xffff) /** * Is this code point a supplementary code point (U+10000..U+10ffff)? * @param c 32-bit code point * @return TRUE or FALSE * @stable ICU 2.8 */ #define U_IS_SUPPLEMENTARY(c) ((uint32_t)((c)-0x10000)<=0xfffff) /** * Is this code point a lead surrogate (U+d800..U+dbff)? * @param c 32-bit code point * @return TRUE or FALSE * @stable ICU 2.4 */ #define U_IS_LEAD(c) (((c)&0xfffffc00)==0xd800) /** * Is this code point a trail surrogate (U+dc00..U+dfff)? * @param c 32-bit code point * @return TRUE or FALSE * @stable ICU 2.4 */ #define U_IS_TRAIL(c) (((c)&0xfffffc00)==0xdc00) /** * Is this code point a surrogate (U+d800..U+dfff)? * @param c 32-bit code point * @return TRUE or FALSE * @stable ICU 2.4 */ #define U_IS_SURROGATE(c) (((c)&0xfffff800)==0xd800) /** * Assuming c is a surrogate code point (U_IS_SURROGATE(c)), * is it a lead surrogate? * @param c 32-bit code point * @return TRUE or FALSE * @stable ICU 2.4 */ #define U_IS_SURROGATE_LEAD(c) (((c)&0x400)==0) /** * Assuming c is a surrogate code point (U_IS_SURROGATE(c)), * is it a trail surrogate? * @param c 32-bit code point * @return TRUE or FALSE * @stable ICU 4.2 */ #define U_IS_SURROGATE_TRAIL(c) (((c)&0x400)!=0) /* include the utfXX.h ------------------------------------------------------ */ #include "unicode/utf8.h" #include "unicode/utf16.h" /* utf_old.h contains deprecated, pre-ICU 2.4 definitions */ #include "unicode/utf_old.h" #endif