The Tor Browser: intl/icu/source/common/unicode/utf8.h@6474c204b198 (annotated)

intl/icu/source/common/unicode/utf8.h@6474c204b198 (annotated)

intl/icu/source/common/unicode/utf8.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 (C) 1999-2013, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 *******************************************************************************
 *   file name:  utf8.h
 *   encoding:   US-ASCII
 *   tab size:   8 (not used)
 *   indentation:4
 *
 *   created on: 1999sep13
 *   created by: Markus W. Scherer
 */
 /**
  * \file
  * \brief C API: 8-bit Unicode handling macros
  *
  * This file defines macros to deal with 8-bit Unicode (UTF-8) code units (bytes) and strings.
  *
  * For more information see utf.h and the ICU User Guide Strings chapter
  * (http://userguide.icu-project.org/strings).
  *
  * <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.
  */
 #ifndef __UTF8_H__
 #define __UTF8_H__
 #include "unicode/umachine.h"
 #ifndef __UTF_H__
 #   include "unicode/utf.h"
 #endif
 /* internal definitions ----------------------------------------------------- */
 /**
  * \var utf8_countTrailBytes
  * Internal array with numbers of trail bytes for any given byte used in
  * lead byte position.
  *
  * This is internal since it is not meant to be called directly by external clients;
  * however it is called by public macros in this file and thus must remain stable,
  * and should not be hidden when other internal functions are hidden (otherwise
  * public macros would fail to compile).
  * @internal
  */
 #ifdef U_UTF8_IMPL
 U_EXPORT const uint8_t
 #elif defined(U_STATIC_IMPLEMENTATION) || defined(U_COMMON_IMPLEMENTATION)
 U_CFUNC const uint8_t
 #else
 U_CFUNC U_IMPORT const uint8_t /* U_IMPORT2? */ /*U_IMPORT*/
 #endif
 utf8_countTrailBytes[256];
 /**
  * Counts the trail bytes for a UTF-8 lead byte.
  * Returns 0 for 0..0xbf as well as for 0xfe and 0xff.
  *
  * This is internal since it is not meant to be called directly by external clients;
  * however it is called by public macros in this file and thus must remain stable.
  *
  * Note: Beginning with ICU 50, the implementation uses a multi-condition expression
  * which was shown in 2012 (on x86-64) to compile to fast, branch-free code.
  * leadByte is evaluated multiple times.
  *
  * The pre-ICU 50 implementation used the exported array utf8_countTrailBytes:
  * #define U8_COUNT_TRAIL_BYTES(leadByte) (utf8_countTrailBytes[leadByte])
  * leadByte was evaluated exactly once.
  *
  * @param leadByte The first byte of a UTF-8 sequence. Must be 0..0xff.
  * @internal
  */
 #define U8_COUNT_TRAIL_BYTES(leadByte) \
     ((leadByte)<0xf0 ? \
         ((leadByte)>=0xc0)+((leadByte)>=0xe0) : \
         (leadByte)<0xfe ? 3+((leadByte)>=0xf8)+((leadByte)>=0xfc) : 0)
 /**
  * Counts the trail bytes for a UTF-8 lead byte of a valid UTF-8 sequence.
  * The maximum supported lead byte is 0xf4 corresponding to U+10FFFF.
  * leadByte might be evaluated multiple times.
  *
  * This is internal since it is not meant to be called directly by external clients;
  * however it is called by public macros in this file and thus must remain stable.
  *
  * @param leadByte The first byte of a UTF-8 sequence. Must be 0..0xff.
  * @internal
  */
 #define U8_COUNT_TRAIL_BYTES_UNSAFE(leadByte) \
     (((leadByte)>=0xc0)+((leadByte)>=0xe0)+((leadByte)>=0xf0))
 /**
  * Mask a UTF-8 lead byte, leave only the lower bits that form part of the code point value.
  *
  * This is internal since it is not meant to be called directly by external clients;
  * however it is called by public macros in this file and thus must remain stable.
  * @internal
  */
 #define U8_MASK_LEAD_BYTE(leadByte, countTrailBytes) ((leadByte)&=(1<<(6-(countTrailBytes)))-1)
 /**
  * Function for handling "next code point" with error-checking.
  *
  * This is internal since it is not meant to be called directly by external clients;
  * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
  * file and thus must remain stable, and should not be hidden when other internal
  * functions are hidden (otherwise public macros would fail to compile).
  * @internal
  */
 U_STABLE UChar32 U_EXPORT2
 utf8_nextCharSafeBody(const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict);
 /**
  * Function for handling "append code point" with error-checking.
  *
  * This is internal since it is not meant to be called directly by external clients;
  * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
  * file and thus must remain stable, and should not be hidden when other internal
  * functions are hidden (otherwise public macros would fail to compile).
  * @internal
  */
 U_STABLE int32_t U_EXPORT2
 utf8_appendCharSafeBody(uint8_t *s, int32_t i, int32_t length, UChar32 c, UBool *pIsError);
 /**
  * Function for handling "previous code point" with error-checking.
  *
  * This is internal since it is not meant to be called directly by external clients;
  * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
  * file and thus must remain stable, and should not be hidden when other internal
  * functions are hidden (otherwise public macros would fail to compile).
  * @internal
  */
 U_STABLE UChar32 U_EXPORT2
 utf8_prevCharSafeBody(const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict);
 /**
  * Function for handling "skip backward one code point" with error-checking.
  *
  * This is internal since it is not meant to be called directly by external clients;
  * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
  * file and thus must remain stable, and should not be hidden when other internal
  * functions are hidden (otherwise public macros would fail to compile).
  * @internal
  */
 U_STABLE int32_t U_EXPORT2
 utf8_back1SafeBody(const uint8_t *s, int32_t start, int32_t i);
 /* single-code point definitions -------------------------------------------- */
 /**
  * Does this code unit (byte) encode a code point by itself (US-ASCII 0..0x7f)?
  * @param c 8-bit code unit (byte)
  * @return TRUE or FALSE
  * @stable ICU 2.4
  */
 #define U8_IS_SINGLE(c) (((c)&0x80)==0)
 /**
  * Is this code unit (byte) a UTF-8 lead byte?
  * @param c 8-bit code unit (byte)
  * @return TRUE or FALSE
  * @stable ICU 2.4
  */
 #define U8_IS_LEAD(c) ((uint8_t)((c)-0xc0)<0x3e)
 /**
  * Is this code unit (byte) a UTF-8 trail byte?
  * @param c 8-bit code unit (byte)
  * @return TRUE or FALSE
  * @stable ICU 2.4
  */
 #define U8_IS_TRAIL(c) (((c)&0xc0)==0x80)
 /**
  * How many code units (bytes) are used for the UTF-8 encoding
  * of this Unicode code point?
  * @param c 32-bit code point
  * @return 1..4, or 0 if c is a surrogate or not a Unicode code point
  * @stable ICU 2.4
  */
 #define U8_LENGTH(c) \
     ((uint32_t)(c)<=0x7f ? 1 : \
         ((uint32_t)(c)<=0x7ff ? 2 : \
             ((uint32_t)(c)<=0xd7ff ? 3 : \
                 ((uint32_t)(c)<=0xdfff || (uint32_t)(c)>0x10ffff ? 0 : \
                     ((uint32_t)(c)<=0xffff ? 3 : 4)\
                 ) \
             ) \
         ) \
     )
 /**
  * The maximum number of UTF-8 code units (bytes) per Unicode code point (U+0000..U+10ffff).
  * @return 4
  * @stable ICU 2.4
  */
 #define U8_MAX_LENGTH 4
 /**
  * Get a code point from a string at a random-access offset,
  * without changing the offset.
  * The offset may point to either the lead byte or one of the trail bytes
  * for a code point, in which case the macro will read all of the bytes
  * for the code point.
  * The result is undefined if the offset points to an illegal UTF-8
  * byte sequence.
  * Iteration through a string is more efficient with U8_NEXT_UNSAFE or U8_NEXT.
  *
  * @param s const uint8_t * string
  * @param i string offset
  * @param c output UChar32 variable
  * @see U8_GET
  * @stable ICU 2.4
  */
 #define U8_GET_UNSAFE(s, i, c) { \
     int32_t _u8_get_unsafe_index=(int32_t)(i); \
     U8_SET_CP_START_UNSAFE(s, _u8_get_unsafe_index); \
     U8_NEXT_UNSAFE(s, _u8_get_unsafe_index, c); \
 }
 /**
  * Get a code point from a string at a random-access offset,
  * without changing the offset.
  * The offset may point to either the lead byte or one of the trail bytes
  * for a code point, in which case the macro will read all of the bytes
  * for the code point.
  *
  * The length can be negative for a NUL-terminated string.
  *
  * If the offset points to an illegal UTF-8 byte sequence, then
  * c is set to a negative value.
  * Iteration through a string is more efficient with U8_NEXT_UNSAFE or U8_NEXT.
  *
  * @param s const uint8_t * string
  * @param start int32_t starting string offset
  * @param i int32_t string offset, must be start<=i<length
  * @param length int32_t string length
  * @param c output UChar32 variable, set to <0 in case of an error
  * @see U8_GET_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_GET(s, start, i, length, c) { \
     int32_t _u8_get_index=(i); \
     U8_SET_CP_START(s, start, _u8_get_index); \
     U8_NEXT(s, _u8_get_index, length, c); \
 }
 #ifndef U_HIDE_DRAFT_API
 /**
  * Get a code point from a string at a random-access offset,
  * without changing the offset.
  * The offset may point to either the lead byte or one of the trail bytes
  * for a code point, in which case the macro will read all of the bytes
  * for the code point.
  *
  * The length can be negative for a NUL-terminated string.
  *
  * If the offset points to an illegal UTF-8 byte sequence, then
  * c is set to U+FFFD.
  * Iteration through a string is more efficient with U8_NEXT_UNSAFE or U8_NEXT_OR_FFFD.
  *
  * This macro does not distinguish between a real U+FFFD in the text
  * and U+FFFD returned for an ill-formed sequence.
  * Use U8_GET() if that distinction is important.
  *
  * @param s const uint8_t * string
  * @param start int32_t starting string offset
  * @param i int32_t string offset, must be start<=i<length
  * @param length int32_t string length
  * @param c output UChar32 variable, set to U+FFFD in case of an error
  * @see U8_GET
  * @draft ICU 51
  */
 #define U8_GET_OR_FFFD(s, start, i, length, c) { \
     int32_t _u8_get_index=(i); \
     U8_SET_CP_START(s, start, _u8_get_index); \
     U8_NEXT_OR_FFFD(s, _u8_get_index, length, c); \
 }
 #endif /* U_HIDE_DRAFT_API */
 /* definitions with forward iteration --------------------------------------- */
 /**
  * Get a code point from a string at a code point boundary offset,
  * and advance the offset to the next code point boundary.
  * (Post-incrementing forward iteration.)
  * "Unsafe" macro, assumes well-formed UTF-8.
  *
  * The offset may point to the lead byte of a multi-byte sequence,
  * in which case the macro will read the whole sequence.
  * The result is undefined if the offset points to a trail byte
  * or an illegal UTF-8 sequence.
  *
  * @param s const uint8_t * string
  * @param i string offset
  * @param c output UChar32 variable
  * @see U8_NEXT
  * @stable ICU 2.4
  */
 #define U8_NEXT_UNSAFE(s, i, c) { \
     (c)=(uint8_t)(s)[(i)++]; \
     if((c)>=0x80) { \
         if((c)<0xe0) { \
             (c)=(((c)&0x1f)<<6)|((s)[(i)++]&0x3f); \
         } else if((c)<0xf0) { \
             /* no need for (c&0xf) because the upper bits are truncated after <<12 in the cast to (UChar) */ \
             (c)=(UChar)(((c)<<12)|(((s)[i]&0x3f)<<6)|((s)[(i)+1]&0x3f)); \
             (i)+=2; \
         } else { \
             (c)=(((c)&7)<<18)|(((s)[i]&0x3f)<<12)|(((s)[(i)+1]&0x3f)<<6)|((s)[(i)+2]&0x3f); \
             (i)+=3; \
         } \
     } \
 }
 /**
  * Get a code point from a string at a code point boundary offset,
  * and advance the offset to the next code point boundary.
  * (Post-incrementing forward iteration.)
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * The length can be negative for a NUL-terminated string.
  *
  * The offset may point to the lead byte of a multi-byte sequence,
  * in which case the macro will read the whole sequence.
  * If the offset points to a trail byte or an illegal UTF-8 sequence, then
  * c is set to a negative value.
  *
  * @param s const uint8_t * string
  * @param i int32_t string offset, must be i<length
  * @param length int32_t string length
  * @param c output UChar32 variable, set to <0 in case of an error
  * @see U8_NEXT_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_NEXT(s, i, length, c) { \
     (c)=(uint8_t)(s)[(i)++]; \
     if((c)>=0x80) { \
         uint8_t __t1, __t2; \
         if( /* handle U+1000..U+CFFF inline */ \
             (0xe0<(c) && (c)<=0xec) && \
             (((i)+1)<(length) || (length)<0) && \
             (__t1=(uint8_t)((s)[i]-0x80))<=0x3f && \
             (__t2=(uint8_t)((s)[(i)+1]-0x80))<= 0x3f \
         ) { \
             /* no need for (c&0xf) because the upper bits are truncated after <<12 in the cast to (UChar) */ \
             (c)=(UChar)(((c)<<12)|(__t1<<6)|__t2); \
             (i)+=2; \
         } else if( /* handle U+0080..U+07FF inline */ \
             ((c)<0xe0 && (c)>=0xc2) && \
             ((i)!=(length)) && \
             (__t1=(uint8_t)((s)[i]-0x80))<=0x3f \
         ) { \
             (c)=(((c)&0x1f)<<6)|__t1; \
             ++(i); \
         } else { \
             /* function call for "complicated" and error cases */ \
             (c)=utf8_nextCharSafeBody((const uint8_t *)s, &(i), (length), c, -1); \
         } \
     } \
 }
 #ifndef U_HIDE_DRAFT_API
 /**
  * Get a code point from a string at a code point boundary offset,
  * and advance the offset to the next code point boundary.
  * (Post-incrementing forward iteration.)
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * The length can be negative for a NUL-terminated string.
  *
  * The offset may point to the lead byte of a multi-byte sequence,
  * in which case the macro will read the whole sequence.
  * If the offset points to a trail byte or an illegal UTF-8 sequence, then
  * c is set to U+FFFD.
  *
  * This macro does not distinguish between a real U+FFFD in the text
  * and U+FFFD returned for an ill-formed sequence.
  * Use U8_NEXT() if that distinction is important.
  *
  * @param s const uint8_t * string
  * @param i int32_t string offset, must be i<length
  * @param length int32_t string length
  * @param c output UChar32 variable, set to U+FFFD in case of an error
  * @see U8_NEXT
  * @draft ICU 51
  */
 #define U8_NEXT_OR_FFFD(s, i, length, c) { \
     (c)=(uint8_t)(s)[(i)++]; \
     if((c)>=0x80) { \
         uint8_t __t1, __t2; \
         if( /* handle U+1000..U+CFFF inline */ \
             (0xe0<(c) && (c)<=0xec) && \
             (((i)+1)<(length) || (length)<0) && \
             (__t1=(uint8_t)((s)[i]-0x80))<=0x3f && \
             (__t2=(uint8_t)((s)[(i)+1]-0x80))<= 0x3f \
         ) { \
             /* no need for (c&0xf) because the upper bits are truncated after <<12 in the cast to (UChar) */ \
             (c)=(UChar)(((c)<<12)|(__t1<<6)|__t2); \
             (i)+=2; \
         } else if( /* handle U+0080..U+07FF inline */ \
             ((c)<0xe0 && (c)>=0xc2) && \
             ((i)!=(length)) && \
             (__t1=(uint8_t)((s)[i]-0x80))<=0x3f \
         ) { \
             (c)=(((c)&0x1f)<<6)|__t1; \
             ++(i); \
         } else { \
             /* function call for "complicated" and error cases */ \
             (c)=utf8_nextCharSafeBody((const uint8_t *)s, &(i), (length), c, -3); \
         } \
     } \
 }
 #endif /* U_HIDE_DRAFT_API */
 /**
  * Append a code point to a string, overwriting 1 to 4 bytes.
  * The offset points to the current end of the string contents
  * and is advanced (post-increment).
  * "Unsafe" macro, assumes a valid code point and sufficient space in the string.
  * Otherwise, the result is undefined.
  *
  * @param s const uint8_t * string buffer
  * @param i string offset
  * @param c code point to append
  * @see U8_APPEND
  * @stable ICU 2.4
  */
 #define U8_APPEND_UNSAFE(s, i, c) { \
     if((uint32_t)(c)<=0x7f) { \
         (s)[(i)++]=(uint8_t)(c); \
     } else { \
         if((uint32_t)(c)<=0x7ff) { \
             (s)[(i)++]=(uint8_t)(((c)>>6)|0xc0); \
         } else { \
             if((uint32_t)(c)<=0xffff) { \
                 (s)[(i)++]=(uint8_t)(((c)>>12)|0xe0); \
             } else { \
                 (s)[(i)++]=(uint8_t)(((c)>>18)|0xf0); \
                 (s)[(i)++]=(uint8_t)((((c)>>12)&0x3f)|0x80); \
             } \
             (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80); \
         } \
         (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); \
     } \
 }
 /**
  * Append a code point to a string, overwriting 1 to 4 bytes.
  * The offset points to the current end of the string contents
  * and is advanced (post-increment).
  * "Safe" macro, checks for a valid code point.
  * If a non-ASCII code point is written, checks for sufficient space in the string.
  * If the code point is not valid or trail bytes do not fit,
  * then isError is set to TRUE.
  *
  * @param s const uint8_t * string buffer
  * @param i int32_t string offset, must be i<capacity
  * @param capacity int32_t size of the string buffer
  * @param c UChar32 code point to append
  * @param isError output UBool set to TRUE if an error occurs, otherwise not modified
  * @see U8_APPEND_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_APPEND(s, i, capacity, c, isError) { \
     if((uint32_t)(c)<=0x7f) { \
         (s)[(i)++]=(uint8_t)(c); \
     } else if((uint32_t)(c)<=0x7ff && (i)+1<(capacity)) { \
         (s)[(i)++]=(uint8_t)(((c)>>6)|0xc0); \
         (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); \
     } else if((uint32_t)(c)<=0xd7ff && (i)+2<(capacity)) { \
         (s)[(i)++]=(uint8_t)(((c)>>12)|0xe0); \
         (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80); \
         (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); \
     } else { \
         (i)=utf8_appendCharSafeBody(s, (i), (capacity), c, &(isError)); \
     } \
 }
 /**
  * Advance the string offset from one code point boundary to the next.
  * (Post-incrementing iteration.)
  * "Unsafe" macro, assumes well-formed UTF-8.
  *
  * @param s const uint8_t * string
  * @param i string offset
  * @see U8_FWD_1
  * @stable ICU 2.4
  */
 #define U8_FWD_1_UNSAFE(s, i) { \
     (i)+=1+U8_COUNT_TRAIL_BYTES_UNSAFE((uint8_t)(s)[i]); \
 }
 /**
  * Advance the string offset from one code point boundary to the next.
  * (Post-incrementing iteration.)
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * The length can be negative for a NUL-terminated string.
  *
  * @param s const uint8_t * string
  * @param i int32_t string offset, must be i<length
  * @param length int32_t string length
  * @see U8_FWD_1_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_FWD_1(s, i, length) { \
     uint8_t __b=(uint8_t)(s)[(i)++]; \
     if(U8_IS_LEAD(__b)) { \
         uint8_t __count=U8_COUNT_TRAIL_BYTES(__b); \
         if((i)+__count>(length) && (length)>=0) { \
             __count=(uint8_t)((length)-(i)); \
         } \
         while(__count>0 && U8_IS_TRAIL((s)[i])) { \
             ++(i); \
             --__count; \
         } \
     } \
 }
 /**
  * Advance the string offset from one code point boundary to the n-th next one,
  * i.e., move forward by n code points.
  * (Post-incrementing iteration.)
  * "Unsafe" macro, assumes well-formed UTF-8.
  *
  * @param s const uint8_t * string
  * @param i string offset
  * @param n number of code points to skip
  * @see U8_FWD_N
  * @stable ICU 2.4
  */
 #define U8_FWD_N_UNSAFE(s, i, n) { \
     int32_t __N=(n); \
     while(__N>0) { \
         U8_FWD_1_UNSAFE(s, i); \
         --__N; \
     } \
 }
 /**
  * Advance the string offset from one code point boundary to the n-th next one,
  * i.e., move forward by n code points.
  * (Post-incrementing iteration.)
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * The length can be negative for a NUL-terminated string.
  *
  * @param s const uint8_t * string
  * @param i int32_t string offset, must be i<length
  * @param length int32_t string length
  * @param n number of code points to skip
  * @see U8_FWD_N_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_FWD_N(s, i, length, n) { \
     int32_t __N=(n); \
     while(__N>0 && ((i)<(length) || ((length)<0 && (s)[i]!=0))) { \
         U8_FWD_1(s, i, length); \
         --__N; \
     } \
 }
 /**
  * Adjust a random-access offset to a code point boundary
  * at the start of a code point.
  * If the offset points to a UTF-8 trail byte,
  * then the offset is moved backward to the corresponding lead byte.
  * Otherwise, it is not modified.
  * "Unsafe" macro, assumes well-formed UTF-8.
  *
  * @param s const uint8_t * string
  * @param i string offset
  * @see U8_SET_CP_START
  * @stable ICU 2.4
  */
 #define U8_SET_CP_START_UNSAFE(s, i) { \
     while(U8_IS_TRAIL((s)[i])) { --(i); } \
 }
 /**
  * Adjust a random-access offset to a code point boundary
  * at the start of a code point.
  * If the offset points to a UTF-8 trail byte,
  * then the offset is moved backward to the corresponding lead byte.
  * Otherwise, it is not modified.
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * @param s const uint8_t * string
  * @param start int32_t starting string offset (usually 0)
  * @param i int32_t string offset, must be start<=i
  * @see U8_SET_CP_START_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_SET_CP_START(s, start, i) { \
     if(U8_IS_TRAIL((s)[(i)])) { \
         (i)=utf8_back1SafeBody(s, start, (i)); \
     } \
 }
 /* definitions with backward iteration -------------------------------------- */
 /**
  * Move the string offset from one code point boundary to the previous one
  * and get the code point between them.
  * (Pre-decrementing backward iteration.)
  * "Unsafe" macro, assumes well-formed UTF-8.
  *
  * The input offset may be the same as the string length.
  * If the offset is behind a multi-byte sequence, then the macro will read
  * the whole sequence.
  * If the offset is behind a lead byte, then that itself
  * will be returned as the code point.
  * The result is undefined if the offset is behind an illegal UTF-8 sequence.
  *
  * @param s const uint8_t * string
  * @param i string offset
  * @param c output UChar32 variable
  * @see U8_PREV
  * @stable ICU 2.4
  */
 #define U8_PREV_UNSAFE(s, i, c) { \
     (c)=(uint8_t)(s)[--(i)]; \
     if(U8_IS_TRAIL(c)) { \
         uint8_t __b, __count=1, __shift=6; \
 \
         /* c is a trail byte */ \
         (c)&=0x3f; \
         for(;;) { \
             __b=(uint8_t)(s)[--(i)]; \
             if(__b>=0xc0) { \
                 U8_MASK_LEAD_BYTE(__b, __count); \
                 (c)|=(UChar32)__b<<__shift; \
                 break; \
             } else { \
                 (c)|=(UChar32)(__b&0x3f)<<__shift; \
                 ++__count; \
                 __shift+=6; \
             } \
         } \
     } \
 }
 /**
  * Move the string offset from one code point boundary to the previous one
  * and get the code point between them.
  * (Pre-decrementing backward iteration.)
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * The input offset may be the same as the string length.
  * If the offset is behind a multi-byte sequence, then the macro will read
  * the whole sequence.
  * If the offset is behind a lead byte, then that itself
  * will be returned as the code point.
  * If the offset is behind an illegal UTF-8 sequence, then c is set to a negative value.
  *
  * @param s const uint8_t * string
  * @param start int32_t starting string offset (usually 0)
  * @param i int32_t string offset, must be start<i
  * @param c output UChar32 variable, set to <0 in case of an error
  * @see U8_PREV_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_PREV(s, start, i, c) { \
     (c)=(uint8_t)(s)[--(i)]; \
     if((c)>=0x80) { \
         (c)=utf8_prevCharSafeBody((const uint8_t *)s, start, &(i), c, -1); \
     } \
 }
 #ifndef U_HIDE_DRAFT_API
 /**
  * Move the string offset from one code point boundary to the previous one
  * and get the code point between them.
  * (Pre-decrementing backward iteration.)
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * The input offset may be the same as the string length.
  * If the offset is behind a multi-byte sequence, then the macro will read
  * the whole sequence.
  * If the offset is behind a lead byte, then that itself
  * will be returned as the code point.
  * If the offset is behind an illegal UTF-8 sequence, then c is set to U+FFFD.
  *
  * This macro does not distinguish between a real U+FFFD in the text
  * and U+FFFD returned for an ill-formed sequence.
  * Use U8_PREV() if that distinction is important.
  *
  * @param s const uint8_t * string
  * @param start int32_t starting string offset (usually 0)
  * @param i int32_t string offset, must be start<i
  * @param c output UChar32 variable, set to U+FFFD in case of an error
  * @see U8_PREV
  * @draft ICU 51
  */
 #define U8_PREV_OR_FFFD(s, start, i, c) { \
     (c)=(uint8_t)(s)[--(i)]; \
     if((c)>=0x80) { \
         (c)=utf8_prevCharSafeBody((const uint8_t *)s, start, &(i), c, -3); \
     } \
 }
 #endif /* U_HIDE_DRAFT_API */
 /**
  * Move the string offset from one code point boundary to the previous one.
  * (Pre-decrementing backward iteration.)
  * The input offset may be the same as the string length.
  * "Unsafe" macro, assumes well-formed UTF-8.
  *
  * @param s const uint8_t * string
  * @param i string offset
  * @see U8_BACK_1
  * @stable ICU 2.4
  */
 #define U8_BACK_1_UNSAFE(s, i) { \
     while(U8_IS_TRAIL((s)[--(i)])) {} \
 }
 /**
  * Move the string offset from one code point boundary to the previous one.
  * (Pre-decrementing backward iteration.)
  * The input offset may be the same as the string length.
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * @param s const uint8_t * string
  * @param start int32_t starting string offset (usually 0)
  * @param i int32_t string offset, must be start<i
  * @see U8_BACK_1_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_BACK_1(s, start, i) { \
     if(U8_IS_TRAIL((s)[--(i)])) { \
         (i)=utf8_back1SafeBody(s, start, (i)); \
     } \
 }
 /**
  * Move the string offset from one code point boundary to the n-th one before it,
  * i.e., move backward by n code points.
  * (Pre-decrementing backward iteration.)
  * The input offset may be the same as the string length.
  * "Unsafe" macro, assumes well-formed UTF-8.
  *
  * @param s const uint8_t * string
  * @param i string offset
  * @param n number of code points to skip
  * @see U8_BACK_N
  * @stable ICU 2.4
  */
 #define U8_BACK_N_UNSAFE(s, i, n) { \
     int32_t __N=(n); \
     while(__N>0) { \
         U8_BACK_1_UNSAFE(s, i); \
         --__N; \
     } \
 }
 /**
  * Move the string offset from one code point boundary to the n-th one before it,
  * i.e., move backward by n code points.
  * (Pre-decrementing backward iteration.)
  * The input offset may be the same as the string length.
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * @param s const uint8_t * string
  * @param start int32_t index of the start of the string
  * @param i int32_t string offset, must be start<i
  * @param n number of code points to skip
  * @see U8_BACK_N_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_BACK_N(s, start, i, n) { \
     int32_t __N=(n); \
     while(__N>0 && (i)>(start)) { \
         U8_BACK_1(s, start, i); \
         --__N; \
     } \
 }
 /**
  * Adjust a random-access offset to a code point boundary after a code point.
  * If the offset is behind a partial multi-byte sequence,
  * then the offset is incremented to behind the whole sequence.
  * Otherwise, it is not modified.
  * The input offset may be the same as the string length.
  * "Unsafe" macro, assumes well-formed UTF-8.
  *
  * @param s const uint8_t * string
  * @param i string offset
  * @see U8_SET_CP_LIMIT
  * @stable ICU 2.4
  */
 #define U8_SET_CP_LIMIT_UNSAFE(s, i) { \
     U8_BACK_1_UNSAFE(s, i); \
     U8_FWD_1_UNSAFE(s, i); \
 }
 /**
  * Adjust a random-access offset to a code point boundary after a code point.
  * If the offset is behind a partial multi-byte sequence,
  * then the offset is incremented to behind the whole sequence.
  * Otherwise, it is not modified.
  * The input offset may be the same as the string length.
  * "Safe" macro, checks for illegal sequences and for string boundaries.
  *
  * The length can be negative for a NUL-terminated string.
  *
  * @param s const uint8_t * string
  * @param start int32_t starting string offset (usually 0)
  * @param i int32_t string offset, must be start<=i<=length
  * @param length int32_t string length
  * @see U8_SET_CP_LIMIT_UNSAFE
  * @stable ICU 2.4
  */
 #define U8_SET_CP_LIMIT(s, start, i, length) { \
     if((start)<(i) && ((i)<(length) || ((length)<0 && (s)[i]!=0))) { \
         U8_BACK_1(s, start, i); \
         U8_FWD_1(s, i, length); \
     } \
 }
 #endif

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intl/icu/source/common/unicode/utf8.h@6474c204b198 (annotated)

intl/icu/source/common/unicode/utf8.h