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Macros | Functions | Variables
utf8.h File Reference

C API: 8-bit Unicode handling macros. More...

`#include "unicode/umachine.h"`
`#include "unicode/utf.h"`

Go to the source code of this file.

## Macros
#define | U8_COUNT_TRAIL_BYTES(leadByte)
| Counts the trail bytes for a UTF-8 lead byte. More...
#define | U8_COUNT_TRAIL_BYTES_UNSAFE(leadByte) (((leadByte)>=0xc0)+((leadByte)>=0xe0)+((leadByte)>=0xf0))
| Counts the trail bytes for a UTF-8 lead byte of a valid UTF-8 sequence. More...
#define | U8_MASK_LEAD_BYTE(leadByte, countTrailBytes) ((leadByte)&=(1<<(6-(countTrailBytes)))-1)
| Mask a UTF-8 lead byte, leave only the lower bits that form part of the code point value. More...
#define | U8_IS_SINGLE(c) (((c)&0x80)==0)
| Does this code unit (byte) encode a code point by itself (US-ASCII 0..0x7f)? More...
#define | U8_IS_LEAD(c) ((uint8_t)((c)-0xc0)<0x3e)
| Is this code unit (byte) a UTF-8 lead byte? More...
#define | U8_IS_TRAIL(c) (((c)&0xc0)==0x80)
| Is this code unit (byte) a UTF-8 trail byte? More...
#define | U8_LENGTH(c)
| How many code units (bytes) are used for the UTF-8 encoding of this Unicode code point? More...
#define | U8_MAX_LENGTH 4
| The maximum number of UTF-8 code units (bytes) per Unicode code point (U+0000..U+10ffff). More...
#define | U8_GET_UNSAFE(s, i, c)
| Get a code point from a string at a random-access offset, without changing the offset. More...
#define | U8_GET(s, start, i, length, c)
| Get a code point from a string at a random-access offset, without changing the offset. More...
#define | U8_GET_OR_FFFD(s, start, i, length, c)
| Get a code point from a string at a random-access offset, without changing the offset. More...
#define | U8_NEXT_UNSAFE(s, i, c)
| Get a code point from a string at a code point boundary offset, and advance the offset to the next code point boundary. More...
#define | U8_NEXT(s, i, length, c)
| Get a code point from a string at a code point boundary offset, and advance the offset to the next code point boundary. More...
#define | U8_NEXT_OR_FFFD(s, i, length, c)
| Get a code point from a string at a code point boundary offset, and advance the offset to the next code point boundary. More...
#define | U8_APPEND_UNSAFE(s, i, c)
| Append a code point to a string, overwriting 1 to 4 bytes. More...
#define | U8_APPEND(s, i, capacity, c, isError)
| Append a code point to a string, overwriting 1 to 4 bytes. More...
#define | U8_FWD_1_UNSAFE(s, i)
| Advance the string offset from one code point boundary to the next. More...
#define | U8_FWD_1(s, i, length)
| Advance the string offset from one code point boundary to the next. More...
#define | U8_FWD_N_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. More...
#define | U8_FWD_N(s, i, length, n)
| Advance the string offset from one code point boundary to the n-th next one, i.e., move forward by n code points. More...
#define | U8_SET_CP_START_UNSAFE(s, i)
| Adjust a random-access offset to a code point boundary at the start of a code point. More...
#define | U8_SET_CP_START(s, start, i)
| Adjust a random-access offset to a code point boundary at the start of a code point. More...
#define | U8_PREV_UNSAFE(s, i, c)
| Move the string offset from one code point boundary to the previous one and get the code point between them. More...
#define | U8_PREV(s, start, i, c)
| Move the string offset from one code point boundary to the previous one and get the code point between them. More...
#define | U8_PREV_OR_FFFD(s, start, i, c)
| Move the string offset from one code point boundary to the previous one and get the code point between them. More...
#define | U8_BACK_1_UNSAFE(s, i)
| Move the string offset from one code point boundary to the previous one. More...
#define | U8_BACK_1(s, start, i)
| Move the string offset from one code point boundary to the previous one. More...
#define | U8_BACK_N_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. More...
#define | U8_BACK_N(s, start, 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. More...
#define | U8_SET_CP_LIMIT_UNSAFE(s, i)
| Adjust a random-access offset to a code point boundary after a code point. More...
#define | U8_SET_CP_LIMIT(s, start, i, length)
| Adjust a random-access offset to a code point boundary after a code point. More...

## Functions
UChar32 | utf8_nextCharSafeBody (const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict)
| Function for handling "next code point" with error-checking. More...
int32_t | utf8_appendCharSafeBody (uint8_t *s, int32_t i, int32_t length, UChar32 c, UBool *pIsError)
| Function for handling "append code point" with error-checking. More...
UChar32 | utf8_prevCharSafeBody (const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict)
| Function for handling "previous code point" with error-checking. More...
int32_t | utf8_back1SafeBody (const uint8_t *s, int32_t start, int32_t i)
| Function for handling "skip backward one code point" with error-checking. More...

## Variables
U_CFUNC U_IMPORT const uint8_t | utf8_countTrailBytes [256]
| Internal array with numbers of trail bytes for any given byte used in lead byte position. More...

## Detailed Description

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).

Usage: 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.

Definition in file utf8.h.

## Macro Definition Documentation

#define U8_APPEND | ( |  | s,
|  |  | i,
|  |  | capacity,
|  |  | c,
|  |  | isError
| ) |  |

Value:
{ \
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)); \
} \
}
utf8_appendCharSafeBody
int32_t utf8_appendCharSafeBody(uint8_t *s, int32_t i, int32_t length, UChar32 c, UBool *pIsError)
Function for handling "append code point" with error-checking.

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.

Parameters

  s | const uint8_t * string buffer
  i | int32_t string offset, must be i<capacity
  capacity | int32_t size of the string buffer
  c | UChar32 code point to append
  isError | output UBool set to TRUE if an error occurs, otherwise not modified

See also
  U8_APPEND_UNSAFE

Stable:
  ICU 2.4

Definition at line 471 of file utf8.h.

#define U8_APPEND_UNSAFE | ( |  | s,
|  |  | i,
|  |  | c
| ) |  |

Value:
{ \
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). "Unsafe" macro, assumes a valid code point and sufficient space in the string. Otherwise, the result is undefined.

Parameters

  s | const uint8_t * string buffer
  i | string offset
  c | code point to append

See also
  U8_APPEND

Stable:
  ICU 2.4

Definition at line 435 of file utf8.h.

#define U8_BACK_1 | ( |  | s,
|  |  | start,
|  |  | i
| ) |  |

Value:
{ \
if(U8_IS_TRAIL((s)[--(i)])) { \
(i)=utf8_back1SafeBody(s, start, (i)); \
} \
}
U8_IS_TRAIL
#define U8_IS_TRAIL(c)
Is this code unit (byte) a UTF-8 trail byte?
Definition: utf8.h:182
utf8_back1SafeBody
int32_t utf8_back1SafeBody(const uint8_t *s, int32_t start, int32_t i)
Function for handling "skip backward one code point" with error-checking.

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.

Parameters

  s | const uint8_t * string
  start | int32_t starting string offset (usually 0)
  i | int32_t string offset, must be start<i

See also
  U8_BACK_1_UNSAFE

Stable:
  ICU 2.4

Definition at line 735 of file utf8.h.

#define U8_BACK_1_UNSAFE | ( |  | s,
|  |  | i
| ) |  |

Value:
{ \
while(U8_IS_TRAIL((s)[--(i)])) {} \
}
U8_IS_TRAIL
#define U8_IS_TRAIL(c)
Is this code unit (byte) a UTF-8 trail byte?
Definition: utf8.h:182

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.

Parameters

  s | const uint8_t * string
  i | string offset

See also
  U8_BACK_1

Stable:
  ICU 2.4

Definition at line 719 of file utf8.h.

#define U8_BACK_N | ( |  | s,
|  |  | start,
|  |  | i,
|  |  | n
| ) |  |

Value:
{ \
int32_t __N=(n); \
while(__N>0 && (i)>(start)) { \
U8_BACK_1(s, start, i); \
--__N; \
} \
}
U8_BACK_1
#define U8_BACK_1(s, start, i)
Move the string offset from one code point boundary to the previous one.
Definition: utf8.h:735

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.

Parameters

  s | const uint8_t * string
  start | int32_t index of the start of the string
  i | int32_t string offset, must be start<i
  n | number of code points to skip

See also
  U8_BACK_N_UNSAFE

Stable:
  ICU 2.4

Definition at line 776 of file utf8.h.

#define U8_BACK_N_UNSAFE | ( |  | s,
|  |  | i,
|  |  | n
| ) |  |

Value:
{ \
int32_t __N=(n); \
while(__N>0) { \
U8_BACK_1_UNSAFE(s, i); \
--__N; \
} \
}
U8_BACK_1_UNSAFE
#define U8_BACK_1_UNSAFE(s, i)
Move the string offset from one code point boundary to the previous one.
Definition: utf8.h:719

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.

Parameters

  s | const uint8_t * string
  i | string offset
  n | number of code points to skip

See also
  U8_BACK_N

Stable:
  ICU 2.4

Definition at line 754 of file utf8.h.

#define U8_COUNT_TRAIL_BYTES | ( |  | leadByte | ) |

Value:
((uint8_t)(leadByte)<0xf0 ? \
((uint8_t)(leadByte)>=0xc0)+((uint8_t)(leadByte)>=0xe0) : \
(uint8_t)(leadByte)<0xfe ? 3+((uint8_t)(leadByte)>=0xf8)+((uint8_t)(leadByte)>=0xfc) : 0)

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.

Parameters

  leadByte | The first byte of a UTF-8 sequence. Must be 0..0xff.

Internal:
  Do not use. This API is for internal use only.

Definition at line 82 of file utf8.h.

#define U8_COUNT_TRAIL_BYTES_UNSAFE | ( |  | leadByte | ) | (((leadByte)>=0xc0)+((leadByte)>=0xe0)+((leadByte)>=0xf0))

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.

Parameters

  leadByte | The first byte of a UTF-8 sequence. Must be 0..0xff.

Internal:
  Do not use. This API is for internal use only.

Definition at line 98 of file utf8.h.

#define U8_FWD_1 | ( |  | s,
|  |  | i,
|  |  | length
| ) |  |

Value:
{ \
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; \
} \
} \
}
U8_IS_LEAD
#define U8_IS_LEAD(c)
Is this code unit (byte) a UTF-8 lead byte?
Definition: utf8.h:174
U8_COUNT_TRAIL_BYTES
#define U8_COUNT_TRAIL_BYTES(leadByte)
Counts the trail bytes for a UTF-8 lead byte.
Definition: utf8.h:82
U8_IS_TRAIL
#define U8_IS_TRAIL(c)
Is this code unit (byte) a UTF-8 trail byte?
Definition: utf8.h:182

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.

Parameters

  s | const uint8_t * string
  i | int32_t string offset, must be i<length
  length | int32_t string length

See also
  U8_FWD_1_UNSAFE

Stable:
  ICU 2.4

Definition at line 513 of file utf8.h.

#define U8_FWD_1_UNSAFE | ( |  | s,
|  |  | i
| ) |  |

Value:
{ \
(i)+=1+U8_COUNT_TRAIL_BYTES_UNSAFE((uint8_t)(s)[i]); \
}
U8_COUNT_TRAIL_BYTES_UNSAFE
#define U8_COUNT_TRAIL_BYTES_UNSAFE(leadByte)
Counts the trail bytes for a UTF-8 lead byte of a valid UTF-8 sequence.
Definition: utf8.h:98

Advance the string offset from one code point boundary to the next.

(Post-incrementing iteration.) "Unsafe" macro, assumes well-formed UTF-8.

Parameters

  s | const uint8_t * string
  i | string offset

See also
  U8_FWD_1

Stable:
  ICU 2.4

Definition at line 496 of file utf8.h.

#define U8_FWD_N | ( |  | s,
|  |  | i,
|  |  | length,
|  |  | n
| ) |  |

Value:
{ \
int32_t __N=(n); \
while(__N>0 && ((i)<(length) || ((length)<0 && (s)[i]!=0))) { \
U8_FWD_1(s, i, length); \
--__N; \
} \
}
U8_FWD_1
#define U8_FWD_1(s, i, length)
Advance the string offset from one code point boundary to the next.
Definition: utf8.h:513

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.

Parameters

  s | const uint8_t * string
  i | int32_t string offset, must be i<length
  length | int32_t string length
  n | number of code points to skip

See also
  U8_FWD_N_UNSAFE

Stable:
  ICU 2.4

Definition at line 562 of file utf8.h.

#define U8_FWD_N_UNSAFE | ( |  | s,
|  |  | i,
|  |  | n
| ) |  |

Value:
{ \
int32_t __N=(n); \
while(__N>0) { \
U8_FWD_1_UNSAFE(s, i); \
--__N; \
} \
}
U8_FWD_1_UNSAFE
#define U8_FWD_1_UNSAFE(s, i)
Advance the string offset from one code point boundary to the next.
Definition: utf8.h:496

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.

Parameters

  s | const uint8_t * string
  i | string offset
  n | number of code points to skip

See also
  U8_FWD_N

Stable:
  ICU 2.4

Definition at line 539 of file utf8.h.

#define U8_GET | ( |  | s,
|  |  | start,
|  |  | i,
|  |  | length,
|  |  | c
| ) |  |

Value:
{ \
int32_t _u8_get_index=(i); \
U8_SET_CP_START(s, start, _u8_get_index); \
U8_NEXT(s, _u8_get_index, length, c); \
}
U8_SET_CP_START
#define U8_SET_CP_START(s, start, i)
Adjust a random-access offset to a code point boundary at the start of a code point.
Definition: utf8.h:601
U8_NEXT
#define U8_NEXT(s, i, length, c)
Get a code point from a string at a code point boundary offset, and advance the offset to the next co...
Definition: utf8.h:344

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.

Parameters

  s | const uint8_t * string
  start | int32_t starting string offset
  i | int32_t string offset, must be start<=i<length
  length | int32_t string length
  c | output UChar32 variable, set to <0 in case of an error

See also
  U8_GET_UNSAFE

Stable:
  ICU 2.4

Definition at line 252 of file utf8.h.

#define U8_GET_OR_FFFD | ( |  | s,
|  |  | start,
|  |  | i,
|  |  | length,
|  |  | c
| ) |  |

Value:
{ \
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); \
}
U8_SET_CP_START
#define U8_SET_CP_START(s, start, i)
Adjust a random-access offset to a code point boundary at the start of a code point.
Definition: utf8.h:601
U8_NEXT_OR_FFFD
#define U8_NEXT_OR_FFFD(s, i, length, c)
Get a code point from a string at a code point boundary offset, and advance the offset to the next co...
Definition: utf8.h:395

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.

Parameters

  s | const uint8_t * string
  start | int32_t starting string offset
  i | int32_t string offset, must be start<=i<length
  length | int32_t string length
  c | output UChar32 variable, set to U+FFFD in case of an error

See also
  U8_GET

Stable:
  ICU 51

Definition at line 283 of file utf8.h.

#define U8_GET_UNSAFE | ( |  | s,
|  |  | i,
|  |  | c
| ) |  |

Value:
{ \
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); \
}
U8_SET_CP_START_UNSAFE
#define U8_SET_CP_START_UNSAFE(s, i)
Adjust a random-access offset to a code point boundary at the start of a code point.
Definition: utf8.h:583
U8_NEXT_UNSAFE
#define U8_NEXT_UNSAFE(s, i, c)
Get a code point from a string at a code point boundary offset, and advance the offset to the next co...
Definition: utf8.h:308

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.

Parameters

  s | const uint8_t * string
  i | string offset
  c | output UChar32 variable

See also
  U8_GET

Stable:
  ICU 2.4

Definition at line 225 of file utf8.h.

#define U8_IS_LEAD | ( |  | c | ) | ((uint8_t)((c)-0xc0)<0x3e)

Is this code unit (byte) a UTF-8 lead byte?

Parameters

  c | 8-bit code unit (byte)

Returns
  TRUE or FALSE

Stable:
  ICU 2.4

Definition at line 174 of file utf8.h.

#define U8_IS_SINGLE | ( |  | c | ) | (((c)&0x80)==0)

Does this code unit (byte) encode a code point by itself (US-ASCII 0..0x7f)?

Parameters

  c | 8-bit code unit (byte)

Returns
  TRUE or FALSE

Stable:
  ICU 2.4

Definition at line 166 of file utf8.h.

#define U8_IS_TRAIL | ( |  | c | ) | (((c)&0xc0)==0x80)

Is this code unit (byte) a UTF-8 trail byte?

Parameters

  c | 8-bit code unit (byte)

Returns
  TRUE or FALSE

Stable:
  ICU 2.4

Definition at line 182 of file utf8.h.

#define U8_LENGTH | ( |  | c | ) |

Value:
((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)\
) \
) \
) \
)

How many code units (bytes) are used for the UTF-8 encoding of this Unicode code point?

Parameters

  c | 32-bit code point

Returns
  1..4, or 0 if c is a surrogate or not a Unicode code point

Stable:
  ICU 2.4

Definition at line 191 of file utf8.h.

#define U8_MASK_LEAD_BYTE | ( |  | leadByte,
|  |  | countTrailBytes
| ) |  | ((leadByte)&=(1<<(6-(countTrailBytes)))-1)

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:
  Do not use. This API is for internal use only.

Definition at line 108 of file utf8.h.

#define U8_MAX_LENGTH 4

The maximum number of UTF-8 code units (bytes) per Unicode code point (U+0000..U+10ffff).

Returns
  4

Stable:
  ICU 2.4

Definition at line 207 of file utf8.h.

#define U8_NEXT | ( |  | s,
|  |  | i,
|  |  | length,
|  |  | c
| ) |  |

Value:
{ \
(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); \
} \
} \
}
utf8_nextCharSafeBody
UChar32 utf8_nextCharSafeBody(const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict)
Function for handling "next code point" with error-checking.
UChar
uint16_t UChar
Define UChar to be UCHAR_TYPE, if that is #defined (for example, to char16_t), or wchar_t if that is ...
Definition: umachine.h:337

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.

Parameters

  s | const uint8_t * string
  i | int32_t string offset, must be i<length
  length | int32_t string length
  c | output UChar32 variable, set to <0 in case of an error

See also
  U8_NEXT_UNSAFE

Stable:
  ICU 2.4

Definition at line 344 of file utf8.h.

#define U8_NEXT_OR_FFFD | ( |  | s,
|  |  | i,
|  |  | length,
|  |  | c
| ) |  |

Value:
{ \
(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); \
} \
} \
}
utf8_nextCharSafeBody
UChar32 utf8_nextCharSafeBody(const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict)
Function for handling "next code point" with error-checking.
UChar
uint16_t UChar
Define UChar to be UCHAR_TYPE, if that is #defined (for example, to char16_t), or wchar_t if that is ...
Definition: umachine.h:337

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.

Parameters

  s | const uint8_t * string
  i | int32_t string offset, must be i<length
  length | int32_t string length
  c | output UChar32 variable, set to U+FFFD in case of an error

See also
  U8_NEXT

Stable:
  ICU 51

Definition at line 395 of file utf8.h.

#define U8_NEXT_UNSAFE | ( |  | s,
|  |  | i,
|  |  | c
| ) |  |

Value:
{ \
(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; \
} \
} \
}
UChar
uint16_t UChar
Define UChar to be UCHAR_TYPE, if that is #defined (for example, to char16_t), or wchar_t if that is ...
Definition: umachine.h:337

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.

Parameters

  s | const uint8_t * string
  i | string offset
  c | output UChar32 variable

See also
  U8_NEXT

Stable:
  ICU 2.4

Definition at line 308 of file utf8.h.

#define U8_PREV | ( |  | s,
|  |  | start,
|  |  | i,
|  |  | c
| ) |  |

Value:
{ \
(c)=(uint8_t)(s)[--(i)]; \
if((c)>=0x80) { \
(c)=utf8_prevCharSafeBody((const uint8_t *)s, start, &(i), c, -1); \
} \
}
utf8_prevCharSafeBody
UChar32 utf8_prevCharSafeBody(const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict)
Function for handling "previous code point" with error-checking.

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.

Parameters

  s | const uint8_t * string
  start | int32_t starting string offset (usually 0)
  i | int32_t string offset, must be start<i
  c | output UChar32 variable, set to <0 in case of an error

See also
  U8_PREV_UNSAFE

Stable:
  ICU 2.4

Definition at line 670 of file utf8.h.

#define U8_PREV_OR_FFFD | ( |  | s,
|  |  | start,
|  |  | i,
|  |  | c
| ) |  |

Value:
{ \
(c)=(uint8_t)(s)[--(i)]; \
if((c)>=0x80) { \
(c)=utf8_prevCharSafeBody((const uint8_t *)s, start, &(i), c, -3); \
} \
}
utf8_prevCharSafeBody
UChar32 utf8_prevCharSafeBody(const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict)
Function for handling "previous code point" with error-checking.

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.

Parameters

  s | const uint8_t * string
  start | int32_t starting string offset (usually 0)
  i | int32_t string offset, must be start<i
  c | output UChar32 variable, set to U+FFFD in case of an error

See also
  U8_PREV

Stable:
  ICU 51

Definition at line 701 of file utf8.h.

#define U8_PREV_UNSAFE | ( |  | s,
|  |  | i,
|  |  | c
| ) |  |

Value:
{ \
(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; \
} \
} \
} \
}
U8_MASK_LEAD_BYTE
#define U8_MASK_LEAD_BYTE(leadByte, countTrailBytes)
Mask a UTF-8 lead byte, leave only the lower bits that form part of the code point value...
Definition: utf8.h:108
U8_IS_TRAIL
#define U8_IS_TRAIL(c)
Is this code unit (byte) a UTF-8 trail byte?
Definition: utf8.h:182
UChar32
int32_t UChar32
Define UChar32 as a type for single Unicode code points.
Definition: umachine.h:357

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.

Parameters

  s | const uint8_t * string
  i | string offset
  c | output UChar32 variable

See also
  U8_PREV

Stable:
  ICU 2.4

Definition at line 628 of file utf8.h.

#define U8_SET_CP_LIMIT | ( |  | s,
|  |  | start,
|  |  | i,
|  |  | length
| ) |  |

Value:
{ \
if((start)<(i) && ((i)<(length) || (length)<0)) { \
U8_BACK_1(s, start, i); \
U8_FWD_1(s, i, length); \
} \
}
U8_BACK_1
#define U8_BACK_1(s, start, i)
Move the string offset from one code point boundary to the previous one.
Definition: utf8.h:735
U8_FWD_1
#define U8_FWD_1(s, i, length)
Advance the string offset from one code point boundary to the next.
Definition: utf8.h:513

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.

Parameters

  s | const uint8_t * string
  start | int32_t starting string offset (usually 0)
  i | int32_t string offset, must be start<=i<=length
  length | int32_t string length

See also
  U8_SET_CP_LIMIT_UNSAFE

Stable:
  ICU 2.4

Definition at line 819 of file utf8.h.

#define U8_SET_CP_LIMIT_UNSAFE | ( |  | s,
|  |  | i
| ) |  |

Value:
{ \
U8_BACK_1_UNSAFE(s, i); \
U8_FWD_1_UNSAFE(s, i); \
}
U8_FWD_1_UNSAFE
#define U8_FWD_1_UNSAFE(s, i)
Advance the string offset from one code point boundary to the next.
Definition: utf8.h:496
U8_BACK_1_UNSAFE
#define U8_BACK_1_UNSAFE(s, i)
Move the string offset from one code point boundary to the previous one.
Definition: utf8.h:719

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.

Parameters

  s | const uint8_t * string
  i | string offset

See also
  U8_SET_CP_LIMIT

Stable:
  ICU 2.4

Definition at line 797 of file utf8.h.

#define U8_SET_CP_START | ( |  | s,
|  |  | start,
|  |  | i
| ) |  |

Value:
{ \
if(U8_IS_TRAIL((s)[(i)])) { \
(i)=utf8_back1SafeBody(s, start, (i)); \
} \
}
U8_IS_TRAIL
#define U8_IS_TRAIL(c)
Is this code unit (byte) a UTF-8 trail byte?
Definition: utf8.h:182
utf8_back1SafeBody
int32_t utf8_back1SafeBody(const uint8_t *s, int32_t start, int32_t i)
Function for handling "skip backward one code point" with error-checking.

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.

Parameters

  s | const uint8_t * string
  start | int32_t starting string offset (usually 0)
  i | int32_t string offset, must be start<=i

See also
  U8_SET_CP_START_UNSAFE

Stable:
  ICU 2.4

Definition at line 601 of file utf8.h.

#define U8_SET_CP_START_UNSAFE | ( |  | s,
|  |  | i
| ) |  |

Value:
{ \
while(U8_IS_TRAIL((s)[i])) { --(i); } \
}
U8_IS_TRAIL
#define U8_IS_TRAIL(c)
Is this code unit (byte) a UTF-8 trail byte?
Definition: utf8.h:182

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.

Parameters

  s | const uint8_t * string
  i | string offset

See also
  U8_SET_CP_START

Stable:
  ICU 2.4

Definition at line 583 of file utf8.h.

## Function Documentation

int32_t utf8_appendCharSafeBody | ( | uint8_t * | s,
|  | int32_t | i,
|  | int32_t | length,
|  | UChar32 | c,
|  | UBool * | pIsError
| ) |  |

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:
  Do not use. This API is for internal use only.

int32_t utf8_back1SafeBody | ( | const uint8_t * | s,
|  | int32_t | start,
|  | int32_t | i
| ) |  |

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:
  Do not use. This API is for internal use only.

UChar32 utf8_nextCharSafeBody | ( | const uint8_t * | s,
|  | int32_t * | pi,
|  | int32_t | length,
|  | UChar32 | c,
|  | UBool | strict
| ) |  |

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:
  Do not use. This API is for internal use only.

UChar32 utf8_prevCharSafeBody | ( | const uint8_t * | s,
|  | int32_t | start,
|  | int32_t * | pi,
|  | UChar32 | c,
|  | UBool | strict
| ) |  |

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:
  Do not use. This API is for internal use only.

## Variable Documentation

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:
  Do not use. This API is for internal use only.

Definition at line 62 of file utf8.h.