plucky (3) Tcl_UtfToChar16DString.3tcl.gz
NAME
Tcl_UniChar, Tcl_UniCharToUtf, Tcl_UtfToUniChar, Tcl_UtfToChar16, Tcl_UtfToWChar,
Tcl_UniCharToUtfDString, Tcl_UtfToUniCharDString, Tcl_Char16ToUtfDString, Tcl_UtfToWCharDString,
Tcl_UtfToChar16DString, Tcl_WCharToUtfDString, Tcl_WCharLen, Tcl_Char16Len, Tcl_UniCharLen,
Tcl_UniCharNcmp, Tcl_UniCharNcasecmp, Tcl_UniCharCaseMatch, Tcl_UtfNcmp, Tcl_UtfNcasecmp,
Tcl_UtfCharComplete, Tcl_NumUtfChars, Tcl_UtfFindFirst, Tcl_UtfFindLast, Tcl_UtfNext, Tcl_UtfPrev,
Tcl_UniCharAtIndex, Tcl_UtfAtIndex, Tcl_UtfBackslash - routines for manipulating UTF-8 strings
SYNOPSIS
#include <tcl.h>
typedef ... Tcl_UniChar;
Tcl_Size
Tcl_UniCharToUtf(ch, buf)
Tcl_Size
Tcl_UtfToUniChar(src, chPtr)
Tcl_Size
Tcl_UtfToChar16(src, uPtr)
Tcl_Size
Tcl_UtfToWChar(src, wPtr)
char *
Tcl_UniCharToUtfDString(uniStr, numUniChars, dsPtr)
char *
Tcl_Char16ToUtfDString(utf16, numUtf16, dsPtr)
char *
Tcl_WCharToUtfDString(wcharStr, numWChars, dsPtr)
Tcl_UniChar *
Tcl_UtfToUniCharDString(src, numBytes, dsPtr)
unsigned short *
Tcl_UtfToChar16DString(src, numBytes, dsPtr)
wchar_t *
Tcl_UtfToWCharDString(src, numBytes, dsPtr)
int
Tcl_Char16Len(utf16)
int
Tcl_WCharLen(wcharStr)
int
Tcl_UniCharLen(uniStr)
int
Tcl_UniCharNcmp(ucs, uct, uniLength)
int
Tcl_UniCharNcasecmp(ucs, uct, uniLength)
int
Tcl_UniCharCaseMatch(uniStr, uniPattern, nocase)
int
Tcl_UtfNcmp(cs, ct, length)
int
Tcl_UtfNcasecmp(cs, ct, length)
int
Tcl_UtfCharComplete(src, numBytes)
int
Tcl_NumUtfChars(src, numBytes)
const char *
Tcl_UtfFindFirst(src, ch)
const char *
Tcl_UtfFindLast(src, ch)
const char *
Tcl_UtfNext(src)
const char *
Tcl_UtfPrev(src, start)
int
Tcl_UniCharAtIndex(src, index)
const char *
Tcl_UtfAtIndex(src, index)
Tcl_Size
Tcl_UtfBackslash(src, readPtr, dst)
ARGUMENTS
char *buf (out) Buffer in which the UTF-8 representation of the Tcl_UniChar
is stored. At most 4 bytes are stored in the buffer.
int ch (in) The Unicode character to be converted or examined.
Tcl_UniChar *chPtr (out) Filled with the Tcl_UniChar represented by the head of the
UTF-8 string.
unsigned short (*uPtr) Filled with the utf-16 represented by the head of the UTF-8
string.
wchar_t *wPtr (out) Filled with the wchar_t represented by the head of the UTF-8
string.
const char *src (in) Pointer to a UTF-8 string.
const char *cs (in) Pointer to a UTF-8 string.
const char *ct (in) Pointer to a UTF-8 string.
const Tcl_UniChar *uniStr (in) A sequence of Tcl_UniChar units with null-termination
optional depending on function.
const Tcl_UniChar *ucs (in) A null-terminated sequence of Tcl_UniChar.
const Tcl_UniChar *uct (in) A null-terminated sequence of Tcl_UniChar.
const Tcl_UniChar *uniPattern (in) A null-terminated sequence of Tcl_UniChar.
const unsigned short *utf16 (in) A sequence of UTF-16 units with null-termination optional
depending on function.
const wchar_t *wcharStr (in) A sequence of wchar_t units with null-termination optional
depending on function.
int numBytes (in) The length of the UTF-8 input in bytes. If negative, the
length includes all bytes until the first null byte.
int numUtf16 (in) The length of the input in UTF-16 units. If negative, the
length includes all bytes until the first null.
int numUniChars (in) The length of the input in Tcl_UniChar units. If negative,
the length includes all bytes until the first null.
int numWChars (in) The length of the input in wchar_t units. If negative, the
length includes all bytes until the first null.
Tcl_DString *dsPtr (in/out) A pointer to a previously initialized Tcl_DString.
const char *start (in) Pointer to the beginning of a UTF-8 string.
Tcl_Size index (in) The index of a character (not byte) in the UTF-8 string.
int *readPtr (out) If non-NULL, filled with the number of bytes in the backslash
sequence, including the backslash character.
char *dst (out) Buffer in which the bytes represented by the backslash
sequence are stored. At most 4 bytes are stored in the
buffer.
int nocase (in) Specifies whether the match should be done case-sensitive (0)
or case-insensitive (1).
________________________________________________________________________________________________________________
DESCRIPTION
These routines convert between UTF-8 strings and Unicode/Utf-16 characters. A UTF-8 character is a
Unicode character represented as a varying-length sequence of up to 4 bytes. A multibyte UTF-8 sequence
consists of a lead byte followed by some number of trail bytes.
TCL_UTF_MAX is the maximum number of bytes that Tcl_UtfToUniChar can consume in a single call.
Tcl_UniCharToUtf stores the character ch as a UTF-8 string in starting at buf. The return value is the
number of bytes stored in buf. The character ch can be or'ed with the value TCL_COMBINE to enable special
behavior, compatible with Tcl 8.x. Then, if ch is a high surrogate (range U+D800 - U+DBFF), the return
value will be 1 and a single byte in the range 0xF0 - 0xF4 will be stored. If ch is a low surrogate
(range U+DC00 - U+DFFF), an attempt is made to combine the result with the earlier produced bytes,
resulting in a 4-byte UTF-8 byte sequence.
Tcl_UtfToUniChar reads one UTF-8 character starting at src and stores it as a Tcl_UniChar in *chPtr. The
return value is the number of bytes read from src. The caller must ensure that the source buffer is long
enough such that this routine does not run off the end and dereference non-existent or random memory; if
the source buffer is known to be null-terminated, this will not happen. If the input is a byte in the
range 0x80 - 0x9F, Tcl_UtfToUniChar assumes the cp1252 encoding, stores the corresponding Tcl_UniChar in
*chPtr and returns 1. If the input is otherwise not in proper UTF-8 format, Tcl_UtfToUniChar will store
the first byte of src in *chPtr as a Tcl_UniChar between 0x00A0 and 0x00FF and return 1.
Tcl_UniCharToUtfDString converts the input in the form of a sequence of Tcl_UniChar code points to UTF-8,
appending the result to the previously initialized output Tcl_DString. The return value is a pointer to
the UTF-8 representation of the appended string.
Tcl_UtfToUniCharDString converts the input in the form of a UTF-8 encoded string to a Tcl_UniChar
sequence appending the result in the previously initialized Tcl_DString. The return value is a pointer
to the appended result which is also terminated with a Tcl_UniChar null character.
Tcl_WCharToUtfDString and Tcl_UtfToWCharDString are similar to Tcl_UniCharToUtfDString and
Tcl_UtfToUniCharDString except they operate on sequences of wchar_t instead of Tcl_UniChar.
Tcl_Char16ToUtfDString and Tcl_UtfToChar16DString are similar to Tcl_UniCharToUtfDString and
Tcl_UtfToUniCharDString except they operate on sequences of UTF-16 units instead of Tcl_UniChar.
Tcl_Char16Len corresponds to strlen for UTF-16 characters. It accepts a null-terminated UTF-16 sequence
and returns the number of UTF-16 units until the null.
Tcl_WCharLen corresponds to strlen for wchar_t characters. It accepts a null-terminated wchar_t sequence
and returns the number of wchar_t units until the null.
Tcl_UniCharLen corresponds to strlen for Unicode characters. It accepts a null-terminated Unicode string
and returns the number of Unicode characters (not bytes) in that string.
Tcl_UniCharNcmp and Tcl_UniCharNcasecmp correspond to strncmp and strncasecmp, respectively, for Unicode
characters. They accept two null-terminated Unicode strings and the number of characters to compare.
Both strings are assumed to be at least uniLength characters long. Tcl_UniCharNcmp compares the two
strings character-by-character according to the Unicode character ordering. It returns an integer
greater than, equal to, or less than 0 if the first string is greater than, equal to, or less than the
second string respectively. Tcl_UniCharNcasecmp is the Unicode case insensitive version.
Tcl_UniCharCaseMatch is the Unicode equivalent to Tcl_StringCaseMatch. It accepts a null-terminated
Unicode string, a Unicode pattern, and a boolean value specifying whether the match should be case
sensitive and returns whether the string matches the pattern.
Tcl_UtfNcmp corresponds to strncmp for UTF-8 strings. It accepts two null-terminated UTF-8 strings and
the number of characters to compare. (Both strings are assumed to be at least length characters long.)
Tcl_UtfNcmp compares the two strings character-by-character according to the Unicode character ordering.
It returns an integer greater than, equal to, or less than 0 if the first string is greater than, equal
to, or less than the second string respectively.
Tcl_UtfNcasecmp corresponds to strncasecmp for UTF-8 strings. It is similar to Tcl_UtfNcmp except
comparisons ignore differences in case when comparing upper, lower or title case characters.
Tcl_UtfCharComplete returns 1 if the source UTF-8 string src of numBytes bytes is long enough to be
decoded by Tcl_UtfToUniChar/Tcl_UtfNext, or 0 otherwise. This function does not guarantee that the UTF-8
string is properly formed. This routine is used by procedures that are operating on a byte at a time and
need to know if a full Unicode character has been seen.
Tcl_NumUtfChars corresponds to strlen for UTF-8 strings. It returns the number of Tcl_UniChars that are
represented by the UTF-8 string src. The length of the source string is length bytes. If the length is
negative, all bytes up to the first null byte are used.
Tcl_UtfFindFirst corresponds to strchr for UTF-8 strings. It returns a pointer to the first occurrence
of the Unicode character ch in the null-terminated UTF-8 string src. The null terminator is considered
part of the UTF-8 string.
Tcl_UtfFindLast corresponds to strrchr for UTF-8 strings. It returns a pointer to the last occurrence of
the Unicode character ch in the null-terminated UTF-8 string src. The null terminator is considered part
of the UTF-8 string.
Given src, a pointer to some location in a UTF-8 string, Tcl_UtfNext returns a pointer to the next UTF-8
character in the string. The caller must not ask for the next character after the last character in the
string if the string is not terminated by a null character. Tcl_UtfCharComplete can be used in that case
to make sure enough bytes are available before calling Tcl_UtfNext.
Tcl_UtfPrev is used to step backward through but not beyond the UTF-8 string that begins at start. If
the UTF-8 string is made up entirely of complete and well-formed characters, and src points to the lead
byte of one of those characters (or to the location one byte past the end of the string), then repeated
calls of Tcl_UtfPrev will return pointers to the lead bytes of each character in the string, one
character at a time, terminating when it returns start.
When the conditions of completeness and well-formedness may not be satisfied, a more precise description
of the function of Tcl_UtfPrev is necessary. It always returns a pointer greater than or equal to start;
that is, always a pointer to a location in the string. It always returns a pointer to a byte that begins
a character when scanning for characters beginning from start. When src is greater than start, it always
returns a pointer less than src and greater than or equal to (src - 4). The character that begins at the
returned pointer is the first one that either includes the byte src[-1], or might include it if the right
trail bytes are present at src and greater. Tcl_UtfPrev never reads the byte src[0] nor the byte
start[-1] nor the byte src[-5].
Tcl_UniCharAtIndex corresponds to a C string array dereference or the Pascal Ord() function. It returns
the Unicode character represented at the specified character (not byte) index in the UTF-8 string src.
The source string must contain at least index characters. If index is negative it returns -1.
Tcl_UtfAtIndex returns a pointer to the specified character (not byte) index in the UTF-8 string src.
The source string must contain at least index characters. This is equivalent to calling Tcl_UtfToUniChar
index times. If index is negative, the return pointer points to the first character in the source
string.
Tcl_UtfBackslash is a utility procedure used by several of the Tcl commands. It parses a backslash
sequence and stores the properly formed UTF-8 character represented by the backslash sequence in the
output buffer dst. At most 4 bytes are stored in the buffer. Tcl_UtfBackslash modifies *readPtr to
contain the number of bytes in the backslash sequence, including the backslash character. The return
value is the number of bytes stored in the output buffer.
See the Tcl manual entry for information on the valid backslash sequences. All of the sequences
described in the Tcl manual entry are supported by Tcl_UtfBackslash.
KEYWORDS
utf, unicode, backslash