Utf(3tcl) Tcl Library Procedures Utf(3tcl)
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NAME
Tcl_UniChar, Tcl_UniCharToUtf, Tcl_UtfToUniChar, Tcl_UniCharToUtfD-
String, Tcl_UtfToUniCharDString, Tcl_UniCharLen, Tcl_UniCharNcmp,
Tcl_UniCharNcasecmp, Tcl_UniCharCaseMatch, Tcl_UtfNcmp, Tcl_UtfN-
casecmp, Tcl_UtfCharComplete, Tcl_NumUtfChars, Tcl_UtfFindFirst,
Tcl_UtfFindLast, Tcl_UtfNext, Tcl_UtfPrev, Tcl_UniCharAtIndex, Tcl_Ut-
fAtIndex, Tcl_UtfBackslash - routines for manipulating UTF-8 strings
SYNOPSIS
#include <tcl.h>
typedef ... Tcl_UniChar;
int
Tcl_UniCharToUtf(ch, buf)
int
Tcl_UtfToUniChar(src, chPtr)
char *
Tcl_UniCharToUtfDString(uniStr, uniLength, dsPtr)
Tcl_UniChar *
Tcl_UtfToUniCharDString(src, length, dsPtr)
int
Tcl_UniCharLen(uniStr)
int
Tcl_UniCharNcmp(ucs, uct, numChars)
int
Tcl_UniCharNcasecmp(ucs, uct, numChars)
int
Tcl_UniCharCaseMatch(uniStr, uniPattern, nocase)
int
Tcl_UtfNcmp(cs, ct, numChars)
int
Tcl_UtfNcasecmp(cs, ct, numChars)
int
Tcl_UtfCharComplete(src, length)
int
Tcl_NumUtfChars(src, length)
const char *
Tcl_UtfFindFirst(src, ch)
const char *
Tcl_UtfFindLast(src, ch)
const char *
Tcl_UtfNext(src)
const char *
Tcl_UtfPrev(src, start)
Tcl_UniChar
Tcl_UniCharAtIndex(src, index)
const char *
Tcl_UtfAtIndex(src, index)
int
Tcl_UtfBackslash(src, readPtr, dst)
ARGUMENTS
char *buf (out) Buffer in which the UTF-8
representation of the
Tcl_UniChar is stored. At
most TCL_UTF_MAX 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.
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 null-terminated Unicode
string.
const Tcl_UniChar *ucs (in) A null-terminated Unicode
string.
const Tcl_UniChar *uct (in) A null-terminated Unicode
string.
const Tcl_UniChar *uniPattern (in) A null-terminated Unicode
string.
int length (in) The length of the UTF-8
string in bytes (not UTF-8
characters). If negative,
all bytes up to the first
null byte are used.
int uniLength (in) The length of the Unicode
string in characters. Must
be greater than or equal to
0.
Tcl_DString *dsPtr (in/out) A pointer to a previously
initialized Tcl_DString.
unsigned long numChars (in) The number of characters to
compare.
const char *start (in) Pointer to the beginning of
a UTF-8 string.
int 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, includ-
ing the backslash charac-
ter.
char *dst (out) Buffer in which the bytes
represented by the back-
slash sequence are stored.
At most TCL_UTF_MAX bytes
are stored in the buffer.
int nocase (in) Specifies whether the match
should be done case-sensi-
tive (0) or case-insensi-
tive (1).
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DESCRIPTION
These routines convert between UTF-8 strings and Tcl_UniChars. A
Tcl_UniChar is a Unicode character represented as an unsigned, fixed-
size quantity. A UTF-8 character is a Unicode character represented as
a varying-length sequence of up to TCL_UTF_MAX 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 it takes to represent
one Unicode character in the UTF-8 representation.
Tcl_UniCharToUtf stores the Tcl_UniChar ch as a UTF-8 string in start-
ing at buf. The return value is the number of bytes stored in buf.
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 not in proper
UTF-8 format, Tcl_UtfToUniChar will store the first byte of src in *ch-
Ptr as a Tcl_UniChar between 0x80 and 0xFF and return 1.
Tcl_UniCharToUtfDString converts the given Unicode string to UTF-8,
storing the result in a previously initialized Tcl_DString. You must
specify uniLength, the length of the given Unicode string. The return
value is a pointer to the UTF-8 representation of the Unicode string.
Storage for the return value is appended to the end of the Tcl_DString.
Tcl_UtfToUniCharDString converts the given UTF-8 string to Unicode,
storing the result in the previously initialized Tcl_DString. In the
argument length, you may either specify the length of the given UTF-8
string in bytes or “-1”, in which case Tcl_UtfToUniCharDString uses
strlen to calculate the length. The return value is a pointer to the
Unicode representation of the UTF-8 string. Storage for the return
value is appended to the end of the Tcl_DString. The Unicode string is
terminated with a Unicode null character.
Tcl_UniCharLen corresponds to strlen for Unicode characters. It ac-
cepts a null-terminated Unicode string and returns the number of Uni-
code characters (not bytes) in that string.
Tcl_UniCharNcmp and Tcl_UniCharNcasecmp correspond to strncmp and strn-
casecmp, 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 numChars characters long.
Tcl_UniCharNcmp compares the two strings character-by-character ac-
cording 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 numChars 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 length
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 Tcl_UniChar 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 Tcl_UniChar ch in the null-ter-
minated 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 Tcl_UniChar ch in the null-termi-
nated 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_Ut-
fCharComplete 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 sat-
isfied, 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 re-
turns a pointer to a byte that begins a character when scanning for
characters beginning from start. When src is greater than start, it al-
ways returns a pointer less than src and greater than or equal to (src
- TCL_UTF_MAX). 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[-TCL_UTF_MAX-1].
Tcl_UniCharAtIndex corresponds to a C string array dereference or the
Pascal Ord() function. It returns the Tcl_UniChar represented at the
specified character (not byte) index in the UTF-8 string src. The
source string must contain at least index characters. Behavior is un-
defined if a negative index is given.
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 a negative index is given, the return pointer points to the
first character in the source string.
Tcl_UtfBackslash is a utility procedure used by several of the Tcl com-
mands. 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 TCL_UTF_MAX 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 se-
quences. All of the sequences described in the Tcl manual entry are
supported by Tcl_UtfBackslash.
KEYWORDS
utf, unicode, backslash
Tcl 8.1 Utf(3tcl)
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