Tcl Source Code

'\"
'\" Copyright (c) 1989-1993 The Regents of the University of California.
'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
.TH Tcl_AddErrorInfo 3 8.5 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_GetReturnOptions, Tcl_SetReturnOptions, Tcl_AddErrorInfo, Tcl_AppendObjToErrorInfo, Tcl_AddObjErrorInfo, Tcl_SetObjErrorCode, Tcl_SetErrorCode, Tcl_SetErrorCodeVA, Tcl_SetErrorLine, Tcl_GetErrorLine, Tcl_PosixError, Tcl_LogCommandInfo \- retrieve or record information about errors and other return options
.SH SYNOPSIS
.nf

'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
.TH Tcl_DString 3 7.4 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_DStringInit, Tcl_DStringAppend, Tcl_DStringAppendElement, Tcl_DStringStartSublist, Tcl_DStringEndSublist, Tcl_DStringLength, Tcl_DStringValue, Tcl_DStringSetLength, Tcl_DStringTrunc, Tcl_DStringFree, Tcl_DStringResult, Tcl_DStringGetResult \- manipulate dynamic strings
.SH SYNOPSIS
.nf

'\"
'\" Copyright (c) 1997-1998 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
.TH Tcl_GetEncoding 3 "8.1" Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_GetEncoding, Tcl_FreeEncoding, Tcl_GetEncodingFromObj, Tcl_ExternalToUtfDString, Tcl_ExternalToUtf, Tcl_UtfToExternalDString, Tcl_UtfToExternal, Tcl_WinTCharToUtf, Tcl_WinUtfToTChar, Tcl_GetEncodingName, Tcl_SetSystemEncoding, Tcl_GetEncodingNameFromEnvironment, Tcl_GetEncodingNames, Tcl_CreateEncoding, Tcl_GetEncodingSearchPath, Tcl_SetEncodingSearchPath, Tcl_GetDefaultEncodingDir, Tcl_SetDefaultEncodingDir \- procedures for creating and using encodings
.SH SYNOPSIS
.nf

.AS "const Tcl_EncodingType" *dstWrotePtr in/out
.AP Tcl_Interp *interp in
Interpreter to use for error reporting, or NULL if no error reporting is
desired.
.AP "const char" *name in
Name of encoding to load.
.AP Tcl_Encoding encoding in
The encoding to query, free, or use for converting text.  If \fIencoding\fR is 
NULL, the current system encoding is used.
.AP Tcl_Obj *objPtr in
Name of encoding to get token for.
.AP Tcl_Encoding *encodingPtr out
Points to storage where encoding token is to be written.
.AP "const char" *src in
For the \fBTcl_ExternalToUtf\fR functions, an array of bytes in the
specified encoding that are to be converted to UTF-8.  For the
\fBTcl_UtfToExternal\fR and \fBTcl_WinUtfToTChar\fR functions, an array of
UTF-8 characters to be converted to the specified encoding.  
.AP "const TCHAR" *tsrc in
An array of Windows TCHAR characters to convert to UTF-8.
.AP int srcLen in 
Length of \fIsrc\fR or \fItsrc\fR in bytes.  If the length is negative, the 
encoding-specific length of the string is used.
.AP Tcl_DString *dstPtr out
Pointer to an uninitialized or free \fBTcl_DString\fR in which the converted
result will be stored.
.AP int flags in
Various flag bits OR-ed together.  
\fBTCL_ENCODING_START\fR signifies that the
source buffer is the first block in a (potentially multi-block) input
stream, telling the conversion routine to reset to an initial state and
perform any initialization that needs to occur before the first byte is
converted. \fBTCL_ENCODING_END\fR signifies that the source buffer is the last
block in a (potentially multi-block) input stream, telling the conversion
routine to perform any finalization that needs to occur after the last
byte is converted and then to reset to an initial state.
\fBTCL_ENCODING_STOPONERROR\fR signifies that the conversion routine should
return immediately upon reading a source character that does not exist in
the target encoding; otherwise a default fallback character will
automatically be substituted.  
.AP Tcl_EncodingState *statePtr in/out
Used when converting a (generally long or indefinite length) byte stream
in a piece-by-piece fashion.  The conversion routine stores its current
state in \fI*statePtr\fR after \fIsrc\fR (the buffer containing the
current piece) has been converted; that state information must be passed
back when converting the next piece of the stream so the conversion
routine knows what state it was in when it left off at the end of the
last piece.  May be NULL, in which case the value specified for \fIflags\fR 
is ignored and the source buffer is assumed to contain the complete string to
convert.
.AP char *dst out
Buffer in which the converted result will be stored.  No more than
\fIdstLen\fR bytes will be stored in \fIdst\fR.
.AP int dstLen in
The maximum length of the output buffer \fIdst\fR in bytes.
.AP int *srcReadPtr out
Filled with the number of bytes from \fIsrc\fR that were actually
converted.  This may be less than the original source length if there was
a problem converting some source characters.  May be NULL.
.AP int *dstWrotePtr out
Filled with the number of bytes that were actually stored in the output
buffer as a result of the conversion.  May be NULL.
.AP int *dstCharsPtr out
Filled with the number of characters that correspond to the number of bytes
stored in the output buffer.  May be NULL.
.AP Tcl_DString *bufPtr out
Storage for the prescribed system encoding name.
.AP "const Tcl_EncodingType" *typePtr in
Structure that defines a new type of encoding.  
.AP Tcl_Obj *searchPath in
List of filesystem directories in which to search for encoding data files.
.AP "const char" *path in
A path to the location of the encoding file.  
.BE
.SH INTRODUCTION
.PP
These routines convert between Tcl's internal character representation,
UTF-8, and character representations used by various operating systems or
file systems, such as Unicode, ASCII, or Shift-JIS.  When operating on
strings, such as such as obtaining the names of files or displaying

message is returned in \fIinterp\fR.
.PP
The encoding package maintains a database of all encodings currently in use.
The first time \fIname\fR is seen, \fBTcl_GetEncoding\fR returns an
encoding with a reference count of 1.  If the same \fIname\fR is requested
further times, then the reference count for that encoding is incremented
without the overhead of allocating a new encoding and all its associated
data structures.  
.PP
When an \fIencoding\fR is no longer needed, \fBTcl_FreeEncoding\fR
should be called to release it.  When an \fIencoding\fR is no longer in use
anywhere (i.e., it has been freed as many times as it has been gotten)
\fBTcl_FreeEncoding\fR will release all storage the encoding was using
and delete it from the database. 
.PP
\fBTcl_GetEncodingFromObj\fR treats the string representation of
\fIobjPtr\fR as an encoding name, and finds an encoding with that
name, just as \fBTcl_GetEncoding\fR does. When an encoding is found,
it is cached within the \fBobjPtr\fR value for future reference, the
\fBTcl_Encoding\fR token is written to the storage pointed to by
\fIencodingPtr\fR, and the value \fBTCL_OK\fR is returned. If no such
encoding is found, the value \fBTCL_ERROR\fR is returned, and no
writing to \fB*\fR\fIencodingPtr\fR takes place. Just as with
\fBTcl_GetEncoding\fR, the caller should call \fBTcl_FreeEncoding\fR
on the resulting encoding token when that token will no longer be
used.
.PP
\fBTcl_ExternalToUtfDString\fR converts a source buffer \fIsrc\fR from the
specified \fIencoding\fR into UTF-8.  The converted bytes are stored in 
\fIdstPtr\fR, which is then null-terminated.  The caller should eventually
call \fBTcl_DStringFree\fR to free any information stored in \fIdstPtr\fR.
When converting, if any of the characters in the source buffer cannot be
represented in the target encoding, a default fallback character will be
used.  The return value is a pointer to the value stored in the DString.
.PP
\fBTcl_ExternalToUtf\fR converts a source buffer \fIsrc\fR from the specified

many characters as could fit were converted though.
.IP \fBTCL_CONVERT_MULTIBYTE\fR 29
The last few bytes in the source buffer were the beginning of a multibyte
sequence, but more bytes were needed to complete this sequence.  A
subsequent call to the conversion routine should pass a buffer containing
the unconverted bytes that remained in \fIsrc\fR plus some further bytes
from the source stream to properly convert the formerly split-up multibyte
sequence.  
.IP \fBTCL_CONVERT_SYNTAX\fR 29
The source buffer contained an invalid character sequence.  This may occur
if the input stream has been damaged or if the input encoding method was
misidentified.
.IP \fBTCL_CONVERT_UNKNOWN\fR 29
The source buffer contained a character that could not be represented in
the target encoding and \fBTCL_ENCODING_STOPONERROR\fR was specified.  
.RE
.LP
\fBTcl_UtfToExternalDString\fR converts a source buffer \fIsrc\fR from UTF-8 
into the specified \fIencoding\fR.  The converted bytes are stored in
\fIdstPtr\fR, which is then terminated with the appropriate encoding-specific
null.  The caller should eventually call \fBTcl_DStringFree\fR to free any
information stored in \fIdstPtr\fR.  When converting, if any of the
characters in the source buffer cannot be represented in the target
encoding, a default fallback character will be used.  The return value is
a pointer to the value stored in the DString.

These functions are essentially wrappers around
\fBTcl_UtfToExternalDString\fR and
\fBTcl_ExternalToUtfDString\fR that convert to and from the
Unicode encoding.
.PP
\fBTcl_GetEncodingName\fR is roughly the inverse of \fBTcl_GetEncoding\fR.
Given an \fIencoding\fR, the return value is the \fIname\fR argument that
was used to create the encoding.  The string returned by 
\fBTcl_GetEncodingName\fR is only guaranteed to persist until the
\fIencoding\fR is deleted.  The caller must not modify this string.
.PP
\fBTcl_SetSystemEncoding\fR sets the default encoding that should be used
whenever the user passes a NULL value for the \fIencoding\fR argument to
any of the other encoding functions.  If \fIname\fR is NULL, the system
encoding is reset to the default system encoding, \fBbinary\fR.  If the

\fBTcl_GetEncoding\fR procedure, the return value is a token that
represents the encoding and can be used in subsequent calls to other
encoding functions.  \fBTcl_CreateEncoding\fR returns an encoding with a
reference count of 1. If an encoding with the specified \fIname\fR
already exists, then its entry in the database is replaced with the new
encoding; the token for the old encoding will remain valid and continue
to behave as before, but users of the new token will now call the new
encoding procedures.  
.PP
The \fItypePtr\fR argument to \fBTcl_CreateEncoding\fR contains information 
about the name of the encoding and the procedures that will be called to
convert between this encoding and UTF-8.  It is defined as follows:
.PP
.CS
typedef struct Tcl_EncodingType {
    const char *\fIencodingName\fR;
    Tcl_EncodingConvertProc *\fItoUtfProc\fR;
    Tcl_EncodingConvertProc *\fIfromUtfProc\fR;
    Tcl_EncodingFreeProc *\fIfreeProc\fR;
    ClientData \fIclientData\fR;
    int \fInullSize\fR;
} \fBTcl_EncodingType\fR;  
.CE
.PP
The \fIencodingName\fR provides a string name for the encoding, by
which it can be referred in other procedures such as
\fBTcl_GetEncoding\fR.  The \fItoUtfProc\fR refers to a callback
procedure to invoke to convert text from this encoding into UTF-8.
The \fIfromUtfProc\fR refers to a callback procedure to invoke to

.PP
The callback procedures \fItoUtfProc\fR and \fIfromUtfProc\fR should match the
type \fBTcl_EncodingConvertProc\fR:
.PP
.CS
typedef int \fBTcl_EncodingConvertProc\fR(
        ClientData \fIclientData\fR,
        const char *\fIsrc\fR, 
        int \fIsrcLen\fR, 
        int \fIflags\fR, 
        Tcl_EncodingState *\fIstatePtr\fR,
        char *\fIdst\fR, 
        int \fIdstLen\fR, 
        int *\fIsrcReadPtr\fR,
        int *\fIdstWrotePtr\fR,
        int *\fIdstCharsPtr\fR);
.CE
.PP
The \fItoUtfProc\fR and \fIfromUtfProc\fR procedures are called by the
\fBTcl_ExternalToUtf\fR or \fBTcl_UtfToExternal\fR family of functions to
perform the actual conversion.  The \fIclientData\fR parameter to these
procedures is the same as the \fIclientData\fR field specified to
\fBTcl_CreateEncoding\fR when the encoding was created.  The remaining
arguments to the callback procedures are the same as the arguments,
documented at the top, to \fBTcl_ExternalToUtf\fR or
\fBTcl_UtfToExternal\fR, with the following exceptions.  If the
\fIsrcLen\fR argument to one of those high-level functions is negative,
the value passed to the callback procedure will be the appropriate
encoding-specific string length of \fIsrc\fR.  If any of the \fIsrcReadPtr\fR, 
\fIdstWrotePtr\fR, or \fIdstCharsPtr\fR arguments to one of the high-level
functions is NULL, the corresponding value passed to the callback
procedure will be a non-NULL location.
.PP
The callback procedure \fIfreeProc\fR, if non-NULL, should match the type 
\fBTcl_EncodingFreeProc\fR:
.PP
.CS
typedef void \fBTcl_EncodingFreeProc\fR(
        ClientData \fIclientData\fR);
.CE
.PP
This \fIfreeProc\fR function is called when the encoding is deleted.  The
\fIclientData\fR parameter is the same as the \fIclientData\fR field
specified to \fBTcl_CreateEncoding\fR when the encoding was created.  
.PP
\fBTcl_GetEncodingSearchPath\fR and \fBTcl_SetEncodingSearchPath\fR
are called to access and set the list of filesystem directories searched
for encoding data files.  
.PP
The value returned by \fBTcl_GetEncodingSearchPath\fR
is the value stored by the last successful call to
\fBTcl_SetEncodingSearchPath\fR.  If no calls to
\fBTcl_SetEncodingSearchPath\fR have occurred, Tcl will compute an initial
value based on the environment.  There is one encoding search path for the
entire process, shared by all threads in the process.

Space would prohibit precompiling into Tcl every possible encoding
algorithm, so many encodings are stored on disk as dynamically-loadable
encoding files.  This behavior also allows the user to create additional
encoding files that can be loaded using the same mechanism.  These
encoding files contain information about the tables and/or escape
sequences used to map between an external encoding and Unicode.  The
external encoding may consist of single-byte, multi-byte, or double-byte
characters.  
.PP
Each dynamically-loadable encoding is represented as a text file.  The
initial line of the file, beginning with a
.QW #
symbol, is a comment
that provides a human-readable description of the file.  The next line
identifies the type of encoding file.  It can be one of the following

Certain bytes are lead bytes, indicating that another byte must follow
and that together the two bytes represent one character.  Other bytes are not
lead bytes and represent themselves.  An example is \fBshiftjis\fR, used by
many Japanese computers.
.IP "[4] \fBE\fR"
An escape-sequence encoding, specifying that certain sequences of bytes
do not represent characters, but commands that describe how following bytes
should be interpreted.  
.PP
The rest of the lines in the file depend on the type.  
.PP
Cases [1], [2], and [3] are collectively referred to as table-based encoding
files.  The lines in a table-based encoding file are in the same
format as this example taken from the \fBshiftjis\fR encoding (this is not
the complete file):
.PP
.CS

212B2030266F266D266A2020202100B6000000000000000025EF000000000000
.CE
.PP
The third line of the file is three numbers.  The first number is the
fallback character (in base 16) to use when converting from UTF-8 to this
encoding.  The second number is a \fB1\fR if this file represents the
encoding for a symbol font, or \fB0\fR otherwise.  The last number (in base
10) is how many pages of data follow.  
.PP
Subsequent lines in the example above are pages that describe how to map
from the encoding into 2-byte Unicode.  The first line in a page identifies
the page number.  Following it are 256 double-byte numbers, arranged as 16
rows of 16 numbers.  Given a character in the encoding, the high byte of
that character is used to select which page, and the low byte of that
character is used as an index to select one of the double-byte numbers in

'\"
'\" Copyright (c) 1996-1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
.TH Tcl_Obj 3 8.5 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_NewObj, Tcl_DuplicateObj, Tcl_IncrRefCount, Tcl_DecrRefCount, Tcl_IsShared, Tcl_InvalidateStringRep \- manipulate Tcl values
.SH SYNOPSIS
.nf

Values are shared as much as possible.
This significantly reduces storage requirements
because some values such as long lists are very large.
Also, most Tcl values are only read and never modified.
This is especially true for procedure arguments,
which can be shared between the caller and the called procedure.
Assignment and argument binding is done by
simply assigning a pointer to the value. 
Reference counting is used to determine when it is safe to
reclaim a value's storage.
.PP
Tcl values are typed.
A value's internal representation is controlled by its type.
Several types are predefined in the Tcl core
including integer, double, list, and bytecode.

.AS Tcl_DString *channelName in/out
.AP Tcl_Interp *interp in
Used for error reporting and to look up a channel registered in it.
.AP "const char" *fileName in
The name of a local or network file.
.AP "const char" *mode in
Specifies how the file is to be accessed.  May have any of the values
allowed for the \fImode\fR argument to the Tcl \fBopen\fR command.  
.AP int permissions in
POSIX-style permission flags such as 0644.  If a new file is created, these
permissions will be set on the created file.
.AP int argc in
The number of elements in \fIargv\fR.
.AP "const char" **argv in
Arguments for constructing a command pipeline.  These values have the same

.AP ClientData handle in
Operating system specific handle for I/O to a file. For Unix this is a
file descriptor, for Windows it is a HANDLE.
.AP int readOrWrite in
OR-ed combination of \fBTCL_READABLE\fR and \fBTCL_WRITABLE\fR to indicate
what operations are valid on \fIhandle\fR.
.AP "const char" *channelName in
The name of the channel. 
.AP int *modePtr out
Points at an integer variable that will receive an OR-ed combination of
\fBTCL_READABLE\fR and \fBTCL_WRITABLE\fR denoting whether the channel is
open for reading and writing.
.AP "const char" *pattern in
The pattern to match on, passed to Tcl_StringMatch, or NULL.
.AP Tcl_Channel channel in
A Tcl channel for input or output.  Must have been the return value
from a procedure such as \fBTcl_OpenFileChannel\fR.
.AP Tcl_Obj *readObjPtr in/out
A pointer to a Tcl value in which to store the characters read from the
channel.
.AP int charsToRead in
The number of characters to read from the channel.  If the channel's encoding 
is \fBbinary\fR, this is equivalent to the number of bytes to read from the 
channel.
.AP int appendFlag in
If non-zero, data read from the channel will be appended to the value.
Otherwise, the data will replace the existing contents of the value.
.AP char *readBuf out
A buffer in which to store the bytes read from the channel.
.AP int bytesToRead in
The number of bytes to read from the channel.  The buffer \fIreadBuf\fR must
be large enough to hold this many bytes.
.AP Tcl_Obj *lineObjPtr in/out
A pointer to a Tcl value in which to store the line read from the
channel.  The line read will be appended to the current value of the
value. 
.AP Tcl_DString *lineRead in/out
A pointer to a Tcl dynamic string in which to store the line read from the
channel.  Must have been initialized by the caller.  The line read will be
appended to any data already in the dynamic string.
.AP "const char" *input in
The input to add to a channel buffer.
.AP int inputLen in

the Unix standard I/O library.
The syntax and meaning of all arguments is similar to those
given in the Tcl \fBopen\fR command when opening a file.
If an error occurs while opening the channel, \fBTcl_OpenFileChannel\fR
returns NULL and records a POSIX error code that can be
retrieved with \fBTcl_GetErrno\fR.
In addition, if \fIinterp\fR is non-NULL, \fBTcl_OpenFileChannel\fR
leaves an error message in \fIinterp\fR's result after any error.  
As of Tcl 8.4, the value-based API \fBTcl_FSOpenFileChannel\fR should 
be used in preference to \fBTcl_OpenFileChannel\fR wherever possible.
.PP
The newly created channel is not registered in the supplied interpreter; to
register it, use \fBTcl_RegisterChannel\fR, described below.
If one of the standard channels, \fBstdin\fR, \fBstdout\fR or \fBstderr\fR was
previously closed, the act of creating the new channel also assigns it as a
replacement for the standard channel.

Beyond that, this command has no further effect.  It cannot be used on
the standard channels (\fBstdout\fR, \fBstderr\fR, \fBstdin\fR), and will return
\fBTCL_ERROR\fR if passed one of those channels.
.PP
Code not associated with a Tcl interpreter can call
\fBTcl_DetachChannel\fR with \fIinterp\fR as NULL, to indicate to Tcl
that it no longer holds a reference to that channel. If this is the last
reference to the channel, unlike \fBTcl_UnregisterChannel\fR, 
it will not be closed.
.SH TCL_ISSTANDARDCHANNEL
.PP
\fBTcl_IsStandardChannel\fR tests whether a channel is one of the
three standard channels, \fBstdin\fR, \fBstdout\fR or \fBstderr\fR.
If so, it returns 1, otherwise 0.
.PP
No attempt is made to check whether the given channel or the standard 
channels are initialized or otherwise valid.
.SH TCL_CLOSE
.PP
\fBTcl_Close\fR destroys the channel \fIchannel\fR, which must denote a
currently open channel. The channel should not be registered in any
interpreter when \fBTcl_Close\fR is called. Buffered output is flushed to
the channel's output device prior to destroying the channel, and any

\fBTcl_RegisterChannel\fR, you should instead use
\fBTcl_UnregisterChannel\fR, which will internally call \fBTcl_Close\fR
when all calls to \fBTcl_RegisterChannel\fR have been matched by
corresponding calls to \fBTcl_UnregisterChannel\fR.
.SH "TCL_READCHARS AND TCL_READ"
.PP
\fBTcl_ReadChars\fR consumes bytes from \fIchannel\fR, converting the bytes
to UTF-8 based on the channel's encoding and storing the produced data in 
\fIreadObjPtr\fR's string representation.  The return value of
\fBTcl_ReadChars\fR is the number of characters, up to \fIcharsToRead\fR,
that were stored in \fIreadObjPtr\fR.  If an error occurs while reading, the
return value is \-1 and \fBTcl_ReadChars\fR records a POSIX error code that
can be retrieved with \fBTcl_GetErrno\fR.
.PP
Setting \fIcharsToRead\fR to \fB\-1\fR will cause the command to read

encoding conversions, regardless of the channel's encoding.  It is deprecated
and exists for backwards compatibility with non-internationalized Tcl
extensions.  It consumes bytes from \fIchannel\fR and stores them in
\fIreadBuf\fR, performing end-of-line translations on the way.  The return value
of \fBTcl_Read\fR is the number of bytes, up to \fIbytesToRead\fR, written in
\fIreadBuf\fR.  The buffer produced by \fBTcl_Read\fR is not null-terminated.
Its contents are valid from the zeroth position up to and excluding the
position indicated by the return value.  
.PP
\fBTcl_ReadRaw\fR is the same as \fBTcl_Read\fR but does not
compensate for stacking. While \fBTcl_Read\fR (and the other functions
in the API) always get their data from the topmost channel in the
stack the supplied channel is part of, \fBTcl_ReadRaw\fR does
not. Thus this function is \fBonly\fR usable for transformational
channel drivers, i.e. drivers used in the middle of a stack of

\fIcharBuf\fR.  The UTF-8 characters in the buffer are converted to the
channel's encoding and queued for output to \fIchannel\fR.  If
\fIbytesToWrite\fR is negative, \fBTcl_WriteChars\fR expects \fIcharBuf\fR
to be null-terminated and it outputs everything up to the null.
.PP
Data queued for output may not appear on the output device immediately, due
to internal buffering.  If the data should appear immediately, call
\fBTcl_Flush\fR after the call to \fBTcl_WriteChars\fR, or set the 
\fB\-buffering\fR option on the channel to \fBnone\fR.  If you wish the data
to appear as soon as a complete line is accepted for output, set the
\fB\-buffering\fR option on the channel to \fBline\fR mode.
.PP
The return value of \fBTcl_WriteChars\fR is a count of how many bytes were
accepted for output to the channel.  This is either greater than zero to
indicate success or \-1 to indicate that an error occurred.  If an error
occurs, \fBTcl_WriteChars\fR records a POSIX error code that may be
retrieved with \fBTcl_GetErrno\fR.
.PP
Newline characters in the output data are translated to platform-specific
end-of-line sequences according to the \fB\-translation\fR option for the
channel.  This is done even if the channel has no encoding.
.PP
\fBTcl_WriteObj\fR is similar to \fBTcl_WriteChars\fR except it
accepts a Tcl value whose contents will be output to the channel.  The
UTF-8 characters in \fIwriteObjPtr\fR's string representation are converted
to the channel's encoding and queued for output to \fIchannel\fR.  
As a performance optimization, when writing to a channel with the encoding
\fBbinary\fR, UTF-8 characters are not converted as they are written.
Instead, the bytes in \fIwriteObjPtr\fR's internal representation as a
byte-array value are written to the channel.  The byte-array representation
of the value will be constructed if it is needed.  In this way,
byte-oriented data can be read from a channel, manipulated by calling
\fBTcl_GetByteArrayFromObj\fR and related functions, and then written to a

'\"
'\" Copyright (c) 1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
.TH Tcl_ParseCommand 3 8.3 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_ParseCommand, Tcl_ParseExpr, Tcl_ParseBraces, Tcl_ParseQuotedString, Tcl_ParseVarName, Tcl_ParseVar, Tcl_FreeParse, Tcl_EvalTokens, Tcl_EvalTokensStandard \- parse Tcl scripts and expressions
.SH SYNOPSIS
.nf

.AP int numBytes in
Number of bytes in string to parse, not including any terminating null
character.  If less than 0 then the script consists of all characters
following \fIstart\fR up to the first null character.
.AP int nested in
Non-zero means that the script is part of a command substitution so an
unquoted close bracket should be treated as a command terminator.  If zero,
close brackets have no special meaning. 
.AP int append in
Non-zero means that \fI*parsePtr\fR already contains valid tokens; the new
tokens should be appended to those already present.  Zero means that
\fI*parsePtr\fR is uninitialized; any information in it is ignored.
This argument is normally 0.
.AP Tcl_Parse *parsePtr out
Points to structure to fill in with information about the parsed

\fBTCL_ERROR\fR is returned, an error message is left in \fIinterp\fR's
result, and no information is left at \fI*parsePtr\fR.
.PP
\fBTcl_ParseBraces\fR parses a string or command argument
enclosed in braces such as
\fB{hello}\fR or \fB{string \et with \et tabs}\fR
from the beginning of its argument \fIstart\fR.
The first character of \fIstart\fR must be \fB{\fR. 
If the braced string was parsed successfully,
\fBTcl_ParseBraces\fR returns \fBTCL_OK\fR,
fills in the structure pointed to by \fIparsePtr\fR
with information about the structure of the string
(see below for details),
and stores a pointer to the character just after the terminating \fB}\fR
in the location given by \fI*termPtr\fR.
If an error occurs while parsing the string
then \fBTCL_ERROR\fR is returned,
an error message is left in \fIinterp\fR's result,
and no information is left at \fI*parsePtr\fR or \fI*termPtr\fR.
.PP
\fBTcl_ParseQuotedString\fR parses a double-quoted string such as
\fB"sum is [expr {$a+$b}]"\fR
from the beginning of the argument \fIstart\fR.
The first character of \fIstart\fR must be \fB\N'34'\fR. 
If the double-quoted string was parsed successfully,
\fBTcl_ParseQuotedString\fR returns \fBTCL_OK\fR,
fills in the structure pointed to by \fIparsePtr\fR
with information about the structure of the string
(see below for details),
and stores a pointer to the character just after the terminating \fB\N'34'\fR
in the location given by \fI*termPtr\fR.
If an error occurs while parsing the string
then \fBTCL_ERROR\fR is returned,
an error message is left in \fIinterp\fR's result,
and no information is left at \fI*parsePtr\fR or \fI*termPtr\fR.
.PP
\fBTcl_ParseVarName\fR parses a Tcl variable reference such as
\fB$abc\fR or \fB$x([expr {$index + 1}])\fR from the beginning of its
\fIstart\fR argument.
The first character of \fIstart\fR must be \fB$\fR. 
If a variable name was parsed successfully, \fBTcl_ParseVarName\fR
returns \fBTCL_OK\fR and fills in the structure pointed to by
\fIparsePtr\fR with information about the structure of the variable name
(see below for details).  If an error
occurs while parsing the command then \fBTCL_ERROR\fR is returned, an
error message is left in \fIinterp\fR's result (if \fIinterp\fR is not
NULL), and no information is left at \fI*parsePtr\fR.

then \fBTcl_FreeParse\fR must be invoked once after each call.
.PP
\fBTcl_EvalTokensStandard\fR evaluates a sequence of parse tokens from
a Tcl_Parse structure.  The tokens typically consist
of all the tokens in a word or all the tokens that make up the index for
a reference to an array variable.  \fBTcl_EvalTokensStandard\fR performs the
substitutions requested by the tokens and concatenates the
resulting values. 
The return value from \fBTcl_EvalTokensStandard\fR is a Tcl completion
code with one of the values \fBTCL_OK\fR, \fBTCL_ERROR\fR,
\fBTCL_RETURN\fR, \fBTCL_BREAK\fR, or \fBTCL_CONTINUE\fR, or possibly
some other integer value originating in an extension.
In addition, a result value or error message is left in \fIinterp\fR's
result; it can be retrieved using \fBTcl_GetObjResult\fR.
.PP

the \fIcommentStart\fR field points to the \fB#\fR character that begins
the first comment and \fIcommentSize\fR indicates the number of bytes
in all of the comments preceding the command, including the newline
character that terminates the last comment.
If the command is not preceded by any comments, \fIcommentSize\fR is 0.
\fBTcl_ParseCommand\fR also sets the \fIcommandStart\fR field
to point to the first character of the first
word in the command (skipping any comments and leading space) and 
\fIcommandSize\fR gives the total number of bytes in the command,
including the character pointed to by \fIcommandStart\fR up to and
including the newline, close bracket, or semicolon character that
terminates the command.  The \fInumWords\fR field gives the
total number of words in the command.
.PP
All parsing procedures set the remaining fields,

is a \fBTCL_TOKEN_OPERATOR\fR token,
the subexpression consists of an operator and its token operands.
If the operator has no operands, the subexpression consists of
just the \fBTCL_TOKEN_OPERATOR\fR token.
Each operand is described by a \fBTCL_TOKEN_SUB_EXPR\fR token.
Otherwise, the subexpression is a value described by
one of the token types \fBTCL_TOKEN_WORD\fR, \fBTCL_TOKEN_TEXT\fR,
\fBTCL_TOKEN_BS\fR, \fBTCL_TOKEN_COMMAND\fR, 
\fBTCL_TOKEN_VARIABLE\fR, and \fBTCL_TOKEN_SUB_EXPR\fR.
The \fInumComponents\fR field
counts the total number of sub-tokens that make up the subexpression;
this includes the sub-tokens for any nested \fBTCL_TOKEN_SUB_EXPR\fR tokens.
.TP
\fBTCL_TOKEN_OPERATOR\fR
.

\fIx\fR, \fIy\fR, and \fIz\fR.
The \fInumComponents\fR field for a \fBTCL_TOKEN_OPERATOR\fR token
is always 0.
.PP
After \fBTcl_ParseCommand\fR returns, the first token pointed to by
the \fItokenPtr\fR field of the
Tcl_Parse structure always has type \fBTCL_TOKEN_WORD\fR or
\fBTCL_TOKEN_SIMPLE_WORD\fR or \fBTCL_TOKEN_EXPAND_WORD\fR.  
It is followed by the sub-tokens
that must be concatenated to produce the value of that word.
The next token is the \fBTCL_TOKEN_WORD\fR or \fBTCL_TOKEN_SIMPLE_WORD\fR
of \fBTCL_TOKEN_EXPAND_WORD\fR token for the second word,
followed by sub-tokens for that
word, and so on until all \fInumWords\fR have been accounted
for.

'\"
'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
.TH Tcl_StringObj 3 8.1 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_NewStringObj, Tcl_NewUnicodeObj, Tcl_SetStringObj, Tcl_SetUnicodeObj, Tcl_GetStringFromObj, Tcl_GetString, Tcl_GetUnicodeFromObj, Tcl_GetUnicode, Tcl_GetUniChar, Tcl_GetCharLength, Tcl_GetRange, Tcl_AppendToObj, Tcl_AppendUnicodeToObj, Tcl_AppendObjToObj, Tcl_AppendStringsToObj, Tcl_AppendStringsToObjVA, Tcl_AppendLimitedToObj, Tcl_Format, Tcl_AppendFormatToObj, Tcl_ObjPrintf, Tcl_AppendPrintfToObj, Tcl_SetObjLength, Tcl_AttemptSetObjLength, Tcl_ConcatObj \- manipulate Tcl values as strings
.SH SYNOPSIS
.nf

.PP
.CS
char buf[SOME_SUITABLE_LENGTH];
sprintf(buf, format, ...);
\fBTcl_NewStringObj\fR(buf, -1);
.CE
.PP
but with greater convenience and no need to 
determine \fBSOME_SUITABLE_LENGTH\fR. The formatting is done with the same
core formatting engine used by \fBTcl_Format\fR.  This means the set of
supported conversion specifiers is that of the \fBformat\fR command and
not that of the \fBsprintf\fR routine where the two sets differ. When a
conversion specifier passed to \fBTcl_ObjPrintf\fR includes a precision,
the value is taken as a number of bytes, as \fBsprintf\fR does, and not
as a number of characters, as \fBformat\fR does.  This is done on the
assumption that C code is more likely to know how many bytes it is
passing around than the number of encoded characters those bytes happen
to represent.  The variable number of arguments passed in should be of
the types that would be suitable for passing to \fBsprintf\fR.  Note in
this example usage, \fIx\fR is of type \fBint\fR.
.PP
.CS
int x = 5;
Tcl_Obj *objPtr = \fBTcl_ObjPrintf\fR("Value is %d", x);
.CE
.PP
If the value of \fIformat\fR contains internal inconsistencies or invalid
specifier formats, the formatted string result produced by
\fBTcl_ObjPrintf\fR will be an error message describing the error. 
It is impossible however to provide runtime protection against 
mismatches between the format and any subsequent arguments.
Compile-time protection may be provided by some compilers.
.PP
\fBTcl_AppendPrintfToObj\fR is an appending alternative form
of \fBTcl_ObjPrintf\fR with functionality equivalent to
.PP
.CS

'\"
'\" Copyright (c) 1997 by Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
.TH Tcl_UtfToUpper 3 "8.1" Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_UniCharToUpper, Tcl_UniCharToLower, Tcl_UniCharToTitle, Tcl_UtfToUpper, Tcl_UtfToLower, Tcl_UtfToTitle \- routines for manipulating the case of Unicode characters and UTF-8 strings
.SH SYNOPSIS
.nf

'\"
'\" Copyright (c) 1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
.TH Utf 3 "8.1" Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_UniChar, Tcl_UniCharToUtf, Tcl_UtfToUniChar, Tcl_UniCharToUtfDString, Tcl_UtfToUniCharDString, 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
.SH SYNOPSIS
.nf

.sp
int
\fBTcl_UtfNcasecmp\fR(\fIcs, ct, numChars\fR)
.sp
int
\fBTcl_UtfCharComplete\fR(\fIsrc, length\fR)
.sp
int 
\fBTcl_NumUtfChars\fR(\fIsrc, length\fR)
.sp
const char *
\fBTcl_UtfFindFirst\fR(\fIsrc, ch\fR)
.sp
const char *
\fBTcl_UtfFindLast\fR(\fIsrc, ch\fR)

.AP "unsigned long" numChars in
The number of characters to compare.
.AP "const char" *start in
Pointer to the beginning of a UTF-8 string.
.AP int index in
The index of a character (not byte) in the UTF-8 string.
.AP int *readPtr out
If non-NULL, filled with the number of bytes in the backslash sequence, 
including the backslash character.
.AP char *dst out
Buffer in which the bytes represented by the backslash sequence are stored.
At most \fBTCL_UTF_MAX\fR bytes are stored in the buffer.
.AP int nocase in
Specifies whether the match should be done case-sensitive (0) or
case-insensitive (1).

and stores it as a Tcl_UniChar in \fI*chPtr\fR.  The return value is the
number of bytes read from \fIsrc\fR.  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, \fBTcl_UtfToUniChar\fR will store the first
byte of \fIsrc\fR in \fI*chPtr\fR as a Tcl_UniChar between 0x0000 and
0x00ff and return 1.  
.PP
\fBTcl_UniCharToUtfDString\fR converts the given Unicode string
to UTF-8, storing the result in a previously initialized \fBTcl_DString\fR.
You must specify \fIuniLength\fR, 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 \fBTcl_DString\fR.

returns the number of Tcl_UniChars that are represented by the UTF-8 string
\fIsrc\fR.  The length of the source string is \fIlength\fR bytes.  If the
length is negative, all bytes up to the first null byte are used.
.PP
\fBTcl_UtfFindFirst\fR corresponds to \fBstrchr\fR for UTF-8 strings.  It
returns a pointer to the first occurrence of the Tcl_UniChar \fIch\fR
in the null-terminated UTF-8 string \fIsrc\fR.  The null terminator is
considered part of the UTF-8 string.  
.PP
\fBTcl_UtfFindLast\fR corresponds to \fBstrrchr\fR for UTF-8 strings.  It
returns a pointer to the last occurrence of the Tcl_UniChar \fIch\fR
in the null-terminated UTF-8 string \fIsrc\fR.  The null terminator is
considered part of the UTF-8 string.  
.PP
Given \fIsrc\fR, a pointer to some location in a UTF-8 string,
\fBTcl_UtfNext\fR 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.
.PP

Pascal Ord() function.  It returns the Tcl_UniChar represented at the
specified character (not byte) \fIindex\fR in the UTF-8 string
\fIsrc\fR.  The source string must contain at least \fIindex\fR
characters.  Behavior is undefined if a negative \fIindex\fR is given.
.PP
\fBTcl_UtfAtIndex\fR returns a pointer to the specified character (not
byte) \fIindex\fR in the UTF-8 string \fIsrc\fR.  The source string must
contain at least \fIindex\fR characters.  This is equivalent to calling 
\fBTcl_UtfNext\fR \fIindex\fR times.  If a negative \fIindex\fR is given,
the return pointer points to the first character in the source string.
.PP
\fBTcl_UtfBackslash\fR 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 \fIdst\fR.  At most \fBTCL_UTF_MAX\fR bytes are stored in the buffer.