#include <tcl.h>
int Tcl_SplitList(interp, list,
argcPtr, argvPtr)
char * Tcl_Merge(argc, argv)
int Tcl_ScanElement(src, flagsPtr)
int Tcl_ScanCountedElement(src, length,
flagsPtr)
int Tcl_ConvertElement(src, dst,
flags)
int Tcl_ConvertCountedElement(src, length,
dst, flags)
- Tcl_Interp *interp (out)
-
Interpreter to use for error reporting. If NULL, then no error
message
is left.
- char *list (in)
-
Pointer to a string with proper list structure.
- int *argcPtr (out)
-
Filled in with number of elements in list.
- char ***argvPtr (out)
-
*argvPtr will be filled in with the address of an
array of
pointers to the strings that are the extracted elements of
list.
There will be *argcPtr valid entries in the array,
followed by
a NULL entry.
- int argc (in)
-
Number of elements in argv.
- char **argv (in)
-
Array of strings to merge together into a single list.
Each string will become a separate element of the list.
- char *src (in)
-
String that is to become an element of a list.
- int *flagsPtr (in)
-
Pointer to word to fill in with information about src.
The value of *flagsPtr must be passed to
Tcl_ConvertElement().
- int length (in)
-
Number of bytes in string src.
- char *dst (in)
-
Place to copy converted list element. Must contain enough characters
to hold converted string.
- int flags (in)
-
Information about src. Must be value returned by previous
call to Tcl_ScanElement(), possibly OR-ed
with TCL_DONT_USE_BRACES.
These procedures may be used to disassemble and reassemble Tcl lists.
Tcl_SplitList() breaks a list up into its constituent
elements,
returning an array of pointers to the elements using
argcPtr and argvPtr.
While extracting the arguments, Tcl_SplitList() obeys the
usual rules for backslash substitutions and braces. The area of
memory pointed to by *argvPtr is dynamically
allocated; in addition to the array of pointers, it
also holds copies of all the list elements. It is the caller's
responsibility to free up all of this storage.
For example, suppose that you have called Tcl_SplitList()
with the following code:
int argc, code;
char *string;
char **argv;
...
code = Tcl_SplitList(interp, string, &argc, &argv);
Then you should eventually free the storage with a call like the
following:
Tcl_Free((char *) argv);
Tcl_SplitList() normally returns TCL_OK, which
means the list was
successfully parsed.
If there was a syntax error in list, then
TCL_ERROR is returned
and the interpreter's result will point to an error message describing the
problem (if interp was not NULL).
If TCL_ERROR is returned then no memory is allocated and
*argvPtr
is not modified.
Tcl_Merge() is the inverse of
Tcl_SplitList(): it
takes a collection of strings given by argc
and argv and generates a result string
that has proper list structure.
This means that commands like index may be used to
extract the original elements again.
In addition, if the result of Tcl_Merge() is passed to
Tcl_Eval(),
it will be parsed into argc words whose values will
be the same as the argv strings passed to
Tcl_Merge().
Tcl_Merge() will modify the list elements with braces
and/or
backslashes in order to produce proper Tcl list structure.
The result string is dynamically allocated
using Tcl_Alloc(); the caller must eventually release the
space
using Tcl_Free().
If the result of Tcl_Merge() is passed to
Tcl_SplitList(),
the elements returned by Tcl_SplitList() will be identical
to
those passed into Tcl_Merge().
However, the converse is not true: if Tcl_SplitList()
is passed a given string, and the resulting argc and
argv are passed to Tcl_Merge(), the
resulting string
may not be the same as the original string passed to
Tcl_SplitList().
This is because Tcl_Merge() may use backslashes and braces
differently than the original string.
Tcl_ScanElement() and
Tcl_ConvertElement() are the
procedures that do all of the real work of Tcl_Merge().
Tcl_ScanElement() scans its src argument
and determines how to use backslashes and braces
when converting it to a list element.
It returns an overestimate of the number of characters
required to represent src as a list element, and
it stores information in *flagsPtr that is needed
by Tcl_ConvertElement().
Tcl_ConvertElement() is a companion procedure to
Tcl_ScanElement().
It does the actual work of converting a string to a list element.
Its flags argument must be the same as the value returned
by Tcl_ScanElement().
Tcl_ConvertElement() writes a proper list element to memory
starting at *dst and returns a count of the total number
of characters written, which will be no more than the result
returned by Tcl_ScanElement().
Tcl_ConvertElement() writes out only the actual list
element
without any leading or trailing spaces: it is up to the caller to
include spaces between adjacent list elements.
Tcl_ConvertElement() uses one of two different approaches
to
handle the special characters in src. Wherever possible, it
handles special characters by surrounding the string with braces.
This produces clean-looking output, but can't be used in some situations,
such as when src contains unmatched braces.
In these situations, Tcl_ConvertElement() handles special
characters by generating backslash sequences for them.
The caller may insist on the second approach by OR-ing the
flag value returned by Tcl_ScanElement() with
TCL_DONT_USE_BRACES.
Although this will produce an uglier result, it is useful in some
special situations, such as when Tcl_ConvertElement() is
being
used to generate a portion of an argument for a Tcl command.
In this case, surrounding src with curly braces would cause
the command not to be parsed correctly.
Tcl_ScanCountedElement() and
Tcl_ConvertCountedElement() are
the same as Tcl_ScanElement() and
Tcl_ConvertElement(), except
the length of string src is specified by the
length
argument, and the string may contain embedded nulls.
Windows 8.1. Windows Server 2012 R2. Windows 10. Windows Server 2016. Windows Server 2019. Windows 11. Windows Server 2022.
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