HPUX SplitList[3]
SplitList in anderen Kapiteln des hpux Handbuch:
Tcl_SplitList(3) Tcl Tcl_SplitList(3)
Tcl Library Procedures Tcl Library Procedures
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NAME
Tcl_SplitList, Tcl_Merge, Tcl_ScanElement, Tcl_ConvertElement -
manipulate Tcl lists
SYNOPSIS
#include <tcl.h>
int
Tcl_SplitList(interp, list, argcPtr, argvPtr)
char *
Tcl_Merge(argc, argv)
int
Tcl_ScanElement(src, flagsPtr)
int
Tcl_ConvertElement(src, dst, flags)
ARGUMENTS
Tcl_Interp *interp (out) Interpreter to use for error
reporting.
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.
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Tcl_SplitList(3) Tcl Tcl_SplitList(3)
Tcl Library Procedures Tcl Library Procedures
int *flagsPtr (in) Pointer to word to fill in with
information about src. The value
of *flagsPtr must be passed to
Tcl_ConvertElement.
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.
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DESCRIPTION
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 by calling
free((char *) *argvPtr)
when the list elements are no longer needed.
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 interp->result will point to an error
message describing the problem. 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 malloc(); the caller must
eventually release the space using free().
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Tcl_SplitList(3) Tcl Tcl_SplitList(3)
Tcl Library Procedures Tcl Library Procedures
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.
KEYWORDS
backslash, convert, element, list, merge, split, strings
- 3 - Formatted: August 11, 1996