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ActiveTcl User Guide |
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Tcl_GetIndexFromObj, Tcl_GetIndexFromObjStruct - lookup string in
table of keywords
#include <tcl.h>
int
Tcl_GetIndexFromObj(interp, objPtr, tablePtr, msg,
flags,
indexPtr)
int
Tcl_GetIndexFromObjStruct(interp, objPtr, structTablePtr,
offset,
msg, flags, indexPtr)
- Tcl_Interp *interp
(in)
- Interpreter to use for error reporting; if NULL, then no
message is provided on errors.
- Tcl_Obj *objPtr (in/out)
- The string value of this object is used to search through
tablePtr. The internal representation is modified to hold
the index of the matching table entry.
- CONST char **tablePtr (in)
- An array of null-terminated strings. The end of the array is
marked by a NULL string pointer.
- CONST VOID *structTablePtr (in)
- An array of arbitrary type, typically some struct type.
The first member of the structure must be a null-terminated string.
The size of the structure is given by offset.
- int offset (in)
- The offset to add to structTablePtr to get to the next entry.
The end of the array is marked by a NULL string pointer.
- CONST char *msg (in)
- Null-terminated string describing what is being looked up, such
as option. This string is
included in error messages.
- int flags (in)
- OR-ed combination of bits providing additional information for
operation. The only bit that is currently defined is
TCL_EXACT.
- int *indexPtr (out)
- The index of the string in tablePtr that matches the
value of objPtr is returned here.
This procedure provides an efficient way for looking up keywords,
switch names, option names, and similar things where the value of
an object must be one of a predefined set of values. ObjPtr
is compared against each of the strings in tablePtr to find
a match. A match occurs if objPtr's string value is
identical to one of the strings in tablePtr, or if it is a
non-empty unique abbreviation for exactly one of the strings in
tablePtr and the TCL_EXACT flag was not specified; in
either case the index of the matching entry is stored at
*indexPtr and TCL_OK is returned.
If there is no matching entry, TCL_ERROR is returned and an
error message is left in interp's result if interp
isn't NULL. Msg is included in the error message to indicate
what was being looked up. For example, if msg is option the error message will have a
form like bad option "firt": must be first, second, or
third.
If Tcl_GetIndexFromObj completes successfully it modifies
the internal representation of objPtr to hold the address of
the table and the index of the matching entry. If
Tcl_GetIndexFromObj is invoked again with the same
objPtr and tablePtr arguments (e.g. during a
reinvocation of a Tcl command), it returns the matching index
immediately without having to redo the lookup operation. Note:
Tcl_GetIndexFromObj assumes that the entries in
tablePtr are static: they must not change between
invocations. If the value of objPtr is the empty string,
Tcl_GetIndexFromObj will treat it as a non-matching value
and return TCL_ERROR.
Tcl_GetIndexFromObjStruct works just like
Tcl_GetIndexFromObj, except that instead of treating
tablePtr as an array of string pointers, it treats it as the
first in a series of string ptrs that are spaced apart by
offset bytes. This is particularly useful when processing
things like Tk_ConfigurationSpec, whose string keys are in
the same place in each of several array elements.
Tcl_WrongNumArgs
index, object, table lookup
Copyright © 1997 Sun Microsystems, Inc.
Copyright © 1995-1997 Roger E. Critchlow Jr.