Tcl_GetIndexFromObj(3) Tcl Library Procedures Tcl_GetIndexFromObj(3)
Tcl_GetIndexFromObj, Tcl_GetIndexFromObjStruct - lookup string in table of keywords
Tcl_GetIndexFromObj(interp, objPtr, tablePtr, msg, flags,
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 mod-
ified 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 |
CONST char *msg (in) Null-terminated string describing what is being looked
up, such as option. This string is included in error
int flags (in) OR-ed combination of bits providing additional infor-
mation 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 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_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 pro- |
cessing things like Tk_ConfigurationSpec, whose string keys are in the same place in each |
of several array elements.
index, object, table lookup
Tcl 8.1 Tcl_GetIndexFromObj(3)