NAME¶
Tcl_ListObjAppendList, Tcl_ListObjAppendElement, Tcl_NewListObj, Tcl_SetListObj,
Tcl_ListObjGetElements, Tcl_ListObjLength, Tcl_ListObjIndex,
Tcl_ListObjReplace - manipulate Tcl objects as lists
SYNOPSIS¶
#include <tcl.h>
int
Tcl_ListObjAppendList(interp, listPtr, elemListPtr)
int
Tcl_ListObjAppendElement(interp, listPtr, objPtr)
Tcl_Obj *
Tcl_NewListObj(objc, objv)
Tcl_SetListObj(objPtr, objc, objv)
int
Tcl_ListObjGetElements(interp, listPtr, objcPtr, objvPtr)
int
Tcl_ListObjLength(interp, listPtr, intPtr)
int
Tcl_ListObjIndex(interp, listPtr, index, objPtrPtr)
int
Tcl_ListObjReplace(interp, listPtr, first, count, objc, objv)
ARGUMENTS¶
- Tcl_Interp *interp (in)
- If an error occurs while converting an object to be a list object, an
error message is left in the interpreter's result object unless
interp is NULL.
- Tcl_Obj *listPtr (in/out)
- Points to the list object to be manipulated. If listPtr does not
already point to a list object, an attempt will be made to convert it to
one.
- Tcl_Obj *elemListPtr (in/out)
- For Tcl_ListObjAppendList, this points to a list object containing
elements to be appended onto listPtr. Each element of *
elemListPtr will become a new element of listPtr. If *
elemListPtr is not NULL and does not already point to a list
object, an attempt will be made to convert it to one.
- Tcl_Obj *objPtr (in)
- For Tcl_ListObjAppendElement, points to the Tcl object that will be
appended to listPtr. For Tcl_SetListObj, this points to the
Tcl object that will be converted to a list object containing the
objc elements of the array referenced by objv.
- int *objcPtr (in)
- Points to location where Tcl_ListObjGetElements stores the number
of element objects in listPtr.
- Tcl_Obj ***objvPtr (out)
- A location where Tcl_ListObjGetElements stores a pointer to an
array of pointers to the element objects of listPtr.
- int objc (in)
- The number of Tcl objects that Tcl_NewListObj will insert into a
new list object, and Tcl_ListObjReplace will insert into
listPtr. For Tcl_SetListObj, the number of Tcl objects to
insert into objPtr.
- Tcl_Obj *const objv[] (in)
- An array of pointers to objects. Tcl_NewListObj will insert these
objects into a new list object and Tcl_ListObjReplace will insert
them into an existing listPtr. Each object will become a separate
list element.
- int *intPtr (out)
- Points to location where Tcl_ListObjLength stores the length of the
list.
- int index (in)
- Index of the list element that Tcl_ListObjIndex is to return. The
first element has index 0.
- Tcl_Obj **objPtrPtr (out)
- Points to place where Tcl_ListObjIndex is to store a pointer to the
resulting list element object.
- int first (in)
- Index of the starting list element that Tcl_ListObjReplace is to
replace. The list's first element has index 0.
- int count (in)
- The number of elements that Tcl_ListObjReplace is to replace.
DESCRIPTION¶
Tcl list objects have an internal representation that supports the efficient
indexing and appending. The procedures described in this man page are used to
create, modify, index, and append to Tcl list objects from C code.
Tcl_ListObjAppendList and
Tcl_ListObjAppendElement both add one or
more objects to the end of the list object referenced by
listPtr.
Tcl_ListObjAppendList appends each element of the list object
referenced by
elemListPtr while
Tcl_ListObjAppendElement appends
the single object referenced by
objPtr. Both procedures will convert
the object referenced by
listPtr to a list object if necessary. If an
error occurs during conversion, both procedures return
TCL_ERROR and
leave an error message in the interpreter's result object if
interp is
not NULL. Similarly, if
elemListPtr does not already refer to a list
object,
Tcl_ListObjAppendList will attempt to convert it to one and if
an error occurs during conversion, will return
TCL_ERROR and leave an
error message in the interpreter's result object if interp is not NULL. Both
procedures invalidate any old string representation of
listPtr and, if
it was converted to a list object, free any old internal representation.
Similarly,
Tcl_ListObjAppendList frees any old internal representation
of
elemListPtr if it converts it to a list object. After appending each
element in
elemListPtr,
Tcl_ListObjAppendList increments the
element's reference count since
listPtr now also refers to it. For the
same reason,
Tcl_ListObjAppendElement increments
objPtr's
reference count. If no error occurs, the two procedures return
TCL_OK
after appending the objects.
Tcl_NewListObj and
Tcl_SetListObj create a new object or modify an
existing object to hold the
objc elements of the array referenced by
objv where each element is a pointer to a Tcl object. If
objc is
less than or equal to zero, they return an empty object. The new object's
string representation is left invalid. The two procedures increment the
reference counts of the elements in
objc since the list object now
refers to them. The new list object returned by
Tcl_NewListObj has
reference count zero.
Tcl_ListObjGetElements returns a count and a pointer to an array of the
elements in a list object. It returns the count by storing it in the address
objcPtr. Similarly, it returns the array pointer by storing it in the
address
objvPtr. The memory pointed to is managed by Tcl and should not
be freed or written to by the caller. If the list is empty, 0 is stored at
objcPtr and NULL at
objvPtr. If
listPtr is not already a
list object,
Tcl_ListObjGetElements will attempt to convert it to one;
if the conversion fails, it returns
TCL_ERROR and leaves an error
message in the interpreter's result object if
interp is not NULL.
Otherwise it returns
TCL_OK after storing the count and array pointer.
Tcl_ListObjLength returns the number of elements in the list object
referenced by
listPtr. It returns this count by storing an integer in
the address
intPtr. If the object is not already a list object,
Tcl_ListObjLength will attempt to convert it to one; if the conversion
fails, it returns
TCL_ERROR and leaves an error message in the
interpreter's result object if
interp is not NULL. Otherwise it returns
TCL_OK after storing the list's length.
The procedure
Tcl_ListObjIndex returns a pointer to the object at element
index in the list referenced by
listPtr. It returns this object
by storing a pointer to it in the address
objPtrPtr. If
listPtr
does not already refer to a list object,
Tcl_ListObjIndex will attempt
to convert it to one; if the conversion fails, it returns
TCL_ERROR and
leaves an error message in the interpreter's result object if
interp is
not NULL. If the index is out of range, that is,
index is negative or
greater than or equal to the number of elements in the list,
Tcl_ListObjIndex stores a NULL in
objPtrPtr and returns
TCL_OK. Otherwise it returns
TCL_OK after storing the element's
object pointer. The reference count for the list element is not incremented;
the caller must do that if it needs to retain a pointer to the element.
Tcl_ListObjReplace replaces zero or more elements of the list referenced
by
listPtr with the
objc objects in the array referenced by
objv. If
listPtr does not point to a list object,
Tcl_ListObjReplace will attempt to convert it to one; if the conversion
fails, it returns
TCL_ERROR and leaves an error message in the
interpreter's result object if
interp is not NULL. Otherwise, it
returns
TCL_OK after replacing the objects. If
objv is NULL, no
new elements are added. If the argument
first is zero or negative, it
refers to the first element. If
first is greater than or equal to the
number of elements in the list, then no elements are deleted; the new elements
are appended to the list.
count gives the number of elements to
replace. If
count is zero or negative then no elements are deleted; the
new elements are simply inserted before the one designated by
first.
Tcl_ListObjReplace invalidates
listPtr's old string
representation. The reference counts of any elements inserted from
objv
are incremented since the resulting list now refers to them. Similarly, the
reference counts for any replaced objects are decremented.
Because
Tcl_ListObjReplace combines both element insertion and deletion,
it can be used to implement a number of list operations. For example, the
following code inserts the
objc objects referenced by the array of
object pointers
objv just before the element
index of the list
referenced by
listPtr:
result = Tcl_ListObjReplace(interp, listPtr, index, 0,
objc, objv);
Similarly, the following code appends the
objc objects referenced by the
array
objv to the end of the list
listPtr:
result = Tcl_ListObjLength(interp, listPtr, &length);
if (result == TCL_OK) {
result = Tcl_ListObjReplace(interp, listPtr, length, 0,
objc, objv);
}
The
count list elements starting at
first can be deleted by simply
calling
Tcl_ListObjReplace with a NULL
objvPtr:
result = Tcl_ListObjReplace(interp, listPtr, first, count,
0, NULL);
SEE ALSO¶
Tcl_NewObj, Tcl_DecrRefCount, Tcl_IncrRefCount, Tcl_GetObjResult
KEYWORDS¶
append, index, insert, internal representation, length, list, list object, list
type, object, object type, replace, string representation