manpagez: man pages & more
man ListObj(3)
Home | html | info | man
Tcl_ListObj(3)               Tcl Library Procedures               Tcl_ListObj(3)



________________________________________________________________________________


NAME

       Tcl_ListObjAppendList, Tcl_ListObjAppendElement, Tcl_NewListObj,
       Tcl_SetListObj, Tcl_ListObjGetElements, Tcl_ListObjLength,
       Tcl_ListObjIndex, Tcl_ListObjReplace - manipulate Tcl values 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, lengthPtr)

       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 a value to be a list
                                                 value, an error message is left
                                                 in the interpreter's result
                                                 value unless interp is NULL.

       Tcl_Obj *listPtr (in/out)                 Points to the list value to be
                                                 manipulated.  If listPtr does
                                                 not already point to a list
                                                 value, an attempt will be made
                                                 to convert it to one.

       Tcl_Obj *elemListPtr (in/out)             For Tcl_ListObjAppendList, this
                                                 points to a list value
                                                 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 value, an
                                                 attempt will be made to convert
                                                 it to one.

       Tcl_Obj *objPtr (in)                      For Tcl_ListObjAppendElement,
                                                 points to the Tcl value that
                                                 will be appended to listPtr.
                                                 For Tcl_SetListObj, this points
                                                 to the Tcl value that will be
                                                 converted to a list value
                                                 containing the objc elements of
                                                 the array referenced by objv.

       int *objcPtr (in)                         Points to location where
                                                 Tcl_ListObjGetElements stores
                                                 the number of element values in
                                                 listPtr.

       Tcl_Obj ***objvPtr (out)                  A location where
                                                 Tcl_ListObjGetElements stores a
                                                 pointer to an array of pointers
                                                 to the element values of
                                                 listPtr.

       int objc (in)                             The number of Tcl values that
                                                 Tcl_NewListObj will insert into
                                                 a new list value, and
                                                 Tcl_ListObjReplace will insert
                                                 into listPtr.  For
                                                 Tcl_SetListObj, the number of
                                                 Tcl values to insert into
                                                 objPtr.

       Tcl_Obj *const objv[] (in)                An array of pointers to values.
                                                 Tcl_NewListObj will insert
                                                 these values into a new list
                                                 value and Tcl_ListObjReplace
                                                 will insert them into an
                                                 existing listPtr.  Each value
                                                 will become a separate list
                                                 element.

       int *lengthPtr (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 value.

       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 values 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 values
       from C code.

       Tcl_ListObjAppendList and Tcl_ListObjAppendElement both add one or more
       values to the end of the list value referenced by listPtr.
       Tcl_ListObjAppendList appends each element of the list value referenced
       by elemListPtr while Tcl_ListObjAppendElement appends the single value
       referenced by objPtr.  Both procedures will convert the value referenced
       by listPtr to a list value if necessary.  If an error occurs during
       conversion, both procedures return TCL_ERROR and leave an error message
       in the interpreter's result value if interp is not NULL.  Similarly, if
       elemListPtr does not already refer to a list value, 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 value if interp is not NULL.  Both procedures
       invalidate any old string representation of listPtr and, if it was
       converted to a list value, free any old internal representation.
       Similarly, Tcl_ListObjAppendList frees any old internal representation of
       elemListPtr if it converts it to a list value.  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
       values.

       Tcl_NewListObj and Tcl_SetListObj create a new value or modify an
       existing value to hold the objc elements of the array referenced by objv
       where each element is a pointer to a Tcl value.  If objc is less than or
       equal to zero, they return an empty value. If objv is NULL, the resulting
       list contains 0 elements, with reserved space in an internal
       representation for objc more elements (to avoid its reallocation later).
       The new value's string representation is left invalid.  The two
       procedures increment the reference counts of the elements in objc since
       the list value now refers to them.  The new list value 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 value.  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 value, 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 value 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 value
       referenced by listPtr.  It returns this count by storing an integer in
       the address lengthPtr.  If the value is not already a list value,
       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 value 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 value at element
       index in the list referenced by listPtr.  It returns this value by
       storing a pointer to it in the address objPtrPtr.  If listPtr does not
       already refer to a list value, 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 value 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 value 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 values in the array referenced by objv.  If
       listPtr does not point to a list value, 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 value if interp is
       not NULL.  Otherwise, it returns TCL_OK after replacing the values.  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 values 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 values referenced by the array of
       value 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 values 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(3), Tcl_DecrRefCount(3), Tcl_IncrRefCount(3),
       Tcl_GetObjResult(3)


KEYWORDS

       append, index, insert, internal representation, length, list, list value,
       list type, value, value type, replace, string representation



Tcl                                    8.0                        Tcl_ListObj(3)

tcl 8.6.13 - Generated Sun Jan 8 15:30:30 CST 2023
© manpagez.com 2000-2024
Individual documents may contain additional copyright information.