vector-push; vector-push-extend

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vector-push, vector-push-extend (Function)

Syntax:

— Function: vector-push new-element vector → new-index-p

— Function: vector-push-extend new-element vector &optional extension → new-index

Arguments and Values:

new-element—an object.

vector—a vector with a fill pointer.

extension—a positive integer. The default is implementation-dependent.

new-index-p—a valid array index for vector, or nil.

new-index—a valid array index for vector.

Description:

vector-push and vector-push-extend store new-element in vector. vector-push attempts to store new-element in the element of vector designated by the fill pointer, and to increase the fill pointer by one. If the (>= (fill-pointer vector) (array-dimension vector 0)), neither vector nor its fill pointer are affected. Otherwise, the store and increment take place and vector-push returns the former value of the fill pointer which is one less than the one it leaves in vector.

vector-push-extend is just like vector-push except that if the fill pointer gets too large, vector is extended using adjust-array so that it can contain more elements. Extension is the minimum number of elements to be added to vector if it must be extended.

vector-push and vector-push-extend return the index of new-element in vector. If (>= (fill-pointer vector) (array-dimension vector 0)), vector-push returns nil.

Examples:

 (vector-push (setq fable (list 'fable))
              (setq fa (make-array 8
                                   :fill-pointer 2
                                   :initial-element 'first-one))) → 2
 (fill-pointer fa) → 3
 (eq (aref fa 2) fable) → true
 (vector-push-extend #\X
                    (setq aa
                          (make-array 5
                                      :element-type 'character
                                      :adjustable t
                                      :fill-pointer 3))) → 3
 (fill-pointer aa) → 4
 (vector-push-extend #\Y aa 4) → 4
 (array-total-size aa) → at least 5
 (vector-push-extend #\Z aa 4) → 5
 (array-total-size aa) → 9 ;(or more)

Affected By:

The value of the fill pointer.

How vector was created.

Exceptional Situations:

An error of type error is signaled by vector-push-extend if it tries to extend vector and vector is not actually adjustable.

An error of type error is signaled if vector does not have a fill pointer.