Fix typo
| author |
Steve Losh <steve@stevelosh.com> |
| date |
Mon, 27 Jul 2020 23:37:04 -0400 |
| parents |
edbdc9c9cb0a |
| children |
edf43f3bf670 |
(in-package :losh.arrays)
(declaim
(ftype (function ((array * *) t)) fill-multidimensional-array)
(ftype (function ((array t *) t)) fill-multidimensional-array-t)
(ftype (function ((array fixnum *) fixnum)) fill-multidimensional-array-fixnum)
(ftype (function ((array single-float *) single-float)) fill-multidimensional-array-single-float))
(defmacro do-array ((value array) &body body)
"Perform `body` once for each element in `array` using `value` for the place.
`array` can be multidimensional.
`value` will be `symbol-macrolet`ed to the appropriate `aref`, so you can use
it as a place if you want.
Returns the array.
Example:
(let ((arr (vector 1 2 3)))
(do-array (x arr)
(setf x (1+ x))))
=> #(2 3 4)
"
(with-gensyms (i)
(once-only (array)
`(iterate (for ,i :index-of-flat-array ,array)
(symbol-macrolet ((,value (row-major-aref ,array ,i)))
,@body)
(finally (return ,array))))))
(defun-inline fill-mda (array item)
;; from #lisp:
;;
;; <scymtym> sjl: the problem with the displaced array version is that it
;; accumulates weak pointers to displaced arrays when the arrays are created
;; and only removes them when the arrays are gced. that list is traversed each
;; time a displaced array is created. so it can get much worse with more
;; repetitions and depends on gc behavior
;;
;; <sjl> scymtym: ugh, that's an sbcl-specific thing then?
;;
;; <scymtym> sjl: probably. i don't know how other implementations handle the
;; problem. the reason for this weak pointer mechanism is that resizing the
;; displaced-to array can propagate to the displaced array which has to be
;; a pretty rare case
#+sbcl
(fill (sb-ext:array-storage-vector array) item)
#-(or sbcl)
(fill (make-array (array-total-size array)
:adjustable nil
:fill-pointer nil
:displaced-to array
:element-type (array-element-type array))
item)
array)
(defun fill-multidimensional-array (array item)
"Fill `array` with `item`.
Unlike `fill`, this works on multidimensional arrays. It won't cons on SBCL,
but it may in other implementations.
"
(fill-mda array item))
(eval-when (:compile-toplevel :load-toplevel :execute)
(defparameter *fmda-docstring*
"Fill `array` (which must be of type `(array ~A *)`) with `item`.
Unlike `fill`, this works on multidimensional arrays. It won't cons on SBCL,
but it may in other implementations.
"))
(defmacro defun-fmda (type)
`(defun ,(symb 'fill-multidimensional-array- type) (array item)
,(format nil *fmda-docstring* type)
(fill-mda array item)))
(defun-fmda t)
(defun-fmda fixnum)
(defun-fmda single-float)
(defun-inlineable bisect-left (predicate vector target &key
(key #'identity)
(start 0)
(end (length vector)))
"Bisect `vector` with `predicate` and return the LEFT element.
Only the subsequence of `vector` bounded by `start` and `end` is considered.
`vector` must be sorted (with `predicate`) before this function is called
(this is not checked).
You can think of this function as partitioning the elements into two halves:
those that satisfy `(predicate (funcall key element) target)` and those that
don't, and then selecting the element on the LEFT side of the split:
satisfying not statisfying
#(.......... ...............)
^
|
result
Two values will be returned: the element and its index. If no element
satisfies the predicate `nil` will be returned for both values.
Examples:
; index
; 0 1 2 3 4 5 val index
(bisect-left '< #(1 3 5 7 7 9) 5) ; => 3, 1
(bisect-left '<= #(1 3 5 7 7 9) 5) ; => 5, 2
(bisect-left '<= #(1 3 5 7 7 9) 7) ; => 7, 4
(bisect-left '< #(1 3 5 7 7 9) 1) ; => nil, nil
(bisect-left '> #(9 8 8 8 1 0) 5) ; => 8, 3
(bisect-left '< #((1) (2 2) (3 3 3)) 2 :key #'length) ; => (1), 0
(bisect-left '<= #((1) (2 2) (3 3 3)) 2 :key #'length) ; => (2 2), 1
"
(if (>= start end)
(values nil nil)
(iterate
(for index = (truncate (+ start end) 2))
(for value = (aref vector index))
(for result = (funcall predicate (funcall key value) target))
(if (= start index)
(return (if result
(values value index)
(values nil nil)))
(if result
(setf start index)
(setf end index))))))
(defun-inlineable bisect-right (predicate vector target &key
(key #'identity)
(start 0)
(end (length vector)))
"Bisect `vector` with `predicate` and return the RIGHT element.
Only the subsequence of `vector` bounded by `start` and `end` is considered.
`vector` must be sorted (with `predicate`) before this function is called
(this is not checked).
You can think of this function as partitioning the elements into two halves:
those that satisfy `(predicate (funcall key element) target)` and those that
don't, and then selecting the element on the RIGHT side of the split:
satisfying not statisfying
#(.......... ...............)
^
|
result
Two values will be returned: the element and its index. If every element
satisfies the predicate `nil` will be returned for both values.
Examples:
; index
; 0 1 2 3 4 5 val index
(bisect-right '< #(1 3 5 7 7 9) 5) ; => 5, 2
(bisect-right '<= #(1 3 5 7 7 9) 5) ; => 7, 3
(bisect-right '<= #(1 3 5 7 7 9) 7) ; => 9, 5
(bisect-right '< #(1 3 5 7 7 9) 10) ; => nil, nil
(bisect-right '> #(9 8 8 8 1 0) 5) ; => 1, 4
(bisect-right '< #((1) (2 2) (3 3 3)) 2 :key #'length) ; => (2 2), 1
(bisect-right '<= #((1) (2 2) (3 3 3)) 2 :key #'length) ; => (3 3 3), 2
"
(if (>= start end)
(values nil nil)
(iterate
(with bottom = (1- start))
(with top = (1- end))
(for index = (ceiling (+ bottom top) 2))
(for value = (aref vector index))
(for result = (funcall predicate (funcall key value) target))
(if (= top index)
(return (if result
(values nil nil)
(values value index)))
(if result
(setf bottom index)
(setf top index))))))
(defun vector-last (vector)
"Return the last element of `vector`, or `nil` if it is empty.
A second value is returned, which will be `t` if the vector was not empty and
`nil` if it was.
The vector's fill-pointer will be respected.
"
(let ((length (length vector)))
(if (zerop length)
(values nil nil)
(values (aref vector (1- length)) t))))