(defun wg-find-buf-in-buf-list (buf buf-list)

  "Find BUF in BUF-LIST.

This is only here for completeness."

  (cl-find buf buf-list))

(defun wg-find-buffer-in-buffer-list (buffer-or-name buffer-list)

  "Find BUFFER-OR-NAME in BUFFER-LIST."

  (cl-find (wg-get-buffer buffer-or-name) buffer-list :key 'wg-get-buffer))

(defun wg-find-buffer-in-buf-list (buffer-or-name buf-list)

  "Find BUFFER-OR-NAME in BUF-LIST."

  (aif (wg-buffer-uid buffer-or-name)

      (wg-find-bufobj-by-uid it buf-list)

    (wg-find-bufobj buffer-or-name buf-list)))

(defun wg-find-buf-in-buffer-list (buf buffer-list)

  "Find BUF in BUFFER-LIST."

  (or (wg-find-bufobj-by-uid (wg-buf-uid buf) buffer-list)

      (wg-find-bufobj buf buffer-list)))

(defun wg-find-buf-by-uid (uid)

  "Find a buf in `wg-buf-list' by UID."

  (wg-find-bufobj-by-uid uid (wg-buf-list)))

(defun wg-set-buffer-uid-or-error (uid &optional buffer)

  "Set BUFFER's buffer local value of `wg-buffer-uid' to UID.

If BUFFER already has a buffer local value of `wg-buffer-uid',

and it's not equal to UID, error."

  (if wg-buffer-uid

      ;;(if (string= wg-buffer-uid uid) uid

      ;;  (error "uids don't match %S and %S" uid wg-buffer-uid))

      (setq wg-buffer-uid uid)))

(defun wg-buffer-special-data (buffer)

  "Return BUFFER's auxiliary serialization, or nil."

  (cl-some (lambda (fn) (funcall fn buffer)) wg-special-buffer-serdes-functions))

(defun wg-serialize-buffer-local-variables ()

  "Return an alist of buffer-local variable symbols and their values.

See `wg-buffer-local-variables-alist' for details."

  (wg-docar (entry wg-buffer-local-variables-alist)

    (wg-dbind (var ser des) entry

      (when (local-variable-p var)

        (cons var (if ser (funcall ser) (symbol-value var)))))))

(defun wg-buffer-to-buf (buffer)

  "Return the serialization (a wg-buf) of Emacs buffer BUFFER."

  (with-current-buffer buffer

    (wg-make-buf

     :name           (buffer-name)

     :file-name      (buffer-file-name)

     :point          (point)

     :mark           (mark)

     :local-vars     (wg-serialize-buffer-local-variables)

     :special-data   (wg-buffer-special-data buffer))))

(defun wg-add-buffer-to-buf-list (buffer)

  "Make a buf from BUFFER, and add it to `wg-buf-list' if necessary.

If there isn't already a buf corresponding to BUFFER in

`wg-buf-list', make one and add it.  Return BUFFER's uid

in either case."

  (with-current-buffer buffer

    (setq wg-buffer-uid

          (aif (wg-find-buffer-in-buf-list buffer (wg-buf-list))

              (wg-buf-uid it)

            (let ((buf (wg-buffer-to-buf buffer)))

              (push buf (wg-buf-list))

              (wg-buf-uid buf))))))

(defun wg-buffer-uid-or-add (buffer)

  "Return BUFFER's uid.

If there isn't already a buf corresponding to BUFFER in

`wg-buf-list', make one and add it."

  (or (wg-buffer-uid buffer) (wg-add-buffer-to-buf-list buffer)))

(defun wg-bufobj-uid-or-add (bufobj)

  "If BUFOBJ is a wg-buf, return its uid.

If BUFOBJ is a buffer or a buffer name, see `wg-buffer-uid-or-add'."

  (cl-etypecase bufobj

    (wg-buf (wg-buf-uid bufobj)) ;; possibly also add to `wg-buf-list'

    (buffer (wg-buffer-uid-or-add bufobj))

    (string (wg-bufobj-uid-or-add (wg-get-buffer bufobj)))))

(defun wg-reset-buffer (buffer)

  "Return BUFFER.

Currently only sets BUFFER's `wg-buffer-uid' to nil."

  (with-current-buffer buffer (setq wg-buffer-uid nil)))

;;; buffer-list-filter commands

(defun wg-update-buffer-in-buf-list (&optional buffer)

  "Update BUFFER's corresponding buf in `wg-buf-list'.

BUFFER nil defaults to `current-buffer'."

  (let ((buffer (or buffer (current-buffer))))

    (wg-when-let ((uid (wg-buffer-uid buffer))

                  (old-buf (wg-find-buf-by-uid uid))

                  (new-buf (wg-buffer-to-buf buffer)))

      (setf (wg-buf-uid new-buf) (wg-buf-uid old-buf))

      (wg-asetf (wg-buf-list) (cons new-buf (remove old-buf it))))))

(defun wg-update-buf-list (&optional buffer-list)

  "Update all bufs in `wg-buf-list' corresponding to buffers in BUFFER-LIST."

  (mapc 'wg-update-buffer-in-buf-list (or buffer-list (wg-buffer-list-emacs))))

(defun wg-buffer-list-display (buffer-list)

  "Return the BUFFER-LIST display string."

  (wg-display-internal

   'wg-buffer-display

   (if wg-center-rotate-buffer-list-display

       (wg-center-rotate-list buffer-list) buffer-list)))

(defun wg-buffer-list-filter-display (&optional workgroup blf-id)

  "Return a buffer-list-filter display string from WORKGROUP and BLF-ID."

  (wg-fontify

    "("

    (wg-workgroup-name (wg-get-workgroup workgroup))

    ":"

    (wg-get-buffer-list-filter-val blf-id 'indicator)

    ")"))

(defun wg-buffer-list-filter-prompt (prompt &optional workgroup blf-id)

  "Return a prompt string from PROMPT indicating WORKGROUP and BLF-ID."

  (wg-fontify

    prompt " "

    (wg-buffer-list-filter-display workgroup blf-id)

    ": "))

(defun wg-buffer-command-display (&optional buffer-list)

  "Return the buffer command display string."

  (concat

   (wg-buffer-list-filter-display) ": "

   (wg-buffer-list-display (or buffer-list (wg-filtered-buffer-list)))))

(defun wg-read-buffer (prompt &optional default require-match)

  "Workgroups' version of `read-buffer'.

Read with PROMT DEFAULT REQUIRE-MATCH."

  (if (not (wg-filter-buffer-list-p))

      (funcall (wg-read-buffer-function) prompt default require-match)

    (wg-with-buffer-list-filters 'read-buffer

      (funcall (wg-read-buffer-function)

               (wg-buffer-list-filter-prompt

                (aif (string-match ": *$" prompt)

                    (substring prompt 0 it) prompt))

               default require-match))))

;;; filtered buffer-list construction

(defun wg-get-buffer-list-filter-id-flexibly (blf-id)

  "Return a buffer-list-filter-id one way or another."

  (or blf-id wg-current-buffer-list-filter-id 'all))

(defun wg-get-buffer-list-filter-val (id key &optional noerror)

  "Return ID's KEY's value in `wg-buffer-list-filter-definitions'.

Lots of possible errors here because

`wg-buffer-list-filter-definitions' can be modified by the user."

  (let ((slot-num (cl-case key (symbol 0) (indicator 1) (constructor 2))))

    (if (not slot-num)

        (unless noerror

          (error "`%S' is not a valid buffer-list-filter definition slot" key))

      (let* ((id (wg-get-buffer-list-filter-id-flexibly id))

             (entry (assq id (wg-local-value

                              'wg-buffer-list-filter-definitions))))

        (if (not entry)

            (unless noerror

              (error "`%S' is an undefined buffer-list-filter" id))

          (or (nth slot-num entry)

              (unless noerror

                (error "Slot `%S' is undefined in `%S's definition"

                       key id))))))))

(defun wg-filtered-buffer-list (&optional names workgroup bfl-id initial)

  "Return a filtered buffer-list from NAMES, WORKGROUP, BLF-ID and INITIAL.

NAMES non-nil means return a list of buffer-names instead of buffer objects.

WORKGROUP non-nil should be any workgroup identifier accepted by

`wg-get-workgroup'.

BLF-ID non-nil should be the identifier of a defined buffer-list-filter.

It defaults to `wg-get-buffer-list-filter-val'.

INITIAL non-nil should be an initial buffer-list to filter.  It defaults to

`wg-interesting-buffers'."

  (let ((buffer-list (funcall (wg-get-buffer-list-filter-val

;;; other control structures

(defmacro wg-destructuring-dolist (spec &rest body)

  "Loop over a list.

Evaluate BODY, destructuring LIST into SPEC, then evaluate RESULT

to get a return value, defaulting to nil.  The only hitch is that

spec must end in dotted style, collecting the rest of the list

into a var, like so: (a (b c) . rest)

\(fn (SPEC LIST [RESULT]) BODY...)"

  (declare (indent 1))

  (wg-dbind (loopspec list &optional result) spec

    (let ((rest (cdr (last loopspec))))

      (wg-with-gensyms (list-sym)

        `(let ((,list-sym ,list))

           (while ,list-sym

             (wg-dbind ,loopspec ,list-sym

               ,@body

               (setq ,list-sym ,rest)))

           ,result)))))

;;; numbers

(defun wg-step-to (n m step)

  "Increment or decrement N toward M by STEP.

Return M when the difference between N and M is less than STEP."

  (cond ((= n m) n)

        ((< n m) (min (+ n step) m))

        ((> n m) (max (- n step) m))))

(defun wg-within (num lo hi &optional hi-inclusive)

  "Return t when NUM is within bounds LO and HI.

HI-INCLUSIVE non-nil means the HI bound is inclusive."

  (and (>= num lo) (if hi-inclusive (<= num hi) (< num hi))))

(defun wg-int-to-b36-one-digit (i)

  "Return a character in 0..9 or A..Z from I, and integer 0<=I<32.

Cribbed from `org-id-int-to-b36-one-digit'."

  (cond ((not (wg-within i 0 36))

         (error "%s out of range" i))

        ((< i 10) (+ ?0 i))

        ((< i 36) (+ ?A i -10))))

(defun wg-b36-to-int-one-digit (i)

  "Turn a character 0..9, A..Z, a..z into a number 0..61.

The input I may be a character, or a single-letter string.

Cribbed from `org-id-b36-to-int-one-digit'."

  (and (stringp i) (setq i (string-to-char i)))

  (cond ((and (>= i ?0) (<= i ?9)) (- i ?0))

        ((and (>= i ?A) (<= i ?Z)) (+ (- i ?A) 10))

        (t (error "Invalid b36 character"))))

(defun wg-int-to-b36 (i &optional length)

  "Return a base 36 string from I."

  (let ((base 36) b36)

    (cl-labels ((add-digit () (push (wg-int-to-b36-one-digit (mod i base)) b36)

                         (setq i (/ i base))))

      (add-digit)

      (while (> i 0) (add-digit))

      (setq b36 (cl-map 'string 'identity b36))

      (if (not length) b36

        (concat (make-string (max 0 (- length (length b36))) ?0) b36)))))

(defun wg-b36-to-int (str)

  "Convert STR, a base-36 string, into the corresponding integer.

Cribbed from `org-id-b36-to-int'."

  (let ((result 0))

    (mapc (lambda (i)

            (setq result (+ (* result 36)

                            (wg-b36-to-int-one-digit i))))

          str)

    result))

;;; lists

(defmacro wg-removef-p (item seq-place &rest keys)

  "If ITEM is a `member*' of SEQ-PLACE, remove it from SEQ-PLACE and return t.

Otherwise return nil.  KEYS can be any keywords accepted by `remove*'."

  `(> (length ,seq-place)

      (length (setf ,seq-place (cl-remove ,item ,seq-place ,@keys)))))

(defmacro wg-pushnew-p (item seq-place &rest keys)

  "If ITEM is not a `member' of SEQ-PLACE, push it to SEQ-PLACE and return t.

Otherwise return nil.  KEYS can be any keyword args accepted by `pushnew'."

  `(< (length ,seq-place)

      (length (cl-pushnew ,item ,seq-place ,@keys))))

(defun wg-take (list n)

  "Return a list of the first N elts in LIST."

  (butlast list (- (length list) n)))

(defun wg-range (start end)

  "Return a list of integers from START up to but not including END."

  (let (accum)

    (dotimes (i (- end start) (nreverse accum))

      (push (+ start i) accum))))

(defun wg-rotate-list (list &optional offset)

  "Rotate LIST by OFFSET.  Positive OFFSET rotates left, negative right."

  (when list

    (let ((split (mod (or offset 1) (length list))))

      (append (nthcdr split list) (wg-take list split)))))

(defun wg-center-rotate-list (list)

  "Rotate LIST so it's first elt is in the center.  When LIST's

length is even, the first elt is left nearer the front."

  (wg-rotate-list list (- (/ (1- (length list)) 2))))

(defun wg-insert-after (elt list index)

  "Insert ELT into LIST after INDEX."

  (let ((new-list (cl-copy-list list)))

    (push elt (cdr (nthcdr index new-list)))

    new-list))

(defun wg-insert-before (elt list index)

  "Insert ELT into LIST before INDEX."

  (if (zerop index) (cons elt list)

    (wg-insert-after elt list (1- index))))

(defun wg-move-elt (elt list index &rest keys)

  "Move ELT before INDEX in LIST.

KEYS is passed to `remove*'."

  (wg-insert-before elt (apply 'cl-remove elt list keys) index))

(defun wg-cyclic-nth (list n)

  "Return the Nth element of LIST, modded by the length of list."

  (nth (mod n (length list)) list))

(defun wg-cyclic-offset-elt (elt list n)

  "Cyclically offset ELT's position in LIST by N."

  (wg-when-let ((pos (cl-position elt list)))

    (wg-move-elt elt list (mod (+ n pos) (length list)))))

(defun wg-cyclic-nth-from-elt (elt list n &rest keys)

  "Return the elt in LIST N places cyclically from ELT.

If ELT is not present is LIST, return nil.

KEYS is passed to `position'."

  (wg-when-let ((pos (apply 'cl-position elt list keys)))

    (wg-cyclic-nth list (+ pos n))))

(defun wg-util-swap (elt1 elt2 list)

  "Return a copy of LIST with ELT1 and ELT2 swapped.

Return nil when ELT1 and ELT2 aren't both present."

  (wg-when-let ((p1 (cl-position elt1 list))

                (p2 (cl-position elt2 list)))

    (wg-move-elt elt1 (wg-move-elt elt2 list p1) p2)))

(defun wg-dups-p (list &rest keys)

  "Return non-nil when LIST contains duplicate elements.

Keywords supported: :test :key

\(fn LIST [KEYWORD VALUE]...)"

  (let ((test (or (plist-get keys :test) 'eq))

        (key (or (plist-get keys :key) 'identity)))

    (cl-loop for (elt . rest) on list

             for elt = (funcall key elt)

             when (cl-find elt rest :test test :key key) return elt)))

(defun wg-string-list-union (&optional list1 list2)

  "Return the `union' of LIST1 and LIST2, using `string=' as the test.

This only exists to get rid of duplicate lambdas in a few reductions."

  (cl-union list1 list2 :test 'string=))

;;; alists

(defun wg-make-alist (&rest kvps)

  "Return a new alist from KVPS."

  (let (alist)

    (while kvps

      (push (cons (car kvps) (cadr kvps)) alist)

      (setq kvps (cddr kvps)))

    (nreverse alist)))

(defun wg-aget (alist key &optional default)

  "Return the value of KEY in ALIST. Uses `assq'.

If PARAM is not found, return DEFAULT which defaults to nil."

  (aif (assq key alist) (cdr it) default))

(defun wg-acopy (alist)

  "Return a copy of ALIST's toplevel list structure."

  (mapcar (lambda (kvp) (cons (car kvp) (cdr kvp))) alist))

(defun wg-aput (alist key value)

  "Return a new alist from ALIST with KEY's value set to VALUE."