| author |
Steve Losh <steve@stevelosh.com> |
| date |
Sun, 17 Jul 2016 16:49:06 +0000 |
| parents |
6c90a65137d9 |
| children |
2df541caba61 |
(in-package #:bones.utils)
(defmacro push-if-new (thing place
&environment env
&key key (test '#'eql))
"Push `thing` into the list at `place` if it's not already there.
Returns whether `thing` was actually pushed. This function is basically
`pushnew` except for the return value.
"
(multiple-value-bind (temps exprs stores store-expr access-expr)
(get-setf-expansion place env)
(declare (ignore stores store-expr))
(with-gensyms (current result)
`(let* (,@(zip temps exprs)
(,current ,access-expr)
(,result (pushnew ,thing ,place :key ,key :test ,test)))
(not (eql ,current ,result))))))
(defun invert-hash-table (hash-table)
"Jesus christ don't actually use this for anything but debugging.
Inverts the keys/values of a `hash-table`.
"
(alist-to-hash-table
(loop :for k :being :the :hash-keys :of hash-table
:using (hash-value v)
:collect (list v k))))
(defmacro repeat (n &body body)
"Repeat `body` `n` times."
`(dotimes (,(gensym) ,n)
,@body))
(defun hex (d)
(format nil "~X" d))
(defun symbolize (&rest args)
(intern (format nil "~{~A~}" args)))
(defmacro when-let ((symbol value) &body body)
"Bind `value` to `symbol` and execute `body` if the value was not `nil`."
`(let ((,symbol ,value))
(when ,symbol ,@body)))
(defmacro dis (arglist &body body)
"Disassemble the code generated for a `lambda*` with `arglist` and `body`.
It will also spew compiler notes so you can see why the garbage box isn't
doing what you think it should be doing.
"
`(->> '(lambda* ,arglist
(declare (optimize speed))
,@body)
macroexpand-1
(compile nil)
disassemble))
(defmacro recursively (bindings &body body)
"Execute body recursively, like Clojure's `loop`/`recur`.
`bindings` should contain a list of symbols and (optional) default values.
In `body`, `recur` will be bound to the function for recurring.
Example:
(defun length (some-list)
(recursively ((list some-list) (n 0))
(if (null list)
n
(recur (cdr list) (1+ n)))))
"
(flet ((extract-var (binding)
(if (atom binding) binding (first binding)))
(extract-val (binding)
(if (atom binding) nil (second binding))))
`(labels ((recur ,(mapcar #'extract-var bindings)
,@body))
(recur ,@(mapcar #'extract-val bindings)))))
(defmacro gethash-or-init (key hash-table default-form)
"Get `key`'s value in `hash-table`, initializing if necessary.
If `key` is in `hash-table`: return its value without evaluating
`default-form` at all.
If `key` is NOT in `hash-table`: evaluate `default-form` and insert it before
returning it.
"
;; TODO: think up a less shitty name for this
(once-only (key hash-table)
(with-gensyms (value found)
`(multiple-value-bind (,value ,found)
(gethash ,key ,hash-table)
(if ,found
,value
(setf (gethash ,key ,hash-table) ,default-form))))))
(defmacro aref-or-init (array index default-form)
"Get `index` in `array`, initializing if necessary.
If `index` is non-nil in `array`: return its value without evaluating
`default-form` at all.
If `index` is nil in `array`: evaluate `default-form` and set it before
returning it.
"
;; TODO: think up a less shitty name for this
(once-only (index array)
`(or (aref ,array ,index)
(setf (aref ,array ,index) ,default-form))))
(defmacro array-push (value array pointer &environment env)
"Push `value` onto `array` at `pointer`, incrementing `pointer` afterword.
Returns the index the value was pushed to.
"
(multiple-value-bind (temp-vars temp-vals stores store access)
(get-setf-expansion pointer env)
(with-gensyms (address)
`(let* (,@(mapcar #'list temp-vars temp-vals)
(,address ,access)
(,(car stores) (1+ ,address)))
(setf (aref ,array ,address) ,value)
,store
,address))))
(defmacro yolo (&body body)
`(locally
#+sbcl (declare (optimize (sb-c::insert-array-bounds-checks 0)
(speed 3)
(debug 0)
(safety 0)))
,@body))
(defun megabytes (n)
"Return the number of 64-bit words in `n` megabytes."
(* 1024 1024 1/8 n))
;;;; Queues
;;; Based on the PAIP queues (thanks, Norvig), but beefed up a little bit to add
;;; tracking of the queue size.
(declaim (inline make-queue enqueue dequeue queue-empty-p))
(defstruct (queue (:constructor make-queue%))
(contents nil :type list)
(last nil :type list)
(size 0 :type fixnum))
(defun make-queue ()
(make-queue%))
(defun queue-empty-p (q)
(zerop (queue-size q)))
(defun enqueue (item q)
(let ((cell (cons item nil)))
(setf (queue-last q)
(if (queue-empty-p q)
(setf (queue-contents q) cell)
(setf (cdr (queue-last q)) cell))))
(incf (queue-size q)))
(defun dequeue (q)
(when (zerop (decf (queue-size q)))
(setf (queue-last q) nil))
(pop (queue-contents q)))
(defun queue-append (q l)
(loop :for item :in l
:for size = (enqueue item q)
:finally (return size)))
;;;; Lookup Tables
(defmacro define-lookup
(name (key value-type default) documentation &rest entries)
"Define a lookup function.
This macro defines a function that looks up a result in a constant array.
It's useful for things where you're looking up keys that are small integers,
like opcodes.
The function should be compiled to a few ASM instructions to read from a bit
of memory in O(1) time, instead of a huge list of CMP instructions that's
O(n) on the number of possibilities.
`name` should be a symbol that will become the name of the function. It will
be munged to make a name for the constant table too, but you shouldn't mess
with that.
`key` should be a symbol that will be used as the argument for the lookup
function.
`value-type` should be the type of your results.
`default` should be a value that will be returned from your function if a key
that does not exist is requested. Note that this same `eq` value will always
be returned.
`entries` should be the list of `(key value)` entries for the table.
Note that `key`, `default`, and all the keys of `entries` must be
macroexpansion-time constants!
"
(let ((max (reduce #'max entries :key #'car))
(entries (apply #'append entries)))
(let ((table (intern (format nil "+~A-TABLE+" name))))
`(progn
(define-constant ,table
(make-array (1+ ,max)
:element-type ',value-type
:initial-contents
(list ,@(loop :for i :from 0 :to max
:collect (getf entries i default))))
:test (lambda (x y) (declare (ignore x y)) t)) ; what could go wrong
(declaim (inline ,name))
(defun ,name (,key)
,documentation
(the ,value-type (aref ,table ,key)))))))
;;;; ecase/tree
;;; See http://www.foldr.org/~michaelw/log/programming/lisp/icfp-contest-2006-vm
(defmacro ecase/tree (keyform &body cases)
(labels ((%case/tree (keyform cases)
(if (<= (length cases) 4)
`(ecase ,keyform ,@cases)
(loop for rest-cases on cases
repeat (truncate (length cases) 2)
collect (first rest-cases) into first-half
finally (return `(if (< ,keyform ,(caar rest-cases))
,(%case/tree keyform first-half)
,(%case/tree keyform rest-cases)))))))
(let (($keyform (gensym "CASE/TREE-")))
`(let ((,$keyform ,keyform))
,(%case/tree $keyform (sort (copy-list cases) #'< :key #'first))))))