Put query code into the front of the main CODE store to run
This removes the ugly edge case of running query code. Now we just load it into
the beginning of the code store, set the program counter to 0, and let it rip.
| author |
Steve Losh <steve@stevelosh.com> |
| date |
Mon, 18 Apr 2016 18:43:12 +0000 |
| parents |
b8bc9b175636 |
| children |
b36cb61805d4 |
(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 (ht)
"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 ht
:using (hash-value v)
:collect (list v k))))
(defmacro repeat (n &body body)
"Repeat `body` `n` times."
`(dotimes (,(gensym) ,n)
,@body))
;;;; Topological Sort
;;; Adapted from the AMOP book to add some flexibility (and remove the
;;; tie-breaker functionality, which we don't need).
(defun topological-sort
(elements constraints &key (key #'identity) (key-test #'eql) (test #'equal))
"Return a topologically sorted list of `elements` given the `constraints`.
`elements` should be a sequence of elements to be sorted.
`constraints` should be a list of `(key . key)` conses where `(foo . bar)`
means element `foo` must precede `bar` in the result.
`key` will be used to turn items in `elements` into the keys in `constraints`.
`key-test` is the equality predicate for keys.
`test` is the equality predicate for (non-keyified) elements.
"
(labels
((minimal-p (element constraints)
;; An element is minimal if there are no other elements that must
;; precede it.
(not (member (funcall key element) constraints
:key #'cdr
:test key-test)))
(in-constraint (val constraint)
;; Return whether val is either part of a constraint.
(or (funcall key-test val (car constraint))
(funcall key-test val (cdr constraint))))
(recur (remaining-constraints remaining-elements result)
(let ((minimal-element
(find-if (lambda (el)
(minimal-p el remaining-constraints))
remaining-elements)))
(if (null minimal-element)
(if (null remaining-elements)
result
(error "Inconsistent constraints."))
(recur (remove (funcall key minimal-element)
remaining-constraints
:test #'in-constraint)
(remove minimal-element remaining-elements :test test)
(cons minimal-element result))))))
(reverse (recur constraints elements (list)))))