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; Memoize Library
; Copyright (C) 2013 Centaur Technology
;
; Contact:
; Centaur Technology Formal Verification Group
; 7600-C N. Capital of Texas Highway, Suite 300, Austin, TX 78731, USA.
; http://www.centtech.com/
;
; License: (An MIT/X11-style license)
;
; Permission is hereby granted, free of charge, to any person obtaining a
; copy of this software and associated documentation files (the "Software"),
; to deal in the Software without restriction, including without limitation
; the rights to use, copy, modify, merge, publish, distribute, sublicense,
; and/or sell copies of the Software, and to permit persons to whom the
; Software is furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in
; all copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
; DEALINGS IN THE SOFTWARE.
;
; Original author: Jared Davis <jared@centtech.com>
;
; This library is a descendant of the memoization scheme developed by Bob Boyer
; and Warren A. Hunt, Jr. which was incorporated into the HONS version of ACL2,
; sometimes called ACL2(h).
(in-package "MEMOIZE")
; A trivial but critical part of memoizing functions is knowing how many
; arguments they take and how many return values they produce.
;
; Interface:
;
; (numargs fn)
; - Tries to detect how many arguments fn takes
; - Returns NIL on failure
;
; (numvals fn)
; - Tries to detect how many return values fn has
; - Returns NIL on failure
;
; (declare-numargs fn nargs nvals)
; - Explicitly asserts that FN has NARGS arguments and NVALS return values
; - This takes precedence over the introspection code in numargs and numvals.
; - You'd better be right, for soundness.
(defparameter *numargs-table*
;; Format: function name -> (nargs . nvals)
;; - nargs and nvals are naturals, or NIL for unknown
(let ((ht (make-hash-table)))
;; Special functions that we want to make sure we pretend
;; we don't know about
(setf (gethash 'if ht) '(nil . nil))
(setf (gethash 'return-last ht) '(nil . nil))
ht))
(declaim (hash-table *numargs-table*))
(defun declare-numargs (fn nargs nvals)
(setf (gethash fn *numargs-table*)
(cons nargs nvals)))
(defun numargs (fn)
(let* ((state acl2::*the-live-state*)
(w (w state))
(pair (gethash fn *numargs-table*)))
(cond ((not (symbolp fn))
nil)
((consp pair)
;; Table takes precedence
(car pair))
;; Magic code that works for proper ACL2 functions.
((let ((formals (getprop fn 'formals t 'current-acl2-world w)))
(and (not (eq t formals))
(length formals))))
((or (not (fboundp fn))
(macro-function fn)
(special-operator-p fn))
nil)
#+Clozure
;; Magic code that works for raw Lisp functions on CCL.
((multiple-value-bind (req opt restp keys)
(ccl::function-args (symbol-function fn))
(and (null restp)
(null keys)
(integerp req)
(eql opt 0)
req)))
(t nil))))
(defun numvals (fn)
(let* ((state acl2::*the-live-state*)
(w (w state))
(pair (gethash fn *numargs-table*)))
(cond ((not (symbolp fn))
nil)
((consp pair)
;; Table takes precedence
(cdr pair))
((let ((formals (getprop fn 'formals t 'current-acl2-world w)))
;; Figures out the number of return values for ACL2 functions.
(and (not (eq t formals))
(len (stobjs-out fn w)))))
(t nil))))
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