/usr/share/acl2-6.3/books/str/istrprefixp.lisp is in acl2-books-source 6.3-5.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 | ; ACL2 String Library
; Copyright (C) 2009-2013 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/
;
; This program is free software; you can redistribute it and/or modify it under
; the terms of the GNU General Public License as published by the Free Software
; Foundation; either version 2 of the License, or (at your option) any later
; version. This program is distributed in the hope that it will be useful but
; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
; FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
; more details. You should have received a copy of the GNU General Public
; License along with this program; if not, write to the Free Software
; Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA.
;
; Original author: Jared Davis <jared@centtech.com>
(in-package "STR")
(include-book "ieqv")
(include-book "iprefixp")
(local (include-book "std/lists/nthcdr" :dir :system))
(local (include-book "arithmetic"))
(local (defthm iprefixp-lemma-1
(implies (and (natp xn)
(natp yn)
(< xn (len x))
(< yn (len y))
(not (ichareqv (nth xn x) (nth yn y))))
(not (iprefixp (nthcdr xn x) (nthcdr yn y))))
:hints(("Goal" :in-theory (enable nthcdr nth iprefixp)))))
(local (defthm iprefixp-lemma-2
(implies (and (natp xn)
(natp yn)
(< xn (len x))
(< yn (len y))
(ichareqv (nth xn x) (nth yn y)))
(equal (iprefixp (nthcdr xn x) (nthcdr yn y))
(iprefixp (cdr (nthcdr xn x)) (cdr (nthcdr yn y)))))
:hints(("Goal" :in-theory (enable iprefixp nth nthcdr)))))
(defsection istrprefixp
:parents (substrings)
:short "Case-insensitive string prefix test."
:long "<p>@(call istrprefixp) determines if the string @('x') is a
case-insensitive prefix of the string @('y').</p>
<p>Logically, this is identical to</p>
@({
(iprefixp (explode x) (explode y))
})
<p>But we use a more efficient implementation which avoids coercing the strings
to lists.</p>"
(defund istrprefixp-impl (x y xn yn xl yl)
(declare (type string x)
(type string y)
(type integer xn)
(type integer yn)
(type integer xl)
(type integer yl)
(xargs :guard (and (stringp x)
(stringp y)
(natp xn)
(natp yn)
(natp xl)
(natp yl)
(= xl (length x))
(= yl (length y))
(<= xn (length x))
(<= yn (length y)))
:measure (min (nfix (- (nfix xl) (nfix xn)))
(nfix (- (nfix yl) (nfix yn))))
:guard-hints (("Goal" :in-theory (enable ichareqv)))))
(cond ((mbe :logic (zp (- (nfix xl) (nfix xn)))
:exec (int= xn xl))
t)
((mbe :logic (zp (- (nfix yl) (nfix yn)))
:exec (int= yn yl))
nil)
((ichareqv (char x xn) (char y yn))
(istrprefixp-impl x y
(+ 1 (lnfix xn))
(+ 1 (lnfix yn))
xl yl))
(t
nil)))
(definline istrprefixp (x y)
(declare (type string x)
(type string y)
(xargs :verify-guards nil))
(mbe :logic (iprefixp (explode x)
(explode y))
:exec (istrprefixp-impl (the string x)
(the string y)
(the integer 0)
(the integer 0)
(the integer (length (the string x)))
(the integer (length (the string y))))))
(defthm istrprefixp-impl-elim
(implies (and (force (stringp x))
(force (stringp y))
(force (natp xn))
(force (natp yn))
(force (= xl (length x)))
(force (= yl (length y)))
(force (<= xn xl))
(force (<= yn yl)))
(equal (istrprefixp-impl x y xn yn xl yl)
(iprefixp (nthcdr xn (coerce x 'list))
(nthcdr yn (coerce y 'list)))))
:hints(("Goal" :in-theory (enable istrprefixp-impl))))
(verify-guards istrprefixp$inline)
(defcong istreqv equal (istrprefixp x y) 1)
(defcong istreqv equal (istrprefixp x y) 2))
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