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; Centaur Lexer 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>
(in-package "CLEX")
(include-book "linecol")
(include-book "charlist-fix")
(include-book "std/util/defaggregate" :dir :system)
(include-book "std/strings/strprefixp" :dir :system)
(include-book "std/strings/istrprefixp" :dir :system)
(include-book "std/strings/charset-fns" :dir :system)
(local (include-book "arithmetic"))
(local (defthm consp-under-iff-when-true-listp
(implies (true-listp x)
(iff (consp x)
x))))
(defaggregate strin
:parents (sin)
:short "Logical representation of the current state of a string input
stream."
((chars character-listp
"Remaining characters in the input stream. Note that you should
typically access these with @(see strin-left), instead of directly
with @(see strin->chars).")
(line posp :rule-classes :type-prescription
"Current line number, starts at 1.")
(col natp :rule-classes :type-prescription
"Current column number.")
(file stringp :rule-classes :type-prescription
"A name describing where these characters are being read from,
typically the name of some file."))
:long "<p>A @('strin-p') structure is intended as a logical fiction to
explain the behavior of the @(see sin) (\"string input\") stobj.</p>
<p>You should not typically create or operate on @('strin-p') structures.
Doing so would create a lot of garbage, and the @(see sin) stobj is generally
more efficient.</p>
<p>We generally think of the line, col, and file fields as a sort of debugging
convenience that, while practically very useful, are not necessarily anything
we want to reason about.</p>
<p>Accordingly, we generally leave all @('strin-p') operations disabled, but
prove some property about their @('chars').</p>"
:tag :strin)
(defthm strin->chars-under-iff
(implies (strin-p x)
(iff (consp (strin->chars x))
(strin->chars x))))
(define strin-left ((x strin-p))
:returns (chars character-listp)
:parents (strin-p)
:short "Remaining characters in a @(see strin-p)."
:long "<p>This is an alternative to @(see strin->chars) that @(see
charlist-fix)es the characters. This is generally preferable to using @(see
strin->chars) directly, and allows us to avoid @(see strin-p) hyps in many
theorems.</p>"
(mbe :logic (charlist-fix (strin->chars x))
:exec (strin->chars x))
///
(defthm true-listp-of-strin-left
(true-listp (strin-left x))
:rule-classes :type-prescription)
(defthm strin-left-of-make-strin
(equal (strin-left (make-strin :chars chars
:line line
:col col
:file file))
(charlist-fix chars))))
(define empty-strin ()
:parents (strin-p)
:short "Create an empty @(see strin-p) structure."
:long "<p>This is very unlikely to be useful to you. It exists only because
we need an abstract @(see strin-p) corresponding to the initial @(see
sin$c).</p>
<p>We just leave this enabled.</p>"
:enabled t
(make-strin :chars nil
:file ""
:line 1
:col 0))
(define strin-init ((contents stringp "The new contents to load into @('chars').")
(filename stringp "The new filename to use.")
(x strin-p "Completely irrelevant."))
:returns (strin "The newly reset @(see strin-p).")
:parents (sin$c-init)
:short "Reset a @(see strin-p) to contain a new string from a new file."
:long "<p>This strange operation exists only because we need a logical
version of @(see sin$c-init) to use in our abstraction. We just leave it
enabled.</p>"
(declare (ignore x))
:enabled t
(make-strin :chars (coerce contents 'list)
:file filename
:line 1
:col 0))
(define strin-endp ((x strin-p))
:parents (strin-p)
:short "Are we at the end of the input stream?"
:long "<p>We just leave this enabled.</p>"
:enabled t
(atom (strin-left x)))
(define strin-len ((x strin-p))
:parents (strin-p)
:short "How many characters are left in the input stream?"
:long "<p>We just leave this enabled.</p>"
:enabled t
(len (strin-left x)))
(define strin-car ((x strin-p))
:parents (strin-p)
:short "Peek at the first character in the input stream."
:long "<p>We just leave this enabled.</p>"
:enabled t
(car (strin-left x)))
(define strin-nth ((n natp) (x strin-p))
:parents (strin-p)
:short "Peek at the @('n')th character in the input stream."
:long "<p>We just leave this enabled.</p>"
:enabled t
(nth n (strin-left x)))
(define strin-firstn ((n natp "Number of characters to extract.")
(x strin-p "The input stream."))
:guard (<= n (strin-len x))
:parents (strin-p)
:short "Extract the first @('n') characters as a string."
:long "<p>We just leave this enabled.</p>"
:enabled t
(coerce (take n (strin-left x)) 'string))
(define strin-cdr ((x strin-p))
:returns (new-x strin-p :hyp :guard)
:parents (strin-p)
:short "Advance the input stream by 1 character."
(b* (((strin x) x)
(chars (strin-left x))
((when (atom chars))
(change-strin x :chars nil))
((cons char1 rest) chars)
((when (eql char1 #\Newline))
(change-strin x
:chars rest
:line (+ 1 x.line)
:col 0)))
(change-strin x
:chars rest
:col (+ 1 x.col)))
///
(defthm strin-left-of-strin-cdr
(equal (strin-left (strin-cdr x))
(cdr (strin-left x)))))
(define strin-nthcdr ((n natp) (x strin-p))
:returns (new-x strin-p :hyp :guard)
:parents (strin-p)
:short "Advance the input stream by @('n') characters."
(b* (((strin x) x)
(chars (strin-left x))
((mv new-chars new-line new-col)
(lc-nthcdr n chars x.line x.col)))
(change-strin x
:chars new-chars
:line new-line
:col new-col))
///
(defthm strin-left-of-strin-nthcdr
(equal (strin-left (strin-nthcdr n x))
(nthcdr n (strin-left x)))))
(define strin-matches-p ((lit stringp) (x strin-p))
:parents (strin-p)
:short "See if some string literal occurs (case sensitively) at the start of
the input stream."
:long "<p>We just leave this enabled.</p>"
:enabled t
(prefixp (coerce lit 'list) (strin-left x)))
(define strin-imatches-p ((lit stringp) (x strin-p))
:parents (strin-p)
:short "See if some string literal occurs (case insensitively) at the start
of the input stream."
:long "<p>We just leave this enabled.</p>"
:enabled t
(str::iprefixp (coerce lit 'list) (strin-left x)))
(define strin-count-charset ((set charset-p)
(x strin-p))
:parents (strin-p)
:short "Count how many characters at the start of the input stream are
members of some particular character set."
:long "<p>We just leave this enabled.</p>"
:enabled t
(count-leading-charset (strin-left x) set))
(define strin-find ((lit stringp)
(x strin-p))
:returns (pos "Starting index of the first match, or @('nil') if there are
no matches.")
:parents (strin-p)
:short "Find the first occurrence of the string literal in the input stream,
and return its position."
:long "<p>We just leave this enabled.</p>"
:enabled t
(listpos (coerce lit 'list) (strin-left x)))
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