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Escape-sequence

Escape-sequence-p

Recognizer for escape-sequence structures.

Signature
(escape-sequence-p x) → *

Definitions and Theorems

Function: escape-sequence-p

(defun escape-sequence-p (x)
  (declare (xargs :guard t))
  (let ((__function__ 'escape-sequence-p))
    (declare (ignorable __function__))
    (and (consp x)
         (cond ((or (atom x) (eq (car x) :b))
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 0)
                     (b* nil t)))
               ((eq (car x) :t)
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 0)
                     (b* nil t)))
               ((eq (car x) :n)
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 0)
                     (b* nil t)))
               ((eq (car x) :f)
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 0)
                     (b* nil t)))
               ((eq (car x) :r)
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 0)
                     (b* nil t)))
               ((eq (car x) :double-quote)
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 0)
                     (b* nil t)))
               ((eq (car x) :single-quote)
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 0)
                     (b* nil t)))
               ((eq (car x) :backslash)
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 0)
                     (b* nil t)))
               (t (and (eq (car x) :octal)
                       (and (true-listp (cdr x))
                            (eql (len (cdr x)) 1))
                       (b* ((value (std::da-nth 0 (cdr x))))
                         (acl2::ubyte8p value))))))))

Theorem: consp-when-escape-sequence-p

(defthm consp-when-escape-sequence-p
  (implies (escape-sequence-p x)
           (consp x))
  :rule-classes :compound-recognizer)