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Syntax-abstraction

Abs-letter

Abstract a letter to an ACL2 character.

Signature
(abs-letter tree) → char
Arguments: tree — Guard (abnf::treep tree).
Returns: char — Type (character-resultp char).

Definitions and Theorems

Function: abs-letter

(defun abs-letter (tree)
  (declare (xargs :guard (abnf::treep tree)))
  (let ((__function__ 'abs-letter))
    (declare (ignorable __function__))
    (b* (((okf tree)
          (check-tree-nonleaf-1-1 tree "letter"))
         (char (abs-uppercase-letter tree))
         ((when (not (reserrp char))) char)
         (char (abs-lowercase-letter tree))
         ((when (not (reserrp char))) char))
      (reserrf (list :found-subtree (tree-info-for-error tree))))))

Theorem: character-resultp-of-abs-letter

(defthm character-resultp-of-abs-letter
  (b* ((char (abs-letter tree)))
    (character-resultp char))
  :rule-classes :rewrite)

Theorem: letter-char-p-of-abs-letter

(defthm letter-char-p-of-abs-letter
  (b* ((common-lisp::?char (abs-letter tree)))
    (implies (not (reserrp char))
             (str::letter-char-p char))))

Theorem: abs-letter-of-tree-fix-tree

(defthm abs-letter-of-tree-fix-tree
  (equal (abs-letter (abnf::tree-fix tree))
         (abs-letter tree)))

Theorem: abs-letter-tree-equiv-congruence-on-tree

(defthm abs-letter-tree-equiv-congruence-on-tree
  (implies (abnf::tree-equiv tree tree-equiv)
           (equal (abs-letter tree)
                  (abs-letter tree-equiv)))
  :rule-classes :congruence)