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• Parse-utils

Vl-maybe-match-token

Compatible with seq. Consume and return a token if it is of the given type, but if not, don't consume anything and return nil.

Signature

(vl-maybe-match-token type &key (tokstream 'tokstream)) 
  → 
(mv errmsg? token new-tokstream)

Arguments

type — Kind of token to match.
    Guard (vl-tokentype-p type).

Returns

errmsg? — Type (equal errmsg? nil).

token — Type (and (iff (vl-token-p token) (vl-is-token? type)) (iff token (vl-is-token? type))) .

Definitions and Theorems

Function: vl-maybe-match-token-fn

(defun vl-maybe-match-token-fn (type tokstream)
  (declare (xargs :stobjs (tokstream)))
  (declare (xargs :guard (vl-tokentype-p type)))
  (let ((__function__ 'vl-maybe-match-token))
    (declare (ignorable __function__))
    (b* ((tokens (vl-tokstream->tokens))
         ((when (atom tokens))
          (mv nil nil tokstream))
         (token1 (car tokens))
         ((unless (eq type (vl-token->type token1)))
          (mv nil nil tokstream))
         (tokstream (vl-tokstream-pop)))
      (mv nil token1 tokstream))))

Theorem: return-type-of-vl-maybe-match-token.errmsg?

(defthm return-type-of-vl-maybe-match-token.errmsg?
  (b* (((mv ?errmsg? ?token ?new-tokstream)
        (vl-maybe-match-token-fn type tokstream)))
    (equal errmsg? nil))
  :rule-classes :rewrite)

Theorem: return-type-of-vl-maybe-match-token.token

(defthm return-type-of-vl-maybe-match-token.token
  (b* (((mv ?errmsg? ?token ?new-tokstream)
        (vl-maybe-match-token-fn type tokstream)))
    (and (iff (vl-token-p token)
              (vl-is-token? type))
         (iff token (vl-is-token? type))))
  :rule-classes :rewrite)

Theorem: vl-maybe-match-token-fails-gracefully

(defthm vl-maybe-match-token-fails-gracefully
  (implies (not (vl-is-token? type))
           (equal (mv-nth 1 (vl-maybe-match-token type))
                  nil)))

Theorem: vl-token->type-of-vl-maybe-match-token

(defthm vl-token->type-of-vl-maybe-match-token
 (implies
      (vl-is-token? type)
      (equal (vl-token->type (mv-nth 1 (vl-maybe-match-token type)))
             type)))

Theorem: vl-maybe-match-token-count-strong-on-value

(defthm vl-maybe-match-token-count-strong-on-value
 (and
     (<= (vl-tokstream-measure
              :tokstream (mv-nth 2 (vl-maybe-match-token type)))
         (vl-tokstream-measure))
     (implies
          (mv-nth 1 (vl-maybe-match-token type))
          (< (vl-tokstream-measure
                  :tokstream (mv-nth 2 (vl-maybe-match-token type)))
             (vl-tokstream-measure))))
 :rule-classes ((:rewrite) (:linear)))