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• Example-lexer

Lex-id/keyword

Match identifier characters to create an :id or :keyword token, as appropriate.

Signature

(lex-id/keyword sin) → (mv tok sin)

Arguments

sin — The sin stobj.

Returns

tok — The id/keyword token taken from the start of the input stream, or nil if the input stream does not start with some valid identifier or keyword.
    Type (equal (token-p tok) (if tok t nil)).

sin — The remaining input stream, with the leading token removed.

Definitions and Theorems

Function: lex-id/keyword

(defun lex-id/keyword (sin)
  (declare (xargs :stobjs (sin)))
  (declare (xargs :guard t))
  (let ((__function__ 'lex-id/keyword))
    (declare (ignorable __function__))
    (b* (((when (sin-endp sin)) (mv nil sin))
         (car (sin-car sin))
         ((unless (char-in-charset-p car (letter-chars)))
          (mv nil sin))
         ((mv match sin)
          (sin-match-charset* (idtail-chars) sin))
         ((when (or (equal match "void")
                    (equal match "int")
                    (equal match "float")))
          (mv (make-token :type :keyword :text match)
              sin)))
      (mv (make-token :type :id :text match)
          sin))))

Theorem: return-type-of-lex-id/keyword.tok

(defthm return-type-of-lex-id/keyword.tok
  (b* (((mv ?tok ?sin) (lex-id/keyword sin)))
    (equal (token-p tok) (if tok t nil)))
  :rule-classes :rewrite)

Theorem: lex-id/keyword-progress-weak

(defthm lex-id/keyword-progress-weak
  (mv-let (tok new-sin)
          (lex-id/keyword sin)
    (declare (ignorable tok new-sin))
    (<= (len (strin-left new-sin))
        (len (strin-left sin))))
  :rule-classes ((:rewrite) (:linear)))

Theorem: lex-id/keyword-progress-strong

(defthm lex-id/keyword-progress-strong
  (mv-let (tok new-sin)
          (lex-id/keyword sin)
    (declare (ignorable tok new-sin))
    (implies tok
             (< (len (strin-left new-sin))
                (len (strin-left sin)))))
  :rule-classes ((:rewrite) (:linear)))

Theorem: lex-id/keyword-reconstruction

(defthm lex-id/keyword-reconstruction
  (b* (((mv tok new-sin) (lex-id/keyword sin)))
    (implies tok
             (equal (append (explode (token->text tok))
                            (strin-left new-sin))
                    (strin-left sin)))))