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• Matching-functions

Sin-match-lit

Match exactly some particular string literal.

Signature

(sin-match-lit lit sin) → (mv match sin)

Arguments

lit — The literal string to search for.
    Guard (stringp lit).

sin — The sin stobj.

Returns

match — nil if no text was matched, or the matched text, i.e., lit itself.
    Type (or (stringp match) (not match)).

sin — The remainder of the input stream after removing the matched text, if applicable.

Examples:

(sin-match-lit "apple" [applesauce])
  -->
("apple" [sauce])

(sin-match-lit "apple" [candyapple])
  -->
(nil [candyapple])

Corner case: when lit is the empty string we always just fail. Matching the empty string would be quite degenerate, and failing in this case we can fit sin-match-lit into the ordinary matching-functions paradigm of progress, etc.

Definitions and Theorems

Function: sin-match-lit

(defun sin-match-lit (lit sin)
  (declare (xargs :stobjs (sin)))
  (declare (xargs :guard (stringp lit)))
  (let ((__function__ 'sin-match-lit))
    (declare (ignorable __function__))
    (b* (((when (or (mbe :logic (not (stringp lit))
                         :exec nil)
                    (equal lit "")))
          (mv nil sin))
         ((unless (sin-matches-p lit sin))
          (mv nil sin))
         (sin (sin-nthcdr (length lit) sin)))
      (mv lit sin))))

Theorem: return-type-of-sin-match-lit.match

(defthm return-type-of-sin-match-lit.match
  (b* (((mv ?match ?sin)
        (sin-match-lit lit sin)))
    (or (stringp match) (not match)))
  :rule-classes :type-prescription)

Theorem: stringp-of-sin-match-lit.match

(defthm stringp-of-sin-match-lit.match
  (b* (((mv ?match ?new-sin)
        (sin-match-lit lit sin)))
    (equal (stringp match)
           (if match t nil))))

Theorem: non-empty-of-sin-match-lit.match

(defthm non-empty-of-sin-match-lit.match
  (b* (((mv ?match ?new-sin)
        (sin-match-lit lit sin)))
    (equal (equal match "") nil)))

Theorem: sin-match-lit-progress-weak

(defthm sin-match-lit-progress-weak
  (b* (((mv ?match ?new-sin)
        (sin-match-lit lit sin)))
    (<= (len (strin-left new-sin))
        (len (strin-left sin))))
  :rule-classes ((:rewrite) (:linear)))

Theorem: sin-match-lit-progress-strong

(defthm sin-match-lit-progress-strong
  (b* (((mv ?match ?new-sin)
        (sin-match-lit lit sin)))
    (implies match
             (< (len (strin-left new-sin))
                (len (strin-left sin)))))
  :rule-classes ((:rewrite) (:linear)))

Theorem: sin-match-lit-reconstruction

(defthm sin-match-lit-reconstruction
  (b* (((mv ?match ?new-sin)
        (sin-match-lit lit sin)))
    (equal (append (explode match)
                   (strin-left new-sin))
           (strin-left sin))))

Theorem: sin-match-lit-graceful-failure

(defthm sin-match-lit-graceful-failure
  (b* (((mv ?match ?new-sin)
        (sin-match-lit lit sin)))
    (implies (not match)
             (equal new-sin sin))))

Theorem: sin-match-lit.match-when-ok

(defthm sin-match-lit.match-when-ok
  (b* (((mv ?match ?new-sin)
        (sin-match-lit lit sin)))
    (implies match (equal match lit))))

Theorem: equal-of-sin-match-lit-and-lit

(defthm equal-of-sin-match-lit-and-lit
  (b* (((mv ?match ?new-sin)
        (sin-match-lit lit sin)))
    (equal (equal match lit)
           (if match (and (stringp lit)
                          (consp (explode lit)))
             (not lit)))))