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Sin-match-until-lit

Match anything that occurs up until the first occurrence of a particular string literal.

Signature

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

Arguments

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

sin — The sin stobj.

Returns

foundp — Was lit found anywhere in the input stream?.
    Type (booleanp foundp).

match — nil when no text is matched, or a non-empty string containing the matched text.
    Type (or (stringp match) (not match)).

sin — The remainder of the input stream, with the match removed, if applicable.

Note: it is possible for match to be nil even when lit is foundp. In particular, this happens if lit occurs immediately at the start of the input stream.

Examples:

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

(sin-match-until-lit "apple" [snakeapple])
  -->
(t "snake" [apple])

(sin-match-until-lit "apple" [applesnake])
  -->
(t nil [applesnake])

Corner case: as in sin-match-lit, when lit is the empty string we always fail.

Definitions and Theorems

Function: sin-match-until-lit

(defun sin-match-until-lit (lit sin)
  (declare (xargs :stobjs (sin)))
  (declare (xargs :guard (stringp lit)))
  (let ((__function__ 'sin-match-until-lit))
    (declare (ignorable __function__))
    (b* (((when (or (mbe :logic (not (stringp lit))
                         :exec nil)
                    (equal lit "")))
          (mv nil nil sin))
         (pos (sin-find lit sin))
         ((unless pos) (mv nil nil sin))
         ((when (eql pos 0)) (mv t nil sin))
         (match1 (sin-firstn pos sin))
         (sin (sin-nthcdr pos sin)))
      (mv t match1 sin))))

Theorem: booleanp-of-sin-match-until-lit.foundp

(defthm booleanp-of-sin-match-until-lit.foundp
  (b* (((mv ?foundp ?match ?sin)
        (sin-match-until-lit lit sin)))
    (booleanp foundp))
  :rule-classes :type-prescription)

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

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

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

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

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

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

Theorem: sin-match-until-lit-progress-weak

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

Theorem: sin-match-until-lit-progress-strong

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

Theorem: sin-match-until-lit-reconstruction

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

Theorem: sin-match-until-lit-graceful-failure

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

Theorem: sin-match-until-lit-match-free-failure

(defthm sin-match-until-lit-match-free-failure
  (b* (((mv ?okp ?match ?new-sin)
        (sin-match-until-lit lit sin)))
    (implies (not okp) (not match))))