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Strprefixp

Case-sensitive string prefix test.

(strprefixp x y) determines if the string x is a prefix of the string y, in a case-sensitive manner.

Logically, this is identical to

(prefixp (explode x) (explode y))

But we use a more efficient implementation which avoids coercing the strings into character lists.

Definitions and Theorems

Function: strprefixp$inline

(defun strprefixp$inline (x y)
 (declare (type string x)
          (type string y))
 (mbe
     :logic (prefixp (explode x) (explode y))
     :exec (strprefixp-impl (the string x)
                            (the string y)
                            (the integer 0)
                            (the integer 0)
                            (the integer (length (the string x)))
                            (the integer (length (the string y))))))

Theorem: streqv-implies-equal-strprefixp-1

(defthm streqv-implies-equal-strprefixp-1
  (implies (streqv x x-equiv)
           (equal (strprefixp x y)
                  (strprefixp x-equiv y)))
  :rule-classes (:congruence))

Theorem: streqv-implies-equal-strprefixp-2

(defthm streqv-implies-equal-strprefixp-2
  (implies (streqv y y-equiv)
           (equal (strprefixp x y)
                  (strprefixp x y-equiv)))
  :rule-classes (:congruence))

Subtopics

Strprefixp-impl

Fast implementation of strprefixp.