• Top
  • Documentation
  • Books
  • Boolean-reasoning
  • Projects
  • Debugging
  • Std
    • Std/lists
    • Std/alists
    • Obags
    • Std/util
    • Std/strings
      • Pretty-printing
      • Printtree
      • Base64
      • Charset-p
      • Strtok!
      • Cases
      • Concatenation
      • Html-encoding
      • Character-kinds
      • Substrings
      • Strtok
      • Equivalences
      • Url-encoding
      • Lines
      • Explode-implode-equalities
      • Ordering
      • Numbers
        • Decimal
        • Hex
          • Parse-hex-from-string
          • Hex-digit-char-p
          • Nat-to-hex-chars
          • Parse-hex-from-charlist
          • Hex-digit-chars-value
          • Hex-digit-char-value
          • Take-leading-hex-digit-chars
          • Hexify
          • Hex-digit-char-list*p
          • Hex-digit-char-listp
          • Hex-digit-string-p
            • Hex-digit-string-p-aux
          • Strval16
          • Skip-leading-hex-digits
          • Nat-to-hex-string
          • Hexify-width
          • Nonzero-hex-digit-char-p
          • Nat-to-hex-string-list
          • Revappend-nat-to-hex-chars
          • Hex-digit-to-char
          • Nat-to-hex-string-size
        • Octal
        • Binary
      • Pad-trim
      • Coercion
      • Std/strings/digit-to-char
      • Substitution
      • Symbols
    • Std/io
    • Std/osets
    • Std/basic
    • Std/system
    • Std/typed-lists
    • Std/bitsets
    • Std/testing
    • Std/typed-alists
    • Std/stobjs
  • Proof-automation
  • Macro-libraries
  • ACL2
  • Interfacing-tools
  • Hardware-verification
  • Software-verification
  • Math
  • Testing-utilities

• Hex

Hex-digit-string-p

Recognizer for strings whose characters are hexadecimal digits.

Signature

(hex-digit-string-p x) → bool

Corner case: this accepts the empty string since all of its characters are hex digits.

Logically this is defined in terms of hex-digit-char-list*p. But in the execution, we use a char-based function that avoids exploding the string. This provides much better performance, e.g., on an AMD FX-8350 with CCL:

;; 0.97 seconds, no garbage
(let ((x "deadbeef"))
  (time$ (loop for i fixnum from 1 to 10000000 do
               (str::hex-digit-string-p x))))

;; 1.74 seconds, 1.28 GB allocated
(let ((x "deadbeef"))
  (time$ (loop for i fixnum from 1 to 10000000 do
               (str::hex-digit-char-list*p (explode x)))))

Definitions and Theorems

Function: hex-digit-string-p$inline

(defun hex-digit-string-p$inline (x)
  (declare (type string x))
  (let ((acl2::__function__ 'hex-digit-string-p))
    (declare (ignorable acl2::__function__))
    (mbe :logic (hex-digit-char-list*p (explode x))
         :exec (hex-digit-string-p-aux x 0 (length x)))))

Theorem: istreqv-implies-equal-hex-digit-string-p-1

(defthm istreqv-implies-equal-hex-digit-string-p-1
  (implies (istreqv x x-equiv)
           (equal (hex-digit-string-p x)
                  (hex-digit-string-p x-equiv)))
  :rule-classes (:congruence))

Subtopics

Hex-digit-string-p-aux