• 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
        • Icharlisteqv
        • Upcase-charlist
        • Downcase-charlist
        • Upcase-string
        • Istreqv
        • Downcase-char
        • Upcase-char
        • Ichareqv
        • Downcase-string
        • Upcase-first-charlist
        • Downcase-first-charlist
        • Downcase-first
        • Upcase-first
        • Down-alpha-p
        • Up-alpha-p
        • Upcase-char-str
        • Downcase-char-str
        • Upcase-string-list
        • Downcase-string-list
      • Concatenation
      • Html-encoding
      • Character-kinds
      • Substrings
      • Strtok
      • Equivalences
      • Url-encoding
      • Lines
      • Explode-implode-equalities
      • Ordering
      • Numbers
      • 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

• Cases

Downcase-char-str

Convert a character into a lower-case one-element string.

Signature

(downcase-char-str c) → str

Returns

str — Type (stringp str).

(downcase-char-str c) is logically equal to:

(implode (downcase-char c))

But we store these strings in a table so that they don't have to be recomputed. This is mainly useful to reduce the creation of temporary strings during downcase-first.

Definitions and Theorems

Function: make-downcase-first-strtbl

(defun make-downcase-first-strtbl (n)
  (declare (xargs :guard (and (natp n) (<= n 255))))
  (cons (cons n
              (implode (list (downcase-char (code-char n)))))
        (if (zp n)
            nil
          (make-downcase-first-strtbl (- n 1)))))

Function: downcase-char-str$inline

(defun downcase-char-str$inline (c)
  (declare (type character c))
  (let ((acl2::__function__ 'downcase-char-str))
    (declare (ignorable acl2::__function__))
    (mbe :logic (implode (list (downcase-char c)))
         :exec (aref1 '*downcase-first-strtbl*
                      *downcase-first-strtbl*
                      (char-code c)))))

Theorem: stringp-of-downcase-char-str

(defthm stringp-of-downcase-char-str
  (b* ((str (downcase-char-str$inline c)))
    (stringp str))
  :rule-classes :type-prescription)