• Top
  • Documentation
  • Books
  • Recursion-and-induction
  • 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
      • Ordering
      • Numbers
      • Pad-trim
        • Rpadstr
        • Rpadchars
        • Lpadchars
        • Lpadstr
        • Trim-bag
        • Trim
      • Coercion
      • Std/strings-extensions
      • Std/strings/digit-to-char
      • Substitution
      • Symbols
    • Std/io
    • Std/osets
    • Std/system
    • Std/basic
    • Std/typed-lists
    • Std/bitsets
    • Std/testing
    • Std/typed-alists
    • Std/stobjs
    • Std-extensions
  • Proof-automation
  • Macro-libraries
  • ACL2
  • Interfacing-tools
  • Hardware-verification
  • Software-verification
  • Testing-utilities
  • Math

• Pad-trim

Rpadstr

Pad a string with spaces on the right.

(rpadstr x len) extends the string x to length len by adding spaces on the right. For instance,

(rpadchars "foo" 5)
   -->
"foo  "

This is completely dumb: we don't try to account for newlines, tabs, or anything like that, and just add #\Space characters until reaching the desired width.

If no new spaces are needed, x is returned unchanged and no consing or coercion is performed.

Definitions and Theorems

Function: rpadstr

(defun
 rpadstr (x len)
 (declare (xargs :guard (and (stringp x) (natp len)))
          (type string x)
          (type integer len))
 (mbe
  :logic (implode (rpadchars (explode x) len))
  :exec
  (let*
    ((x-len (length (the string x)))
     (diff (- len x-len)))
    (if (> diff 0)
        (let ((spaces (repeat diff #\Space)))
             (implode (mbe :logic (append-chars x spaces)
                           :exec (if (zp x-len)
                                     spaces
                                     (append-chars-aux x (- x-len 1)
                                                       spaces)))))
        x))))

Theorem: stringp-of-rpadstr

(defthm stringp-of-rpadstr
        (stringp (rpadstr x len))
        :rule-classes :type-prescription)

Theorem: len-of-explode-of-rpadstr

(defthm len-of-explode-of-rpadstr
        (implies (force (stringp x))
                 (equal (len (explode (rpadstr x len)))
                        (max (length x) (nfix len)))))

Theorem: streqv-implies-equal-rpadstr-1

(defthm streqv-implies-equal-rpadstr-1
        (implies (streqv x x-equiv)
                 (equal (rpadstr x len)
                        (rpadstr x-equiv len)))
        :rule-classes (:congruence))

Theorem: istreqv-implies-istreqv-rpadstr-1

(defthm istreqv-implies-istreqv-rpadstr-1
        (implies (istreqv x x-equiv)
                 (istreqv (rpadstr x len)
                          (rpadstr x-equiv len)))
        :rule-classes (:congruence))