letter-digit-uscore-chars

(in-package "STR")

(include-book "std/strings/charset" :dir :system)

(include-book "xdoc/constructors" :dir :system)

(local (include-book "std/basic/code-char-char-code-with-force" :dir :system))

(defcharset letter/digit/uscore
  (b* ((code (char-code x)))
    (or (and (<= (char-code #\A) code)
        (<= code (char-code #\Z)))
      (and (<= (char-code #\a) code)
        (<= code (char-code #\z)))
      (and (<= (char-code #\0) code)
        (<= code (char-code #\9)))
      (eql x #\_)))
  :parents (character-kinds)
  :short "Recognize ASCII letters, decimal digits, and underscores.")