Node:Transforming Scheme name to C name, Next:Structuring argument lists for C functions, Up:Primitives

20.1.1 Transforming Scheme name to C name

Normally, the name of a C function can be derived given its Scheme name, using some simple textual transformations:

• Replace - (hyphen) with _ (underscore).
• Replace ? (question mark) with "_p".
• Replace ! (exclamation point) with "_x".
• Replace internal -> with "_to_".
• Replace <= (less than or equal) with "_leq".
• Replace >= (greater than or equal) with "_geq".
• Replace < (less than) with "_less".
• Replace > (greater than) with "_gr".
• Replace @ with "at". [Omit?]
• Prefix with "gh_" (or "scm_" if you are ignoring the gh interface).
• [Anything else? -ttn, 2000/01/16 15:17:28]

Here is an Emacs Lisp command that prompts for a Scheme function name and inserts the corresponding C function name into the buffer.

(defun insert-scheme-to-C (name &optional use-gh)
  "Transforms Scheme NAME, a string, to its C counterpart, and inserts it.
Prefix arg non-nil means use \"gh_\" prefix, otherwise use \"scm_\" prefix."
  (interactive "sScheme name: \nP")
  (let ((transforms '(("-"  . "_")
                      ("?"  . "_p")
                      ("!"  . "_x")
                      ("->" . "_to_")
                      ("<=" . "_leq")
                      (">=" . "_geq")
                      ("<"  . "_less")
                      (">"  . "_gr")
                      ("@"  . "at"))))
    (while transforms
      (let ((trigger (concat "\\(.*\\)"
                             (regexp-quote (caar transforms))
                             "\\(.*\\)"))
            (sub (cdar transforms))
            (m nil))
        (while (setq m (string-match trigger name))
          (setq name (concat (match-string 1 name)
                             sub
                             (match-string 2 name)))))
      (setq transforms (cdr transforms))))
  (insert (if use-gh "gh_" "scm_") name))