Function: byte-compile-trueconstp

byte-compile-trueconstp is a byte-compiled function defined in byte-opt.el.gz.

Signature

(byte-compile-trueconstp FORM)

Documentation

Return non-nil if FORM always evaluates to a non-nil value.

Source Code

;; Defined in /usr/src/emacs/lisp/emacs-lisp/byte-opt.el.gz
(defun byte-compile-trueconstp (form)
  "Return non-nil if FORM always evaluates to a non-nil value."
  (setq form (byte-opt--bool-value-form form))
  (cond ((consp form)
         (let ((head (car form)))
           ;; FIXME: Lots of other expressions are statically non-nil.
           (cond ((memq head '(quote function)) (cadr form))
                 ((eq head 'list) (cdr form))
                 ((memq head
                        ;; FIXME: Replace this list with a function property?
                        '( length safe-length cons lambda
                           string unibyte-string make-string concat
                           format format-message
                           substring substring-no-properties string-replace
                           replace-regexp-in-string symbol-name make-symbol
                           compare-strings string-distance
                           mapconcat
                           vector make-vector vconcat make-record record
                           regexp-quote regexp-opt
                           buffer-string buffer-substring
                           buffer-substring-no-properties
                           current-buffer buffer-size get-buffer-create
                           point point-min point-max buffer-end count-lines
                           following-char preceding-char get-byte max-char
                           region-beginning region-end
                           line-beginning-position line-end-position
                           pos-bol pos-eol
                           + - * / % 1+ 1- min max abs mod expt logb
                           logand logior logxor lognot ash logcount
                           floor ceiling round truncate
                           sqrt sin cos tan asin acos atan exp log copysign
                           ffloor fceiling fround ftruncate float
                           ldexp frexp
                           number-to-string string-to-number
                           int-to-string char-to-string
                           prin1-to-string read-from-string
                           byte-to-string string-to-vector string-to-char
                           capitalize upcase downcase
                           propertize
                           string-as-multibyte string-as-unibyte
                           string-to-multibyte string-to-unibyte
                           string-make-multibyte string-make-unibyte
                           string-width char-width
                           make-hash-table hash-table-count
                           unibyte-char-to-multibyte multibyte-char-to-unibyte
                           sxhash sxhash-equal sxhash-eq sxhash-eql
                           sxhash-equal-including-properties
                           make-marker copy-marker point-marker mark-marker
                           set-marker
                           kbd key-description
                           always))
                  t)
                 ((eq head 'if)
                  (and (byte-compile-trueconstp (nth 2 form))
                       (byte-compile-trueconstp (car (last (cdddr form))))))
                 ((memq head '(not null))
                  (byte-compile-nilconstp (cadr form)))
                 ((eq head 'or)
                  (and (cdr form)
                       (byte-compile-trueconstp (car (last (cdr form)))))))))
        ((not (symbolp form)))
        ((eq form t))
        ((keywordp form))))